JP2004119393A - EL device and hole-transporting condensate used for the production thereof - Google Patents

Abstract

An EL element having heat resistance and capable of insolubilizing or patterning a hole transport layer or a hole transport light emitting layer in an organic solvent is provided.
The use of a hole-transporting condensate having a high Tg produced by addition condensation of an aromatic tertiary amine having a triarylamine structure with a carbonyl compound such as an aldehyde provides high heat resistance and a crosslinking group. This is effective in forming a hole transporting injection layer or a hole transporting light emitting layer which is patterned by mask exposure.
[Selection diagram] None

Description

The present invention relates to an EL device utilizing the electroluminescence (hereinafter simply referred to as EL) phenomenon of a thin film, and can be used for a thin display or the like.

An EL element is a light-emitting element utilizing the electroluminescence (hereinafter referred to as EL) phenomenon of a phosphor used in a light-emitting layer, and is used as a self-luminous flat display element or a flat light source. Among the EL devices, an organic thin film EL device in which the fluorescent substance is an organic substance is C.I. W. Tang et al., JP-A-59-194393, JP-A-63-264692, JP-A-63-295695, Applied Physics Letter Vol. 51, No. 12, page 913 (1987) ), And Journal of Applied Physics, Vol. 65, No. 9, page 3610 (1989).

In general, an organic thin-film EL device comprises an anode (2), an organic hole injection / transport layer (3), an organic light-emitting layer (4), and a cathode (1) on a transparent insulating substrate (1) as shown in FIG. 5) The layers are stacked in this order, and are manufactured as described below.

First, a transparent conductive film made of a composite oxide of indium and tin (hereinafter referred to as ITO) is formed as an anode (2) on a transparent insulating substrate (1) such as glass or a resin film by vapor deposition or sputtering. It is formed by a method or the like. Next, on this anode, 1,1-bis (4-di-p-tolylaminophenyl) as an organic hole injecting and transporting layer (3) capable of forming an amorphous and smooth film in order to make it difficult for the element to undergo dielectric breakdown. ) Single-layer film made of organic hole injecting and transporting material such as low molecular weight aromatic tertiary amine such as cyclohexane [glass transition temperature (Tg) 84 ° C] or copper which is crystalline but has high resistance to redox A multilayer film in which phthalocyanine or the like is laminated on the ITO interface is formed with a thickness of about 100 nm or less.

Further, on the organic hole injecting and transporting layer (3), an organic phosphor film such as tris (8-quinolinol) aluminum (hereinafter, referred to as Alq) is formed as an organic light emitting layer (4) with a thickness of about 100 nm or less. , Formed by a vapor deposition method. An organic thin film EL element is manufactured by forming an alloy film of Mg: Ag or the like as the cathode (5) with a thickness of about 200 nm on the organic light emitting layer by a co-evaporation method.

In the organic thin-film EL element manufactured as described above, holes and electrons are injected into the organic light-emitting layer by applying a low direct-current voltage between the electrodes, and light emission is generated by their recombination. The low DC voltage applied to this device is usually 20 to 30 V or less, and a device using a Mg: Ag alloy for the cathode has a luminance of 1000 cd / m ² or more. If the organic light emitting layer is doped with a coumarin-based, pyran-based, quinacridone-based fluorescent dye having a high fluorescence quantum yield by a method such as co-evaporation, the EL luminance can be further increased to twice or more.

According to JP-A-7-65958, as shown in FIG. 2, N, N′-diphenyl-N, N′-bis (3-methylphenyl) -1,1′-biphenyl-4, 4′-Diamine (hereinafter abbreviated as TPD; melting point: 159 to 163 ° C., Tg: 67 ° C.) The hole transport layer is doped with a luminescent material such as rubrene to form an organic hole transport light emitting layer (6), and Alq is further injected with organic electrons. By laminating as the transport layer (7), a relatively stable organic thin film EL device is obtained.

However, most of the hole transporting materials used in the above-mentioned organic thin film EL devices have been occupied by low molecular compounds so far, and most of them have low heat resistance at Tg of 100 ° C. or lower, and have a low heat resistance during device fabrication. When the temperature reached around Tg due to heat or heat generated during driving, it was mixed with other layers, or crystallized by storage or use in a high temperature environment to generate pinholes, which often caused deterioration of the element and electrical short circuit.

In addition, because of high solubility in an organic solvent such as toluene, there is a problem that it is difficult to further laminate a film by a wet method using the same organic solvent, or it is difficult to pattern the layer.

As described above, an object of the present invention is to provide an EL device which has higher heat resistance than a device using a conventional hole injection / transport material and is hard to cause an electric short circuit, and a hole transportable condensate used for the production thereof. In addition, by cross-linking the layer containing the hole-transporting condensate, heat resistance and mechanical strength are increased, the solvent is insolubilized, and application on the cross-linked layer by a wet method is enabled. An object of the present invention is to provide an EL device which can also perform patterning of a layer containing a hole transporting condensate.

