JP7236002B2 - light emitting device - Google Patents

Description

TECHNICAL FIELD The present invention relates to a light-emitting device, and more particularly to a light-emitting device comprising a light-emitting element that emits blue light and a quantum dot that absorbs part of the blue light emitted by the light-emitting element and emits green light.

As a light-emitting device that emits white light, a light-emitting element that emits blue light and a green phosphor that absorbs part of the blue light emitted by the light-emitting element and emits green light (or a yellow-green phosphor that emits yellow-green light) are used. and a red phosphor that absorbs part of the blue light emitted by the light emitting element and emits red light. Light-emitting devices that emit such white light are used in various applications including backlights and lighting devices for various displays such as liquid crystal displays.

In recent years, light-emitting devices have been developed in which all or part of phosphors are replaced with quantum dots (QDs). A quantum dot is a semiconductor particle having a diameter of several nanometers to several tens of nanometers, and like a phosphor, it absorbs light such as blue light emitted by a light-emitting element, and emits light different from the absorbed light. .
A green quantum dot that absorbs blue light emitted by a light emitting element and emits green light, and a red quantum dot that absorbs blue light emitted by a light emitting element and emits red light, without including a green phosphor and a red phosphor Light-emitting devices including quantum dots are known. Also, Patent Literature 1 discloses a light-emitting device including a yellow-green phosphor and red quantum dots.

Quantum dots are characterized by their sharp emission peaks, that is, their emission peaks have a small (narrow) half width. Therefore, a light-emitting device using quantum dots has the advantage of widening the color reproduction range when combined with a color filter such as a liquid crystal display. Furthermore, by matching the peak wavelength of the color filter (the wavelength at which the transmittance peaks) to the emission peak of the quantum dots, more light can pass through the color filter, resulting in light attenuation when using the color filter. is reduced, and the light extraction efficiency is improved.
In particular, conventional green phosphors and yellowish-green phosphors have broad emission peaks, so that the use of green quantum dots makes it possible to obtain these effects more remarkably.

JP-A-2008-544553

However, conventional light-emitting devices using such quantum dots use red quantum dots, which causes a problem of secondary absorption. That is, the red quantum dots absorb part of the green light (or yellow-green light) emitted by the green quantum dots or green phosphor (or yellow-green phosphor) that has absorbed blue light, and emit red light. When such secondary absorption occurs, there is a problem that the luminous efficiency of the entire light emitting device is lowered.
On the other hand, many applications such as displays and lighting devices require light emitting devices that can emit brighter light with less power consumption, ie, have higher luminous efficiency.

The present invention has been made to meet such a demand, and provides a light-emitting device that uses quantum dots, particularly green quantum dots, and has high luminous efficiency.

A light-emitting element that emits blue light, a quantum dot that absorbs part of the blue light emitted by the light-emitting element and emits green light, and the composition thereof is represented by the following general formula (1), and the light-emitting element A KSF phosphor that absorbs part of the emitted blue light and emits red light and its composition are represented by the following general formula (2), and absorb part of the blue light emitted by the light emitting element to emit red light and at least one of an MGF phosphor that emits

_{A2 [} M1 _- aMn4 ⁺ _aF6 ] (1)
(Wherein, A is at least one selected from the group consisting of K ⁺ , Li ⁺ , Na ⁺ , Rb ⁺ , Cs ⁺ and NH ₄ ⁺ , and M is from Group 4 elements and Group 14 elements is at least one element selected from the group consisting of a satisfying 0<a<0.2.)

(xa)MgO.(a/2 ₎ Sc2O3.yMgF2.cCaF2 _. (1 _- b)GeO2 _. (b/2) _{Mt2O3 :} ^zMn4+ ₍ 2)
(In the formula, x, y, z, a, b, and c are 2.0≦x≦4.0, 0<y<1.5, 0<z<0.05, 0≦a<0.5, satisfying 0<b<0.5, 0≤c<1.5, y+c<1.5, and Mt is at least one selected from Al, Ga, and In.)

A light-emitting device using quantum dots, particularly green quantum dots, and having high luminous efficiency can be provided.

