JP7112708B2 - Organic EL element - Google Patents

Description

The present invention relates to a coating type organic EL element.

Organic EL is a phenomenon of self-luminescence when current is injected, and organic EL devices (OLEDs) using this phenomenon have features such as wide viewing angle, high contrast, ultra-thin structure, low voltage drive, and high response speed. Therefore, it is expected to be applied to lighting and displays as a next-generation surface emitting device.

A vapor deposition type and a coating type are known as such OLED production processes. Among these, the coating type OLED is advantageous in terms of large area and low cost, but generally the coating type OLED tends to be inferior in performance to the vapor deposition type OLED, and there is a problem in improving the luminous efficiency. In order to improve the luminous efficiency, it is effective to separate the functions of charge transport and light emission by stacking different organic materials in order to efficiently recombine electrons and holes in the light-emitting layer. must be prevented from re-dissolving. Until now, the materials that can be used for the lower layer have been limited to some polymers with excellent solvent resistance. From the viewpoint of high purity and easy control of the molecular structure, there is a demand for a technology that can form a laminated structure even with low-molecular-weight materials. It is

In addition, large organic EL displays of 50 inches or more require higher brightness than small and medium-sized displays, and the tandem type (multi-photon type), which is a long-life technology already used in vapor deposition, is indispensable. It is said that In order to improve the performance of tandem-type organic EL devices, which are expected to achieve both high brightness and long life, it is necessary to improve the performance of the electron injection layer (EIL) and the adjacent upper charge generation layer (CGL). In particular, the EIL must simultaneously achieve excellent electron injection properties, a solvent permeation prevention function for preventing permeation of the upper layer coating solvent into the lower layer, and high driving stability. So far, we have reduced zinc oxide nanoparticles (ZnONPs) and ethoxylated polyethyleneimine (PEIE) for EIL and phosphomolybdic acid (PMA) for CGL (Non-Patent Document 1). It has been found that PMA can be driven at a low voltage without post-treatment after film formation.

Pu et al., Adv. Mater. 2015, 27, 1327-1332.

However, since reduced PMA is mainly soluble in alcoholic solvents, it cannot be applied and laminated onto the underlying PEIE, which is soluble in alcoholic solvents. As a method of solving such a problem, there is a method of cross-linking PEIE to make it insoluble. there were. Therefore, it was necessary to consider making the polyethylenimine derivative insoluble in an alcohol solvent by cross-linking. Accordingly, it is an object of the present invention to provide a polyethyleneimine derivative material suitable for the electron injection layer of a coating type organic EL device and an organic EL device using the same.

In the organic EL device of the present invention, an organic thin film layer consisting of one or more layers is sandwiched between a pair of electrodes, and at least one of the organic thin film layers comprises a polyethyleneimine derivative represented by the following structural formula and a cross-linking agent. It is characterized by being an insolubilized film made of a crosslinked product of

Preferably, the polyethyleneimine derivative is PEI, and the cross-linking agent having an ionic functional group is a dihalogenated alkane. The cross-linking agent is preferably a compound having an ionic site.

The dihalogenated alkanes include 1,4-diiodobutane (DIB), 1,6-diiodohexane (DIH), 1,8-diiodooctane (DIO), 1,10-diiododecane (DID), 1,6- Dibromohexane (DBH), 1,8-dibromooctane (DBO) or 1,10-dibromodecane (DBD) are preferred.
Preferably, the polyethyleneimine derivative is PEIE, and the cross-linking agent is a silane coupling agent.

