JPH06200244A - Organic thin-film el element - Google Patents

Abstract

PURPOSE:To overcome the problem with degradation due to poor heat resistance, low film strengths, and ease of crystallization of an org. material for the subject element, and thus to obtain the element having a high luminance and a long life. CONSTITUTION:The objective element at least comprises an anode, a hole injection and transport layer, an org. luminescent layer, and a cathode. In the element, org.-compd.-contg. layers between the anode and the cathode contain a polyphosphazene compd. having hole-transporting, luminescent, or electron- transporting group on the side chains, a polyether compd. with a main chain with arom. tert. amino groups, or a polyphosphoric ester compd.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an organic thin film EL device utilizing the electroluminescence (hereinafter simply referred to as EL) phenomenon of an organic thin film.

[0002]

2. Description of the Related Art C. of Eastman Kodak Company. W. T
The organic thin film EL device developed by Ang et al. is disclosed in JP-A-59-194393 and JP-A-63-264692.
Publication No. 63-295695, Applied Physics Letters Vol. 51 No. 12, 913 (1987), and Journal of Applied Physics Vol. 65 No. 9, 3610 (1989).
In general, the anode, the organic hole injecting and transporting layer, the organic light emitting layer, and the cathode are formed in this order, and are manufactured as follows.

As shown in FIG. 1, first, on a transparent insulating substrate (1) such as glass or a resin film, a transparent conductive material of a complex oxide of indium and tin (hereinafter referred to as ITO) is formed by vapor deposition or sputtering. The positive electrode (2) of the functional coating is formed. Next, as the organic hole injecting and transporting layer (3), copper phthalocyanine (hereinafter abbreviated as CuPc) or a compound represented by the following (Chemical Formula 1):

[0004]

[Chemical 1]

1,1-bis (4-di-p-tolylaminophenyl) cyclohexane (melting point 181.4 ° C.-18
2.4 ° C.) or a compound represented by (Chemical Formula 2):

[0006]

[Chemical 2]

N, N, N ', N'-tetra-p-tolyl-1,1'-biphenyl-4,4'-diamine (melting point 1
(20 ° C.) tetraaryldiamine or the like having a thickness of about 0.1 μm or less is formed as a single layer or a laminated layer by vapor deposition.

Next, an organic phosphor such as tris (8-quinolinol) aluminum (hereinafter abbreviated as Alq ₃ ) is vapor-deposited on the organic hole injecting and transporting layer (3) to a thickness of about 0.1 μm or less to emit organic light. Form the layer (4). Finally, as a cathode (5), Mg: Ag, Ag: Eu, Mg: Cu, and
An alloy of Mg: In, Mg: Sn, etc. is formed by a co-evaporation method.
The vapor deposition is about 0 nm.

Further, Adachi et al. Prepared an element by providing an organic electron injecting and transporting layer (6) between the organic light emitting layer and the cathode (5). Applied Physics Letter Vol. 57, Vol. 6
No. 531 (1990), the device is
As an organic hole injecting and transporting layer (3) on the anode of TO, N,
N′-diphenyl-N, N′-bis (3-methylphenyl) -1,1′-biphenyl-4,4′-diamine [melting point 159 to 163 ° C., glass transition temperature 67 ° C. (under nitrogen,
Measured by DSC at a heating rate of 20 ° C./min); hereinafter abbreviated as TPD], 1- [4-N, N-bis (p-methoxyphenyl) aminostyryl] naphthalene as an organic light emitting layer (4), organic electron 2- (4-biphenylyl) -5- (4-t-butylphenyl) -1,3 as the injecting and transporting layer (6)
4-oxadiazole (hereinafter simply referred to as BPBD),
An alloy of Mg and Ag is sequentially stacked as the cathode (5).

In the device manufactured as described above, holes and electrons are injected into the light emitting layer by applying a direct current low voltage of 20 to 30 V or less with the transparent electrode side serving as an anode, and the light is recombined to emit light of 1000 cd. A brightness of about / m ² can be obtained.
However, in the hole injecting and transporting material shown above, CuPc is heat resistant but has a large absorption in the visible light wavelength region, and since it is crystalline, the deposited film becomes uneven, and only CuPc is injected into the organic hole injecting material. The element used as a transport material has a low EL emission extraction efficiency, and thus has a problem that the element is easily electrically short-circuited.