FIG. 1 is a schematic cross-sectional view of a light emitting device 100 according to Embodiment 1 of the present invention. FIG. 2 is a schematic cross-sectional view of a light emitting device 100A according to Embodiment 2 of the present invention. 3A and 3B are schematic cross-sectional views for explaining advantages of the light emitting device 100, and FIG. 3A is a schematic cross-sectional view showing an embodiment in which the red phosphor 14 is arranged inside the sealing resin 12. , and FIG. 3B is a schematic cross-sectional view showing an embodiment in which the red phosphor 14 is arranged inside the translucent material 22 . FIG. 4 is a schematic cross-sectional view showing a liquid crystal display 200 using a light emitting device 100B according to Embodiment 3 of the present invention.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, it should be noted that the embodiments described below are intended to embody the technical idea of the present invention and are not intended to limit the technical scope of the present invention. Configurations described in one embodiment are also applicable to other embodiments unless otherwise specified. In the following description, terms indicating specific directions and positions (e.g., "upper", "lower", "right", "left", and other terms including those terms) are used as necessary, but they are is used to facilitate understanding of the invention with reference to the drawings, and the technical scope of the present invention is not limited by the meaning of these terms.
It should be noted that the sizes, positional relationships, etc. of members shown in each drawing may be exaggerated for clarity of explanation. Also, parts with the same reference numerals appearing in a plurality of drawings indicate the same parts or members. Furthermore, members indicated by a code consisting of a number and an alphabet, such as code "10A", have the same number but no alphabet, such as code "10", unless otherwise specified. It may have the same configuration as the members indicated by and the members indicated by the reference numerals having the same numerals and different alphabets.

As a result of intensive studies, the inventors of the present application have found that by using at least one of the KSF phosphor and the MGF phosphor as the red phosphor instead of using the red quantum dots, it is possible to achieve high luminous efficiency using green quantum dots. It was found that a light-emitting device having The KSF phosphor and the MGF phosphor, which will be detailed later, absorb blue light emitted by the light emitting element and emit red light, but hardly absorb green light emitted by the green quantum dots. That is, no secondary absorption occurs. Therefore, the light emitting device according to the embodiment of the present invention has high luminous efficiency. In addition, the peaks in the emission spectra of the KSF phosphor and the MGF phosphor have a narrow half width of about 10 to 20 nm. Therefore, even when the light is passed through a color filter that transmits substantially the entire wavelength range of red, red light with a narrow half-value width can be obtained, so that red light with high color purity can be obtained.
Light-emitting devices according to multiple embodiments of the present invention will be described in detail below.

1. Embodiment 1
FIG. 1 is a schematic cross-sectional view of a light emitting device 100 according to Embodiment 1 of the present invention. The light emitting device 100 includes a light emitting element 1 that emits blue light, a green quantum dot 24 that absorbs part of the blue light emitted by the light emitting element 1 and emits green light, and part of the blue light emitted by the light emitting element 1. and a red phosphor 14 that emits red light. The red phosphor 14 is at least one of a KSF phosphor and an MGF phosphor, details of which will be described later.

In the light-emitting device according to the present invention, the positional relationship of the red phosphor 14 and the green quantum dots 24 with respect to the light-emitting element 1 is not particularly limited. That is, (1) the red phosphor 14 may be positioned closer to the light emitting element 1 than the green quantum dots 24, and (2) the red phosphor 14 may be closer to the light emitting element 1. , may be positioned farther than the green quantum dot 24, and (3) the red phosphor 14 and the green quantum dot 24 are positioned at approximately the same distance from the light emitting element 1 as in Embodiment 2 described later. You can
In Embodiment 1, the red phosphor 14 is positioned closer to the light emitting element 1 than the green quantum dots 24 are.

A light emitting device 100 includes a light emitting device package 10 . The light emitting device package 10 includes a resin package 3 having a bottom surface, side walls, a cavity surrounded by the bottom surface and the side walls and having an open top, a light emitting device 1 disposed on the bottom surface of the cavity of the resin package 3, and a sealing resin 12 filled in the cavity of the resin package 3 . The light-emitting element 1 has its positive and negative electrodes connected to an external power supply via a conductive means such as a metal wire, metal bump, or plating, and emits blue light when current (power) is supplied from the external power supply. do. The sealing resin 12 covers the periphery of the light emitting element 1 (in the embodiment shown in FIG. 1, the top surface and side surfaces of the light emitting element 1 excluding the bottom surface). The encapsulating resin 12 contains a red phosphor 14 . That is, the red phosphors 14 are dispersedly arranged inside the sealing resin 12 .
In addition, in the embodiment shown in FIG. 1, the red phosphors 14 are uniformly dispersed in the sealing resin 12, but the form of dispersion arrangement of the red phosphors is not limited to this. The red phosphor 14 may be arranged at a higher density in a part of the sealing resin 12 , such as being arranged at a higher density in the vicinity of the light emitting element 1 . As such an arrangement, there is a so-called sedimentation arrangement in which the dispersion density of the red phosphor is small at the top of the sealing resin and high at the bottom of the sealing resin 12 (including directly above the light emitting element 1). In the sedimentation arrangement, for example, after the cavity of the resin package 3 is filled with the uncured sealing resin 12 in which the red phosphor 14 is uniformly dispersed, the uncured sealing resin 12 is allowed to stand for a predetermined time. , the red phosphor 14 in the encapsulating resin 12 is moved by gravity and its distribution becomes higher at the bottom of the encapsulating resin 12, and then the encapsulating resin 12 is cured. It may be sedimented by centrifugal force.