The silane coupling agent includes dimethyloctadecyl[3-(trimethoxysilyl)propyl]ammonium chloride (DMOAP), 3-(2-aminoethylamino)propyltriethoxysilane (AAPTS), (3-bromopropyl)trimethoxy Silane (BPTMS), Trimethoxyphenylsilane (TMPS), Trimethoxy[3-(phenylamino)propyl]silane (TPAPS), 1,2-bis(trimethoxysilyl)ethane (BTMSE), 3-(2-aminoethyl Amino)propyltriethoxysilane (AEAPTMS) or trimethoxy[3-(phenylamino)propyl]silane (PAPMS) are preferred.
The silane coupling agent is preferably a silane coupling agent having an ammonium ion in its molecule.
The content of the cross-linking agent having an ionic functional group in the insolubilized film is preferably 4-10 wt %.
The organic thin film layer is preferably an electron injection layer.

The polyethyleneimine derivative of the present invention can form a solvent-insoluble organic thin film layer in an organic EL device by cross-linking with a specific cross-linking agent. That is, even if an upper layer is formed on the organic thin film layer by a coating method, the layer does not dissolve again.
The organic EL device of the present invention having an organic thin film layer comprising the polyethyleneimine derivative exhibits electron injection properties, driving voltage and driving stability equal to or greater than those of conventional organic EL devices.

FIG. 1 shows a device configuration according to one embodiment of the present invention. FIG. 2 shows the results after heat treatment of a coating film of polyethyleneimine (PEI) alone and a mixture of PEI and 1,8-diiodooctane (DIO) (10 wt% DIO) formed on a quartz substrate. - represents the UV-vis absorption spectrum after rinsing with butanol (BuOH). FIG. 3 shows ethoxylated polyethyleneimine (PEIE) alone and mixtures of PEIE and dimethyloctadecyl[3-(trimethoxysilyl)propyl]ammonium chloride (DMOAP) (10 wt % DMOAP and 20 wt % DMOAP) formed on quartz substrates. % DMOAP) after heat treatment and after rinsing with 1-butanol (BuOH) respectively.

FIG. 4 shows current density-voltage characteristics (a), luminance-voltage characteristics (b), and lifetime characteristics (change in relative luminance over time) ( c). FIG. 5 shows current density-voltage characteristics (a), luminance-voltage characteristics (b), and lifetime characteristics when cross-linked PEIE, cross-linked PEIE: 10 wt% DMOAP, and cross-linked PEIE: 20 wt% DMOAP are used for the electron injection layer, respectively. (Change over time of relative luminance) (c) is shown. FIG. 6 shows the current density-voltage characteristics when cross-linked PEIE, cross-linked PEIE: 10 wt % TMPS, cross-linked PEIE: 10 wt % TPAPS, and cross-linked PEIE: 20 wt % BTMSE are used for the electron injection layer in the device of Example 3. (a), current density-voltage characteristics (b), luminance-voltage characteristics (c), quantum efficiency-current density characteristics (d), current efficiency-current density characteristics (e), power efficiency-current density (f), EL spectrum (g), lifetime characteristics (change in relative luminance over time) (h), and voltage/lifetime (change in voltage over time) (i) are shown.

In the organic EL device of the present invention, an organic thin film layer consisting of one or more layers is sandwiched between a pair of electrodes, and at least one of the organic thin film layers comprises a polyethyleneimine derivative represented by the following structural formula and an ionic functional It is an insolubilized film made of a cross-linked product with a cross-linking agent having a group. The constituent elements of the present invention will be described in detail below.

The organic EL device has a structure (single-layer type) having at least an anode, a light-emitting layer and a cathode on a support substrate. Specifically showing the layer structure of the organic EL element, anode/hole transport layer/light emitting layer + electron transport layer/cathode (two-layer type), anode/hole transport layer/light emitting layer/electron transport layer/cathode (three layers) layer type), anode/hole injection layer/hole transport layer/light emitting layer/electron injection layer/cathode (four-layer type), anode/hole injection layer/hole transport layer/light emitting layer/electron transport layer/electron injection layer/cathode (five-layer type) and the like.
In addition to the organic thin film layers described above, a layer such as a hole blocking layer or an electron blocking layer may be provided as necessary.