Compounds represented by (Chemical Formula 1) and (Chemical Formula 2) and T
PD is an amorphous and smooth vapor-deposited film that does not absorb in the visible wavelength region, but has a low melting point and glass transition temperature, so it is mixed with the light-emitting layer due to heat generated during the device manufacturing process and device driving. There was a problem that the film crystallized and became uneven as time passed. For example, when a thin film having a thickness of about 50 nm and TPD and Alq ₃ layers were laminated, both layers were mixed at a temperature of about 95 ° C.

Further, the hole injecting and transporting layer consisting of only low molecular weight has a weak mechanical strength of the film, and an element in which the organic layer is formed only by vapor deposition of low molecular weight is likely to be short-circuited at the step portion of the etching pattern of ITO. There was a problem.

Television Society Technical Report Vol. 16, No. 2,
According to P. 47 (1992), Wakimoto et al. Used a single-layer deposited film of TPD for the hole injecting and transporting layer and an Alq3 deposited film with quinacridone (hereinafter referred to as Qd) for the light emitting layer to obtain a maximum brightness of 68000 cd / m ^2. (Just before melting and breaking). This device had a low initial luminance of 275 cd / M when driven at a constant current of 4 mA / cm ² and a luminance half life of 130 hours. Generally, the organic thin film EL element has a problem that the deterioration rate becomes faster when the current density is increased to increase the brightness, and it is difficult to obtain an element having both high brightness and long life.

[0014]

DISCLOSURE OF THE INVENTION The present invention aims to solve the problems of heat resistance and film strength of the conventional organic thin film EL element organic materials described above, and deterioration due to crystallization.
The layer made of CuPc or Qd, which has high heat resistance, has been made for the purpose of providing an organic thin film EL element having high brightness and long life by improving the problem of the layer structure such as low translucency.

[0015]

The present invention has been made in view of the above problems, and is an organic thin film E including at least an anode, a hole injecting and transporting layer, an organic light emitting layer, and a cathode.
In the L element, the layer containing an organic compound between the anode and the cathode comprises a polyphosphazene compound having a hole-transporting or light-emitting or electron-transporting group as a side chain, or an aromatic tertiary amine main chain. 2. An organic thin film EL device comprising the polyether compound or the polyphosphate ester compound according to 1.

Furthermore, the polyphosphazene compound, the polyether compound or the polyphosphoric acid ester compound is used for the hole injecting and transporting layer, and if necessary, the hole injecting and transporting layer has a multilayer structure. It is a characteristic organic thin film EL element. A further feature of the present invention is an organic thin film EL device characterized in that the above-mentioned compound, that is, a polyphosphazene compound or a polyether compound or a polyphosphate ester compound, is formed by coating a solution of an organic solvent. is there.

The organic thin film EL element of the present invention will be described below with reference to FIGS. 1 to 4. FIG. 1 shows an organic thin film EL device according to the present invention, which comprises an anode (2), a hole injecting and transporting layer (3), an organic light emitting layer (4), a cathode (5) and a sealing layer (7) on a substrate (1). ) And glass plate (8)
This is an example in which the compound is adhered with an adhesive resin (9) and hermetically sealed, and the polyphosphazene compound, the polyether compound or the polyphosphate ester compound in the present invention is used for the hole injecting and transporting layer (3) or the organic light emitting layer ( It can be used for either or both of 4).

FIG. 2 shows the case where the hole injecting and transporting layer has a two-layer structure, and the first hole injecting and transporting layer (10) is between the second hole injecting and transporting layer (11) and the work function of the anode. By using a material having a work function value, hole injection efficiency into the organic light emitting layer (4) is improved, and EL light emission can be obtained at a low voltage. In the layer containing the polyphosphazene compound, the polyether compound, or the polyphosphate ester compound in the present invention, either the first or second hole injecting and transporting layer (11) or the first hole injecting and transporting layer (10) is used. When it is insoluble in the solvent used for forming the second hole injecting and transporting layer (11), it can be used for both layers.