The light emitting device package 10 has its upper surface as an emission surface, and emits blue light and red light. More specifically, part of the blue light emitted from the light emitting element 1 is transmitted through the sealing resin 12 and emitted outward from the upper surface of the sealing resin 12 . Even if part of the blue light emitted from the light emitting device package 10 is reflected from the side and/or bottom surface of the resin package 3 while traveling inside the sealing resin 12, it may be emitted from the upper surface of the sealing resin 12. good. Another part of the blue light emitted from the light emitting element 1 is absorbed by the red phosphor 14 while traveling inside the sealing resin 12, and the red phosphor 14 emits red light. The red light emitted from the red phosphor 14 is transmitted through the sealing resin 12 and emitted outward from the upper surface of the sealing resin 12 . A part of the red light emitted by the red phosphor 14 may be reflected from the side surface and/or the bottom surface of the resin package 3 while traveling inside the sealing resin 12 , and then emitted from the upper surface of the sealing resin 12 . .

A green quantum dot-containing layer 20 is arranged outside the sealing resin 12, that is, on top of the sealing resin 12 (or the resin package 3) in FIG. Green quantum dot-containing layer 20 includes translucent material 22 and green quantum dots 24 . That is, the green quantum dots 24 are dispersed within the translucent material 22 . The green quantum dot-containing layer 20 may have any morphology. One of the preferred forms is a sheet shape (or film shape) as shown in FIG. This is because the thickness of the green quantum dot-containing layer 20 can be made uniform, and color unevenness can be suppressed.

With such a configuration, in the light-emitting device 100 , the red phosphor 14 is positioned closer to the light-emitting element 1 than the green quantum dots 24 . A KSF phosphor or MGF phosphor having a large particle size (or diameter) of, for example, 20 to 50 μm is placed near the light emitting element, and green quantum dots 24 having a particle size (or diameter) of, for example, 2 to 10 nm are formed. By arranging it near the light emitting element 1, it is possible to suppress scattering of light, especially scattering of green light by the red phosphor 14, and as a result, it is possible to further improve the light extraction efficiency (that is, luminous efficiency).
The improvement of the light extraction efficiency will be described in detail after the configuration of the second embodiment is described later.

Most of the red light emitted from the top surface of the light emitting device package 10 enters the inside from the bottom surface of the green quantum dot containing layer 20, and after passing through the translucent material 22 of the green quantum dot containing layer 20, the green quantum dot containing It exits from the upper surface of layer 20 to the outside.
Most of the blue light emitted from the top surface of the light emitting device package 10 enters from the bottom surface of the green quantum dot containing layer 20 . Part of the blue light entering from the bottom surface of the green quantum dot-containing layer 20 passes through the translucent material 22 of the green quantum dot-containing layer 20, and then exits from the top surface of the green quantum dot-containing layer 20. . Another part of the blue light entering from the lower surface of the green quantum dot containing layer 20 is absorbed by the green quantum dots 24, and the green quantum dots 24 emit green light. Most of the green light emitted by the green quantum dots 24 travels inside the translucent material 22 and exits from the upper surface of the green quantum dot-containing layer 20 to the outside. As a result, outside the upper surface of the green quantum dot-containing layer 20, blue light, red light, and green light are mixed to obtain white light.

Part of the green light emitted by the green quantum dots 24 travels downward, exits from the bottom surface of the green quantum dot-containing layer 20 , and enters the sealing resin 12 from the top surface of the light emitting device package 10 . However, the red phosphor 14, which is at least one of the KSF phosphor and the MGF phosphor, does not easily absorb green light. For this reason, for example, after being reflected by the inner surface of the resin package 3 , the green light emitted from the upper surface of the light-emitting device package 10 enters from the lower surface of the green quantum dot-containing layer 20 and exits from the upper surface of the green quantum dot-containing layer 20 . there is light The existence of such green light contributes to improvement in the extraction efficiency of the light emitting device 100 .