Examples of the layer provided between the cathode and the light-emitting layer include an electron injection layer, an electron transport layer, a hole blocking layer, and the like. When both the electron injection layer and the electron transport layer are provided between the cathode and the light emitting layer, the layer closer to the cathode is the electron injection layer and the layer closer to the light emitting layer is the electron transport layer. Layers provided between the anode and the light-emitting layer include a hole injection layer, a hole transport layer, an electron blocking layer, and the like. When both the hole injection layer and the hole transport layer are provided between the anode and the light emitting layer, the layer closer to the anode is the hole injection layer and the layer closer to the light emitting layer is the hole transport layer.
The organic thin film layer in the present invention refers to a hole injection layer, a hole transport layer, a light emitting layer, an electron transport layer, an electron injection layer, and the like. FIG. 1 shows a five-layer device structure of an embodiment.

In the organic EL of the present invention, at least one layer of the organic thin film layer is an insolubilizing film comprising a crosslinked product of a polyethyleneimine derivative represented by the following structural formula and a crosslinking agent having an ionic functional group.

The polyethyleneimine derivative is polyethyleneimine (PEI) or ethoxylated polyethyleneimine (PEIE), which is effective as an electron injection material because its amino group and hydroxyl group form a large dipole. Since these compounds are soluble in water and alcohol, a layer can be formed by coating. However, as already mentioned above, when it is attempted to apply water-alcohol-soluble materials to form an upper layer, there is the problem that these compounds dissolve again and cannot be applied. Further, due to the insolubilization, there is also a problem that NH and OH exhibiting electron injection properties are lost when the PEI layer or PEIE layer is crosslinked after being formed.

In the present invention, it has been found that by cross-linking polyethyleneimine (PEI) or ethoxylated polyethyleneimine (PEIE) with a specific cross-linking agent, the organic thin film layer can be insolubilized without reducing the electron injection properties.

When the polyethyleneimine derivative is polyethyleneimine (PEI), the cross-linking agent having an ionic functional group is preferably a dihalogenated alkane.

The dihalogenated alkane is preferably solid or liquid at room temperature and has a boiling point of 120 to 200° C. Specifically, 1,4-diiodobutane (DIB), 1,6-diiodohexane (DIH ), 1,8-diiodooctane (DIO), 1,10-diiododecane (DID), 1,6-dibromohexane (DBH), 1,8-dibromooctane (DBO) or 1,10-dibromodecane (DBD ) is more preferred.

A mixed solution of PEI and the dihalogenated alkane is spin-coated on the substrate and heated at approximately 120 to 200° C., preferably 120 to 140° C. to form a crosslinked film on the substrate.
The amount of the dihalogenated alkane to be added is approximately 1 to 75 wt%, preferably 1 to 20 wt%, more preferably 4 to 10 wt% in the mixed solution.

The crosslinked film heated with the amount of the dihalogenated alkane added has excellent solvent resistance to 1-butanol, and can be suitably used, for example, as an electron injection layer.

On the other hand, when the polyethyleneimine derivative is ethoxylated polyethyleneimine (PEIE), the cross-linking agent is preferably a silane coupling agent represented by the following structural formula. Specifically, the silane coupling agent includes dimethyloctadecyl[3-(trimethoxysilyl)propyl]ammonium chloride (DMOAP), 3-(2-aminoethylamino)propyltriethoxysilane (AAPTS), (3- bromopropyl)trimethoxysilane (BPTMS), trimethoxyphenylsilane (TMPS), trimethoxy[3-(phenylamino)propyl]silane (TPAPS), 1,2-bis(trimethoxysilyl)ethane (BTMSE), 3- (2-Aminoethylamino)propyltriethoxysilane (AEAPTMS) or trimethoxy[3-(phenylamino)propyl]silane (PAPMS) are preferred.

A mixed solution of PEIE and the silane coupling agent is spin-coated on the substrate and heated at approximately 60 to 120° C., preferably 60 to 80° C. to form a crosslinked film on the substrate.
The amount of the silane coupling agent added is generally 1 to 20 wt%, preferably 4 to 10 wt%, in the mixed solution.

