JP7828045B2 - Bright silver-based quaternary nanostructure-containing films - Google Patents

Description

The present invention relates to the field of nanotechnology. More specifically, the present invention provides a thin, heavy-metal-free, nanostructured color conversion film that has a high photon conversion efficiency (PCE) of greater than 32% at a peak emission wavelength of 480-545 nm when excited using a blue light source having a wavelength of approximately 450 nm.

Efficient color conversion is important for lighting and display applications. In display applications, blue light sources with a wavelength of approximately 450 nm are most commonly used as backlights. Most applications require materials that are free of heavy metals such as Cd and Pb.

Improved efficiency translates into less wasted power and increased light emission. Color-converting thin films are characterized by their photon conversion efficiency (PCE), defined as the number of emitted photons divided by the number of source photons. Green heavy-metal-free QD color-converting films used in displays typically perform poorly due to limited absorption in the excited blue light. Blue absorption is often inherently limited by the material system used, resulting in the need for thicker films to adequately absorb 450 nm light.

Thin films formed by deposition of QD inks are typically cured by UV irradiation, often followed by thermal processing at 180°C for up to 1 hour in the presence of air. The photon conversion efficiency of these films is limited by a combination of poor absorption and poor photoconversion due to instability throughout these processing steps.

There remains a need in the art for Ag/In/Ga/S (AIGS) nanostructures that have high band-edge emission (BE), narrow full width at half maximum (FWHM), high quantum yield (QY), and reduced red shift, and are useful for preparing films with high (greater than 32%) photon conversion efficiencies (PCEs) at peak emission wavelengths of 480-545 nm using an excitation wavelength of approximately 450 nm.

The present invention provides a thin, heavy-metal-free, nanostructured color conversion film that exhibits a high photon conversion efficiency (PCE) of greater than 32% at a peak emission wavelength of 480-545 nm when excited using a blue light source having a wavelength of approximately 450 nm. This is achieved by using Ag/In/Ga/S (AIGS) nanostructures in an ink formulation containing one or more ligands, with all ink handling, film deposition, processing, and measurements occurring in an oxygen-free environment prior to exposure to blue or ultraviolet light. In some embodiments, the AIGS nanostructures have a FWHM of 28-38 nm. In other embodiments, the AIGS nanostructures have a FWHM of less than 32 nm. This narrow FWHM is achieved by adding at least one polyamino ligand to the AIGS nanostructures and fabricating the film layer, with all nanostructure ink handling, ink deposition, film processing, and measurements occurring in an oxygen-free environment.

Thin films formed by deposition of QD inks are typically cured by UV irradiation, often followed by thermal processing at 180°C for up to 1 hour in the presence of air. Photon conversion efficiency has been found to be reduced by insufficient absorption and photoconversion due to instabilities caused by these processing steps.

Disclosed herein are films comprising AIGS nanostructures in an ink formulation with at least one ligand that achieve a PCE of greater than (>) 32% after thermal processing. In some embodiments, films are provided that comprise AIGS nanostructures and at least one ligand and exhibit a PCE of greater than 32% at a peak emission wavelength of 480-545 nm when excited using a blue light source having a wavelength of 450 nm. The PCE is calculated by integrating the emission spectrum from 484 nm to 700 nm, with the green portion defined as 484-588 nm. In some embodiments, the film is a thin (5-15 μm) color conversion film.

These films, as prepared, have good (>95%) blue light absorption near the absorption at about 450 nm, but moderate luminescence properties. However, if the films are processed and/or encapsulated in the absence of oxygen and/or light before exposing them to UV or blue light, the luminescence properties of these films are significantly improved.

In some embodiments, the film further comprises at least one monomer incorporated into the ligand coating the AIGS surface. In some embodiments, the at least one monomer is an acrylate. In some embodiments, the monomer is at least one of ethyl acrylate, hexamethylene diacrylate (HDDA), tetrahydrofurfuryl acrylate, tri(propylene glycol) diacrylate, 1,4-bis(acryloyloxy)butane, or isobornyl acrylate.

A method for preparing an AIGS film is provided,
(a) providing an AIGS nanostructure and at least one ligand coating the nanostructure;
(b) mixing at least one organic resin with the AIGS nanostructures of (a);
(c) preparing a first film on the first barrier layer, the first film comprising mixed AIGS nanostructures, at least one ligand coating the nanostructures, and at least one organic resin;
(d) curing the film by UV irradiation and/or baking;
(e) encapsulating the first film between a first barrier layer and a second barrier layer;
The encapsulated film exhibits a photoconversion efficiency (PCE) of over 32% with a peak emission wavelength of 480-545 nm when excited using a blue light source with a wavelength of about 450 nm.

In some embodiments, the AIGS nanostructure further comprises at least one monomer incorporated into at least one ligand coating the AIGS surface.

Also,
Also provided is a method further comprising: (f) adding at least one oxygen reactive material to the mixture of AIGS nanostructures and ligands of (a), adding at least one oxygen reactive material to the mixture of (b), and/or forming a second film comprising at least one oxygen reactive material on the first film prepared in (c); and/or (g) forming a sacrificial barrier layer on the first film prepared in (c) that temporarily blocks oxygen and/or water, measuring the PCE of the film, and then removing the sacrificial barrier layer.

Also,
(a) encapsulating the film prior to thermal processing and/or measurement;
Methods are also provided that include (b) the use of an oxygen reactive material as part of the formulation during thermal processing or exposure, and/or (c) the temporary blocking of oxygen by the use of a sacrificial barrier layer.

In some embodiments, the nanostructures have an emission spectrum with a FWHM of less than 40 nm. In some embodiments, the nanostructures have an emission spectrum with a FWHM of 24-38 nm. In some embodiments, the nanostructures have an emission spectrum with a FWHM of 27-32 nm. In some embodiments, the nanostructures have an emission spectrum with a FWHM of 29-31 nm.

In some embodiments, the nanostructures have a QY of 80-99.9%. In some embodiments, the nanostructures have a QY of 85-95%. In some embodiments, the nanostructures have a QY of about 86-94%. In some embodiments, the nanostructures have an OD ₄₅₀ /mass (mL ^. mg ^{−1 .} cm ⁻¹ ) of 0.8 or greater, where OD is optical density. In some embodiments, the nanostructures have an OD ₄₅₀ /mass (mL ^. mg ^{−1 .} cm ⁻¹ ) ranging from 0.8 to 2.5, inclusive. In some embodiments, the nanostructures have an OD ₄₅₀ /mass (mL ^. mg ^{−1 .} cm ⁻¹ ) ranging from 0.87 to 1.9, inclusive. In some embodiments, the nanostructures have an average diameter of less than 10 nm by transmission electron microscopy (TEM). In some embodiments, the average diameter is about 5 nm.

In some embodiments, at least about 80% of the emission is band-edge emission. In some embodiments, at least about 90% of the emission is band-edge emission. In some embodiments, 92-98% of the emission is band-edge emission. In some embodiments, 93-96% of the emission is band-edge emission.

In some embodiments, the AIGS nanostructures have a peak emission wavelength (PWL) of about 450 nm.

In some embodiments, the AIGS nanostructure comprises a gradient from increased gallium from the surface of the nanostructure to decreased gallium in the center of the nanostructure.

In some embodiments, at least one ligand is an amino ligand, a polyamino ligand, a ligand containing a mercapto group, or a ligand containing a silane group. It has been unexpectedly discovered that the use of a polyamino ligand results in AIGS-containing films having a FWHM greater than 32 nm.

In some embodiments, the at least one polyamino ligand is a polyaminoalkane, polyaminocycloalkane, polyaminoheterocycle, polyamino-functionalized silicone, or polyamino-substituted ethylene glycol. In some embodiments, the polyamino ligand is a C _2-20 alkane or C _2-20 cycloalkane substituted with two or three amino groups, optionally containing one or two amino groups in place of a carbon group. In some embodiments, the polyamino-ligand is 1,3-cyclohexanebis(methylamine), 2,2-dimethyl-1,3-propanediamine, or tris(2-aminoethyl)amine.

In some embodiments, the ligand is a compound of Formula I:
During the ceremony,
x is 1 to 100;
y is 0 to 100;
^R2 is C _1-20 alkyl.

In some embodiments, x=19, y=3, and R ² =—CH ₃ .

In some embodiments, at least one ligand is (3-aminopropyl)trimethoxysilane, (3-mercaptopropyl)triethoxysilane, DL-α-lipoic acid, 3,6-dioxa-1,8-octanedithiol, 6-mercapto-1-hexanol, methoxypolyethylene glycolamine (approximately m.w. 500), poly(ethylene glycol) methyl ether thiol (approximately m.w. 800), diethylphenylphosphonite, dibenzyl N,N-diisopropyl phosphoramidite, di-tert-butyl N,N-diisopropyl phosphoramidite, tris(2-carboxyethyl)phosphine hydrochloride, poly(ethylene glycol) methyl ether thiol (approximately m.w. 2000), methoxypolyethylene glycolamine (approximately m.w. 750), acrylamide, or polyethyleneimine. The m.w. of the polymer is determined by mass spectrometry.

In some embodiments, at least one ligand is a combination of amino-polyalkylene oxide (about m.w. 1000) and methoxypolyethylene glycol amine (about m.w. 500), amino-polyalkylene oxide (about m.w. 1000) and 6-mercapto-1-hexanol, amino-polyalkylene oxide (about m.w. 1000) and (3-mercaptopropyl)triethoxysilane, and 6-mercapto-1-hexanol and methoxypolyethylene glycol amine (about m.w. 500).

In some embodiments, the AIGS nanostructure further comprises at least one monomer incorporated into at least one ligand coating the AIGS surface.

Also,
A nanostructure composition is provided that includes: (a) AIGS nanostructures that exhibit a PCE greater than 32%, and (b) at least one organic resin.

In some embodiments, at least one organic resin is cured.

Also provided is a method for preparing the nanostructure composition described herein, comprising:
(a) providing an AIGS nanostructure and at least one ligand coating the nanostructure;
(b) mixing at least one organic resin with the nanostructures of (a);
(c) preparing a first film on the first barrier layer, the first film comprising mixed AIGS nanostructures, at least one ligand coating the nanostructures, and at least one organic resin;
(d) curing the film by UV irradiation and/or baking;
(e) encapsulating the first film between a first barrier layer and a second barrier layer;
The encapsulated film exhibits a photoconversion efficiency (PCE) of over 32% with a peak emission wavelength of 480-545 nm when excited using a blue light source with a wavelength of about 450 nm.

In some embodiments, the nanostructure of (a) further comprises at least one monomer incorporated into the ligand coating the AIGS surface. In some embodiments, the at least one monomer is an acrylate. In some embodiments, the monomer is at least one of ethyl acrylate, HDDA, tetrahydrofurfuryl acrylate, tri(propylene glycol) diacrylate, 1,4-bis(acryloyloxy)butane, or isobornyl acrylate.

In some embodiments, the method is performed before the encapsulated film is exposed to air for measurement of the emission spectrum of the AIGS nanostructures. In some embodiments, the method is performed under an inert atmosphere.

In some embodiments, the method comprises:
(f) adding at least one oxygen-reactive material into the mixture of the AIGS nanostructures and the ligands of (a);
(g) adding at least one oxygen-reactive material to the mixture of (b); and/or (h) forming a second film comprising at least one oxygen-reactive material on the first film prepared in (c); and/or (i) forming a sacrificial barrier layer that temporarily blocks oxygen and/or water on the first film prepared in (c), measuring the PCE of the film, and then removing the sacrificial barrier layer.

In some embodiments, the two barrier layers exclude oxygen and/or water.

In some embodiments, 92-98% of the emission is band-edge emission. In some embodiments, 93-96% of the emission is band-edge emission.

Also provided is a method for preparing a composition, comprising:
(a) providing an AIGS nanostructure and at least one ligand coating the nanostructure surface;
(b) combining the composition obtained in (a) with at least one second ligand.

In some embodiments, the composition in (a) further comprises an organic resin. In some embodiments, the composition in (a) further comprises at least one monomer incorporated into the ligand that coats the AIGS surface. In some embodiments, the method further comprises inkjet printing the composition.

In some embodiments, the method further comprises preparing a film comprising the composition obtained in (b). In some embodiments, the method further comprises curing the film. In some embodiments, the film is cured by heating. In some embodiments, the film is cured by exposure to electromagnetic radiation.

A device including the above film is also provided.

Also,
(a) a first conductive layer;
(b) a second conductive layer;
(c) a film comprising an AIGS nanostructure layer between a first conductive layer and a second conductive layer;
The nanostructured layer comprises AIGS nanostructures with a PCE of greater than 32%.

Also,
a backplane;
a display panel disposed on the backplane;
and a film comprising an AIGS nanostructure layer comprising AIGS nanostructures having a PCE greater than 32%, the nanostructure layer being disposed on a display panel.

In some embodiments, the nanostructured layer comprises a patterned nanostructured layer. In some embodiments, the backplane comprises an LED, LCD, OLED, or microLED.

Further features and advantages of the present invention, as well as the structure and operation of various embodiments of the present invention, are described in detail below with reference to the accompanying drawings. It should be noted that the present invention is not limited to the specific embodiments described herein. Such embodiments are presented herein for illustrative purposes only. Additional embodiments will be apparent to one skilled in the art(s) based on the teachings contained herein.

The accompanying drawings, which are incorporated in and form a part of this specification, illustrate the present embodiments and, together with the specification, further serve to explain the principles of the present embodiments and to enable one of ordinary skill in the art to make and use the present embodiments.

From left to right, the first and third films, which did not contain polyamino ligands, showed stretch wrinkles, while the second and fourth films, which contained polyamino ligands, did not show wrinkles. AC are TEM images showing the AIGS nanostructure before ion-exchange treatment (A), after one ion-exchange treatment (B), and after two ion-exchange treatments (C). 1A is a schematic diagram of an unencapsulated film (A) and an encapsulated film (B). 1A is a schematic diagram of an unencapsulated film (A) and an encapsulated film (B). FIG. 1 is a scatter plot showing the QY% exhibited by mixtures of different ligands. FIG. 1 is a scatter plot showing ligand combinations that provide improved QY% (good combinations) and combinations that provide reduced QY% (poor combinations). 1 is a graph showing the QY% of various ligand combinations before ligand exchange (NG), after ligand exchange (LE), and after a 30 minute thermal test. 1 is a graph showing the QY% of various ligand combinations at various ligand ratios. 1 shows two scatter plots showing the PCE of AIGS films with normal post-bake (PoB) measurements (left graph) and encapsulation before PCE measurements (right graph). 1 shows two scatter plots showing the PCE of AIGS films baked at 180° C. without (left graph) and with (right graph) encapsulation before PCE measurement. 1 is a bar graph showing the photoluminescence quantum yield (PLQY) of ligand-exchanged AIGS nanostructures in various solvents at room temperature and 80° C. 1 is a bar graph showing the QY of ligand-exchanged AIGS nanostructures in the presence of various monomers. 1 is a line graph showing the film external quantum efficiency (EQE) of AIGS nanostructures after being ligand exchanged, treated with various monomers, and UV cured. 1 is a bar graph showing blue light absorption of AIGS nanostructure inks that have been ligand exchanged and treated with various monomers and spin coated at 800 rpm. 1 is a line graph showing the effect of diamine (1,3-bis(aminomethyl)cyclohexane) on film EQE after UV and post-bake (POB) at 180° C. for 30 minutes. 1 is a line graph showing the effect of added diamine on viscosity, where viscosity was measured indirectly as blue light absorption in the film after spin coating at 800 RPM. 1 is a bar graph showing the effect of ligand exchange (LE) with diamine (DA) on solution QY. The graph shows that the decrease in QY after heating at 180° C. decreased with increasing amounts of diamine. 1 is a line graph showing the effect of increasing amounts of DA on film PCE after UV curing. 1 is a line graph showing the effect on film blue light absorption of increasing amounts of DA in the film. 1 is a line graph showing the effect of added DA in the monomer dispersion, in LE, and in both the monomer dispersion and LE on the blue light absorption of PCE films. 1 is a line graph showing the effect of added DA on film viscosity and blue light absorption in monomer dispersion, in LE, and in both monomer dispersion and LE. 1 is a line graph showing the effect of various additives on initial film EQE. 1 is a line graph showing the effect of various additives on film EQE after POB. 1 is a line graph showing the effect of additional additives on film EQE and blue light absorption.

The features and advantages of the present invention will become more apparent from the detailed description set forth below when considered in conjunction with the drawings in which like reference characters identify corresponding elements throughout. In the drawings, like reference numbers generally indicate identical, functionally similar, and/or structurally similar elements. The drawing in which an element first appears is indicated by the left-most digit(s) of the corresponding reference number. Unless otherwise indicated, the drawings provided throughout this disclosure should not be construed as drawings to scale.

Definitions Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this invention belongs. The following definitions supplement definitions in the art and are directed to this application and should not be attributed to any related or unrelated cases, such as any co-owned patents or applications. Although any methods and materials similar or equivalent to those described herein can be used in the practice of testing the present invention, preferred materials and methods are described herein. Therefore, the terminology used herein is intended only to describe specific embodiments and is not intended to be limiting.

As used in this specification and the appended claims, the singular forms "a," "an," and "the" include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to a "nanostructure" includes a plurality of such nanostructures, and so forth.

As used herein, the term "about" indicates that a given quantity value varies by +/- 10% of that value. For example, "about 100 nm" encompasses a size range of 90 nm to 110 nm (inclusive).