In the embodiment shown in FIG. 1, the green quantum dot-containing layer 20 and the sealing resin 12 (or resin package 3) are separated. As a result, it is possible to more reliably suppress the transmission of heat generated by the light emitting element 1 to the green quantum dots 24 that are vulnerable to heat.
However, it is not limited to this, and the green quantum dot-containing layer 20 and the sealing resin 12 (or the resin package 3) may be in contact with each other. In this case, more light emitted from the light-emitting device package 10 enters the green quantum dot-containing layer 20, making it possible to further increase the extraction efficiency. Even if the green quantum dot containing layer 20 and the sealing resin 12 (or the resin package 3) are in contact with each other, the light emitting element 1 and the green quantum dots 24 are separated from each other to some extent. An effect of suppressing thermal deterioration can be obtained.

In the embodiment shown in FIG. 1, the light emitting device package 10 has a bottom surface (lower surface) as a mounting surface, and a surface opposite to the light extraction surface as a mounting surface (for example, an upper surface as a light extraction surface, It is a top-view type light-emitting device package (with the lower surface as the mounting surface). However, the light-emitting device package 10 is not limited to this, and may be configured as a so-called side-view type in which a surface adjacent to the light extraction surface is used as a mounting surface.
Further, although the light emitting device package 10 including the resin package 3 is used in the embodiment shown in FIG. 1, the present invention is not limited to this. Instead of the light emitting element package 10, a so-called packageless form in which a phosphor layer containing the red phosphor 14 is formed on the surface of the light emitting element 1 without using a resin package may be used.

Next, details of each element of the light emitting device 100 are shown.
1) Light-Emitting Element The light-emitting element 1 may be any known light-emitting element, and may be a blue LED chip, as long as it emits blue light (having an emission peak wavelength in the range of 435 to 465 nm). The light emitting device 1 may include a semiconductor laminate, and preferably includes a nitride semiconductor laminate. A semiconductor laminate (preferably a nitride semiconductor laminate) may have, in order, a first semiconductor layer (eg, n-type semiconductor layer), a light-emitting layer, and a second semiconductor layer (eg, p-type semiconductor layer).
As a preferred nitride semiconductor material, specifically, In _X Al _Y Ga _1-XY N (0≦X, 0≦Y, X+Y≦1) may be used. The film thickness and layer structure of each layer may be those known in the art.

2) Red Phosphor The red phosphor 14 is at least one of a KSF phosphor and an MGF phosphor. The KSF and MGF phosphors have the advantage that they absorb little green light and therefore produce little secondary absorption. Further, the half width of the emission peak is as small as 35 nm or less, preferably 10 nm or less. The KSF phosphor and MGF phosphor are described in detail below.

(KSF phosphor)
The KSF phosphor is a red phosphor whose emission wavelength peak is in the range of 610-650 nm. Its composition is represented by the following general formula (1).

_{A2 [} M1 _- aMn4 ⁺ _aF6 ] (1)
(Wherein, A is at least one selected from the group consisting of K ⁺ , Li ⁺ , Na ⁺ , Rb ⁺ , Cs ⁺ and NH ₄ ⁺ , and M is from Group 4 elements and Group 14 elements is at least one element selected from the group consisting of a satisfying 0<a<0.2.)

The half width of the emission peak of the KSF phosphor is 10 nm or less.
For this KSF phosphor, reference may be made to Japanese Patent Application No. 2014-122887 filed earlier by the applicant of the present application.

An example of a method for manufacturing a KSF phosphor will be described. First, KHF ₂ and K ₂ MnF ₆ are weighed so as to obtain a desired composition ratio. A solution A is prepared by dissolving a weighed amount of KHF ₂ in an aqueous HF solution. Also, a solution B is prepared by dissolving the weighed K ₂ MnF ₆ in an aqueous HF solution. Further, an aqueous solution containing H ₂ SiF ₆ is prepared so as to have a desired composition ratio to obtain a solution C containing H ₂ SiF ₆ . Then, while stirring the solution A at room temperature, the solution B and the solution C are added dropwise. The obtained precipitate is subjected to solid-liquid separation, washed with ethanol, and dried to obtain a KSF phosphor.

(MGF phosphor)
MGF is a red phosphor that emits deep red fluorescence. That is, the peak of the emission wavelength is 650 nm or more on the longer wavelength side than that of the KSF phosphor, and the phosphor is activated with Mn ⁴⁺ . An example of the compositional formula is 3.5MgO·0.5MgF ₂ ·GeO ₂ :Mn ⁴⁺ . The half width of the MGF phosphor is 15 nm or more and 35 nm or less.