The crosslinked film heated with the amount of the dihalogenated alkane added has excellent solvent resistance to 1-butanol, and can be suitably used, for example, as an electron injection layer.
As the silane coupling agent, a silane coupling agent having an ammonium ion in the molecule is more preferable because it has ionicity, and DMOAP is particularly preferable. When DMOAP is used for cross-linking, excellent resistance to solvents such as 1-butanol is obtained, and ionic sites remain even after cross-linking, so that a good charge transfer effect is exhibited.

The content of the cross-linking agent in the insolubilized film is preferably 4 to 10 wt %.
It is particularly preferable to use the organic thin film layer for the electron injection layer because the formation of dipoles is large.

Next, constituent materials of each layer constituting the organic EL element will be described.
<Supporting substrate>
For the support substrate, in the case of the bottom emission type organic EL element, a material exhibiting light transmittance is used, and in the case of the top emission type organic EL element, a light transmittance or non-light transmittance material is used.
Specifically, a glass plate, a metal plate, a plastic, a polymer film, a silicon plate, and a laminate of these are used as the support substrate.

<Anode>
In the case of a bottom emission type organic EL device, an electrode exhibiting light transparency is used as the anode, and examples thereof include thin films of metal oxides, metal sulfides and metals with high electrical conductivity. , indium oxide, zinc oxide, tin oxide, indium tin oxide (ITO), indium zinc oxide (IZO), gold, platinum, silver, copper, and the like. Alternatively, an organic transparent conductive film such as polyaniline or its derivative, or polythiophene or its derivative may be used as the anode.
In the case of a top emission type organic EL device, a material that reflects light may be used for the anode, and such materials are preferably metals, metal oxides, and metal sulfides having a work function of 3.0 eV or more. .
The film thickness of the anode is usually 20 nm to 1 μm, preferably 50 nm to 500 nm.

<Hole injection layer>
Hole injection materials include oxides such as vanadium oxide, molybdenum oxide, ruthenium oxide, and aluminum oxide, as well as phenylamines, starburst amines, phthalocyanines, amorphous carbon, polyaniline, and poly(3,4-ethylenediethylene). oxythiophene) (PEDOT:PSS) and other polythiophene derivatives.
The hole injection layer can be formed, for example, from a solution containing a hole injection material. Examples of the solvent at this time include chloroform, methylene chloride, dichloroethane, tetrahydrofuran, toluene, xylene, acetone, methyl ethyl ketone, ethyl acetate, butyl acetate, ethyl cellosolve acetate, and water.
The film thickness of the hole injection layer is usually 1 nm to 1 μm, preferably 5 nm to 200 nm.

In the case of a coating type organic EL device, from the viewpoint of improving the lifetime, an organic compound having an electron-donating property such as poly(9,9 -dioctylfluorene-alto-N-(4-butylphenyl)diphenylamine) (TFB) and the like may be used.

<Light emitting layer>
The light-emitting layer usually contains a host material as a main component and a guest material (dopant) as a minor component. Among the three primary colors of red, green, and blue, the emission of red and green, in particular, is caused by the properties of the guest material.
An electron-transporting or hole-transporting material is used as the host material. Specific examples include 4,4'-biscarbazolylbiphenyl (CBP), 2,9-dimethyl-4,7-diphenyl-9,10-phenanthroline (BCP), and the like.
The guest material is selected according to the desired emission color. Materials that emit green light include, for example, iridium complexes (tris(2-phenylpyridinato)iridium(III) (Ir(ppy) ₃ )), quinacridone derivatives, coumarin derivatives, polymers thereof, poly paraphenylene vinylene derivatives, polyfluorene derivatives and the like. Materials emitting red light include, for example, tris[1-phenylisoquinoline-C ² ,N]iridium(III) (Ir(piq) ₃ ), tris[2-(benzo[b]thiophen-2-yl)pyridinato —C ³ ,N]iridium(III) (Ir(btpy) ₃ ), bis(2-benzo[b]thiophen-2-yl-pyridine)(acetylacetone)iridium(III)(Ir(btp) ₂ acac), bis(2-phenylquinoline)(acetylacetonato)iridium(III) (Ir(2-phq) ₂ acac);