FIG. 3 shows a case where a third hole injecting and transporting layer (12) is formed between the second hole injecting and transporting layer (11) and the organic light emitting layer (4) to further improve the stability of the device. It is also possible to form more layers. Further, as shown in FIG. 4, an electron injecting and transporting layer (6) for blocking the flow of holes at the interface between the organic light emitting and emitting layer (4) and the cathode (5) is provided, and the substrate (1) is provided. An anode (2), an organic hole injecting and transporting layer (3), an organic light emitting layer (4), an organic electron injecting and transporting layer (6), a cathode (5), and a sealing layer (7) may be formed in this order. Alternatively, the same structure may be formed on the substrate in the reverse order from the cathode. Hereinafter, the material and the method of manufacturing the element will be described in more detail.

The anode (2) is formed by vacuuming a transparent conductive material such as ITO (work function 4.6 to 4.8 eV) or zinc aluminum oxide on a transparent insulating substrate (1) such as glass or plastic film. Surface resistance covered by vapor deposition or sputtering method 10 to 50Ω / □, visible light transmittance 80%
The transparent electrode described above, a semitransparent electrode in which gold or platinum is thinly vapor-deposited, or a semitransparent electrode coated with a polymer such as polyaniline, polypyrrole, or polythiophene is preferable.

In another case, however, the anode (2) is opaque and the organic light emitting layer (4) passes through the hole injecting and transporting layer (3).
A metal plate such as gold, platinum, palladium, nickel, or the like having a large work function value for easily injecting holes into a semiconductor substrate, a semiconductor substrate such as silicon, gallium phosphide, or amorphous silicon carbide having a work function of 4.6 eV or more, or a metal thereof. Anode (2) in which a semiconductor is coated on an insulating substrate (1)
The cathode (5) can also be used as a transparent electrode or a semitransparent electrode. If the cathode (5) is also opaque, at least one end of the organic light emitting layer (4) needs to be transparent.

Next, the organic hole injecting and transporting layer (3) of the present invention is formed on the anode (2). The hole injecting and transporting layer used in the present invention can be formed as a single layer containing the polyphosphazene compound represented by the general formula (Formula 3) or the polyether compound represented by the general formula (Formula 6).

[0023]

[Chemical 3]

[0024]

[Chemical 4]

[0025]

[Chemical 5]

[0026]

[Chemical 6]

However, in order to improve the hole injection efficiency by reducing the step difference of the work function between the anode and the light emitting layer, to improve the adhesion between the layers, to prevent deterioration, to adjust the color tone, etc. 4-72009, Japanese Patent Application No. 4-114692
Japanese Patent Application No. 4-142791, Japanese Patent Application Laid-Open No. 4-23099.
No. 7,265,496, US Pat. Nos. 3,265,496, 4,025,341, 3,873,311,
No. 3,873,312, European Patent No. 295115, No. 29.
5125 and 295127, a layer of a hole-transporting polymer material, a layer of a metal or metal-free phthalicyanine such as CuPc or phthalocyanine, a layer of a heat-resistant low-molecular-weight hole injecting and transporting material such as Qd, or ( A layer of a low molecular weight aromatic tertiary amine hole transporting material represented by Chemical formula 7) or a layer containing an inorganic compound such as amorphous Si, SiC, or Se, and is a multilayer hole injection of two or more layers. A transport layer can be formed.

[0028]

[Chemical 7]

At this time, various film forming methods such as a vacuum vapor deposition method, a spin coating method, a dip coating method, a roll coating method, an ion plating method and a plasma CVD method can be applied to each layer.

Next, examples of specific chemical structures of the polyphosphazene compounds R ₁ and R ₂ represented by (Chemical Formula 3) contained in the hole transport layer of the present invention, their glass transition temperatures (Tg) and work functions. Values are shown in Table 1, but the chemical structure shown here does not limit the kind of the polyphosphazene compound contained in the organic hole injecting and transporting layer of the present invention.