In the MGF phosphor, some of the Mg elements of MgO in its composition are Li, Na, K, Sc, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er , Tm, Yb, Lu, V, Nb, Ta, Cr, Mo, W, etc., and part of the Ge element in GeO ₂ may be replaced by other elements such as B, Al, Ga, In, etc. You may improve luminous efficiency by substituting with the element of. Preferably, by substituting Sc and Ga for both Mg and Ge, respectively, the emission intensity of light in the 600 to 670 nm wavelength region called deep red can be further improved.

The MGF phosphor is a phosphor represented by the following general formula (2).

(xa)MgO.(a/2 ₎ Sc2O3.yMgF2.cCaF2 _. (1 _- b)GeO2 _. (b/2) _{Mt2O3 :} ^zMn4+ ₍ 2)
(In the formula, x, y, z, a, b, and c are 2.0≦x≦4.0, 0<y<1.5, 0<z<0.05, 0≦a<0.5, satisfying 0<b<0.5, 0≤c<1.5, y+c<1.5, and Mt is at least one selected from Al, Ga, and In.)

By setting 0.05≦a≦0.3 and 0.05≦b<0.3 in the general formula (2), the brightness of the emitted red light can be further improved. As for the MGF phosphor, reference may be made to Japanese Patent Application No. 2014-113515 previously filed by the applicant of the present application.

An example of the manufacturing method of the MGF phosphor according to the embodiment of the present invention will be described. First, MgO, MgF ₂ , Sc ₂ O ₃ , GeO ₂ , Ga ₂ O ₃ and MnCO ₃ as raw materials are weighed so as to obtain a desired composition ratio. After mixing these raw materials, the mixed raw materials are charged in a crucible and fired at 1000 to 1300° C. in the atmosphere.

3) Green Quantum Dots The green quantum dots 24 are semiconductor materials, for example compound semiconductors of Groups II-VI, III-V or IV-VI, more specifically CdSe, core-shell CdS _x Se ₁ Nano-sized particles such as _-x /ZnS and GaP can be used. The green quantum dots 24 have, for example, a particle size (average particle size) of 1 to 20 nm. The green quantum dots 24, for example, emit green light with a peak emission wavelength in the range of 510-560 nm. The half width of the emission peak of the green quantum dots 24 is as small as 40 nm or less, preferably 30 nm or less.
Green quantum dots may be surface-modified or stabilized, for example, with resins such as PMMA (polymethyl methacrylate). In this case, the particle size means the particle size of the core portion made of the semiconductor material, which does not include the portion such as the resin attached for surface modification and stabilization.

4) Translucent Material The translucent material 22 can transmit blue light, green light and red light. The translucent material preferably transmits 60% or more, more preferably 70% or more, 80% or more, or 90% or more of the light emitted from the light emitting element 1 and incident on the translucent material 22 .
Preferred translucent materials 22 include high strain point glass, soda glass (Na2O.CaO.SiO2 ₎ , borosilicate glass ( _{Na2O.B2O3.SiO2 )} , _and forsterite ( _{2MgO.SiO2 ) .} ), lead glass (Na ₂ O.PbO.SiO ₂ ), and alkali-free glass. Alternatively, polymethyl methacrylate (polymethyl methacrylate, PMMA), polyvinyl alcohol (PVA), polyvinylphenol (PVP), polyethersulfone (PES), polyimide, polycarbonate (PC), polyethylene terephthalate (PET), polystyrene (PS) , polyethylene naphthalate (PEN), cyclic amorphous polyolefins, polyfunctional acrylates, polyfunctional polyolefins, unsaturated polyesters, epoxy resins, and silicone resins. polymer materials such as plastic films, plastic sheets, and plastic substrates).

5) Sealing resin The sealing resin 12 can transmit blue light and red light, and preferably also transmit green light. The translucent material preferably transmits 60% or more, more preferably 70% or more, 80% or more, or 90% or more of the light emitted from the light emitting element 1 and incident on the translucent material 22 .
Preferred sealing resins 12 include silicone resins, silicone-modified resins, epoxy resins, epoxy-modified resins, phenol resins, polycarbonate resins, acrylic resins, TPX resins, polynorbornene resins, and hybrid resins containing at least one of these resins. can be mentioned. Of these, silicone resins and epoxy resins are preferred, and silicone resins, which are particularly excellent in light resistance and heat resistance, are more preferred.