<Electron injection layer>
The electron injection layer includes at least a layer obtained by cross-linking the polyethyleneimine derivative of the present invention.
In addition to the above-described crosslinked polyethyleneimine derivative layer, the electron injection layer further includes cesium carbonate (Cs ₂ CO ₃ ); sodium 8-quinolinolato (Naq), lithium 8-hydroxyquinolinolato (Liq), lithium alkali metal salts such as (2-pyridyl)phenolate (Lipp) and lithium phenolate salts such as lithium 2-(2′,2″-bipyridin-6′-yl)phenolate (Libpp); and zinc oxide (ZnO ). These materials are usually used by adding them to an organic solvent such as 2,2,3,3-tetrafluoropropanol (TFPO) or an organic polymer binder.
The layer composed of the crosslinked polyethylenimine derivative exists stably in the atmosphere and has excellent charge injection and transport properties, so that a device that emits light with high brightness can be obtained.
The crosslinked polyethyleneimine derivative layer is formed by coating the polyethyleneimine derivative and then heating it at 60 to 140° C. to crosslink it.
The film thickness of the electron injection layer should be such that the driving voltage and the luminous efficiency are appropriate values and the thickness does not cause pinholes. 5 nm to 1 μm is more preferable from the viewpoint of

<Cathode>
A metal electrode of Al is generally used for the cathode. In addition, for example, a thin film made of a conductive resin such as PEDOT:PSS, a thin film made of a resin and a conductive filler, and the like are used.
In the case of a thin film made of a resin and a conductive filler, a conductive resin can be used as the resin, and fine metal particles, a conductive wire, or the like can be used as the conductive filler. Au, Ag, Al, Cu, C, etc. can be used for the conductive filler.

The organic EL element of the present invention is formed by successively laminating each of the layers described above by a coating method. However, the anode may be formed by a vacuum vapor deposition method, a sputtering method, an ion plating method, a plating method, or the like, in addition to the solution coating method. Also, the cathode may be formed by a so-called lamination method instead of the coating film forming method.

As an example, a method for forming a five-layer device will be described. First, a support substrate having an ITO electrode formed in advance on its surface is prepared, and an ink containing PEDOT:PSS as a hole injection material is applied onto the support substrate to form a hole injection layer. An ink containing TFB as an interlayer material is coated on the hole injection layer to form an interlayer layer, and then an ink containing a host material and a light-emitting material Ir(ppy) ₃ is applied onto the hole transport layer. After forming a light-emitting layer by applying a film, an ink containing ZnO nanoparticles as an electron-transporting material is applied on the light-emitting layer, and an ink containing the polyethyleneimine derivative as an electron-injecting material is applied on the electron-transporting layer. An electron injection layer is formed by coating. An Al cathode is formed by coating to produce an organic EL element.

The organic EL device of the present invention obtained as described above is a coating-type organic EL device having electron injection properties, driving voltage and driving stability equal to or greater than those of conventional organic EL devices. Application to EL panel applications can be expected.

EXAMPLES The present invention will be more specifically described below based on examples, but the present invention is not limited to the following examples.

[Test Example] Crosslinking and Solvent Resistance Test of Polyethyleneimine Derivatives Polyethyleneimine (PEI) and ethoxylated polyethyleneimine (PEIE) were crosslinked and tested for solvent resistance to 1-butanol (BuOH), the upper layer coating solvent. rice field.
A single polyethyleneimine derivative (PEI and PEIE) or a mixed solution of a polyethyleneimine derivative and a cross-linking agent was spin-coated on a quartz substrate, and rinsed with BuOH after heat treatment. Solvent resistance was evaluated from the difference in absorbance in the UV-vis absorption spectrum before and after rinsing.