A "nanostructure" is a structure having at least one region or characteristic dimension having a dimension of less than about 500 nm. In some embodiments, a nanostructure has a dimension of less than about 200 nm, less than about 100 nm, less than about 50 nm, less than about 20 nm, or less than about 10 nm. Typically, the region or characteristic dimension is along the smallest axis of the structure. Examples of such structures include nanowires, nanorods, nanotubes, branched nanostructures, nanotetrapods, tripods, bipods, nanocrystals, nanodots, quantum dots, nanoparticles, and the like. Nanostructures can be, for example, substantially crystalline, substantially monocrystalline, polycrystalline, amorphous, or combinations thereof. In some embodiments, each of the three dimensions of a nanostructure has a dimension of less than about 500 nm, less than about 200 nm, less than about 100 nm, less than about 50 nm, less than about 20 nm, or less than about 10 nm.

The term "heterostructure," when used with reference to a nanostructure, refers to a nanostructure characterized by at least two different and/or distinguishable material types. Typically, one region of the nanostructure comprises a first material type and a second region of the nanostructure comprises a second material type. In certain embodiments, the nanostructure comprises a core of a first material and at least one shell of a second (or third, etc.) material, where the different material types are distributed radially, e.g., about the long axis of a nanowire, the long axis of an arm of a branched nanowire, or the center of a nanocrystal. The shell can, but need not, completely cover the adjacent material to be considered a shell or for the nanostructure to be considered a heterostructure; for example, a nanocrystal characterized by a core of one material coated with islands of a second material is a heterostructure. In other embodiments, the different material types are distributed at different locations within the nanostructure, e.g., along the major (long) axis of a nanowire or along the long axis of an arm of a branched nanowire. Different regions within a heterostructure can include entirely different materials, or different regions can include a base material (e.g., silicon) with different dopants or different concentrations of the same dopant.

As used herein, the "diameter" of a nanostructure refers to the diameter of a cross section perpendicular to a first axis of the nanostructure, the first axis having the greatest difference in length relative to the second and third axes (the second and third axes being two axes whose lengths are approximately equal to one another). The first axis is not necessarily the longest axis of the nanostructure; for example, for a disk-shaped nanostructure, the cross section is a substantially circular cross section perpendicular to the short longitudinal axis of the disk. If the cross section is not circular, the diameter is the average of the long and short axes of the cross section. For elongated or high-aspect ratio nanostructures, such as nanowires, the diameter is measured across a cross section perpendicular to the longest axis of the nanowire. For spherical nanostructures, the diameter is measured from one side to the other through the center of the sphere.

The terms "crystalline" or "substantially crystalline," when used with respect to nanostructures, refer to the fact that the nanostructure typically exhibits long-range ordering across one or more dimensions of the structure. It will be understood by those skilled in the art that the term "long-range ordering" depends on the absolute size of a particular nanostructure, as the ordering of a single crystal cannot extend beyond the boundaries of the crystal. In this case, "long-range ordering" refers to substantial order across at least most of the dimensions of the nanostructure. In some instances, the nanostructure may have an oxide or other coating, or may consist of a core and at least one shell. In such cases, it will be understood that the oxide, shell(s), or other coating can, but need not, exhibit such ordering (e.g., it may be amorphous, polycrystalline, or otherwise). In such cases, the phrases "crystalline," "substantially crystalline," "substantially monocrystalline," or "monocrystalline" refer to the central core of the nanostructure (excluding any coating layers or shells). As used herein, the terms "crystalline" or "substantially crystalline" are intended to encompass structures containing various defects, stacking faults, atomic substitutions, and the like, so long as the structure exhibits substantial long-range ordering (e.g., order over at least about 80% of the length of at least one axis of the nanostructure or its core). In addition, it will be understood that the interface between the core and the exterior of the nanostructure, or between the core and an adjacent shell, or between a shell and a second adjacent shell, may contain non-crystalline regions or may even be amorphous. This does not prevent the nanostructure from being crystalline or substantially crystalline as defined herein.

The term "single crystal," when used with respect to a nanostructure, indicates that the nanostructure is substantially crystalline and comprises substantially a single crystal. When used with respect to a nanostructure heterostructure comprising a core and one or more shells, "single crystal" indicates that the core is substantially crystalline and comprises substantially a single crystal.

A "nanocrystal" is a nanostructure that is substantially monocrystalline. Thus, a nanocrystal has at least one region or characteristic dimension having a dimension of less than about 500 nm. In some embodiments, a nanocrystal has a dimension of less than about 200 nm, less than about 100 nm, less than about 50 nm, less than about 20 nm, or less than about 10 nm. The term "nanocrystal" is intended to encompass substantially monocrystalline nanostructures that contain various defects, stacking faults, atomic substitutions, etc., as well as substantially monocrystalline nanostructures that are free of such defects, imperfections, or substitutions. In the case of nanocrystal heterostructures comprising a core and one or more shells, the core of the nanocrystal is typically substantially monocrystalline, but the shell(s) need not be. In some embodiments, each of the three dimensions of the nanocrystal has a dimension of less than about 500 nm, less than about 200 nm, less than about 100 nm, less than about 50 nm, less than about 20 nm, or less than about 10 nm.

The term "quantum dot" (or "dot") refers to a nanocrystal that exhibits quantum or exciton confinement. Quantum dots can be substantially homogeneous in material properties or, in certain embodiments, can be heterogeneous, e.g., comprising a core and at least one shell. The optical properties of quantum dots can be affected by their particle size, chemical composition, and/or surface composition and can be determined by suitable optical tests available in the art. The ability to tune nanocrystal size, e.g., in the range of about 1 nm to about 15 nm, allows for a range of photoemission across the optical spectrum, providing great versatility in color rendering.

The term "oxygen-free ligand" as used herein refers to a coordination molecule that does not contain an oxygen atom capable of coordinating to or reacting with a metal ion.

A "ligand" is a molecule that can interact (weakly or strongly) with one or more faces of a nanostructure, for example, through covalent, ionic, van der Waals, or other molecular interactions with the surface of the nanostructure.

"Photoluminescence quantum yield" (QY) is the ratio of photons emitted to photons absorbed, for example, by a nanostructure or ensemble of nanostructures. As known in the art, quantum yield is typically determined by the absolute change in photon count upon illuminating a sample in an integrating sphere, or by comparative methods using well-characterized standard samples with known quantum yield values.

"Peak emission wavelength" (PWL) is the wavelength at which the radiometric emission spectrum of a light source reaches its maximum value.

As used herein, the term "full width at half maximum" (FWHM) is a measure of the size distribution of nanostructures. The emission spectrum of nanostructures generally has the shape of a Gaussian curve. The width of the Gaussian curve, defined as the FWHM, gives an idea of the particle size distribution. A smaller FWHM corresponds to a narrower nanostructure nanocrystal size distribution. The FWHM also depends on the maximum emission wavelength.

Band-edge emission is centered at higher energies (lower wavelengths) and has a smaller offset from the absorption onset energy compared to the corresponding defect emission. In addition, band-edge emission has a narrower wavelength distribution compared to defect emission. Both band-edge and defect emission follow a regular (nearly Gaussian) wavelength distribution.

Optical density (OD) is a method commonly used to quantify the concentration of solutes or nanoparticles. According to Beer-Lambert's law, the absorbance (also known as "extinction") of a particular sample is proportional to the concentration of the solute that absorbs a particular wavelength of light.

Optical density is the light attenuation per centimeter of material, typically measured using a standard spectrometer specified for a 1 cm path length. Nanostructure solutions are often measured by their optical density instead of mass or molar concentration because optical density is directly proportional to concentration and is a more convenient way to express the amount of optical absorption occurring within a nanostructure solution at the wavelength of interest. A nanostructure solution with an OD of 100 is 100 times more concentrated (has 100 times more particles per mL) than a product with an OD of 1.

Optical density can be measured at any wavelength of interest, such as a wavelength selected to excite fluorescent nanostructures. Optical density is a measure of the intensity lost when light at a particular wavelength passes through a solution of nanostructures.
OD= _log10 *( _IOUT / _IIN )
is calculated using the formula:
_IOUT = intensity of radiation entering the cell;
I _IN =Intensity of radiation transmitted through the cell.

The optical density of a nanostructure solution can be measured using a UV-VIS spectrometer. Therefore, by using a UV-VIS spectrometer, it is possible to calculate the optical density and determine the amount of nanostructures present in a sample.

Unless expressly indicated otherwise, ranges set forth herein are inclusive.

Various additional terms are defined or characterized herein.

AIGS Nanostructures Nanostructures comprising Ag, In, Ga, and S are provided, having a peak emission wavelength (PWL) between 480 and 545 nm. In some embodiments, at least about 80% of the emission is band-edge emission. The percentage of band-edge emission is calculated by fitting Gaussian peaks (typically two or more) of the nanostructure emission spectrum and comparing the area of the peak closer in energy to the nanostructure band gap (representing the band-edge emission) to the sum of all peak areas (band-edge plus defect emission).

In one embodiment, the nanostructures have an FWHM emission spectrum of less than 40 nm. In another embodiment, the nanostructures have an FWHM of 36-38 nm. In some embodiments, the nanostructures have an emission spectrum with an FWHM of 27-32 nm. In some embodiments, the nanostructures have an emission spectrum with an FWHM of 29-31 nm.

In another embodiment, the nanostructures have a QY of about 80% to 99.9%. In another embodiment, the nanostructures have a QY of 85-95%. In another embodiment, the nanostructures have a QY of about 86% to about 94%. In some embodiments, at least 80% of the emission is band-edge emission. In other embodiments, at least 90% of the emission is band-edge emission. In other embodiments, at least 95% of the emission is band-edge emission. In some embodiments, 92-98% of the emission is band-edge emission. In some embodiments, 93-96% of the emission is band-edge emission.

AIGS nanostructures provide high blue light absorption. As an estimate of blue light absorption efficiency, optical density at 450 nm per mass (OD ₄₅₀ /mass) is calculated by measuring the optical density of a solution of nanostructures in a 1 cm pathlength cuvette and dividing by the dry mass per mL (mg/mL) of the same solution after removing all volatiles under vacuum (<200 mTorr). In one embodiment, the nanostructures provided herein have an OD ₄₅₀ /mass (mL ^. mg ^{-1 .} cm ^-1 ) of at least 0.8. In another embodiment, the nanostructures have an OD ₄₅₀ /mass (mL ^. mg ^{-1 .} cm ^-1 ) of 0.8 to 2.5. In another embodiment, the nanostructures have an OD ₄₅₀ /mass (mL ^. mg ^{-1 .} cm ^-1 ) of 0.87 to 1.9.

In one embodiment, the nanostructure is treated with gallium ions to cause ion exchange of gallium with indium throughout the AIGS nanostructure. In another embodiment, the nanostructure has Ag, In, Ga, and S in the core and is treated by ion exchange with gallium ions and S. In another embodiment, the nanostructure has Ag, In, Ga, and S in the core and is treated by ion exchange with silver ions, gallium ions, and S. In some embodiments, the ion exchange treatment results in a gradient of gallium, silver, and/or sulfur throughout the nanostructure.

In one embodiment, the nanostructures have an average diameter of less than 10 nm as measured by TEM. In another embodiment, the average diameter is about 5 nm.

AIGS Nanostructures Prepared Using _GaX3 (X = F, Cl, or Br) Precursors and Oxygen-Free Ligands. Literature reports of AIGS preparation have not attempted to eliminate oxygen-containing ligands. In coating AIGS with gallium, oxygen-containing ligands are often used to stabilize the Ga precursor. Gallium(III) acetylacetonate is typically used as a precursor that is easily air-processed, while Ga(III) chloride requires careful handling due to its moisture sensitivity. For example, as described in Kameyama et al., ACS Appl. Mater. Interfaces 10:42844-42855 (2018), gallium(III) acetylacetonate was used as a precursor for core and core/shell structures. Gallium has a high affinity for oxygen, so oxygen-containing ligands using gallium precursors not prepared under oxygen-free conditions can result in undesirable side reactions, such as gallium oxide, when Ga and S precursors are used to produce nanostructures containing significant gallium content. These side reactions can lead to defects in the nanostructures and result in low quantum yields.

In some embodiments, AIGS nanostructures are prepared using oxygen-free _GaX3 (X = F, Cl, or Br) as a precursor in the preparation of the AIGS core. In some embodiments, AIGS nanostructures are prepared using _GaX3 (X = F, Cl, or Br) as a precursor and oxygen-free ligands in the preparation of Ga-enriched AIGS nanostructures. In some embodiments, AIGS nanostructures are prepared using _GaX3 (X = F, Cl, or Br) as a precursor and oxygen-free ligands in the preparation of the AIGS core. In some embodiments, AIGS nanostructures are prepared using _GaX3 (X = F, Cl, or Br) as a precursor and oxygen-free ligands in the preparation of the AIGS core and the ion-exchange treatment of the AIGS core.

Nanostructures comprising Ag, In, Ga, and S are provided, having a peak emission wavelength (PWL) of 480-545 nm, and prepared using GaX ₃ (X=F, Cl, or Br) precursors and oxygen-free ligands.

In some embodiments, nanostructures prepared using GaX ₃ (X=F, Cl, or Br) precursors and oxygen-free ligands exhibit a FWHM emission spectrum of 35 nm or less. In some embodiments, nanostructures prepared using GaX ₃ (X=F, Cl, or Br) precursors and oxygen-free ligands exhibit a FWHM of 30-38 nm. In some embodiments, nanostructures prepared using GaX ₃ (X=F, Cl, or Br) precursors and oxygen-free ligands have a QY of at least 75%. In some embodiments, nanostructures prepared using GaX ₃ (X=F, Cl, or Br) precursors and oxygen-free ligands have a QY of 75-90%. In some embodiments, nanostructures prepared using GaX ₃ (X=F, Cl, or Br) precursors and oxygen-free ligands have a QY of about 80%.

The AIGS nanostructures prepared herein provide high blue light absorption. In some embodiments, the nanostructures have an OD ₄₅₀ /mass (mL mg ⁻¹ cm ⁻¹ ) of at least 0.8. In some embodiments, the nanostructures have an OD ₄₅₀ /mass (mL ^{mg −1} cm ⁻¹ ) of 0.8 to 2.5. In other embodiments, the nanostructures have an OD ₄₅₀ /mass (mL ^{mg −1} cm ⁻¹ ) of 0.87 to 1.9.

In some embodiments, the nanostructures are treated with gallium ions to cause ion-exchange of gallium with indium throughout the AIGS nanostructure. In some embodiments, the nanostructures comprise Ag, In, Ga, and S in the core, with a gallium gradient between the surface and center of the nanostructure. In some embodiments, the nanostructures are AGS-treated AIGS cores prepared using _GaX3 (X = F, Cl, or Br) precursors and oxygen-free ligands in the core. In some embodiments, the nanostructures are AIGS nanostructures prepared using _GaX3 (X = F, Cl, or Br) precursors and oxygen-free ligands. In some embodiments, the AIGS nanostructures are prepared by reacting a preformed In-Ga reagent with an _Ag2S nanostructure to obtain an AIGS nanostructure, followed by ion-exchange with gallium by reaction with an oxygen-free Ga salt to form the AIGS nanostructure.

Method for Making AIGS Nanostructures A method for making AIGS nanostructures is provided, comprising:
(a) preparing a mixture comprising an AIGS core, a sulfur source, and a ligand;
(b) adding the mixture obtained in (a) to a mixture of gallium carboxylate and ligand at a temperature of 180-300°C to obtain ion-exchanged nanostructures having a gallium gradient from the surface to the center of the nanostructures;
(c) isolating the nanostructures.

In some embodiments, the nanostructures have a PWL between 480 and 545 nm, with at least about 60% of the emission being band-edge emission.

Also provided is a method for making an AIGS nanostructure,
(a) reacting Ga(acetylacetonate) ₃ , InCl ₃ , and a ligand, optionally in a solvent, at a temperature sufficient to obtain an In—Ga reagent;
(b) reacting an In—Ga reagent with the Ag ₂ S nanostructures at a temperature sufficient to produce AIGS nanostructures;
(c) reacting the AIGS nanostructure with an oxygen-free Ga salt in a solvent containing the ligand at a temperature sufficient to obtain an ion-exchanged nanostructure having a gallium gradient from the surface to the center of the nanostructure.

In some embodiments, the nanostructures have a PWL between 480 and 545 nm, with at least about 60% of the emission being band-edge emission.

In some embodiments, the ligand is an alkylamine. In some embodiments, the alkylamine ligand is oleylamine. In some embodiments, the ligand is used in excess and acts as a solvent, and the listed solvent is not present during the reaction. In some embodiments, a solvent is present during the reaction. In some embodiments, the solvent is a high-boiling solvent. In some embodiments, the solvent is octadecene, squalane, dibenzyl ether, or xylene. In some embodiments, a temperature sufficient for (a) is 100-280°C, a temperature sufficient for (b) is 150-260°C, and a temperature sufficient for (c) is 170-280°C. In some embodiments, a temperature sufficient for (a) is about 210°C, a temperature sufficient for (b) is about 210°C, and a temperature sufficient for (c) is about 240°C.

In some embodiments, at least 80% of the emission is band-edge emission. In other embodiments, at least 90% of the emission is band-edge emission. In other embodiments, at least 95% of the emission is band-edge emission. In some embodiments, 92-98% of the emission is band-edge emission. In some embodiments, 93-96% of the emission is band-edge emission.

Examples of ligands are disclosed in U.S. Patent Nos. 7,572,395, 8,143,703, 8,425,803, 8,563,133, 8,916,064, 9,005,480, 9,139,770, and 9,169,435, and U.S. Patent Application Publication No. 2008/0118755. In one embodiment, the ligand is an alkylamine. In some embodiments, the ligand is an alkylamine selected from the group consisting of dodecylamine, oleylamine, hexadecylamine, dioctylamine, and octadecylamine.