6) Resin Package The resin package 3 may be made of any kind of resin. Preferred resins include thermoplastic resins containing at least one of aromatic polyamide resins, polyester resins, and liquid crystal resins, epoxy resins, modified epoxy resins, phenolic resins, silicone resins, modified silicone resins, hybrid resins, acrylate resins, and urethane resins. Examples include resins and thermosetting resins containing at least one of these resins. The resin package 3 is preferably made of white resin. This is because more of the light that has reached the resin package 3 out of the light that travels inside the sealing resin 12 can be reflected.

2. Embodiment 2
FIG. 2 is a schematic cross-sectional view of a light emitting device 100A according to Embodiment 2 of the present invention. In the light emitting device 100 described above, the sealing resin 12 contains the red phosphor 14 . However, in the light-emitting device 100</b>A, the translucent material 22 contains the red phosphor 14 instead of the sealing resin 12 containing the red phosphor 14 . Therefore, the red phosphor 14 and the green quantum dots 24 are arranged inside the translucent material 22 , so that the distance between the red phosphor 14 and the green quantum dots 24 is approximately the same with respect to the light emitting element 1 . will be located in

The light-emitting element package 10A may have the same configuration as the light-emitting element package 10 of the first embodiment except that the sealing resin 12 does not contain the red phosphor 14 . Also, the green quantum dot-containing layer 20A may have the same configuration as the green quantum dot-containing layer 20 of the first embodiment except that it contains the red phosphor 14 in addition to the green quantum dots 24 .

As described above, in the light-emitting device 100 according to Embodiment 1, the red phosphor 14 is positioned closer to the light-emitting element 1 than the green quantum dots 24, and the light-emitting device according to Embodiment 2 In 100A, the red phosphor 14 and the green quantum dot 24 are located at approximately the same distance from the light emitting element 1. FIG. Each embodiment has different advantages. The advantages are described below.

1) Advantages of Light Emitting Device 100 FIGS. 3A and 3B are schematic cross-sectional views for explaining advantages of the light emitting device 100. FIG. It is a schematic cross-sectional view showing an embodiment, and FIG. 3B is a schematic cross-sectional view showing an embodiment in which a red phosphor 14 is arranged inside a translucent material 22 . As described above, the particle size of the red phosphor 14 is 20 to 50 μm, and the particle size of the green quantum dot 24 is 2 to 10 nm.
FIGS. 3A and 3B are schematic diagrams intended to more clearly show the advantage of the light-emitting device 100 based on the difference in particle size. Compared to FIGS. 1 and 2, the red phosphor The difference in particle size between 14 and green quantum dots 24 is shown more clearly.

Reference numeral 114 in FIG. 3A schematically indicates red light (part) emitted by the red phosphor 14X, which is one of the plurality of red phosphors 14, and reference numeral 124 indicates a plurality of green quanta. Green light (part) emitted by a green quantum dot 24X, which is one of the dots 24, is schematically shown. Similarly, reference numeral 114A in FIG. 3B schematically indicates red light (part) emitted by the red phosphor 14Y, which is one of the plurality of red phosphors 14, and reference numeral 124A indicates a plurality of red phosphors 14Y. 1 schematically shows green light (a part) emitted by a green quantum dot 24Y, which is one of the green quantum dots 24 of .

As shown in FIG. 3B, when the red phosphor 14 having a large particle size is arranged in the translucent material 22, the green light 124A emitted from the green quantum dot 24Y is emitted from the red light existing in its path. The red light 114A is scattered by the phosphor 14 and does not reach the top surface of the green quantum dot-containing layer 20A (in FIG. 3B, the red light 114A is emitted from the top surface of the green quantum dot-containing layer 20A, but the green light 124A does not reach the upper surface of the green quantum dot-containing layer 20A). Such scattering of part of the green light caused by the presence of the red phosphor 14 having a large particle size in the green quantum dot-containing layer 20A can be a factor in slightly lowering the luminous efficiency.

On the other hand, as shown in FIG. 3( a ), the green quantum dot-containing layer 20 does not contain the red phosphor 14 having a large particle size, and the green quantum dots 24 contains only And the green light traveling through the green quantum dot-containing layer 20 is much less likely to be scattered by the green quantum dots 24 with very small particle sizes (in FIG. 3( a ), the red light 114 and the green light 124 are green It protrudes outside from the upper surface of the quantum dot containing layer 20.). Therefore, higher luminous efficiency can be obtained.