[0031]

[Table 1]

Here, Tg is measured by a DSC in a nitrogen atmosphere at a temperature rising rate of 20 ° C./min, and the work function is a value measured in the atmosphere by a surface analyzer AC-1 manufactured by Riken Keiki Co., Ltd. . The energy level of the lowest unoccupied molecular orbital (LUMO) of the molecule was determined by measuring the ultraviolet-visible absorption spectrum of each material and subtracting the absorption edge energy (Eg) from the work function.

In Table 2, Tg of an example (P9) of the specific chemical structure of the polyether compound represented by (Chemical Formula 6) and Tg of an example (P10) of the specific chemical structure of the polyphosphoric acid compound,
W. The energy level values of F and LUMO are listed,
It is not limited to these examples. Table 2 also shows the values of CuPc and TPD that can be used for the multilayer hole injecting and transporting layer.

[0034]

[Table 2]

These polymers can be dissolved in general organic solvents such as toluene, tetrahydrofuran, chloroform, dioxane, dimethylacetamide, dimethylformamide, and microhexanone, and the spin coating method, dip coating method, roll coating method and the like can be used. A thin film having a strength stronger than that of a smooth and transparent low-molecular film can be obtained by applying it onto the substrate with.

The heat resistance of the organic thin film EL element is
In order to improve the properties of the device as compared with the device using as a hole transporting material, it is desired to use a hole transporting material having a high Tg which is more difficult to crystallize than TPD. However, like P3, T
Even a material having a low g may be disposed between the layers of the high Tg material with a thickness of several nm or less for the purpose of improving the adhesion between the layers.

In addition, a polymerized version of TPD P8-
In the material of P10, it is considered that the concentration of the hole transport unit is lowered by polymerizing, and the hole mobility is lower than that of TPD. However, the rate-determining step of the flow of holes in the device is a region having a work function step. It is considered that the material has a large step, for example, a material having a high hole mobility of a low molecule (CuPc, Qd, TPD, etc.) only between the anode and the hole injecting and transporting layer or between the hole injecting and transporting layer and the light emitting layer. As a first hole injecting and transporting layer or a third hole injecting and transporting layer having a thickness of about 1 to 30 nm, preferably 15 nm or less, the whole is equivalent to a material having a high hole mobility. The ability to inject and transport holes to the anode can be obtained.

As described above, in the hole injecting and transporting layer composed of three layers according to the present invention, a layer containing the polymer of the present invention having a Tg higher than TPD is used as the second hole injecting and transporting layer in an amount of 10 to 10
When it is arranged with a thickness of about 0 nm, it has heat resistance, but it has higher translucency, smoothness, and film strength than the hole injecting and transporting layer of the same thickness made of only CuPc or Qd, which is crystalline and has high absorbance. Further, a hole injecting and transporting layer having the same thickness and having higher heat resistance and less crystallization and higher film strength than the hole injecting and transporting layer consisting of TPD alone can be obtained, and the organic thin film EL element can be stabilized.

Next, the organic light emitting layer (4) is formed on the hole injecting and transporting layer (3). When the polyphosphazene compound of the present invention is used as a light emitting layer, it is preferable to use a polymer obtained by reacting polydichlorophosphazene with a fluorescent dye having one hydroxy group or amino group or one monosubstituted amino group as a side chain. it can.

Examples of fluorescent dyes used in the reaction include Coumarin 4, Coumarin 120, Coumarin 2, Coumarin 151, Coumarin 307, Coumarin 500, Fluorol 7GA and the like, which are listed in the Laser Die Catalog of Lambda Fizzic Co., USA. The obtained polymer is dissolved in an organic solvent and applied on the hole transport layer (3) by a method such as spin coating or dip coating. In addition, depending on the conditions, the polymer shown in (Chemical Formula 3) may be added to the organic light emitting layer (4).
It can be used as In addition, the phosphor used for the organic light emitting layer (4) can be any phosphor that has fluorescence in the visible region and can be formed into a film by an appropriate method.