In some embodiments, the sulfur source in (a) comprises trioctylphosphine sulfide, elemental sulfur, octanethiol, dodecanethiol, octadecanethiol, tributylphosphine sulfide, cyclohexyl isothiocyanate, α-toluenethiol, ethylene trithiocarbonate, allyl mercaptan, bis(trimethylsilyl) sulfide, trioctylphosphine sulfide, or a combination thereof. In some embodiments, the sulfur source in (a) is derived from _S8 .

In one embodiment, the sulfur source is derived from _S8 .

In one embodiment, the temperature of (a) and (b) is approximately 270°C.

In some embodiments, the mixture (b) further comprises a solvent. In some embodiments, the solvent is trioctylphosphine, dibenzyl ether, or squalane.

In some embodiments, the gallium carboxylate is a gallium C _2-24 carboxylate. Examples of C _2-24 carboxylates include acetate, propionate, butanoate, pentanoate, hexanoate, heptanoate, octanoate, nonanoate, decanoate, undecanoate, tridecanoate, tetradecanoate, pentadecanoate, hexadecanoate, octadecanoate (oleate), nonadecanoate, and icosanoate. In one embodiment, the gallium carboxylate is gallium oleate.

In some embodiments, the ratio of gallium carboxylate to the AIGS core is 0.008 to 0.2 mmol of gallium carboxylate per mg of AIGS. In one embodiment, the ratio of gallium carboxylate to the AIGS core is about 0.04 mmol of gallium carboxylate per mg of AIGS.

In further embodiments, the AIGS nanostructures are isolated, for example, by precipitation. In some embodiments, the AIGS nanostructures are precipitated by the addition of a non-solvent for the AIGS nanostructures. In some embodiments, the non-solvent is a toluene/ethanol mixture. The precipitated nanostructures can be further isolated by centrifugation and washing with a non-solvent for the nanostructures.

Also provided is a method of fabricating a nanostructure,
(a) preparing a mixture comprising an AIGS core and a gallium halide in a solvent and holding the mixture for a time sufficient to obtain an ion-exchanged nanostructure having a gallium gradient from the surface to the center of the nanostructure;
(b) isolating the nanostructures.

In some embodiments, the nanostructures have a PWL between 480 and 545 nm, with at least about 60% of the emission being band-edge emission.

In some embodiments, at least 80% of the emission is band-edge emission. In other embodiments, at least 90% of the emission is band-edge emission. In other embodiments, at least 95% of the emission is band-edge emission.

In some embodiments, the gallium halide is gallium chloride, gallium bromide, or gallium iodide. In one embodiment, the gallium halide is gallium iodide.

In some embodiments, the solvent comprises trioctylphosphine. In some embodiments, the solvent comprises toluene.

In some embodiments, the sufficient time in (a) is 0.1 to 200 hours. In some embodiments, the sufficient time in (a) is about 20 hours.

In some embodiments, the mixture is held at 20-100°C. In one embodiment, the mixture is held at about room temperature (20-25°C).

In some embodiments, the molar ratio of gallium halide to the AIGS core is from about 0.1 to about 30.

In further embodiments, the AIGS nanostructures are isolated, for example, by precipitation. In some embodiments, the AIGS nanostructures are precipitated by the addition of a non-solvent for the AIGS nanostructures. In some embodiments, the non-solvent is a toluene/ethanol mixture. The precipitated nanostructures can be further isolated by centrifugation and/or washing the nanostructures with the non-solvent.

Also provided is a method of fabricating a nanostructure,
(a) preparing a mixture comprising an AIGS nanostructure, a sulfur source, and a ligand;
(b) adding the mixture obtained in (a) to a mixture of GaX ₃ (X=F, Cl, or Br) and oxygen-free ligands at a temperature of 180-300° C. to obtain ion-exchanged nanostructures having a gallium gradient from the surface to the center of the nanostructures;
(d) isolating the nanostructures.

In some embodiments, the nanostructures have a PWL of 480-545 nm.

In some embodiments, the preparation in (a) is performed under oxygen-free conditions. In some embodiments, the preparation in (a) is performed in a glove box.

In some embodiments, the addition in (b) is under oxygen-free conditions. In some embodiments, the addition in (b) is in a glove box.

In some embodiments, at least 80% of the emission is band-edge emission. In other embodiments, at least 90% of the emission is band-edge emission. In other embodiments, at least 95% of the emission is band-edge emission.

Examples of ligands are disclosed in U.S. Patent Nos. 7,572,395, 8,143,703, 8,425,803, 8,563,133, 8,916,064, 9,005,480, 9,139,770, and 9,169,435, and U.S. Patent Application Publication No. 2008/0118755. In some embodiments, the ligand in (a) is an oxygen-free ligand. In some embodiments, the ligand in (b) is an oxygen-free ligand. In some embodiments, the ligand in (a) and (b) is an alkylamine. In some embodiments, the ligand is an alkylamine selected from the group consisting of dodecylamine, oleylamine, hexadecylamine, dioctylamine, and octadecylamine. In some embodiments, the ligand in (a) is oleylamine. In some embodiments, the ligand in (b) is oleylamine. In some embodiments, the ligand in (a) and (b) is oleylamine.

In one embodiment, the sulfur source is derived from _S8 .

In one embodiment, the temperature of (a) and (b) is approximately 270°C.

In some embodiments, the mixture (b) further comprises a solvent. In some embodiments, the solvent is trioctylphosphine, dibenzyl ether, or squalane.

In some embodiments, _GaX3 is gallium chloride, gallium fluoride, or gallium iodide. In some embodiments, _GaX3 is gallium chloride. In some embodiments, _GaX3 is Ga(III) chloride.

In some embodiments, the ratio of _GaX3 to the AIGS core is 0.008 to 0.2 mmol of _GaX3 per mg of AIGS. In some embodiments, the molar ratio of _GaX3 to the AIGS core is about 0.1 to about 30. In some embodiments, the ratio of _GaX3 to the AIGS core is about 0.04 mmol of _GaX3 per mg of AIGS.

In some embodiments, the AIGS nanostructures are isolated, for example, by precipitation. In some embodiments, the AIGS nanostructures are precipitated by the addition of a non-solvent for the AIGS nanostructures. In some embodiments, the non-solvent is a toluene/ethanol mixture. The precipitated nanostructures can be further isolated by centrifugation and/or washing the nanostructures with the non-solvent.

In some embodiments, the mixture in (a) is maintained at about 20°C to 100°C. In some embodiments, the mixture in (a) is maintained at about room temperature (20°C to 25°C).

In some embodiments, the mixture in (b) is held at 200°C to 300°C for 0.1 hours to 200 hours. In some embodiments, the mixture in (b) is held at 200°C to 300°C for about 20 hours.

Doped AIGS Nanostructures In some embodiments, the AIGS nanostructures are doped. In some embodiments, the dopant of the nanocrystalline core comprises a metal, including one or more transition metals. In some embodiments, the dopant is a transition metal selected from the group consisting of Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Mn, Tc, Re, Fe, Ru, Os, Co, Rh, Ir, Ni, Pd, Pt, Cu, Ag, Au, and combinations thereof. In some embodiments, the dopant comprises a non-metal. In some embodiments, the dopant is ZnS, ZnSe, ZnTe, CdSe, CdS, CdTe, HgS, HgSe, HgTe, _CuInS2 , CuInSe2, _AlN , AlP, AlAs, GaN, GaP, or GaAs.

In some embodiments, the cores are purified by precipitation from a non-solvent. In some embodiments, the AIGS nanostructures are filtered to remove precipitate from the core solution.

Nanostructure Compositions In some embodiments, the present disclosure provides a nanostructure composition comprising:
(a) at least one population of AIGS nanostructures;
(b) at least one organic resin.

In some embodiments, the nanostructures have a PWL of 480-545 nm.

In some embodiments, at least 80% of the nanostructure emission is band-edge emission. In other embodiments, at least 90% of the emission is band-edge emission. In other embodiments, at least 95% of the emission is band-edge emission. In some embodiments, 92-98% of the emission is band-edge emission. In some embodiments, 93-96% of the emission is band-edge emission.

In some embodiments, the nanostructure composition further comprises at least one second population of nanostructures. Nanostructures having a PWL between 480 and 545 nm emit green light. Additional populations of nanostructures emitting in the green, yellow, orange, and/or red regions of the spectrum may be added. These nanostructures have a PWL greater than 545 nm. In some embodiments, the nanostructures have a PWL between 550 and 750 nm. The size of the nanostructures determines the emission wavelength. The at least one second population of nanostructures may comprise III-V nanocrystals selected from the group consisting of BN, BP, BAs, BSb, AlN, AlP, AlAs, AlSb, GaN, GaP, GaAs, GaSb, InN, InP, InAs, and InSb. In some embodiments, the cores of the second population of nanostructures are InP nanocrystals.

Organic Resin In some embodiments, the organic resin is a thermosetting resin or an ultraviolet (UV) curable resin. In some embodiments, the organic resin is cured by a method that facilitates roll-to-roll processing.

Thermosetting resins require curing, which undergoes an irreversible molecular crosslinking process that renders the resin infusible. In some embodiments, the thermosetting resin is preferably an epoxy resin, a phenolic resin, a vinyl resin, a melamine resin, a urea resin, an unsaturated polyester resin, a polyurethane resin, an allyl resin, an acrylic resin, a polyamide resin, a polyamide-imide resin, a phenolamine condensation polymerization resin, a urea-melamine condensation polymerization resin, or a combination thereof.

In some embodiments, the thermosetting resin is an epoxy resin. Epoxy resins are easily cured without generating volatiles or by-products from a wide range of chemicals. Epoxy resins are also compatible with most substrates and tend to wet surfaces easily. See Boyle, M. A., et al., "Epoxy Resins," Composites, Vol. 21, ASM Handbook, pages 78-89 (2001).

In some embodiments, the organic resin is a silicone thermoset resin. In some embodiments, the silicone thermoset resin is OE6630A or OE6630B (Dow Corning Corporation, Auburn, MI).

In some embodiments, a thermal initiator is used. In some embodiments, the thermal initiator is AIBN [2,2'-azobis(2-methylpropionitrile)] or benzoyl peroxide.

UV-curable resins are polymers that cure and solidify rapidly when exposed to specific wavelengths of light. In some embodiments, UV-curable resins are resins that have, as functional groups, radically polymerizable groups such as (meth)acrylyloxy groups, vinyloxy groups, styryl groups, or vinyl groups, or cationically polymerizable groups such as epoxy groups, thioepoxy groups, vinyloxy groups, or oxetanyl groups. In some embodiments, the UV-curable resin is a polyester-based resin, a polyester-based resin, a (meth)acrylic-based resin, an epoxy resin, a urethane-based resin, an alkyd-based resin, a spiroacetal-based resin, a polybutadiene-based resin, or a polythiolpolyene-based resin.

In some embodiments, the UV-curable resin is isobornyl acrylate, isobornyl methacrylate, phenoxyethyl acrylate, phenoxyethyl methacrylate, urethane acrylate, allyloxide cyclohexyl diacrylate, bis(acryloxyethyl)hydroxyl isocyanurate, bis(acryloxyneopentyl glycol) adipate, bisphenol A diacrylate, bisphenol A dimethacrylate, 1,4-butanediol diacrylate, 1,4-butanediol dimethacrylate, 1,3-butylene glycol diacrylate, 1,3- Butylene glycol dimethacrylate, dicyclopentanyl diacrylate, diethylene glycol diacrylate, diethylene glycol dimethacrylate, dipentaerythritol hexaacrylate, dipentaerythritol monohydroxypentaacrylate, di(trimethylolpropane)tetraacrylate, ethylene glycol dimethacrylate, glycerol methacrylate, 1,6-hexanediol diacrylate, 1,6-hexanediol dimethacrylate, neopentyl glycol dimethacrylate, neopentyl glycol hydroxypivalate, di Acrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, dimethacrylate phosphate, polyethylene glycol diacrylate, polypropylene glycol diacrylate, tetraethylene glycol diacrylate, tetrabromobisphenol A diacrylate, triethylene glycol divinyl ether, triglycerol diacrylate, trimethylolpropane triacrylate, tripropylene glycol diacrylate, tris(acryloxyethyl)isocyanurate, triacrylate phosphate, diacrylate phosphate, a Selected from the group consisting of acrylic acid propargyl ester, vinyl-terminated polydimethylsiloxane, vinyl-terminated diphenylsiloxane-dimethylsiloxane copolymer, vinyl-terminated polyphenylmethylsiloxane, vinyl-terminated trifluoromethylsiloxane-dimethylsiloxane copolymer, vinyl-terminated diethylsiloxane-dimethylsiloxane copolymer, vinylmethylsiloxane, monomethacryloyloxypropyl-terminated polydimethylsiloxane, monovinyl-terminated polydimethylsiloxane, monoallyl-monotrimethylsiloxy-terminated polyethylene oxide, and combinations thereof.

In some embodiments, the UV-curable resin is a mercapto-functional compound that can crosslink with isocyanates, epoxies, or unsaturated compounds under UV curing conditions. In some embodiments, the polythiol is selected from the group consisting of pentaerythritol tetra(3-mercaptopropionate) (PETMP), trimethylol-propane tri(3-mercaptopropionate) (TMPMP), glycol di(3-mercaptopropionate) (GDMP), tris[25-(3-mercaptopropionyloxy)ethyl]isocyanurate (TEMPIC), dipentaerythritol hexa(3-mercaptopropionate) (DMP), and methylol-propane tri(3-mercaptopropionate) (DMP). ) (Di-PETMP), ethoxylated trimethylolpropane tri(3-mercapto-propionate) (ETTMP1300 and ETTMP700), polycaprolactone tetra(3-mercapto-propionate) (PCL4MP1350), pentaerythritol tetramercaptoacetate (PETMA), trimethylolpropane trimercaptoacetate (TMPMA), or glycol dimercaptoacetate (GDMA). These compounds are sold under the trade name THIOCURE® by Bruno Bock, Marschacht, Germany.

In some embodiments, the UV-curable resin is a polythiol. In some embodiments, the UV-curable resin is a polythiol selected from the group consisting of ethylene glycol bis(thioglycolate), ethylene glycol bis(3-mercaptopropionate), trimethylolpropane tris(thioglycolate), trimethylolpropane tris(3-mercaptopropionate), pentaerythritol tetrakis(thioglycolate), pentaerythritol tetrakis(3-mercaptopropionate) (PETMP), and combinations thereof. In some embodiments, the UV-curable resin is PETMP.

In some embodiments, the UV-curable resin is a thiol-ene formulation including a polythiol and 1,3,5-triallyl-1,3,5-triazine-2,4,6(1H,3H,5H)-trione (TTT). In some embodiments, the UV-curable resin is a thiol-ene formulation including PETMP and TTT.

In some embodiments, the UV-curable resin further comprises a photoinitiator. The photoinitiator initiates the crosslinking and/or curing reaction of the photosensitive material during exposure. In some embodiments, the photoinitiator is an acetophenone, benzoin, or thioxatenon.

In some embodiments, the photoinitiator is a vinyl acrylate resin. In some embodiments, the photoinitiator is MINS-311RM (Minuta Technology Co., Ltd., Korea).

In some embodiments, the photoinitiator is IRGACURE® 127, IRGACURE® 184, IRGACURE® 184D, IRGACURE® 2022, IRGACURE® 2100, IRGACURE® 250, IRGACURE® 270, IRGACURE® 2959, IRGACURE® 369, IRGACURE® 369EG, IRGACURE® 379, IRGACURE® 500, IRGACURE® 65 1, IRGACURE® 754, IRGACURE® 784, IRGACURE® 819, IRGACURE® 819Dw, IRGACURE® 907, IRGACURE® 907FF, IRGACURE® Oxe01, IRGACURE® TPO-L, IRGACURE® 1173, IRGACURE® 1173D, IRGACURE® 4265, IRGACURE® BP, or IRGACURE® MBF (BASF Corporation, Wyandotte, MI). In some embodiments, the photoinitiator is TPO (2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide) or MBF (methylbenzoyl formate).

In some embodiments, the weight percent of the at least one organic resin in the nanostructure composition is about 5% to about 99%, about 5% to about 95%, about 5% to about 90%, about 5% to about 80%, about 5% to about 70%, about 5% to about 60%, about 5% to about 50%, about 5% to about 40%, about 5% to about 30%, about 5% to about 20%, about 5% to about 10%, about 10% to about 99%, about 10% to about 95%, about 10% to about 90%, about 10% up to about 80%, about 10% to about 70%, about 10% to about 60%, about 10% to about 50%, about 10% to about 40%, about 10% to about 30%, about 10% to about 20%, about 20% to about 99%, about 20% to about 95%, about 20% to about 90%, about 20% to about 80%, about 20% to about 70%, about 20% to about 60%, about 20% to about 50%, about 20% to about 40%, about 20% to about 30%, about 30% to about 99%, about 30% to about 95 %, about 30% to about 90%, about 30% to about 80%, about 30% to about 70%, about 30% to about 60%, about 30% to about 50%, about 30% to about 40%, about 40% to about 99%, about 40% to about 95%, about 40% to about 90%, about 40% to about 80%, about 40% to about 70%, about 40% to about 60%, about 40% to about 50%, about 50% to about 99%, about 50% to about 95%, about 50% to about 90%, about 50% to about 80%, about 5 0% to about 70%, about 50% to about 60%, about 60% to about 99%, about 60% to about 95%, about 60% to about 90%, about 60% to about 80%, about 60% to about 70%, about 70% to about 99%, about 70% to about 95%, about 70% to about 90%, about 70% to about 80%, about 80% to about 99%, about 80% to about 95%, about 80% to about 90%, about 90% to about 99%, about 90% to about 95%, or about 95% to about 99%.