In the cross-linking of PEI, 1,8-diiodooctane (DIO) was used as a cross-linking agent (Stolz et al., J. Mater. Chem. C, 2016, 4, 11150-11156.). A mixed solution of PEI and DIO (10 wt % DIO) was applied to form a film on a quartz substrate, and then heat-treated at 140° C. for cross-linking. The absorbance of PEI alone decreased after the BuOH rinse treatment, confirming redissolution (Fig. 2(a)). On the other hand, the absorbance of crosslinked PEI:DIO did not decrease before and after rinsing, confirming that PEI was insolubilized by the reaction with DIO (Fig. 2(b)).

For PEIE cross-linking, a silane-based material dimethyloctadecyl[3-(trimethoxysilyl)propyl]ammonium chloride (DMOAP) having a hydrolyzable group was used as a cross-linking agent. A mixed solution of PEIE and DMOAP (10 wt % DMOAP or 20 wt % DMOAP) was applied to the substrate to form a film, and then heat-treated at 65° C. to crosslink. The absorbance of PEIE alone decreased after the BuOH rinse treatment, confirming re-dissolution in BuOH (Fig. 3(a)). On the other hand, those to which 10 wt % of DMOAP was added showed some solvent resistance. When 20 wt % of DMOAP was added, there was no change in absorbance before and after rinsing, confirming complete insolubilization of PEIE (FIG. 3(b)).

ＰＥＩ及びＰＥＩＥはいずれも架橋することができ、特にＰＥＩＥは６５℃という低温処理で架橋することができた。 PEIE and DMOAP are shown below.

Both PEI and PEIE could be crosslinked, and in particular PEIE could be crosslinked by a low temperature treatment of 65°C.

[Example 1] Application of crosslinked PEI to coating-type organic EL device In order to verify the electron injection property of crosslinked PEI, a coating-type organic EL device having the following device structure was produced by spin coating.
[ITO/PEDOT: PSS (30 nm)/IL (20 nm)/Small molecule host: 10 wt% Ir(ppy) ₃ (70 nm)/ZnONPs (10 nm)/EIL (20 nm)/Al (100 nm)]
The following compounds were used as low-molecular-weight hosts.

デバイス特性と寿命特性を図４に示す。架橋ＰＥＩ：４ｗｔ％ ＤＩＯは、ＰＥＩ単体の有機ＥＬ素子と同等の電子注入性（図４（ａ））、駆動電圧（図４（ｂ））、及び駆動安定性（図４（ｃ））を示した。 PEI alone and crosslinked PEI: 4 wt % DIO were used for EIL (electron injection layer), and TFB was used for IL (interlayer).
PEDOT:PSS and TFB are shown below.

Device characteristics and lifetime characteristics are shown in FIG. Crosslinked PEI: 4 wt% DIO has the same electron injection property (FIG. 4(a)), driving voltage (FIG. 4(b)), and driving stability (FIG. 4(c)) as the organic EL element of PEI alone. Indicated.

[Example 2] Application of crosslinked PEIE to coating type organic EL device In order to verify the electron injection property of crosslinked PEIE, a coating type organic EL device having the following device structure was produced by spin coating.
[ITO/PEDOT: PSS (30 nm)/IL (20 nm)/Small molecule host: 10 wt% Ir(ppy) ₃ (70 nm)/ZnO NPs (10 nm)/EIL (20 nm)/Al (100 nm)]