For example, anthracene, salicylate, pyrene, coronene, perylene, tetraphenylbutadiene, 9,10-bis (phenylethynyl) anthracene, lithium 8-quinolinol, Alq ₃ , tris (5,7-dichloro, 8-quinolinol). ) Aluminum, tris (5-chloro-8-quinolinol) aluminum, bis (8-quinolinol) zinc, tris (5-fluoro-8-quinolinol) aluminum, tris (8
-Quinolinol) scandium, bis [8- (paratosyl) aminoquinoline] zinc complex and cadmium complex, 1,2,3,4-tetraphenylcyclopentadiene, pentaphenylcyclopentadiene, poly-2.5
-Diheptyloxy-P-phenylene vinylene, or JP-A-4-31488, US Pat. No. 5,141,671
The fluorescent substances and the like referred to in the specification and No. 4,769,292 are mentioned.

The film forming method of these organic light emitting layer materials is carried out by vacuum vapor deposition method, cumulative film method, or by dispersing them in a suitable resin binder and coating them by a method such as spin coating.

The film thickness of the organic light emitting layer (4) is 1 μm or less, preferably 1 to 100 nm even when it is formed by a single layer or a laminated layer. In addition, these fluorescent polymers and molecules include vinyl group, acrylic group, methacryloyloxymethyl group, methacryloyloxy group, methacryloyloxyethyl group, acryloyl group, acryloyloxymethyl group, acryloyloxyethyl group, cinnamoyl group, styrenemethyloxy group. It is also possible to use a material having a polymerizable or crosslinkable group such as a propioloyl group or a propargyl group introduced therein, and polymerize or crosslink by heat, light or radiation after the film formation.

Further, the phosphor in the organic light emitting layer (4) is a coumarin-based material described in a laser die catalog of Lambda Fizzick Co. or Eastman Kodak Co., Ltd. in order to convert emission wavelength and improve luminous efficiency. You may dope two or more kinds of phosphors such as quinacridone type, perylene type, pyran type, etc., or stack two or more light emitting layers of various kinds of phosphors, one of which is in the infrared region or the ultraviolet region. It may exhibit fluorescence.

Table 3 shows Al, which is a typical organic light emitting layer material.
q ₃ and coumarin 6 which is a doping dye for improving luminous efficiency
The values of the work function of (C6) and Qd and the energy level of LUMO are summarized.

[0046]

[Table 3]

Next, when the organic electron injecting and transporting layer (6) is laminated on the organic light emitting layer (4), the preferable conditions of the organic electron injecting and transporting material are that the electron mobility is high and the LUMO energy level is organic light emitting. It may be between the LUMO energy level of the layer material and the Fermi level (work function) of the cathode material, the work function is larger than that of the organic light emitting layer material, and the film forming property may be good. Further, in the element in which the anode (2) is opaque and the light is extracted from the transparent or semitransparent cathode (5), it is necessary that it is substantially transparent at least in the fluorescence wavelength region of the organic light emitting layer material.

The electron injecting and transporting layer in the present invention comprises a polymer in which the R ₁ and R ₂ groups of the polyphosphazene compound represented by (Chemical formula 3) are represented by (Chemical formula 8), and BPB.
D, 2,5-bis (1-naphthyl) -1,3,4-oxadiazole, oxadiazole derivatives synthesized by Hamada et al. (Journal of the Chemical Society of Japan, page 1540, 1991), etc. It is not particularly limited to the above examples, and in some cases, it may be possible to use the compounds described in the examples of the organic light emitting layer material.

[0049]

[Chemical 8]

The method for forming the organic electron injecting and transporting layer (6) is as follows.
It is applied by a method such as a spin coat method or a method such as a vacuum vapor deposition method or a cumulative film method to form a film having a thickness of 1 to 100 nm.

Next, the cathode (5) is formed on the organic light emitting layer (4) or the organic electron injecting and transporting layer (6). For the cathode, a material having a low work function is used on the surface in contact with the organic light emitting layer (4) or the electron injecting and transporting layer (6) to effectively inject electrons, and Li, Na, Mg, La, Ce, Ca are used. , Sr, A
Metal element simple substance such as l, Ag, In, Sn, Zn, Zr,
Or two components containing them to improve stability,
A ternary alloy system is used.