In some embodiments, the nanostructure composition further comprises at least one monomer incorporated into the ligand that coats the AIGS surface. AIGS nanostructures containing at least one monomer incorporated into the ligand that coats the AIGS surface have been found to have high QY, good compatibility with HDDA, a common monomer used in inkjet printable inks, and good blue light absorption.

In some embodiments, at least one monomer is an acrylate. Examples of acrylate monomers include methyl methacrylate, ethyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, tert-butyl methacrylate, n-amyl methacrylate, isoamyl methacrylate, n-hexyl methacrylate, tridecyl methacrylate, stearyl methacrylate, decyl methacrylate, dodecyl methacrylate, methoxydiethylene glycol methacrylate, polypropylene glycol monomethacrylate, phenyl methacrylate, phenoxyethyl methacrylate, tetrahydrofurfuryl methacrylate, tert-butylcyclohexyl methacrylate, behenyl methacrylate, dicyclopentanyl methacrylate, dicyclopentenyloxyethyl methacrylate, 2-ethylhexyl methacrylate, and octyl methacrylate. acrylate, isooctyl methacrylate, n-decyl methacrylate, isodecyl methacrylate, lauryl methacrylate, hexadecyl methacrylate, octadecyl methacrylate, benzyl methacrylate, 2-phenylethyl methacrylate, 2-phenoxyethyl acrylate, ethyl acrylate, methyl acrylate, n-butyl acrylate, 2-hydroxyethyl acrylate, 2-carboxyethyl acrylate, acrylic acid, ethylene glycol diacrylate, 1,3-propanediol diacrylate, 1,4-bis(acryloyloxy)butane, isobornyl acrylate, tetrahydrofurfuryl acrylate, cyclic trimethylolpropane formal acrylate, cyclohexyl methacrylate, and 4-tert-butylcyclohexyl acrylate.

In some embodiments, the monomer is at least one of ethyl acrylate, HDDA, tetrahydrofurfuryl acrylate, tri(propylene glycol) diacrylate, 1,4-bis(acryloyloxy)butane, or isobornyl acrylate.

Methods for Preparing an AIGS Nanostructure Composition The present disclosure provides a method for preparing a nanostructure composition, the method comprising:
(a) providing at least one population of AIGS nanostructures;
(b) mixing at least one organic resin with the composition of (a).

In some embodiments, the nanostructures have a PWL between 480 and 545 nm, and at least about 80% of the emission is band-edge emission. In some embodiments, at least 80% of the emission is band-edge emission. In other embodiments, at least 90% of the emission is band-edge emission. In other embodiments, at least 95% of the emission is band-edge emission. In some embodiments, 92-98% of the emission is band-edge emission. In some embodiments, 93-96% of the emission is band-edge emission.

The present disclosure also provides a method for preparing a nanostructure composition, the method comprising:
(a) providing at least one population of AIGS nanostructures, the nanostructures being prepared using GaX ₃ (X=F, Cl, or Br) precursors and oxygen-free ligands;
(b) mixing at least one organic resin with the composition of (a).

In some embodiments, the nanostructures have a PWL between 480 and 545 nm, with at least about 60% of the emission being band-edge emission.

The present disclosure also provides a method for preparing a nanostructure composition, the method comprising:
(a) providing at least one population of AIGS nanostructures, wherein the nanostructures have a PWL between 480 and 545 nm, at least about 80% of the emission is band edge emission, and the nanostructures exhibit a QY between 80 and 99%;
(b) mixing at least one organic resin with the composition of (a).

In some embodiments, at least one population of nanostructures is rotated at a speed of about 100 rpm to about 10,000 rpm, about 100 rpm to about 5,000 rpm, about 100 rpm to about 3,000 rpm, about 100 rpm to about 1,000 rpm, about 100 rpm to about 500 rpm, about 500 rpm to about 10,000 rpm, about 500 rpm to about 5,000 rpm, or about 500 rpm to about 3,000 rpm. , and mixed with at least one organic resin at a stirring speed of about 500 rpm to about 1,000 rpm, about 1,000 rpm to about 10,000 rpm, about 1,000 rpm to about 5,000 rpm, about 1,000 rpm to about 3,000 rpm, about 3,000 rpm to about 10,000 rpm, about 3,000 rpm to about 10,000 rpm, or about 5,000 rpm to about 10,000 rpm.

In some embodiments, at least one population of nanostructures is heated for about 10 minutes to about 24 hours, about 10 minutes to about 20 hours, about 10 minutes to about 15 hours, about 10 minutes to about 10 hours, about 10 minutes to about 5 hours, about 10 minutes to about 1 hour, about 10 minutes to about 30 minutes, about 30 minutes to about 24 hours, about 30 minutes to about 20 hours, about 30 minutes to about 15 hours, about 30 minutes to about 10 hours, about 30 minutes to about 5 hours, about 30 minutes to about 1 hour, about 1 hour to about 24 hours ... It is mixed with at least one organic resin for about 20 hours, about 1 hour to about 15 hours, about 1 hour to about 10 hours, about 1 hour to about 5 hours, about 5 hours to about 24 hours, about 5 hours to about 20 hours, about 5 hours to about 15 hours, about 5 hours to about 10 hours, about 10 hours to about 24 hours, about 10 hours to about 20 hours, about 10 hours to about 15 hours, about 15 hours to about 24 hours, about 15 hours to about 20 hours, or about 20 hours to about 24 hours.

In some embodiments, at least one population of nanostructures is mixed with at least one organic resin at a temperature of about -5°C to about 100°C, about -5°C to about 75°C, about -5°C to about 50°C, about -5°C to about 23°C, about 23°C to about 100°C, about 23°C to about 75°C, about 23°C to about 50°C, about 50°C to about 100°C, about 50°C to about 75°C, or about 75°C to about 100°C. In some embodiments, at least one organic resin is mixed with at least one population of nanostructures at a temperature of about 23°C to about 50°C.

In some embodiments, when two or more organic resins are used, the organic resins are added and mixed together. In some embodiments, the first organic resin is rotated at a speed of about 100 rpm to about 10,000 rpm, about 100 rpm to about 5,000 rpm, about 100 rpm to about 3,000 rpm, about 100 rpm to about 1,000 rpm, about 100 rpm to about 500 rpm, about 500 rpm to about 10,000 rpm, about 500 rpm to about 5,000 rpm, about 500 rpm to about 3,000 rpm, or about It is mixed with the second organic resin at a stirring speed of 500 rpm to about 1,000 rpm, about 1,000 rpm to about 10,000 rpm, about 1,000 rpm to about 5,000 rpm, about 1,000 rpm to about 3,000 rpm, about 3,000 rpm to about 10,000 rpm, about 3,000 rpm to about 10,000 rpm, or about 5,000 rpm to about 10,000 rpm.

In some embodiments, the first organic resin is cured for about 10 minutes to about 24 hours, about 10 minutes to about 20 hours, about 10 minutes to about 15 hours, about 10 minutes to about 10 hours, about 10 minutes to about 5 hours, about 10 minutes to about 1 hour, about 10 minutes to about 30 minutes, about 30 minutes to about 24 hours, about 30 minutes to about 20 hours, about 30 minutes to about 15 hours, about 30 minutes to about 10 hours, about 30 minutes to about 5 hours, about 30 minutes to about 1 hour, about 1 hour to about 24 hours, about 1 hour It is mixed with the second organic resin for up to about 20 hours, about 1 hour to about 15 hours, about 1 hour to about 10 hours, about 1 hour to about 5 hours, about 5 hours to about 24 hours, about 5 hours to about 20 hours, about 5 hours to about 15 hours, about 5 hours to about 10 hours, about 10 hours to about 24 hours, about 10 hours to about 20 hours, about 10 hours to about 15 hours, about 15 hours to about 24 hours, about 15 hours to about 20 hours, or about 20 hours to about 24 hours.

In some embodiments, the AIGS nanostructures are combined with at least one monomer incorporated into the ligand that coats the AIGS surface before being combined with the resin. In some embodiments, the monomer is an acrylate. In some embodiments, the monomer is at least one of ethyl acrylate, HDDA, tetrahydrofurfuryl acrylate, tri(propylene glycol) diacrylate, 1,4-bis(acryloyloxy)butane, or isobornyl acrylate.

Properties of AIGS Nanostructures In some embodiments, AIGS nanostructures exhibit high photoluminescence quantum yields. In some embodiments, the nanostructures exhibit high photoluminescence quantum yields, such as from about 50% to about 99%, from about 50% to about 95%, from about 50% to about 90%, from about 50% to about 85%, from about 50% to about 80%, from about 50% to about 70%, from about 50% to about 60%, from 60% to about 99%, from about 60% to about 95%, from about 60% to about 90%, from about 60% to about 85%, from about 60% to about 80%, from about 60% to about 70%, from about 70% to about 99%, from about 70% to about 95 ... The nanostructures exhibit a photoluminescence quantum yield of 0% to about 90%, about 70% to about 85%, about 70% to about 80%, about 80% to about 99%, about 80% to about 95%, about 80% to about 90%, about 80% to about 85%, about 85% to about 99%, about 85% to about 95%, about 80% to about 85%, about 85% to about 99%, about 85% to about 90%, about 90% to about 99%, about 90% to about 95%, or about 95% to about 99%. In some embodiments, the nanostructures exhibit a photoluminescence quantum yield of about 82% to about 96%, about 85% to about 96%, and about 93% to about 94%.

The photoluminescence spectrum of the nanostructures can cover a wide, desired portion of the spectrum. In some embodiments, the photoluminescence spectrum of the nanostructures has an emission maximum between 300 nm and 750 nm, between 300 nm and 650 nm, between 300 nm and 550 nm, between 300 nm and 450 nm, between 450 nm and 750 nm, between 450 nm and 650 nm, between 450 nm and 550 nm, between 450 nm and 750 nm, between 450 nm and 650 nm, between 450 nm and 550 nm, between 550 nm and 750 nm, between 550 nm and 650 nm, or between 650 nm and 750 nm. In some embodiments, the photoluminescence spectrum of the nanostructures has an emission maximum between 450 nm and 550 nm.

The size distribution of the nanostructures can be relatively narrow. In some embodiments, the photoluminescence spectrum of the population of nanostructures can have a full width at half maximum of 10 nm to 60 nm, 10 nm to 40 nm, 10 nm to 30 nm, 10 nm to 20 nm, 20 nm to 60 nm, 20 nm to 40 nm, 20 nm to 30 nm, 25 nm to 60 nm, 25 nm to 40 nm, 25 nm to 30 nm, 30 nm to 60 nm, 30 nm to 40 nm, or 40 nm to 60 nm. In some embodiments, the photoluminescence spectrum of the population of nanostructures can have a full width at half maximum of 24 nm to 50 nm.

In some embodiments, the nanostructures emit light having a peak emission wavelength (PWL) of about 400 nm to about 650 nm, about 400 nm to about 600 nm, about 400 nm to about 550 nm, about 400 nm to about 500 nm, about 400 nm to about 450 nm, about 450 nm to about 650 nm, about 450 nm to about 600 nm, about 450 nm to about 550 nm, about 450 nm to about 500 nm, about 500 nm to about 650 nm, about 500 nm to about 600 nm, about 500 nm to about 550 nm, about 550 nm to about 650 nm, about 550 nm to about 600 nm, or about 600 nm to about 650 nm. In some embodiments, the nanostructures emit light having a PWL of about 500 nm to about 550 nm.

As an estimate of blue light absorption efficiency, the optical density at 450 nm per mass basis ( _OD450 /mass) can be calculated by measuring the optical density of the nanostructure solution in a 1 cm path length cuvette and dividing by the dry mass per mL of the same solution after removing all volatiles under vacuum (<200 mTorr). In some embodiments, the nanostructures have an optical density at 450 nm per mass basis (OD450/mass) of about 0.28/mg to about 0.5/mg, about 0.28/mg to about 0.4/mg, about 0.28/mg to about 0.35/mg, about 0.28/mg to about 0.32/mg, about 0.32/mg to about 0.5/mg, about 0.32/mg to about 0.4/mg, about 0.32/mg to about 0.35/mg, about 0.35/mg to about 0.5/mg, about 0.35/mg to about 0.4/mg, or about 0.4/mg to about _0.5 /mg.

Films The nanostructures of the present invention can be embedded in a polymer matrix using any suitable method. As used herein, the term "embedded" is used to indicate that the nanostructures are surrounded or enveloped by the polymer that constitutes the majority of the matrix's components. In some embodiments, at least one population of nanostructures is preferably uniformly distributed throughout the matrix. In some embodiments, at least one population of nanostructures is distributed according to an application-specific distribution. In some embodiments, the nanostructures are mixed into a polymer and applied to the surface of a substrate.

In some embodiments, the present disclosure provides:
(a) a composition comprising at least one population of AIGS nanostructures and at least one ligand bound to the nanostructures;
(b) at least one organic resin.

In some embodiments, a portion of the ligands are bound to the nanostructure. In other embodiments, the nanostructure surface is saturated with the ligands.

In some embodiments, the nanostructures have a PWL of 480-545 nm.

In some embodiments, the composition comprising at least one population of AIGS nanostructures further comprises at least one monomer incorporated into the ligand coating the AIGS surface. In some embodiments, the at least one monomer is an acrylate. In some embodiments, the monomer is at least one of ethyl acrylate, HDDA, tetrahydrofurfuryl acrylate, tri(propylene glycol) diacrylate, 1,4-bis(acryloyloxy)butane, or isobornyl acrylate.

The present disclosure also provides a method for preparing a nanostructured film layer, the method comprising:
(a) providing at least one population of AIGS nanostructures;
(b) mixing at least one organic resin with the composition of (a).
In some embodiments, the nanostructures have a PWL of 480-545 nm.

In some embodiments, at least 80% of the emission is band-edge emission. In other embodiments, at least 90% of the emission is band-edge emission. In other embodiments, at least 95% of the emission is band-edge emission. In some embodiments, 92-98% of the emission is band-edge emission. In some embodiments, 93-96% of the emission is band-edge emission.

In some embodiments, the nanostructure composition further comprises an amino ligand having formula I:
During the ceremony,
x is 1 to 100;
y is 0 to 100;
^R2 is C _1-20 alkyl.

In some embodiments, x is 1 to 100, 1 to 50, 1 to 20, 1 to 10, 1 to 5, 5 to 100, 5 to 50, 5 to 20, 5 to 10, 10 to 100, 10 to 50, 10 to 20, 20 to 100, 20 to 50, or 50 to 100. In some embodiments, x is 10 to 50. In some embodiments, x is 10 to 20. In some embodiments, x is 1. In some embodiments, x is 19. In some embodiments, x is 6. In some embodiments, x is 10.

In some embodiments, R ² is C _1-20 alkyl. In some embodiments, R ² is C _1-10 alkyl. In some embodiments, R ² is C _1-5 alkyl. In some embodiments, R ² is —CH ₂ CH ₃ .

In some embodiments, the compound of Formula I is an amine-terminated polymer commercially available from Huntsman Petrochemical Corporation. In some embodiments, the amine-terminated polymer of Formula I has x=1, y=9, and ^R2 = _-CH3 and is JEFFAMINE M-600 (Huntsman Petrochemical Corporation, Texas). JEFFAMINE M-600 has a molecular weight of about 600. In some embodiments, the amine-terminated polymer of Formula I has x=19, y=3, and ^R2 = _-CH3 and is JEFFAMINE M-1000 (Huntsman Petrochemical Corporation, Texas). JEFFAMINE M-1000 has a molecular weight of about 1,000. In some embodiments, the amine-terminated polymer of Formula I has x=6, y=29, and ^R2 = _-CH3 and is JEFFAMINE M-2005 (Huntsman Petrochemical Corporation, Texas). JEFFAMINE M-2005 has a molecular weight of about 2,000. In some embodiments, the amine-terminated polymer of Formula I has x=31, y=10, and ^R2 = _-CH3 and is JEFFAMINE M-2070 (Huntsman Petrochemical Corporation, Texas). JEFFAMINE M-2070 has a molecular weight of about 2000. In another embodiment, the ligand is a polyethylene glycol amine, such as PEG550-amine and PEG350-amine, available from CreativePEGWorks.

In some embodiments, the nanostructured film layer is a color conversion layer.

The nanostructure composition can be deposited by any suitable method known in the art, including, but not limited to, painting, spray coating, solvent spraying, wet coating, adhesive coating, spin coating, tape coating, roll coating, flow coating, inkjet vapor jetting, drop casting, blade coating, mist deposition, or combinations thereof. In some embodiments, the nanostructure composition is cured after deposition. Suitable curing methods include photocuring, such as UV curing, and thermal curing. Conventional laminate film processing methods, tape coating methods, and/or roll-to-roll fabrication methods can be employed in forming the nanostructured films of the present invention. The nanostructure composition can be coated directly onto the desired layer of the substrate. Alternatively, the nanostructure composition can be formed into a solid layer as a separate element and then applied to the substrate. In some embodiments, the nanostructure composition can be deposited on one or more barrier layers.