2) Advantages of Light Emitting Device 100A Green quantum dot-containing layer 20A of light emitting device 100A contains both red phosphor 14 and green quantum dots 24 as described above. Although the red phosphor 14 is less susceptible to heat deterioration than the green quantum dots 24 , by adopting such a configuration, it is possible to suppress transmission of heat generated by the light emitting element 1 to the red phosphor 14 as well. , the deterioration of the red phosphor 14 can be suppressed more reliably.
In addition, since the red phosphor 14 and the green quantum dots 24 are arranged inside the translucent material 22 , the wavelength conversion material can be arranged only in the translucent material 22 , and the sealing resin 12 can contain the red phosphor and the green quantum dots 24 . Since it is not necessary to arrange 14, the manufacturing process is simplified.

As described above, in the light-emitting device 100A, the translucent material 22 of the green quantum dot-containing layer 20A contains the red phosphor 14, and the sealing resin 12 of the light-emitting element package 10A does not contain the red phosphor 14. Both the translucent material 22 of the green quantum dot containing layer 20A and the sealing resin 12 of the light emitting device package 10A may contain the red phosphor 14 .

3. Embodiment 3
FIG. 4 is a schematic cross-sectional view showing a liquid crystal display 200 using a light emitting device 100B according to Embodiment 3 of the present invention. The light emitting device 100B includes a light emitting device package 10 , a green quantum dot containing layer 20 , and a light guide plate 52 arranged between the light emitting device package 10 and the green quantum dot containing layer 20 .
In the embodiment shown in FIG. 4 , a light guide plate 52 is arranged between the sealing resin 12 of the light emitting device package 10 and the green quantum dot containing layer 20 . More specifically, the sealing resin 12 is arranged to face one side surface of the light guide plate 52 , and the green quantum dot-containing layer 20 is arranged to face the upper surface of the light guide plate 52 . In the embodiment shown in FIG. 4, the light emitting device package 10 is of a top-view type, but is not limited to this, and may have other forms such as the above-described side-view type.

The light-emitting device 100</b>B has the light-guide plate 52 arranged such that the light that has reached the lower surface of the light-guide plate 52 out of the light incident on the light-guide plate 52 from the light-emitting element package 10 is reflected upward and directed toward the upper surface of the light-guide plate 52 . A reflector 51 may be provided on the lower surface.

In the embodiment shown in FIG. 4, the light emitting device package 10 is arranged apart from the light guide plate 52, but this is not restrictive. The light emitting device package 10 and the light guide plate 52 may be brought into contact with each other by, for example, contacting the side surface of the light emitting device package 10 .
The green quantum dot-containing layer 20 may be arranged in contact with the upper surface of the light guide plate 52 or may be arranged apart from the light guide plate 52 .

A lower polarizing film 53A is arranged on the green quantum dot-containing layer 20 . A liquid crystal cell 54 is arranged on the lower polarizing film 53A, and a color filter array 55 is arranged on the liquid crystal cell 54. As shown in FIG. The color filter array 55 includes, for example, a red color filter portion 55A, a green color filter portion 55B, and a blue color filter portion 55C. have a department. An upper polarizing film 53B is arranged on the color filter array 55 .

Next, the operation of the liquid crystal display 200 will be described. A part of the blue light emitted by the light emitting element 1 is absorbed by the red phosphor 14 arranged in the sealing resin 12 , and red light is emitted from the red phosphor 14 . come out from That is, the light emitting device package 10 emits violet light in which blue light and red light are mixed, and this violet light (blue light + red light) enters the green quantum dot-containing layer 20 via the light guide plate 52. . A portion of the blue light entering the green quantum dot-containing layer 20 is absorbed by the green quantum dots 24, and the green quantum dots 24 emit green light. As a result, white light in which blue light, green light, and red light are mixed is emitted from the upper surface of the green quantum dot-containing layer 20, and this white light enters the lower polarizing film 53A. Part of the white light (blue light+green light+red light) entering the lower polarizing film 53A passes through the lower polarizing film 53A and enters the liquid crystal cell 54. FIG. Part of the white light entering the liquid crystal cell 54 passes through the liquid crystal cell 54 and reaches the color filter array 55 .

Each of the blue light, green light, and red light that reaches the color filter array 55 can pass through the corresponding filter section. For example, red light passes through red color filter portion 55A, green light passes through green color filter portion 55B, and blue light passes through blue color filter portion 55C. Part of each of the blue, green and red light that has passed through the color filter array 55 passes through the upper polarizing film 53B. Thereby, the liquid crystal display 200 can display a desired image.
As described above, the red light emitted by the red phosphor 14 and the green light emitted by the green quantum dots 24 have narrow half widths of emission peaks, and thus have high color purity. Further, since more light can pass through the red color filter portion 55A and the green color filter portion 55B, the efficiency can be improved.
The present invention includes the following aspects.