As an example of the work function, Mg alone is about 3.6.
It is eV and decreases to 3.1 to 3.2 eV when an alkali metal such as Li is added to Mg. When a low work function cathode containing an alkali metal is used, Mg. Al. You may laminate | stack a metal layer, such as Ag, as a protective layer. The cathode (5) is formed by co-evaporation by a resistance heating method under a vacuum of the order of 10 ^-5 Torr or less while monitoring each component with a crystal oscillator film thickness meter from different vapor deposition sources. At this time, 0.01-0.
Although formed with a film thickness of about 3 μm, an electron beam evaporation method,
It is also possible to form a film by using an alloy target instead of co-evaporation by the ion plating method or the sputtering method.

Next, a sealing layer (7) is formed on the device in order to prevent oxidation of the organic layers and electrodes of the device. The sealing layer (7) is
It is formed immediately after the formation of the cathode (5). Examples of the sealing layer material include SiO ₂ , SiO, GeO, MgO, and Al ₂ O.
₃ , TiO ₂ , GeO ₃ , ZnO, TeO ₂ , Sb
O _3, SnO, oxides such as _{B 2 O 3, MgF 2,} Li
Examples include fluorides such as F, BaF ₂ , AlF ₃ , FeF ₃ , and CaF ₂ , gases such as sulfides such as ZnS, GeS, and SnS, and inorganic compounds having a high water vapor barrier property, but are not limited to the above examples. is not. These are used alone or in combination to form a film by vapor deposition, sputtering, ion plating or the like. In the case of vapor deposition by the resistance heating method, GeO, which can be vapor-deposited at low temperature, is excellent. In order to protect the cathode, a mixed layer of a sealing inorganic compound and an alkali metal such as Li or an alkaline earth metal such as Ca may be provided in the sealing layer or on the surface in contact with the sealing layer.

Further, an adhesive resin layer such as a commercially available low hygroscopic photo-curable adhesive, epoxy adhesive, silicone adhesive, cross-linked ethylene-vinyl acetate copolymer adhesive sheet, etc. for preventing invasion of moisture. Using (9), a sealing plate (8) such as a glass plate is adhered and sealed. In addition to glass plates, metal plates,
A plastic plate or the like can also be used.

In the organic thin film EL element constructed as described above, the organic hole injecting and transporting layer (3) side is positive and the power source (1
3) is connected by a lead wire (14) to apply a DC voltage, and emits light, but even when an AC voltage is applied, while the electrode on the hole injecting and transporting layer (3) side is positively applied with voltage. Emits light. In particular, the organic thin film EL device having the three-layer structure hole injection / transport layer according to the present invention can obtain stable EL light emission for a long period of time. By arranging the organic thin film EL device according to the present invention two-dimensionally on the substrate, a thin display capable of displaying characters and images can be obtained.

[0056]

【Example】

<Example 1> As a transparent insulating substrate (1), a thickness of 1.
Use a 1mm blue plate glass plate, and 120-220n on it.
m of ITO was coated to form an anode (2). This transparent conductive substrate was thoroughly washed with water, ultraviolet rays, and plasma before use, and then C was used as the first hole injecting and transporting layer (10).
uPc was vapor-deposited with a thickness of 15 nm. Next, as a second hole injecting and transporting layer (11), a toluene solution of P1 (60 mg / 5 m
l) is spin coated at 1000 rpm 7
The film was formed to a thickness of 2 nm.

Next, 50 nm of Alq ₃ was vapor-deposited as an organic light emitting layer (4), and Mg and A as a cathode (5) were formed on the upper surface thereof.
220 g was vapor-deposited at a vapor deposition rate ratio of 10: 1. Finally, after depositing GeO as a sealing layer (7) by 1.8 μm, the glass plate (8) was adhered and sealed with a photocurable resin (9).
This device emitted green light by a DC voltage of 3 V or more, had a maximum luminance of 385 cd / m ^{2 at} 12 V and a current density of 94 mA / cm ² .