Spin Coating: In some embodiments, the nanostructure composition is deposited onto the substrate using spin coating. In spin coating, a small amount of material is deposited onto the center of a substrate loaded into a machine called a spinner, which is usually held in place by a vacuum. High speed rotation is applied to the substrate through the spinner, which creates a centripetal force that spreads the material from the center to the edge of the substrate. Most of the material is shaken off, but some remains on the substrate, forming a thin film of material on the surface as rotation continues. The final thickness of the film is determined by the properties of the material being deposited and the substrate, as well as the parameters selected for the spin process, such as spin speed, acceleration, and spin time. For typical films, spin speeds of 1500-6000 rpm are used with spin times of 10-60 seconds. In some embodiments, films are deposited at very low speeds, e.g., less than 1000 rpm. In some embodiments, films are cast at about 300, 400, 500, 600, 700, 800, or 900 rpm.

Mist Deposition. In some embodiments, the nanostructure composition is deposited onto a substrate using mist deposition. Mist deposition occurs at room temperature and atmospheric pressure, and film thickness can be precisely controlled by modifying the process conditions. During mist deposition, a liquid source material is transformed into a very fine mist and carried into the deposition chamber by nitrogen gas. The mist is then attracted to the wafer surface by a high voltage potential between the field screen and the wafer holder. Once the droplets coalesce on the wafer surface, the wafer is removed from the chamber and thermally cured to evaporate the solvent. The liquid precursor is a mixture of solvent and material to be deposited. It is carried to the atomizer by pressurized nitrogen gas. Price, S. C., et al., "Formation of Ultra-Thin Quantum Dot Films by Mist Deposition," ESC Transactions 11:89-94 (2007).

Spray Coating In some embodiments, the nanostructure composition is deposited on the substrate using spray coating. Typical equipment for spray coating includes a spray nozzle, a sprayer, a precursor solution, and a carrier gas. In the spray deposition process, the precursor solution is broken into micro-sized droplets using a carrier gas or by atomization (e.g., ultrasonic, air blast, or electrostatic). The droplets coming out of the sprayer are accelerated by the substrate surface through the nozzle with the help of the carrier gas, which is controlled and adjusted as desired. The relative motion between the spray nozzle and the substrate is dictated by the design to completely cover the substrate.

In some embodiments, the application of the nanostructure composition further comprises a solvent. In some embodiments, the solvent for the application of the nanostructure composition is water, an organic solvent, an inorganic solvent, a halogenated organic solvent, or a mixture thereof. Exemplary solvents include, but are not limited to, water, D ₂ O, acetone, ethanol, dioxane, ethyl acetate, methyl ethyl ketone, isopropanol, anisole, γ-butyrolactone, dimethylformamide, N-methylpyrrolidone, dimethylacetamide, hexamethylphosphoramide, toluene, dimethylsulfoxide, cyclopentanone, tetramethylene sulfoxide, xylene, ε-caprolactone, tetrahydrofuran, tetrachloroethylene, chloroform, chlorobenzene, dichloromethane, 1,2-dichloroethane, 1,1,2,2-tetrachloroethane, or a mixture thereof.

Inkjet Printing Suitable solvents for inkjet printing of nanostructures are known to those skilled in the art. In some embodiments, the organic solvent is a substituted aromatic or heteroaromatic solvent as described in U.S. Patent Application Publication No. 2018/0230321, which is incorporated herein by reference in its entirety.

In some embodiments, the organic solvent used in the nanostructure composition used as an inkjet printing formulation is defined by its boiling point, viscosity, and surface tension. The properties of organic solvents suitable for inkjet printing formulations are shown in Table 1.

In some embodiments, the organic solvent has a boiling point of about 150°C to about 350°C at 1 atmosphere. In some embodiments, the organic solvent has a boiling point of about 150°C to about 350°C, about 150°C to about 300°C, about 150°C to about 250°C, about 150°C to about 200°C, about 200°C to about 350°C, about 200°C to about 300°C, about 200°C to about 250°C, about 250°C to about 350°C, about 250°C to about 300°C, or about 300°C to about 350°C at 1 atmosphere.

In some embodiments, the organic solvent has a viscosity of about 1 ^mPa.s to about 15 ^mPa.s. In some embodiments, the organic solvent has a viscosity of about 1 ^mPa.s to about 15 ^mPa.s , about 1 mPa.s to about 10 ^mPa.s , about 1 ^mPa.s to about 8 ^mPa.s , about 1 ^mPa.s to about 6 mPa.s, about 1 ^mPa.s to about 4 ^mPa.s , about ^{1 mPa.s} to about 2 mPa.s, about 2 ^mPa.s to about ^{15 mPa.s} , about ^{2 mPa.s} to about 10 ^mPa.s , about 2 ^mPa.s to about 8 ^mPa.s , or about 2 ^mPa.s to about 6 ^mPa.s. The composition has a viscosity of about 2 ^mPa.s to about 4 ^mPa.s , about 4 ^mPa.s to about 15 ^mPa.s , about 4 ^mPa.s to about 10 ^mPa.s , about 4 ^mPa.s to about 8 ^mPa.s , about 4 ^mPa.s to about 6 ^mPa.s , about 6 ^mPa.s to about 15 ^mPa.s , about 6 mPa.s ^to about 10 ^mPa.s , about 6 ^mPa.s to about 8 ^mPa.s , about 8 ^mPa.s to about 15 ^mPa.s , about 8 ^mPa.s to about 10 ^mPa.s , or about 10 ^mPa.s to about 15 ^mPa.s.

In some embodiments, the organic solvent has a surface tension of about 20 dynes/cm to about 50 dynes/cm. In some embodiments, the organic solvent has a surface tension of about 20 dynes/cm to about 50 dynes/cm, about 20 dynes/cm to about 40 dynes/cm, about 20 dynes/cm to about 35 dynes/cm, about 20 dynes/cm to about 30 dynes/cm, about 20 dynes/cm to about 25 dynes/cm, about 25 dynes/cm to about 50 dynes/cm, about 25 dynes/cm to about 40 dynes/cm, or about 25 dynes/cm. The surface tension is from about 25 dynes/cm to about 35 dynes/cm, from about 25 dynes/cm to about 30 dynes/cm, from about 30 dynes/cm to about 50 dynes/cm, from about 30 dynes/cm to about 40 dynes/cm, from about 30 dynes/cm to about 35 dynes/cm, from about 35 dynes/cm to about 50 dynes/cm, from about 35 dynes/cm to about 40 dynes/cm, or from about 40 dynes/cm to about 50 dynes/cm.

In some embodiments, the organic solvent used in the nanostructure composition is an alkyl naphthalene, alkoxy naphthalene, alkyl benzene, aryl, alkyl substituted benzene, cycloalkyl benzene, _C9 - _C20 alkane, diaryl ether, alkyl benzoate, aryl benzoate, or alkoxy substituted benzene.

In some embodiments, the organic solvent used in the nanostructure composition is 1-tetralone, 3-phenoxytoluene, acetophenone, 1-methoxynaphthalene, n-octylbenzene, n-nonylbenzene, 4-methylanisole, n-decylbenzene, p-diisopropylbenzene, pentylbenzene, tetralin, cyclohexylbenzene, chloronaphthalene, 1,4-dimethylnaphthalene, 3-isopropylbiphenyl, p-methylcumene, dipentylbenzene, o-diethylbenzene, m-diethylbenzene, p-diethylbenzene, 1,2,3,4-tetramethylbenzene, 1,2,3,5-tetramethylbenzene, 1,2,4,5-tetramethylbenzene, butylbenzene, dodecylbenzene, 1-methylnaphthalene, 1,2,4-trichlorobenzene, diphenyl ether, diphenylmethane, 4-isopropylbiphenyl, benzyl benzoate, 1,2-bi(3,4-dimethylphenyl)ethane, 2-isopropylnaphthalene, dibenzyl ether, or a combination thereof. In some embodiments, the organic solvent used in the nanostructure composition is 1-methylnaphthalene, n-octylbenzene, 1-methoxynaphthalene, 3-phenoxytoluene, cyclohexylbenzene, 4-methylanisole, n-decylbenzene, or a combination thereof.

In some embodiments, the organic solvent is an anhydrous organic solvent. In some embodiments, the organic solvent is a substantially anhydrous organic solvent.

In some embodiments, the organic solvent is a non-volatile monomer or combination of monomers selected from the list presented above.

In some embodiments, the weight percent of the organic solvent in the nanostructure composition is about 70% to about 99%. In some embodiments, the weight percent of the organic solvent in the nanostructure composition is about 70% to about 99%, about 70% to about 98%, about 70% to about 95%, about 70% to about 90%, about 70% to about 85%, about 70% to about 80%, about 70% to about 75%, about 75% to about 99%, about 75% to about 98%, about 75% to about 95%, about 75% to about 90%, about 75% to about 85%, about 75% to about 80%, about 80% to about 99%, about 80% to about 98%, about 80% to about 95%, about 80% to about 90%, about 80% to about 85%, about 85% to about 99%, about 85% to about 98%, about 85% to about 95%, about 85% to about 90%, about 90% to about 99%, about 90% to about 98%, about 90% to about 95%, about 95% to about 99%, about 95% to about 98%, or about 98% to about 99%. In some embodiments, the weight percent of organic solvent in the nanostructure composition is about 95% to about 99%.

In some embodiments, the inkjet printing composition further includes a monomer incorporated into the ligand coating the AIGS surface. In some embodiments, the monomer is an acrylate. In some embodiments, the monomer is at least one of ethyl acrylate, HDDA, tetrahydrofurfuryl acrylate, tri(propylene glycol) diacrylate, 1,4-bis(triloyloxy)butane incorporated into the ligand coating the AIGS surface, or isobornyl acrylate. The use of a monomer in the inkjet composition has been found to provide better compatibility of the AIGS nanostructures in the inkjet composition, improve QY, and improve blue light absorption.

Film Curing: In some embodiments, the composition is thermally cured to form a nanostructured layer. In some embodiments, the composition is cured using UV light. In some embodiments, the nanostructure composition is coated directly onto the barrier layer of the nanostructured film, and an additional barrier layer is subsequently deposited on the nanostructured layer to produce the nanostructured film. A supporting substrate can be used under the barrier film to add strength, stability, and coating uniformity, as well as to prevent material inconsistencies, bubble formation, and wrinkling or folding of the barrier layer material or other materials. Additionally, one or more barrier layers may be deposited over the nanostructured layer to seal the material between the top and bottom barrier layers. Preferably, the barrier layers are deposited as a laminated film, optionally sealed or further processed, before the nanostructured film can be incorporated into a specific lighting device. The nanostructure composition deposition process can include additional or different components, as will be understood by those skilled in the art. Such embodiments would allow for in-line process tuning of nanostructure emission characteristics, such as brightness and color (e.g., to adjust the quantum film white point), as well as nanostructured film thickness and other properties. Additionally, these embodiments will allow for periodic testing of nanostructured film properties during production, as well as any necessary changes to achieve precise nanostructured film properties. Because a computer program can be used to electronically vary the amounts of each mixture used in forming the nanostructured film, such testing and adjustments can also be achieved without changing the mechanical configuration of the processing line.

It has been discovered that nanostructured films with high PCE can be obtained when the films are processed without exposing the AIGS nanocrystals to blue or UV light prior to providing an oxygen-free environment for the nanostructures.
(a) encapsulating the film with an oxygen barrier prior to thermal processing and/or exposure to blue light for PCE measurement;
(b) the use of oxygen reactive materials as part of the formulation during thermal processing or exposure, and/or (c) temporary blocking of oxygen through the use of a sacrificial barrier layer.

In some embodiments, improved PCE can be achieved by any method capable of forming an oxygen barrier on the AIGS layer. For mass production of devices containing these AIGS-CC layers, encapsulation can be achieved using a vapor deposition process. A typical process flow in this case involves inkjet printing of the AIGS layer, followed by curing with UV exposure, baking at 180°C to remove volatiles, deposition of an organic planarization layer, and then deposition of an inorganic barrier layer. Techniques used to deposit the inorganic layer can include atomic layer deposition (ALD), molecular layer deposition (MLD), chemical vapor deposition (CVD) (with or without plasma enhancement), pulsed vapor deposition (PVD), sputtering, or metal evaporation. Other potential encapsulation methods include solution-processed or printed organic layers, UV- or thermal-curable adhesives, and lamination using barrier films.

In some embodiments, the film is encapsulated in an inert atmosphere. In some embodiments, the film is encapsulated in a nitrogen or argon atmosphere.

Oxygen-reactive materials include any material that is more reactive to oxygen than AIGS nanostructures. Examples of oxygen-reactive materials include, but are not limited to, phosphines, phosphites, organometallic precursors, titanium nitride, and tantalum nitride. In some embodiments, the phosphine can be any one of C _1-20 trialkylphosphines. In one embodiment, the phosphine is trioctylphosphine. In some embodiments, the phosphite can be a trialkylphosphite, an alkylarylphosphite, or a triarylphosphite. In some embodiments, the organometallic precursor can be a trialkylaluminum, a trialkylgallium, a trialkylindium, a dialkylzinc, or the like.

Examples of sacrificial barrier layers include polymer layers that can be dissolved in a solvent and washed away. Examples of such polymers include, but are not limited to, polyvinyl alcohol, polyvinyl acetate, and polyethylene glycol. Other examples of sacrificial barrier layers include inorganic compounds or salts, such as lithium silicate and lithium fluoride. Examples of solvents that can be used to wash away the sacrificial layer include water and organic solvents such as alcohols (e.g., ethanol, methanol), halocarbons (e.g., methylene chloride and ethylene chloride), aromatic hydrocarbons (e.g., toluene, xylene), aliphatic hydrocarbons (e.g., hexane, octane, octadecene), tetrahydrofuran, C _4-20 ethers such as diethyl ether, and C _2-20 esters such as ethyl acetate.

Nanostructured Film Features and Embodiments In some embodiments, the nanostructured films of the present invention are used to form display devices. As used herein, a display device refers to any system with an illuminated display. Such devices include, but are not limited to, devices encompassing liquid crystal displays (LCDs), televisions, computers, mobile phones, smartphones, personal digital assistants (PDAs), gaming devices, electronic reading devices, digital cameras, augmented reality/virtual reality (AR/VR) glasses, optical projection systems, heads-up displays, and the like.

In some embodiments, the nanostructured film is part of a nanostructured color conversion layer.

In some embodiments, the display device includes a nanostructured color converter. In some embodiments, the display device includes a backplane, a display panel disposed on the backplane, and a nanostructured layer. In some embodiments, the nanostructured layer is disposed on the display panel. In some embodiments, the nanostructured layer includes a patterned nanostructured layer.

In some embodiments, the backplane comprises a blue LED, LCD, OLED, or microLED.

In some embodiments, the nanostructured layer is disposed on the light source element. In some embodiments, the nanostructured layer comprises a patterned nanostructured layer. The patterned nanostructured layer may be prepared by any method known in the art. In one embodiment, the patterned nanostructured layer is prepared by inkjet printing of a solution of nanostructures. Suitable solvents for the solution include, but are not limited to, dipropylene glycol monomethyl ether acetate (DPMA), polyglycidyl methacrylate (PGMA), diethylene glycol monoethyl ether acetate (EDGAC), and propylene glycol methyl ether acetate (PGMEA). Volatile solvents can also be used for inkjet printing to enable rapid drying. Volatile solvents include ethanol, methanol, 1-propanol, 2-propanol, acetone, methyl ethyl ketone, methyl isobutyl ketone, ethyl acetate, tetrahydrofuran, and the like. Alternatively, "solventless" inks in which AIGS nanostructures are dispersed in ink monomers may be used for inkjet printing.

In some embodiments, AIGS nanostructures are inkjet printed with a composition that also includes at least one monomer incorporated into the ligand coating the AIGS surface. In some embodiments, the at least one monomer is an acrylate. In some embodiments, the acrylate is at least one of ethyl acrylate, tetrahydrofurfuryl acrylate, tri(propylene glycol) diacrylate, 1,4-bis(acryloyloxy)butane, or isobornyl acrylate. It has been discovered that AIGS nanostructures treated with at least one monomer during ligand exchange provide better compatibility with HDDA, a common monomer used in inkjet printable inks, and improve QY and blue light absorption.

In some embodiments, the nanostructured layer has a thickness of about 1 μm to about 25 μm. In some embodiments, the nanostructured layer has a thickness of about 5 μm to about 25 μm. In some embodiments, the nanostructured layer has a thickness of about 10 μm to about 12 μm.

In some embodiments, the nanostructured display device exhibits a PCE of at least 32%. In some embodiments, the nanostructured compact exhibits a PCE of 32-40%. In some embodiments, the nanostructured compact exhibits a PCE of 33-40%, 34-40%, 35-40%, 36-40%, 37-40%, 38-40%, 39-40%, 33-39%, 34-39%, 35-39%, 36-39%, 37-39%, 38-39%, 33-38%, 34-38%, 35-38%, 36-38%, 37-38%, 33-37%, 34-37%, 35-37%, 36-37%, 33-36%, 34-36%, 35-36%, 33-35%, or 34-35%.

In some embodiments, optical films including nanostructured layers are substantially free of cadmium. As used herein, the term "substantially free of cadmium" contemplates that the nanostructure composition contains less than 100 ppm by weight of cadmium. The RoHS compliance definition requires that no more than 0.01% by weight (100 ppm) of cadmium should be present in the raw homogeneous precursor material. Cadmium concentrations can be measured by inductively coupled plasma mass spectrometry (ICP-MS) and are in parts per billion (ppb) levels. In some embodiments, "substantially free of cadmium" optical films contain 10-90 ppm of cadmium. In other embodiments, substantially free of cadmium optical films contain less than about 50 ppm, less than about 20 ppm, less than about 10 ppm, or less than about 1 ppm of cadmium.