Aspect 1:
a light-emitting element that emits blue light;
A quantum dot that absorbs part of the blue light emitted by the light emitting element and emits green light;
The composition is represented by the following general formula (1), the KSF phosphor that absorbs part of the blue light emitted by the light emitting element and emits red light, and the composition thereof are represented by the following general formula (2): at least one MGF phosphor that absorbs part of the blue light emitted by the light emitting element and emits red light;
A light-emitting device comprising:

_{A2 [} M1 _- aMn4 ⁺ _aF6 ] (1)
(Wherein, A is at least one selected from the group consisting of K ⁺ , Li ⁺ , Na ⁺ , Rb ⁺ , Cs ⁺ and NH ₄ ⁺ , and M is from Group 4 elements and Group 14 elements is at least one element selected from the group consisting of a satisfying 0<a<0.2.)

(xa)MgO.(a/2 ₎ Sc2O3.yMgF2.cCaF2 _. (1 _- b)GeO2 _. (b/2) _{Mt2O3 :} ^zMn4+ ₍ 2)
(In the formula, x, y, z, a, b, and c are 2.0≦x≦4.0, 0<y<1.5, 0<z<0.05, 0≦a<0.5, satisfying 0<b<0.5, 0≤c<1.5, y+c<1.5, and Mt is at least one selected from Al, Ga, and In.)
Aspect 2:
a sealing resin covering the light emitting element;
a quantum dot-containing layer containing a translucent material and the quantum dots and arranged outside the sealing resin;
The light-emitting device according to aspect 1, comprising:
Aspect 3:
The light-emitting device according to aspect 2, wherein the sealing resin contains the KSF phosphor.
Aspect 4:
The light-emitting device according to aspect 2 or 3, wherein the quantum dot-containing layer is a sheet and is separated from the sealing resin.
Aspect 5:
The light-emitting device according to mode 3 or 4, wherein a light guide plate is arranged between the sealing resin and the quantum dot-containing layer.
Aspect 6:
The light-emitting device according to aspect 5, wherein the sealing resin is arranged to face one side surface of the light guide plate, and the quantum dot-containing layer is arranged to face the upper surface of the light guide plate. .
Aspect 7:
The light-emitting device according to aspect 2, wherein the KSF phosphor is disposed in the quantum dot-containing layer.

1 Light emitting element 3 Resin packages 10, 10A Light emitting element package 12 Sealing resin 14 Red phosphors 20, 20A Green quantum dot containing layer 22 Translucent material 24, 24X, 24Y Green quantum dots 51 Reflector 52 Light guide plate 53A Bottom Polarizing film 53B Upper polarizing film 54 Liquid crystal cell 55 Color filter array 55A Red color filter section 55B Green color filter green 55C Blue color filter section 100, 100A, 100B Light emitting device 114, 114A Red light 124, 124A Green light 200 Liquid crystal display

Claims (9)

a light-emitting element that emits blue light;
A quantum dot that absorbs part of the blue light emitted by the light emitting element and emits green light;
a phosphor that absorbs part of the blue light emitted by the light emitting element and emits red light;
a sealing resin covering the light emitting element;
a quantum dot-containing layer that includes a translucent material and the quantum dots, and is spaced apart from the sealing resin;
The phosphor is arranged in the quantum dot-containing layer,
A light-emitting device, wherein the half width of the emission peak of the phosphor is 35 nm or less. 2. The light emitting device according to claim 1, wherein said sealing resin does not contain said phosphor. 3. The light-emitting device according to claim 1, wherein the quantum dot-containing layer is a sheet. 4. The light emitting device according to claim 2, wherein a light guide plate is arranged between said sealing resin and said quantum dot containing layer. 5. The light emission according to claim 4, wherein the sealing resin is arranged to face one side surface of the light guide plate, and the quantum dot-containing layer is arranged to face the upper surface of the light guide plate. Device. 6. The light emitting device according to claim 1, wherein the half width of the emission peak of said phosphor is 10 nm or less. The light-emitting device according to any one of claims 1 to 6, wherein the quantum dots have a particle size of 2 to 10 nm. The light-emitting device according to any one of claims 1 to 7, wherein the half width of the emission peak of the quantum dots is 40 nm or less. The light-emitting device according to any one of claims 1 to 8, wherein the particle size of the quantum dots is smaller than the particle size of the phosphor.

Images