Example 2 Example 1 As the second hole injecting and transporting layer (11) of the device, a layer of P2 was used instead of P1 of 57n.
An element was manufactured in the same manner as in Example 1 except that the layer was formed. This device emits light by applying a direct current voltage of 4 V or more, and the maximum brightness is 514 cd / m ^{2 at} 16 V and the current density is 121.
It was mA / cm ² .

Example 3 Example 1 Instead of the first and second hole injecting and transporting layers (11) of the device, a chloroform solution of P9 (41 mg / 5 ml) was spin-coated at 1000 rpm to form a single layer having a thickness of 55 nm. An element was produced in the same manner as in Example 1 except that the organic hole injecting and transporting layer (3) was formed. The maximum brightness of this device is 1153 cd at 21V
/ M ^{2 The} current density was 115 mA / cm ² .

Example 4 In place of the organic hole injecting and transporting layer (3) made of P9 of Example 3, a toluene solution of P8 (60 mg / 5 ml) was spin-coated at 1000 rpm to form a single layer having a thickness of 45 nm. An element was produced in the same manner as in Example 3 except that the organic hole injecting and transporting layer (3) was formed. The maximum brightness of this device was 4023 cd / m ^{2 at} 15 V and a current density of 270 mA / cm ² .

<Embodiment 5> Second hole injection of the device of Embodiment 1
As a transport layer (11), a layer of P8 is used instead of P1.
nm, and then C6 of 0.5 is formed as the organic light emitting layer (4).
Alq containing mol% ₃Was deposited to a thickness of 50 nm. Shade on its top
Al and Li as the electrode (5) at a deposition rate ratio of 3: 1 of 40n
After forming m, only 170 nm of Al was laminated. afterwards
A device was manufactured in the same manner as in Example 1.

This device emits light at 3 V or more, and has a maximum brightness of 7926 cd / m ^{2 at} 10 V and a current density of 434 m.
It was A / cm ² . In addition, this element is 20 mA / cm
The initial luminance when driven at a constant current density of ² was 560 cd / m ^{2 at} 6.1 V, and the luminance half time was about 6 hours.

Example 6 In place of the organic light emitting layer (4) of the device of Example 5, Alq ₃ containing 0.5 mol% of Qd was formed to a thickness of 5 nm by the co-evaporation method, and then Alq ₃ was added to the organic electron injecting and transporting layer. As (12), 45 nm was vapor-deposited. Other than that produced the element similarly to Example 5.

This device emits light at 3 V or more and has a luminance of 5980 cd / m ² and a current density of 184 mA / 10 V at 10 V.
cm ² and the maximum brightness is 11090c at 12V
It was d / m ² and the current density was 649 mA / cm ² . The initial luminance of this device when driven at a constant current density of 20 mA / cm ² is 675 cd / d at 7.5V.
m ² , and the luminance half-life was about 0.6 hours.

Example 7 TPD of 5 nm was vapor-deposited as a third hole injecting and transporting layer (12) between the second hole injecting and transporting layer (11) and the organic light emitting layer (4) of the device of Example 6. An element was produced in the same manner as the element of Example 6 except for the above. This element is 3
It emits light above V and the maximum brightness is 1831 at 11V.
The current density was 0 cd / m ² and the current density was 434 mA / cm ² .

When the device was driven at a constant current density of 20 mA / cm ² , the initial brightness was 6 at 7.2V.
After reaching 757 cd / m ² after 60 cd / m ² and 146 seconds, it decreased and the half-time of the initial luminance was 141 hours. Since the brightness is inversely proportional to the logarithm of the driving time, 10
The expected decay time up to 0 cd / m ² was about 4000 hours.

<Example 8> As the second hole injecting and transporting layer (11) of Example 1, a toluene solution of P10 (24 mg / 2 ml) was spin-coated at 1300 rpm instead of P1, and the second positive electrode having a film thickness of 50 nm was formed. After forming the hole injecting and transporting layer (11), TPD was vapor-deposited with a thickness of 5 nm as the third hole injecting and transporting layer (12). Next, as an organic light emitting layer (4), Alq ₃
Is vapor-deposited to a thickness of 5 nm and Al and L are used as a cathode (5) on the upper surface
After i was deposited to a thickness of 30 nm at a deposition rate ratio of 3: 1, only Al was deposited to a thickness of 190 nm and laminated. After that, sealing was performed in the same manner as in Example 1 to fabricate an element. This element emits green light with a DC voltage of 4V or more, and the maximum brightness is 1V at 17V.
219 cd / m ² , current density at that time is 570 mA / c
It was m ² .