In some embodiments, the present disclosure provides a nanostructured compact.
(a) a first barrier layer;
(b) a second barrier layer; and
(c) providing a nanostructured body comprising: a nanostructured layer between a first barrier layer and a second barrier layer, the nanostructured layer comprising a population of nanostructures comprising AIGS nanostructures; and at least one organic resin.

In some embodiments, the nanostructures have a PWL of 480-545 nm.

In some embodiments, at least 80% of the emission is band-edge emission. In other embodiments, at least 90% of the emission is band-edge emission. In other embodiments, at least 95% of the emission is band-edge emission. In some embodiments, 92-98% of the emission is band-edge emission. In some embodiments, 93-96% of the emission is band-edge emission. In some embodiments, the nanostructured body exhibits a PCE of at least 32%. In some embodiments, the nanostructured body exhibits a PCE of 32-40%. In some embodiments, the nanostructured body exhibits a PCE of 33-40%, 34-40%, 35-40%, 36-40%, 37-40%, 38-40%, 39-40%, 33-39%, 34-39%, 35-39%, 36-39%, 37-39%, 38-39%, 33-38%, 34-38%, 35-38%, 36-38%, 37-38%, 33-37%, 34-37%, 35-37%, 36-37%, 33-36%, 34-36%, 35-36%, 33-35%, or 34-35%.

Barrier Layers: In some embodiments, the nanostructured body includes one or more barrier layers disposed on either or both sides of the nanostructured layer. Suitable barrier layers protect the nanostructured layer and the nanostructured body from environmental conditions such as high temperature, oxygen, and moisture. Suitable barrier materials include non-yellowing, transparent optical materials that are hydrophobic, chemically and mechanically compatible with the nanostructured body, exhibit optical and chemical stability, and can withstand high temperatures. In some embodiments, the one or more barrier layers are index-matched to the nanostructured body. In some embodiments, the matrix material of the nanostructured body and one or more adjacent barrier layers are index-matched to have similar refractive indices so that a majority of light transmitted through the barrier layer toward the nanostructured body is transmitted from the barrier layer into the nanostructured layer. This index-matching reduces optical loss at the interface between the barrier material and the matrix material.

The barrier layer is preferably a solid material and may be a hardened liquid, gel, or polymer. The barrier layer may comprise a flexible or non-flexible material, depending on the particular application. The barrier layer is generally a planar layer and may comprise any suitable shape and surface area configuration, depending on the particular lighting application. In some embodiments, one or more barrier layers are compatible with laminated film processing techniques, whereby a nanostructured layer is disposed on at least a first barrier layer and at least a second barrier layer is disposed on the opposite nanostructured layer to form a nanostructured body according to an embodiment of the present invention. Suitable barrier materials include any suitable barrier material known in the art. For example, suitable barrier materials include glass, polymers, and oxides. Suitable barrier layer materials include, but are not limited to, polymers such as polyethylene terephthalate (PET) and oxides such as silicon oxide, titanium oxide, or aluminum oxide (e.g., SiO ₂ , SiO ₂ O ₃ , TiO ₂ , or Al ₂ O ₃ ), and suitable combinations thereof. In some embodiments, each barrier layer of the nanostructured compact comprises at least two layers comprising different materials or compositions, such that the multi-layer barrier eliminates or reduces alignment of pinhole defects in the barrier layers and provides an effective barrier against oxygen and moisture penetration into the nanostructured layer. The nanostructured layer can comprise any suitable material or combination of materials, and any suitable number of barrier layers on one or both sides of the nanostructured layer. The material, thickness, and number of barrier layers depend on the particular application and are suitably selected to maximize the barrier protection and brightness of the nanostructured layer while minimizing the thickness of the nanostructured compact. In some embodiments, each barrier layer comprises a laminate film, in some embodiments a bilaminate film, with the thickness of each barrier layer being sufficiently thick to eliminate wrinkles in roll-to-roll or layer-by-layer manufacturing processes. The number or thickness of the barriers may further depend on regulatory toxicity guidelines in embodiments where the nanostructures contain heavy metals or other toxic materials, which may require more or thicker barrier layers. Additional considerations for the barriers include cost, availability, and mechanical strength.

In some embodiments, the nanostructured film comprises two or more barrier layers adjacent to each side of the nanostructured layer, e.g., two or three layers on each side of the nanostructured layer, or two barrier layers on each side. In some embodiments, each barrier layer comprises a thin glass sheet, e.g., a glass sheet having a thickness of about 100 μm, 100 μm or less, or 50 μm or less.

Each barrier layer of the nanostructured film of the present invention can have any suitable thickness, depending on the specific requirements and characteristics of the lighting device and application, as well as the individual film components, such as the barrier layer and nanostructured layer, as will be understood by those skilled in the art. In some embodiments, each barrier layer can have a thickness of 50 μm or less, 40 μm or less, 30 μm or less, 25 μm or less, 20 μm or less, or 15 μm or less. In certain embodiments, the barrier layer comprises an oxide coating that can include materials such as silicon oxide, titanium oxide, and aluminum oxide (e.g., SiO ₂ , Si ₂ O ₃ , TiO ₂ , or Al ₂ O ₃ ). The oxide coating can have a thickness of about 10 μm or less, 5 μm or less, 1 μm or less, or 100 nm or less. In certain embodiments, the barrier comprises a thin oxide coating having a thickness of about 100 nm or less, 10 nm or less, 5 nm or less, or 3 nm or less. The upper and/or lower barrier can consist of a thin oxide coating, or can comprise a thin oxide coating and one or more additional material layers.
Display device with nanostructured color conversion layer

In some embodiments, the present invention provides
(a) a first light-emitting display panel;
(b) a backlight unit that provides a first light to the display panel;
(c) a color filter including at least one pixel region including a color conversion layer.

In some embodiments, the color filter comprises at least 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 pixel regions. When blue light is incident on the color filter, red, white, green, and/or blue light is emitted through the pixel regions. In some embodiments, the color filter is described in U.S. Patent No. 9,971,076, which is incorporated herein by reference in its entirety.

In some embodiments, each pixel region includes a color conversion layer. In some embodiments, the color conversion layer includes nanostructures described herein configured to convert incident light to light of a first color. In some embodiments, the color conversion layer includes nanostructures described herein configured to convert incident light to blue light.

In some embodiments, the display device includes 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 color conversion layers. In some embodiments, the display device includes one color conversion layer comprising the nanostructures described herein. In some embodiments, the display device includes two color conversion layers comprising the nanostructures described herein. In some embodiments, the display device includes three color conversion layers comprising the nanostructures described herein. In some embodiments, the display device includes four color conversion layers comprising the nanostructures described herein. In some embodiments, the display device includes at least one red conversion layer, at least one green conversion layer, and at least one blue conversion layer.

In some embodiments, the color conversion layer has a thickness of about 3 μm to about 10 μm, about 3 μm to about 8 μm, about 3 μm to about 6 μm, about 6 μm to about 10 μm, about 6 μm to about 8 μm, or about 8 μm to about 10 μm. In some embodiments, the color conversion layer has a thickness of about 3 μm to about 10 μm.

The nanostructured color conversion layer may be deposited by any suitable method known in the art, including, but not limited to, painting, spray coating, solvent spraying, wet coating, adhesive coating, spin coating, tape coating, roll coating, flow coating, inkjet printing, photoresist patterning, drop casting, blade coating, mist deposition, or a combination thereof. In some embodiments, the nanostructured color conversion layer is deposited by photoresist patterning. In some embodiments, the nanostructured color conversion layer is deposited by inkjet printing.

Compositions Comprising AIGS Nanostructures and Ligands In some embodiments, the AIGS nanostructure composition further comprises one or more ligands, including amino-ligands, polyamino-ligands, mercapto-ligands, phosphino-ligands, silane ligands, and polymeric or oligomeric chains such as polyethylene glycol bearing amine and silane groups.

In some embodiments, the amino ligand has formula I:
During the ceremony,
x is 1 to 100;
y is 0 to 100;
^R2 is C _1-20 alkyl.

In some embodiments, the polyamino-ligand is a polyaminoalkane, polyamine-cycloalkane, polyaminoheterocycle, polyamino-functionalized silicone, or polyamino-substituted ethylene glycol. In some embodiments, the polyamino ligand is a C _2-20 alkane or C _2-20 cycloalkane substituted with two or three amino groups, optionally containing one or two amino groups in place of a carbon group. In some embodiments, the polyamino ligand is ethylenediamine, 1,2-diaminopropane, 1,2-diamino-2-methylpropane, N-methylethylenediamine, N-ethyl-ethylenediamine, N-isopropylethylenediamine, N-cyclohexyl-ethylenediamine, N-cyclohexyl-ethylenediamine, N-octylethylenediamine, N-decylethylenediamine, N-dodecyl-ethylenediamine, N,N-dimethylethylenediamine, N,N-diethylethylenediamine, N,N'-diethyl-ethylenediamine, N,N'-diisopropylethylenediamine, N,N,N'-trimethyl-ethylenediamine, diethylenetriamine, N-isopropyl-diethylenetriamine, N-(2-aminoethyl)-1,3-propanediamine, triethylenetetramine, N,N'-bis(3-aminopropyl)ethylenediamine, N,N'- Bis(2-aminoethyl)-1,3-propanediamine, tris(2-aminoethyl)amine, tetraethylenepentamine, pentaethylenehexamine, 2-(2-aminoethylamino)ethanol, N,N-bis(hydroxyethyl)ethylenediamine, N-(hydroxyethyl)diethylenetriamine, N-(hydroxyethyl)triethylenetetramine, piperazine, 1-(2-aminoethyl)piperazine, 4-(2-amino Ethyl)morpholine, polyethyleneimine, 1,3-diaminopropane, 1,4-diaminobutane, 1,3-diaminopentane, 1,5-diminopemane, 2,2-dimethyl-1,3-propanediamine, hexamethylenediamine, 2-methyl-1,5-diaminopropane, 1,7-diaminoheptane, 1,8-diaminooctane, 2,2,4-trimethyl-1,6-hexanediamine, 2,4,4-trimethyl-1,6-hexanediamine Amines, 1,9-diaminononane, 1,10-diaminodecane, 1,12-diaminododecane, N-methyl-1,3-propanediamine, N-ethyl-1,3-propanediamine, N-isopropyl-1,3-propanediamine, N,N-dimethyl-1,3-propanediamine, N,N'-dimethyl-1,3-propanediamine, N,N'-diethyl-1,3-propanediamine, N,N'-diisopropyl-1,3-propanediamine amine, N,N,N'-trimethyl-1,3-propanediamine, 2-butyl-2-ethyl-1,5-pentanediamine, N,N'-dimethyl-1,6-hexanediamine, 3,3'-diamino-N-methyl-dipropylamine, N-(3-aminopropyl)-1,3-propanediamine, spermidine, bis(hexamethylene)triamine, N,N',N"-trimethyl-bis(hexamethylene)triamine, 4-amino-1,8- octanediamine, N,N'-bis(3-aminopropyl)-1,3-propidiamine, spermine, 4,4'-methylenebis(cyclohexylamine), 1,2-diaminocyclohexane, 1,4-diaminocyclohexane, 1,3-cyclohexanebis(methylamine), 1,4-cyclohexanebis(methylamine), 1,2-bis(aminoethoxy)ethane, 4,9-dioxa-1,12-dodecanediamine, 4,7,10-trioxa-1,13-tridecanediamine, 1,3-diamino-hydroxy-propane, 4,4-methylenedipiperidine, 4-(aminomethyl)piperidine, 3-(4-aminobutyl)piperidine, or polyallylamine. In some embodiments, the polyamino-ligand is 1,3-cyclohexanebis(methylamino), 2,2-dimethyl-1,3-propanediamine, or tris(2-aminoethyl)amine.

In some embodiments, the polyamino-ligand is a polyamino heterocyclic compound. In some embodiments, the polyamino heterocyclic compound is 2,4-diamino-6-phenyl-1,3,5-triazino, 6-methyl-1,3,5-triazino-2,4-diamine, 2,4-diamino-6-diethylamino-1,3,5-triazino, 2-N,4-N,6-N-tripropyl-1,3,5-triazino-2,4,6-triamine, 2,4-diaminopyrimidine, 2,4,6-triaminopyrimidine, 2,5-diaminopyridine, 2,4,5,6-tetraaminopyrimidine, pyridine-2,4,5-triamine, 1-(3-aminopropyl)imidazole, 4-phenyl-1H-imidazole-1,2-diamine , 1H-imidazole-2,5-diamine, 4-phenyl-N(1)-[(E)-phenylmethylidene]-1H-imidazole-1,2-diamine, 2-phenyl-1H-imidazole-4,5-diamine, 1H-imidazole-2,4,5-triamine, 1H-pyrrole-2,5-diamine, 1,2,4,5-tetrazine-3,6-diamine, N,N'-dicyclohexyl-1,2,4,5-tetrazine-3,6-diamine, N3-propyl-1H-1,2,4-triazole-3,5-diamine, or N,N'-bis(2-methoxybenzyl)-1H-1,2,4-triazole-3,5-diamine.

In some embodiments, the polyamino-ligand is a polyamino-functionalized silicone. In some embodiments, the polyamino-functionalized silicone is
It is one of them.

In some embodiments, the polyamino ligand is a polyamino-substituted ethylene glycol. In some embodiments, the polyamino-substituted ethylene glycol is 2-[3-amino-4-[2-[2-amino-4-(2-hydroxyethyl)phenoxy]ethoxy]phenyl]ethanol, 1,5-diamino-3-oxapentane, 1,8-diamino-3,6-dioxaoctane, bis[5-chloro-1H-indol-2-yl-carbonyl-aminoethyl]-ethylene glycol, amino-PEG8-t-Boc-hydrazide, or 2-(2-(2-ethoxyethoxy)ethoxy)ethanamine.

In some embodiments, the mercapto ligand is (3-mercaptopropyl)triethoxysilane, 3,6-dioxa-1,8-octanedithiol, 6-mercapto-1-hexanol, mercaptosuccinic acid, mercaptoundecanoic acid, mercaptohexanoic acid, mercaptopropionic acid, mercaptoacetic acid, cysteine, methionine, and mercaptopoly(ethylene glycol).

In some embodiments, the silane-ligand is an aminoalkyltrialkoxysilane or a thioalkyltrialkoxysilane. In some embodiments, the aminoalkyltrialkoxysilane is 3-aminopropyl)triethoxysilane or 3-mercaptopropyl)triethoxysilane.

In some embodiments, the ligands include, but are not limited to, amino-polyalkylene oxides (e.g., about m.w. 1000), (3-aminopropyl)trimethoxysilane), (3-mercaptopropyl)triethoxysilane, DL-α-lipoic acid, 3,6-dioxa-1,8-octanedithiol, 6-mercapto-1-hexanol, methoxypolyethylene glycolamine (about m.w. 500), poly(ethylene glycol) methyl ether thiol (about m.w. 800), diethylphenylphosphonite, dibenzyl N,N-diisopropyl phosphoramidite, di-tert-butyl N,N-diisopropyl phosphoramidite, tris(2-carboxyethyl)phosphine hydrochloride, poly(ethylene glycol) methyl ether thiol (about m.w. 2000), methoxypolyethylene glycolamine (about m.w. 750), acrylamide, and polyethyleneimine.

Specific combinations of ligands, including amino-polyalkylene oxide (approximately m.w. 1000) and methoxypolyethylene glycol amine (approximately m.w. 500), amino-polyalkylene oxide (approximately m.w. 1000) and 6-mercapto-1-hexanol, amino-polyalkylene oxide (approximately m.w. 1000) and (3-mercaptopropyl)triethoxysilane, and 6-mercapto-1-hexanol and methoxypolyethylene glycol amine (approximately m.w. 500), provided excellent dispersibility and thermal stability. See Example 9.

Films containing AIGS nanostructures and polyamino ligands exhibit higher film photoconversion efficiencies (PCEs) and less film wrinkling and delamination compared to AIGS-containing films without polyamino ligands and compared to monoamino ligands. Therefore, compositions containing AIGS-polyamino-ligands are uniquely suitable for use in nanostructured color conversion layers.

The following examples are illustrative, but not limiting, of the products and processes described herein. Suitable modifications and adaptations of the variety of conditions, formulations, and other parameters normally encountered in the art and which are obvious to those skilled in the art in light of this disclosure are within the spirit and scope of the invention.

Example 1: AIGS Core Synthesis Sample ID1 was prepared using the following representative synthesis of an AIGS core: 4 mL of 0.06 _{M CH3CO2Ag} in oleylamine, ₁ mL of 0.2 M InCl3 in ethanol, 1 mL of 0.95 M sulfur in oleylamine, and 0.5 mL of dodecanethiol were injected into a flask containing 5 mL of degassed octadecene, 300 mg of trioctylphosphine oxide, and 170 mg of gallium acetylacetonate. The mixture was heated to 40°C for 5 minutes, then the temperature was increased to 210°C and held for 100 minutes. After cooling to 180°C, 5 mL of trioctylphosphine was added. The reaction mixture was transferred to a glove box and diluted with 5 mL of toluene. The final AIGS product was precipitated by adding 75 mL of ethanol, centrifuged, and redispersed in toluene. Samples ID2 and ID3 were also prepared using this method. The optical properties of the AIGS cores were measured and are summarized in Table 2. The size and morphology of the AIGS cores were characterized by transmission electron microscopy (TEM).