PEIE single film, crosslinked PEIE: 10 wt% DMOAP, and crosslinked PEIE: 20 wt% DMOAP were used for EIL, and (TFB) was used for IL.
Device characteristics and lifetime characteristics are shown in FIG. PEIE: 10 wt% DMOAP exhibited the same electron injection properties, drive voltage, and drive stability as the organic EL device using PEIE alone as the EIL. Cross-linked PEIE: 20 wt% DMOAP showed a driving voltage equivalent to that of PEIE alone (Fig. 5(b)), but had a higher voltage in terms of electron injection (Fig. 5(a)) and had a shorter life in terms of driving stability. (Fig. 5(c)). It is considered that the reason for the high voltage is that PEIE becomes rigid due to the increased insulation and cross-linking due to the amount of DMOAP added, making it difficult to form dipoles that contribute to electron injection.

The crosslinked polyethyleneimine derivative exhibited almost the same electron injection properties, drive voltage, and drive stability as those of the PEI single film and the PEIE single film. By optimizing the heating conditions and searching for new cross-linking agents, it is expected that the performance of coating-type organic EL devices can be improved.

[Example 3] Application of crosslinked PEI to coating-type organic EL device In order to verify the electron injection property of crosslinked PEI when TMPS, TPAPS, and BTMSE are used as crosslinking agents, the following device structure was formed by spin coating. A coating type organic EL device having [1] to [4] was produced.
[1] ITO/PEDOT: PSS/TFB/BCTIC: 10 wt% Ir(ppy) ₃ /ZnO/PEIE (20 nm)/Al
[2] ITO/PEDOT: PSS/TFB/BCTIC: 10 wt% Ir(ppy) ₃ /ZnO/PEIE: 10 wt% TMPS (20 nm)/Al
[3] ITO/PEDOT: PSS/TFB/BCTIC: 10 wt% Ir(ppy) ₃ /ZnO/PEIE: 10 wt% TPAPS (20 nm)/Al
[4] ITO/PEDOT: PSS/TFB/BCTIC: 10 wt% Ir(ppy) ₃ /ZnO/PEIE: 20 wt% BTMSE (20 nm)/Al

TMPS, TPAPS, and BTMSE are shown below.

デバイス特性を図６に示す。
ＰＥＩＥ単膜よりも、ＰＥＩＥと架橋剤（ＴＭＰＳ、ＴＰＡＰＳ、ＢＴＭＳＥ）との架橋ＰＥＩＥを用いた場合のほうがデバイスが長寿命化することを確認した。

Device characteristics are shown in FIG.
It was confirmed that the use of cross-linked PEIE of PEIE and a cross-linking agent (TMPS, TPAPS, BTMSE) prolongs the life of the device, rather than the single PEIE film.

Claims (5)

An organic EL device having one or more organic thin film layers sandwiched between a pair of electrodes, wherein at least one of the organic thin film layers is an insolubilized film made of a crosslinked product of a polyethyleneimine derivative and a crosslinking agent. and
The polyethyleneimine derivative is PEIE having the following structural formula,
An organic EL device, wherein the cross-linking agent is a silane coupling agent .

the silane coupling agent is dimethyloctadecyl[3-(trimethoxysilyl)propyl]ammonium chloride (DMOAP), 3-(2-aminoethylamino)propyltriethoxysilane (AAPTS);
(3-bromopropyl)trimethoxysilane (BPTMS), trimethoxyphenylsilane (TMPS), trimethoxy[3-(phenylamino)propyl]silane (TPAPS)
), 1,2-bis(trimethoxysilyl)ethane (BTMSE), 3-(2-aminoethylamino)propyltriethoxysilane (AEAPTMS) or trimethoxy[3-(phenylamino)propyl]silane (PAPMS). The organic EL device according to claim 1 . 2. The organic EL element according to claim 1 , wherein said silane coupling agent is a silane coupling agent having an ammonium ion in its molecule. The organic EL device according to any one of claims 1 to 3 , wherein the content of the cross-linking agent in the insolubilized film is 4 to 10 wt%. 5. The organic EL device according to claim 1 , wherein said organic thin film layer is an electron injection layer.

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