[0068]

INDUSTRIAL APPLICABILITY The polyphosphazene compound, the polyether compound or the polyphosphoric acid compound according to the present invention is transparent and has a Tg higher than that of TPD. Therefore, a monolayer film or another material using them is laminated. The multilayer film thus obtained has high film strength and translucency, and has an effect of being less likely to be crystallized than a film composed of a TPD single layer.

Particularly, when the hole injecting and transporting layer having a three-layer structure in which the polyphosphazene compound in the present invention is used as the second hole injecting and transporting layer is used, the organic thin film EL device can emit light with high brightness and can be stabilized. It was very effective.

Further, by introducing a compound such as coumarin or oxadiazole, which cannot form a crystalline and smooth film by itself, as a side chain group of polyphosphazene to have low crystallinity, a smooth film having film strength can be obtained. Can be formed, and it can be used for an organic light emitting layer or an organic electron injecting and transporting layer of an organic thin film EL element.

[0071]

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing an example of an organic thin film EL element of the present invention.

FIG. 2 is an explanatory view showing another embodiment of the organic thin film EL element of the present invention.

FIG. 3 is an explanatory view showing another embodiment of the organic thin film EL element of the present invention.

FIG. 4 is an explanatory view showing another embodiment of the organic thin film EL element of the present invention.

[Explanation of symbols]

 (1) ... Substrate (2) ... Anode (3) ... Hole injecting and transporting layer (4) ... Organic light emitting layer (5) ... Cathode (6) ... Organic electron injecting and transporting layer (7) ... Sealing layer (8) Glass plate (9) Adhesive resin layer (10) First hole injecting and transporting layer (11) Second hole injecting and transporting layer (12) Third hole injecting and transporting layer (13) Power supply ( 14) ... Lead wire (15) ... Cathode outlet

Claims (7)

[Claims] 1. An organic thin film EL device comprising at least an anode, a hole injecting and transporting layer, an organic light emitting layer and a cathode,
An organic thin film E characterized in that the layer containing an organic compound between the anode and the cathode contains a polyphosphazene compound having a side chain having a hole transporting or light emitting or electron transporting group.
L element. 2. An organic thin film EL device comprising at least an anode, a hole injecting and transporting layer, an organic light emitting layer and a cathode,
An organic thin film E characterized in that the layer containing an organic compound between the anode and the cathode contains a polyether compound or a polyphosphate compound having an aromatic tertiary amine in the main chain.
L element. 3. A layer containing an organic compound between an anode and a cathode of an organic thin film EL element is a hole injecting and transporting layer, and the hole injecting and transporting layer has a multi-layer structure of two or more layers. 3. The organic thin film EL according to claim 1 or 2,
element. 4. The organic thin film EL element according to claim 1, wherein the hole injecting and transporting layer on the side in contact with the light emitting layer of the organic thin film EL element has a thickness of 10 nm or less. 5. The hole injecting and transporting layer on the side of the organic thin film EL element which is in contact with the anode is a phthalocyanine compound having a thickness of 30 nm or less.
The organic thin film EL device as described in 1. 6. The hole injecting and transporting layer on the side of the organic thin film EL device that is in contact with the light emitting layer is made of a low molecular weight aromatic tertiary amine hole injecting and transporting material. , 4
Alternatively, the organic thin film EL element described in 5 above. 7. A layer containing a polyphosphazene compound having a hole-transporting or light-emitting or electron-transporting group in a side chain of an organic thin film EL device, or a poly-containing aromatic tertiary amine in a main chain. 7. The organic thin film EL device according to claim 1, wherein the layer containing the ether compound or the polyphosphoric acid compound is formed by applying a solution of an organic solvent containing the compound. .