Example 2: AIGS nanostructures with ion-exchange treatment. Sample ID4 was prepared using the following typical ion-exchange treatment. 2 mL of a 0.3 M gallium oleate solution in octadecene and 12 mL of oleylamine were introduced into a flask and degassed. The mixture was heated to 270°C. 1 mL of a 0.95 M sulfur solution in oleylamine and 1 mL of a premixed solution of isolated AIGS cores (15 mg/mL) were co-injected. The reaction was stopped after 30 minutes. The final product was transferred to a glove box, washed with toluene/ethanol, centrifuged, and redispersed in toluene. Samples ID4-8 were also prepared using this method. The optical properties of the AIGS nanostructures thus produced are summarized in Table 3. Ion-exchange with gallium ions resulted in nearly complete band-edge emission. An increase in the average particle size was observed by TEM.

Example 3: Ion-exchange treatment of gallium halide and trioctylphosphine. A room-temperature ion-exchange reaction with AIGS nanostructures was carried out by adding a _GaI3 solution (0.01-0.25 M) in trioctylphosphine to AIGS QDs and keeping them at room temperature for 20 hours. This treatment resulted in a significant enhancement of the band-edge emission, as summarized in Table 4, while substantially maintaining the peak wavelength (PWL).

The compositional changes before and after GaI ₃ addition were monitored by inductively coupled plasma atomic emission spectroscopy (ICP-AES) and energy dispersive X-ray spectroscopy (EDS), as summarized in Table 4. The composite images of In and Ga elemental distribution before and after GaI ₃ /TOP treatment show the radial distribution of In versus Ga, thus indicating that the ion exchange treatment resulted in a gradient of higher amounts of gallium near the surface of the nanostructure and lesser amounts of gallium in the center of the nanostructure.

Example 4: AIGS ion-exchange treatment using an oxygen-free Ga source. Samples IDs 14 and 15 were prepared using the following representative treatment of AIGS nanoparticles using an oxygen-free Ga source. To 8 mL of degassed oleylamine, 400 mg of _GaCl3 dissolved in 400 μL of toluene was added, followed by the addition of 40 mg of AIGS cores, and then 1.7 mL of 0.95 M sulfur in oleylamine. After heating to 240°C, the reaction was held for 2 hours and then cooled. The final product was transferred to a glove box, washed with toluene/ethanol, centrifuged, and dispersed in toluene. Samples IDs 15 and 16 were also prepared using this method. Samples IDs 11-13 were prepared using the method in Example 2. The optical properties of the treated AIGS materials are shown in Table 5.

As shown in Table 5, the quantum yield of the processed AIGS nanostructures can be improved by using Ga(III) chloride rather than Ga(III) acetylacetonate or gallium oleate when oleylamine is used as the solvent. The final material subjected to ion exchange using Ga(III) chloride yielded similar size and band-edge to trap emission characteristics as the starting nanostructures. Therefore, the increase in quantum yield (QY) is not simply due to an increase in the trap emission component. Also, unexpectedly, when Ga(III) iodide was used instead of Ga(III) chloride, the AIGS nanostructures appeared to dissolve in the reaction mixture, and ion exchange did not occur.

High-resolution TEM with energy-dispersive X-ray spectroscopy (EDS) of sample 14 indicates that the nanostructure likely contains a slight gradient of In decreasing from the center to the surface of the AIGS nanostructure, indicating that processing under these conditions results from a process in which In leaves the AIGS structure and is replaced by Ga, while Ag is present throughout the structure rather than growing a separate layer of GS. This may also contribute to improving the quantum yield of the nanostructure due to less strain.

Example 5: AIGS Cores from Hot Injection of Preformed _Ag2S Nanostructures Mixed with Preformed In-Ga Reagent To prepare _Ag2S nanostructures, 0.5 g of AgI and 2 mL of oleylamine were added to a 20 mL vial under _N2 atmosphere and stirred at 58 °C until a clear solution was obtained. In another 20 mL vial, 5 mL of DDT and 9 mL of 0.95 M sulfur in oleylamine were mixed. The DDT + S-OYA mixture was added to the AgI solution and stirred at 58 °C for 10 min. The resulting _Ag2S nanoparticles were used without washing.

To make the In-Ga reagent mixture, 1.2 g of Ga(acetylacetonate) ₃ , 0.35 g of InCl ₃ , 2.5 mL of oleylamine, and 2.5 mL of ODE were placed in a 100 mL flask. Under _{N 2} atm, the mixture was heated to 210° C. and held for 10 minutes. An orange viscous product was obtained.

To form AIGS nanoparticles, 1.75 g of TOPO, 23 mL of oleylamine, and 25 mL of ODE were added to a 250 mL flask under _N2 . After degassing under vacuum, this solvent mixture was heated to 210 °C over 40 minutes. In a 40 mL vial, the _Ag2S and In-Ga reagent mixture from above were mixed at 58 °C and transferred to a syringe. The Ag-In-Ga mixture was then injected into the solvent mixture at 210 °C and held for 3 hours. After cooling to 180 °C, 5 mL of trioctylphosphine was added. The reaction mixture was transferred to a glove box and diluted with 50 mL of toluene. The final product was precipitated by adding 150 mL of ethanol, centrifuged, and redispersed in toluene. The AIGS nanostructures were then ion-exchanged by the method described in Example 4. The optical properties of the material produced by this method at a scale of up to 24 times the above are shown in Table 6.

Example 7: Repeated gallium ion exchange improves the photoluminescence stability of AIGS nanostructures.

7.1 First Ion Exchange Process Oleylamine (OYA, 2.5 L) is degassed under vacuum at 40°C for 40 minutes. AIGS nanostructures (25.4 g in toluene) are added, followed by _GaCl3 (127 g in a minimum amount of toluene) and sulfur dissolved in OYA (0.95 M, 570 mL). The mixture is heated to 240°C over 40 minutes and held for 4 hours. After cooling, the mixture is diluted with 1 volume of toluene. After centrifugation to remove some by-products, the material is washed with 2 volumes of ethanol, collected by centrifugation, and redissolved in toluene. After the second wash, the nanostructures are dissolved in heptane for storage.

7.2 Second Ion-Exchange Process Oleylamine (OYA, 960 mL) is degassed under vacuum at 40°C for 20 minutes. AIGS ion-exchange nanostructures (12 g in heptane) as from Example 7.1 are added to the OYA, followed by _GaCl3 (22.5 g in a minimum volume of toluene) and then sulfur (0.95 M, 100 mL) dissolved in OYA. The mixture is heated to 240°C over 40 minutes and held for 3 hours. After cooling, the mixture is diluted with 1 vol of toluene, then washed (precipitated with 1.6 vol of ethanol, centrifuged), and redispersed in toluene or heptane as needed. If ligand exchange is being performed for ink formulation, an additional ethanol wash is applied, and the QDs are redispersed in heptane.

7.3 Alternating Second Ion Exchange Process Oleylamine (15 mL) is degassed under vacuum at 60°C for 20 minutes. _GaCl3 (360 mg in a minimum volume of toluene) is added to OYA, followed by AIGS (200 mg in heptane) as from Example 7.1, and then sulfur (0.95 M, 1.6 mL) dissolved in OYA. The mixture is heated to 240°C over 40 minutes and held for 3 hours. After cooling, the mixture is washed as described in Example 7.1.

7.4 Alternating Second Ion Exchange Process This example was carried out as described for Example 7.3, but on a three-fold scale.

7.5 Alternating Second Ion Exchange Process Oleylamine (10 mL) and oleic acid (5 mL) are degassed under vacuum at 90°C for 20 minutes. (Ga( _NMe3 ) ₃ ) ₂ (206 mg) and _GaCl3 (180 mg in a minimum volume of toluene) are added, followed by AIGS (200 mg in heptane) as from Example 7.1. After heating to 130°C, _TMS2S (0.65 mL of a 50% solution in ODE) is added over 20 minutes, and the mixture is held for 2.5 hours. After cooling, the mixture is washed as described in Example 7.1.

7.6 Results The AIGS nanostructures were subjected to an ion-exchange process in which In was exchanged for Ga. Compared to core growth, the higher temperature used in this process (240 °C vs. 210 °C) results in ripening such that the average size is larger than that of the pristine nanostructures. The nanostructures do not have a well-defined shell structure, which can be observed in cross-sectional TEM elemental mapping. The lack of a higher bandgap shell is expected to limit the retention of photoluminescence in these materials during film processing.

After the second ion-exchange process, the average TEM size did not increase (Figures 2A-2C), but TEM elemental mapping demonstrated that a more pronounced gradient toward Ga-rich (higher band gap) regions occurred in the QDs.

The elemental compositions for the single and multiple ion exchange processes are shown in Table 7. Values are the average of 10-20 samples from Examples 7.1 and 7.2.

The properties of the ion-exchanged AIGS nanostructures are shown in Table 8. The metal ratios are molar ratios determined by ICP.

The film PCE retained after UV curing and 180°C bake is significantly improved by the second ion-exchange process, as shown in Table 9. This is believed to be because the process of increasing the Ga concentration in the outer layer of the nanostructures results in a gradient into the higher bandgap region introduced by ion exchange.

Example 8 - Composition Comprising AIGS Nanostructures and Polyamino Ligands Abbreviations Jeffamine - Jeffamine M-1000
HDDA - 1-6 hexanediol diacrylate Bismethylamine - 1,3 cyclohexanebismethylamine PCE - Photon conversion efficiency

The crude AIGS QD growth solution was purified by washing with ethanol and redispersing in heptane (Solution 1). 6-mercapto-1-hexanol was added to Solution 1, heated at 50 °C for 30 min, washed with ethanol, and redispersed in heptane (Solution 2). 2 μL of 6-mercapto-1-hexanol was added per 100 mg of QD inorganic solids. Jeffamine and HDDA were added to Solution 2 for the ligand exchange step, heated at 80 °C for 1 h, precipitated with heptane, and redispersed in HDDA (Solution 3). 83 mg of Jeffamine was added per 100 mg of QD inorganic solids. 0.42 g of HDDA was added per 100 mg of QD inorganic solids. Solution 3 and HDDA were added to an inkjet ink composition containing 10 wt% _TiO2 and 90 wt% monomer. The inkjet formulation had a composition of 10 wt% QD inorganic mass, 4 wt% _TiO2 , and the remaining 86 wt% was a combination of ligands (bound and unbound), HDDA, monomers, photoinitiators, and various other organics left over from the QD solution. This ink formulation was Solution 4.

To solution 4, polyamino ligand bismethylamine (50 mg of bismethylamine per 100 mg of QD inorganic solid) was added, and the composition was then cast as a film.

Film Casting Solution 4 was spin-coated onto a 2" x 2" glass substrate. The film was cured with a UV LED curing lamp. The film's photoconversion efficiency (PCE), a measure of brightness, was then tested. The film was then baked on a hotplate set at 180°C for 30 minutes at a temperature slightly higher than the hotplate. Alternatively, the film was baked with a hotplate set at 180°C for 10 minutes in direct contact with the hotplate surface.

The film's PCE was then tested. A 1" x 1" array of masked blue 448 nm LEDs provided the excitation source for the film. An integrating sphere was placed over the film and connected to a fluorometer. See Figures 3A and 3B. The collected spectra were analyzed to obtain the PCE.

PCE is the ratio of the number of green photons emitted in the forward direction to the number of blue photons generated by the test platform. The emission spectrum from 484 nm to 700 nm is used to calculate PCE, but the green emission is expected to have a peak wavelength between 484 and 545 nm, with the majority of the emission below 588 nm. The PCE, LRR, and film morphology are reported in Table 10. Unexpectedly, the presence of the ligands 1,3-cyclohexanebis(methylamine), tris(2-aminoethyl)amine, and 2,2-dimethyl-1,3-propanediamine resulted in high retention of PCE, high LRR, and no wrinkling after a 180°C bake compared to films without the ligands.

Figure 1 shows the effect of diamine addition on film morphology. From left to right, the films in Figure 1 contained no additive (wrinkled), 2,2-dimethyl-1,3-propanediamine (diamine, no wrinkles), cyclohexanemethylamine (monoamine, wrinkled), and tris(2-aminoethyl)amine (triamine, no wrinkles). From left to right, the first and third films, which did not contain diamine, exhibited extensive wrinkling. In contrast, the second and fourth films exhibited no wrinkling. Unexpectedly, the use of diamino ligands in AIGS films resulted in a significant reduction in film wrinkling.

Example 9 - Testing of Additional Ligands for AIGS Nanostructures In this experiment, additional ligands for AIGS nanoparticles were tested for enhanced QY, high compatibility, and good thermal stability. In addition, these ligands were evaluated for protecting the AIGS nanostructures from degradation and oxidation. Combinations of ligands that can be incorporated into AIGS ink compositions were also tested.

Ligand exchange with these ligands was carried out in organic solvents such as ethyl acetate, PGMEA, acetone, xylene, 1,2-dichlorobenzene (ODCB), butyl acetate, and diethylene glycol monoethyl ether (DGMEE).

AIGS nanostructures were ligand-exchanged with ligands containing polymer or oligomer chains such as polyethylene glycol bearing amine and silane groups, and soft bases such as phosphino-, mercapto-, and combinations thereof for co-passivation.

Figure 4 shows quantum yield values for a number of individual ligands and AIGS nanostructures subjected to a single ion-exchange treatment as described herein. In this graph, NG: native AIGS, NG-NL1: amino-polyalkylene oxide, approximately m.w. 1000, NG-NL2: (3-aminopropyl)trimethoxysilane, NG-NL3: (3-mercaptopropyl)triethoxysilane, NG-NL4: DL-α-lipoic acid, NG-NL5: 3,6-dioxa-1,8-octanedithiol, NG-NL6: 6-mercapto-1-hexanol, NG-NL7: methoxypolyethylene glycolamine 500, NG-NL8: poly(ethylene glycol) methyl ether thiol Mn800, NG-NL9: diethylphenylphosphonium nit, NG-NL10: dibenzyl N,N-diisopropyl phosphoramidite, NG-NL11: di-tert-butyl N,N-diisopropyl phosphoramidite, NG-NL12: tris(2-carboxyethyl)phosphine hydrochloride, NG-NL13: poly(ethylene glycol) methyl ether thiol Mn 2000, NG-NL14: methoxypolyethylene glycolamine 750, NG-NL15: acrylamide, and NG-NL16: polyethyleneimine).

As seen in Figure 4, treatment of AIGS nanostructures with 3-mercaptopropyltriethoxysilane (NL3), 3,6-dioxa-1,8-octanedithiol (NL5), and 6-mercapto-1-hexanol (NL6) resulted in high QYs (73.7%, 72.9%, and 76.1%, respectively). Therefore, the present invention provides AIGS nanostructure compositions containing at least one mercapto-substituted ligand that provides improved QYs. It is believed that the mercapto-substituted ligand provides high QYs by passivating the surface of the AIGS nanostructures and reducing defect emission. Amino-substituted ligands also improved QYs.

In this single-ligand study, polyethylene glycol amine-substituted ligands (L1, L7, L8, and L13), thiol-substituted ligands (L3, L5, and L6), and silane ligand (L2) exhibited better QY compared to native AIGS nanostructures. Furthermore, ligands L1, L7, and L8 provided better compatibility with the monomer when dispersed in HDDA.

Figure 5 is a graph showing the QY% of various two-ligand combinations that provided improved QY% (good combinations) and reduced QY% (poor combinations). Surface defects can be reduced by adding a thiol ligand. The combination of L6 and L7 provided better stability than the others. However, for ink compositions that are relatively hydrophilic, better ligands are relatively hydrophilic ligands such as methoxypolyethylene glycol amine and poly(ethylene glycol) methyl ether thiol. This thiol also improves QY by passivating surface defects.

Suitable temperatures for ligand exchange are room temperature to 120°C. The total amount of ligand in the composition can be 60% to 150% of the AIGS mass.

Table 11 shows the relative changes in QY, PWL, and FWHM before and after ligand exchange with several ligands. Table 11 shows that L6 and L7 were the most effective ligand combinations for the ink formulation, especially when combined with acrylate monomers. Combinations of L2 and L7, L2 and L6, and L2 and L3, L6 and L7 provided excellent dispersibility and thermal stability. See Figure 6.

Ligand combinations that provided good thermal stability when heated to 180°C for 30 minutes in a glove box were further investigated. Ligand combinations L6 & L7, L2 & L6, and L2 & L3 provided better stability than single ligand L1. See Figure 6.

We also investigated the effect of different ratios of ligand combinations on QY. The weight ratio of the ligands was varied, but the total amount of ligand was fixed. The best QY was achieved at a 7:3 L6 to L7 ratio (see Figure 7). All combinations of L6 and L7, except for the 9:1 ratio, showed enhanced QY compared to native AIGS nanostructures. Even though the mixtures showed high QY, they were difficult to purify due to the lack of precipitation. Mixtures of L6 & L2, L3 & L7, and L5 & L7 are good ligand mixtures for AIGS nanostructures. These ligand combinations can be used in combination with various monomers, such as tetrahydrofurfuryl acrylate, tri(propylene glycol) diacrylate, 1,4-bis(acryloyloxy)butane, diethylene glycol ethyl ether acrylate, isobornyl acrylate, hydroxypropyl acrylate, 2-(acryloyloxy)ethyl hydrogen succinate, and 1,6-hexanediol diacrylate.

Example 10 - Improvement of PCE in AIGS Films In an _N2 -filled glove box, AIGS QDs coated with appropriate ligands were mixed into inks containing one or more monomers, _TiO2 scattering particles, and a photoinitiator. These inks were cast into films by spin-coating and then cured using UV irradiation. The films were then baked on a hotplate at 180 °C for 30 minutes to remove any remaining volatile components. All of these processes were carried out in an inert atmosphere in an _N2 -filled glove box.

Typically, at this stage, the film is measured in air by placing it film-side up over a blue LED light source. An integrating sphere connected to a spectrophotometer is placed over the QD film (see Figures 3A and 3B) to capture the emission spectrum of the film. The measurement is repeated using a blank glass substrate (no QDs). The blue light absorption and photon conversion efficiency (PCE) of the QD film are measured using the following equations:
Blue absorption = number of blue photons transmitted through the QD film / number of incident blue photons PCE = number of forward-emitting green photons (484-588 nm) / number of incident blue photons

To study the effects of air and moisture during measurements, the baked QD films were encapsulated before leaving the _N2 glove box. This was done by applying a few drops of UV-curable transparent adhesive onto the QD layer, then placing a glass coverslip and curing the adhesive with UV irradiation. QD films encapsulated in this way using glass and adhesive were measured in air using the method described above.

The results indicate that encapsulating the QD films before measuring in air is important for achieving high photon conversion efficiency (PCE). Table 12 shows the results from a set of films measured with and without encapsulation. For comparison, PCE values from a typical QDCC film containing InP QDs are also shown. When measured with encapsulation, the films containing AIGS nanostructures had higher post-bake PCE values than InP at much lower QD loadings. Further improvement in PCE was achieved by irradiating the films with a blue light source (approximately 6 mW/cm ² ) for 1 hour. Additionally, QDCC films made with AIGS QDs exhibit a much narrower emission (FWHM approximately 30 nm) compared to films made with InP QDs (FWHM 36 nm). This is a result of the lower FWHM of AIGS QDs in solution (34 nm vs. 39 nm), combined with the use of mono- and polyamino ligands that allow for good dispersion in the ink resin.

Figure 8 shows the effect of encapsulation and blue light treatment across a much wider range of samples. Unexpectedly, the PCE values achieved with encapsulation were significantly higher (over 32%) than without encapsulation.

Figure 9 shows the emission linewidth (FWHM) of the film after a 180°C bake step and subsequent encapsulation. The median FWHM of the 180°C baked film is 30.5 nm, which narrows further to 30.1 nm upon encapsulation. This narrowing may be the result of the film becoming brighter upon encapsulation.

While the samples in this study were encapsulated using glass and adhesive, this improvement in PCE can be achieved by any method capable of forming an oxygen barrier on the QD layer. For mass production of devices containing these QDCC surface layers, encapsulation will likely be performed using a vapor deposition process. A typical process flow in this case involves inkjet printing of the QD layer, followed by curing with UV exposure, baking at 180°C to remove volatiles, deposition of an organic planarization layer, and then deposition of an inorganic barrier layer. Techniques used to deposit the inorganic layer can include atomic layer deposition (ALD), molecular layer deposition (MLD), chemical vapor deposition (CVD) (with or without plasma enhancement), pulsed vapor deposition (PVD), sputtering, or metal evaporation. Other potential encapsulation methods include solution-processed or printed organic layers, UV- or thermal-curable adhesives, and lamination using barrier films.

Example 11 - AIGS Ink with Monomer Incorporated into the Ligand Coating the AIGS Surface It was discovered that ligand exchange (LE) of AIGS nanostructures in the presence of monomer results in higher solution QY, better compatible ink, and better film performance compared to LE performed purely in solvent. This was demonstrated through LE and film evaluation using 16 different media.

LE of quantum dots (QDs) such as CdSe and InP can be performed in organic solvents to replace the native ligands with desired ligands. The resulting QDs can then be formulated into solvent-free inks by dispersing the QDs in a monomer, removing the original solvent, and adding other ink components such as a scattering medium and photoinitiator.

This procedure can also be used for LE of AIGS nanostructures, resulting in high QY retention. However, this approach typically results in poor dispersion of the nanostructures in the monomer upon solvent removal. Good dispersion of the AIGS nanostructures in the ink and efficient passivation of the nanostructure surface by the ligand are necessary to maintain film performance through harsh processing conditions such as UV exposure and high-temperature baking. Therefore, AIGS nanostructures ligand-exchanged using conventional processes are not suitable for QDCC applications.

Figure 10 shows the PLQY of ligand-exchanged AIGS nanostructures in various organic solvents, including acetone, PGMEA, ethyl acetate, toluene, dichloromethane (DCM), chloroform, dimethylformamide (DMF), and ethanol, at two temperatures—room temperature (25°C) and 80°C. Jeffamine M1000 was used as the ligand at a mass ratio of 0.8:1 relative to the AIGS nanostructures.

Some solvents, PGMEA, ethyl acetate, toluene, and DCM, were very effective in maintaining the QY after LE. In particular, LE at room temperature resulted in a higher QY than LE at 80°C. Other solvents tested, such as acetone, chloroform, DMF, and ethanol, resulted in lower QYs.

However, as shown in Table 13 (o = clear dispersion; Δ = cloudy dispersion), AIGS nanostructures ligand-exchanged in solvent at room temperature had poor compatibility with HDDA, a common monomer used in inkjet-printable inks. AIGS nanostructures ligand-exchanged at 80°C had better compatibility with HDDA but a lower QY. Therefore, it was difficult to find effective LE conditions that resulted in high QY and good compatibility with HDDA.

The LE studies were repeated using a series of common monomers (shown in Table 14) as a medium instead of organic solvents. LE was performed by mixing the starting AIGS nanostructures (in heptane) with the monomers, followed by the addition of Jeffamine M1000 and heating at 80 °C.

Figure 11 shows the QY after LE in the presence of monomer. In all 16 cases, the QY increased upon LE and was higher than the QY achieved by LE in organic solvents.

After LE, the AIGS nanostructures were isolated and purified by precipitation in heptane, and the yield was calculated by recording the starting and final QD masses. Unlike LE in solvent, where only small changes in mass were observed, the mass of the exchanged QD ligand in the monomer increased by 30-100%, depending on the monomer. Because most of the tested monomers were miscible with heptane and were removed during QD precipitation, this indicated that a certain amount of monomer was incorporated into the ligand coating the QD surface.

All 16 AIGS samples were dispersed in HDDA and then mixed into an ink containing a scattering medium and photoinitiator. Unlike the nanostructures ligand-exchanged in solvent, all 16 samples tested here showed good compatibility in HDDA. Three films were cast from each ink by spin-coating at 700, 800, and 900 rpm and then cured with UV irradiation.

As shown in Figure 12, some monomers M2, M3, M4, M5, M6, and M8 exhibit high film EQE and may be good LE media for AIGS QDs.

Figure 13 shows the blue absorption of AIGS nanostructures film-spun at 800 RPM. M7, M10, M13, M15, and M16 provided very high blue absorption.

Example 12: Increased Blue Absorption with Polyamino Ligands A typical film deposition process involves a very high-temperature hard bake, usually around 200°C, to completely remove any residual solvents and volatile components. This hard bake prevents outgassing during the deposition of other layers on top of the QDCC layer. This harsh bake can result in a very low EQE. Also, the nanostructures may be damaged by the high temperature, or the ligands may desorb from the nanostructures, resulting in agglomeration. Table 15 shows the EQE of a typical AIGS film after UV curing and a 180°C hard bake. The EQE was good, greater than 33% after UV curing, but decreased to less than 19% after 30 minutes at 180°C. The light retention ratio (LRR), which is the ratio of the EQE after baking to the EQE before baking, was very low at less than 60%, meaning that the film performance decreased by more than 40% after baking.

To overcome this high EQE loss during hard baking and the resulting low LRR, two approaches to improving the LRR were tested.

To keep the AIGS nanostructures uniformly dispersed throughout the film and prevent aggregation, a diamine (1,3-bis(aminomethyl)cyclohexane) was added to the AIGS-monomer dispersion before ink formulation. Alternatively, it can be added to the ink formulation after mixing other ink components, such as the scattering medium and photoinitiator, into the AIGS-monomer dispersion. As seen in Figure 14, adding a diamine to the AIGS-monomer dispersion before ink formulation increased the EQE after UV curing and POB. When the diamine was added at 5% w/w of the AIGS inorganic mass, the EQE after UV curing increased by 3%. Further addition of diamine did not further improve the EQE. The effect of the diamine on improving the EQE was even greater after POB. Compared to when no diamine was present in the monomer, the EQE improved by 5% with the addition of 5% diamine. With the addition of 30% diamine, the EQE increased from 25% to 32% and the LRR was 92%, similar to the results seen with the InP green QD film. A side effect of the diamine was an increase in viscosity, as seen in Figure 15. However, for monomers such as ethyl acrylate, the ink viscosity dramatically decreased to levels below 20 cP at room temperature.

As an alternative approach to increasing the EQE, better AIGS surface passivation with diamine was attempted. As shown in Figure 16, the QY of the ligand-exchanged AIGS nanostructures in the presence of diamine was enhanced by more than 12% immediately after LE. It should be noted that the QY of the AIGS nanostructures also improved after thermal treatment, which simulated a hard bake at 180°C for 30 minutes in the presence of monomer. The decrease in QY after 30 minutes at 180°C became smaller with increasing diamine loading in the LE. At 50% w/w diamine in the LE, the QY before and after the thermal process were nearly equal, and the QY after the thermal process was higher when 70% diamine was used in the LE.

The performance of QDCC films using these AIGS nanostructures is plotted in Figure 17. The EQE of the films was better when diamines were used in LE compared to when no diamines were used during LE, and the improvement was even greater with increasing diamine loading up to 50%. The EQE obtained with 70% diamine loading and LE was lower than 30% and 50%. When a higher amount of diamine is used for LE, the amount of diamine incorporated onto the AIGS surface increases, which is presumably a reduction in the amount of ligand and/or monomer on the AIGS surface. The observed decrease in QD mass after LE with diamines is likely the result of fewer ligands and/or monomers on the QD surface. This also occurs when diamines are added to the monomers for LE, resulting in an increase in ink viscosity.

As can be seen in Figure 19, when these two approaches were used to improve film EQE, the effect of diamine on film EQE was highest when the diamine was added to both the ligand exchange and monomer dispersion. Viscosity does not necessarily depend on the total amount of diamine in the ink. The sample with the highest diamine content, where diamine was used in both the LE and monomer dispersion, had an intermediate viscosity. This viscosity was lower than when the same amount of diamine was used in the LE alone.

EQE improvement using diamines in the LE and/or monomer dispersion was tested using 1,3-bis(aminomethyl)cyclohexane and five additional additives listed in Table 16. All additives had similar effects on the initial EQE, with A1, A5, and A6 being slightly better than the others when added directly with the monomer. However, after hard baking, A1 and A6 were the two best additives in the final film EQE. In addition, good EQE was obtained without using the same additive in the LE and monomer additions among the listed amines. Even when the same diamine is used in the LE and monomer additions, its effectiveness in improving EQE can differ. For example, as seen in Figure 23, A6 was as effective at maintaining EQE as A1 when used in the monomer addition, but not as effective as A1 when used in the LE.

While various embodiments have been described above, it should be understood that they have been presented by way of example only, and not limitation. It will be apparent to those skilled in the art that various changes in form and detail can be made therein without departing from the spirit and scope of the invention. Accordingly, the breadth and scope should not be limited by any of the above-described exemplary embodiments, but should instead be defined only in accordance with the following claims and their equivalents.

All publications, patents, and patent applications mentioned in this specification are indicative of the level of skill of those skilled in the art to which this invention pertains and are herein incorporated by reference to the same extent as if each individual publication, patent, or patent application was specifically and individually indicated to be incorporated by reference.

Claims (25)

Ag, In, Ga, and S (AIGS) nanostructures, at least one ligand, and at least one organic resin;
exhibiting a photon conversion efficiency (PCE) of greater than 32% with a peak emission wavelength of 480-545 nm when excited using a blue light source with a wavelength of 450 nm;
the nanostructures have an emission spectrum with a full width at half maximum (FWHM) of less than 40 nm, a quantum yield (QY) of 80-99.9%, and an OD ₄₅₀ /mass (mL ^. mg ^{−1 .} cm ⁻¹ ) of 0.8 or greater;
At least 80% of the emission produced when the nanostructures are excited with the blue light source is band edge emission.
film. Ag, In, Ga, and S (AIGS) nanostructures, at least one ligand, and at least one organic resin;
exhibiting a photon conversion efficiency (PCE) of greater than 32% with a peak emission wavelength of 480-545 nm when excited using a blue light source with a wavelength of 450 nm;
the at least one ligand is a polyamino ligand;
film. 3. The film of claim 2 , wherein the nanostructures have an emission spectrum with a full width at half maximum (FWHM) of less than 40 nm. 4. The film of claim 2 or 3 , wherein the nanostructures have a quantum yield (QY) of 80 to 99.9%. The film of any one of claims 2 to 4 , wherein the nanostructures have an OD ₄₅₀ /mass (mL ^· mg ^{−1 ·} cm ⁻¹ ) of 0.8 or greater. The film of any one of claims 1 to 5 , wherein the nanostructures have an average diameter of less than 10 nm as measured by TEM. The film of claim 2 , wherein at least 80% of the emission produced when the nanostructures are excited with the blue light source is band edge emission. The film of any one of claims 1 , 3 to 7 , wherein the at least one ligand is an amino ligand, a ligand containing a mercapto group, or a ligand containing a silane group. The film of any one of claims 1 , 3 to 7 , wherein the at least one ligand is a polyamino ligand. 10. The film of claim 2 or 9 , wherein the polyamino ligand is a polyaminoalkane, a polyaminocycloalkane, a polyaminoheterocycle, a polyamino-functionalized silicone, or a polyamino-substituted ethylene glycol. 10. The film of claim 2 or 9, wherein the polyamino ligand is a C _2-20 alkane or C _2-20 cycloalkane substituted with two or three amino groups, optionally containing one or two amino groups in place of carbon groups. 10. The film of claim 2 or 9 , wherein the polyamino ligand is 1,3-cyclohexanebis(methylamino), 2,2-dimethyl-1,3-propanediamine, tris(2-aminoethyl)amine, or 2-methyl-1,5-diaminopentane. The at least one ligand is a compound of formula I:
During the ceremony,
x is 1 to 100;
y is 0 to 100;
The film of any one of claims 1 , 3 to 7 , wherein ^R2 is a _C1-20 alkyl. The film of any one of claims 1, 3 to 7, and 13, wherein the at least one ligand is (3-aminopropyl)trimethoxysilane, (3-mercaptopropyl)triethoxysilane, DL-α-lipoic acid, 3,6-dioxa-1,8-octanedithiol, 6-mercapto-1-hexanol, methoxypolyethylene glycolamine, poly(ethylene glycol) methyl ether thiol, diethylphenylphosphonite, dibenzyl N,N-diisopropylphosphoramidite, di-tert-butyl N,N-diisopropylphosphoramidite , tris(2- carboxyethyl )phosphine hydrochloride, poly(ethylene glycol) methyl ether thiol, methoxypolyethylene glycolamine, acrylamide, or polyethyleneimine. The film of any one of claims 1, 3 to 7, 13 and 14, wherein the at least one ligand is a combination of amino-polyalkylene oxide and methoxypolyethylene glycol amine, amino-polyalkylene oxide and 6-mercapto-1-hexanol, amino-polyalkylene oxide and (3- mercaptopropyl )triethoxysilane , and 6-mercapto-1-hexanol and methoxypolyethylene glycol amine. The film of any one of claims 1 to 15 , wherein the at least one organic resin is cured. 17. The film of any one of claims 1 to 16 , which exhibits greater than 95% blue light absorption at 450 nm. 18. The film of any one of claims 1 to 17 , wherein the AIGS nanostructure comprises a gradient from increased gallium from the surface of the nanostructure to decreased gallium at the center of the nanostructure. A method for preparing a film according to any one of claims 1 to 18 , said method comprising:
(a) providing an AIGS nanostructure prepared by a process comprising ion-exchanging with gallium by reacting with an oxygen-free Ga salt and at least one ligand coating the surface of the AIGS nanostructure;
(b) mixing at least one organic resin with the AIGS nanostructures of (a);
(c) preparing a first film on a first barrier layer, the first film comprising the mixed AIGS nanostructures, the at least one ligand coating the surface, and the at least one organic resin;
(d) curing the film; and
(e) encapsulating the first film between the first barrier layer and a second barrier layer;
The method wherein the encapsulated film exhibits a photon conversion efficiency (PCE) of greater than 32% at a peak emission wavelength of 480-545 nm when excited using a blue light source having a wavelength of 450 nm. 20. The method of claim 19 , wherein the method is performed before exposing the encapsulated film to a blue LED light source in air. 21. The method of claim 19 or 20 , wherein the method is carried out under an inert atmosphere. The method comprises:
22. The method of claim 19, further comprising: adding at least one oxygen-reactive material to the mixture of AIGS nanostructures and ligands in (a); adding at least one oxygen-reactive material to the mixture in (b); and/or forming a second film comprising at least one oxygen-reactive material on the first film prepared in (c); and/or forming a sacrificial barrier layer on the first film prepared in (c) that temporarily blocks oxygen and/or water ; measuring the PCE of the film; and then removing the sacrificial barrier layer. The method of any one of claims 19 to 22 , wherein the two barrier layers exclude oxygen and/or water. In the above (a), the oxygen-free Ga salt is oxygen-free GaX ₃ (wherein X is F, Cl, or Br). The method according to any one of claims 19 to 24, wherein in (a), the AIGS nanostructure is an AIGS nanostructure prepared by a process comprising using the oxygen-free Ga salt and an oxygen-free ligand, and reacting the oxygen-free Ga salt to perform ion exchange with gallium.