The present invention relates to a hole transport obtained by the addition condensation of a carbonyl compound with a tertiary amine compound containing one or more triarylamine structures and at least two para positions on the aryl group are hydrogen. An EL device comprising a layer containing a sexual condensate.

As described above, according to the present invention, an EL element having high heat resistance can be obtained by using a hole transporting condensate having a high Tg generated by addition condensation of an aromatic tertiary amine and an aldehyde. Can be. Furthermore, when a hole transporting condensate having a crosslinking group is used and crosslinked, an EL element having higher heat resistance can be obtained. When used as a hole transporting light emitting layer, a pattern of the hole transporting light emitting layer can be formed by mask exposure.

Hereinafter, embodiments of the present invention will be described. FIG. 1 shows an EL device according to the present invention, in which an anode (2), an organic hole injection / transport layer (3), an organic light emitting layer (4), a cathode (5), and a sealing layer (8) are formed on a substrate (1). This is an example in which the sealing plate (10) is adhered and sealed with an adhesive material (9).

FIG. 2 shows an organic hole transporting / emitting layer (6) in which the hole injecting / transporting layer and the organic light emitting layer are combined into one layer to enhance electron injection efficiency into the emitting layer or suppress the flow of holes to the cathode. This is a case of a two-layer structure of the organic electron injection / transport layer (7) having an effect.

FIG. 3 shows the case where the organic hole injecting and transporting layer has a two-layer structure, and the ionization energy between the work function of the second hole injecting and transporting layer (12) and the anode as the first hole injecting and transporting layer (11). By using a material that is stable against oxidation and reduction, the efficiency of hole injection into the organic light emitting layer (4) is improved, and low voltage driving and stabilization of the EL element can be achieved.

FIG. 4 shows an example in which the organic hole injecting and transporting layer (3), the organic hole injecting and transporting layer (6), and the organic electron injecting and transporting layer (7) are constituted.

FIG. 5 shows an example in which the organic hole transporting and emitting layer (6) of FIG. 4 is patterned in red (R), green (G), and blue (B).

A similar structure can be formed on the substrate in the reverse order from the cathode, depending on the material used.

The EL device of the present invention is obtained by addition condensation of a tertiary amine compound containing at least one triarylamine structure and having at least two para-positions on the aryl group being hydrogen with a carbonyl compound. The hole transporting condensate compound is desirably used as the organic hole injecting and transporting layer (3), the first hole injecting and transporting layer (11), the second hole injecting and transporting layer (12), and the organic positive electrode in FIGS. At least one layer in the hole transporting light emitting layer (6) is used alone or in combination of a plurality of materials.

Hereinafter, the method of manufacturing the material and the element will be described in more detail.

The substrate (1) uses a transparent insulating material such as a plastic film such as glass or polyethersulfone. The substrate (1) is colored for improving contrast and durability, and provided on the inner and outer surfaces with a circular polarization filter, a multilayer antireflection filter, an ultraviolet absorption filter, an RGB color filter, a fluorescence wavelength conversion filter, a silica coating layer, and the like. Is also good.

The anode (2) usually uses a transparent electrode having a surface resistance of 1 to 50 Ω / □ and a visible light transmittance of 80% or more. For example, an amorphous or microcrystalline transparent conductive film of ITO (work function of 4.6 to 4.8 eV) or zinc aluminum oxide, or silver or copper having a thickness of about 10 nm for reducing resistance, or silver and copper is used. Transparent insulating film such as glass or plastic film formed by vacuum deposition or sputtering, etc. of a film in which an alloy is sandwiched between amorphous or microcrystalline transparent conductive films such as ITO, indium zinc composite oxide, titanium oxide, tin oxide, etc. It is desirable to form it on the substrate (1) and use it as a transparent electrode.

(4) When used for a simple matrix drive display, it is desirable to provide a metal bus line made of a low-resistance metal such as Cu or Al in contact with the line of the transparent electrode to further reduce the resistance. In addition, a translucent electrode on which gold or platinum is thinly deposited, a translucent electrode coated with a polymer such as polyaniline, polypyrrole, or polythiophene can be used.

However, in other cases, the anode (2) may be opaque. In this case, the anode (2) is made of a metal plate such as gold, platinum, palladium, or nickel having a large work function that facilitates hole injection into the organic light emitting layer (4) through the organic hole injection transport layer (3). A semiconductor substrate having a work function of 4.6 eV or more of silicon, gallium phosphide, amorphous silicon carbide or the like, or a substrate in which the metal or semiconductor is coated on an insulating substrate (1), and the cathode (5) is transparent An electrode or translucent electrode. If the cathode (5) is also opaque, at least one end of the organic light emitting layer (4) needs to be transparent.

Next, an organic hole injection / transport layer (3) is formed on the anode (2). In the present invention, a tertiary amine compound containing one or more triarylamine structures as a hole-transporting material and having at least two para groups on the aryl group being hydrogen is a carbonyl compound. A hole transporting condensed compound obtained by addition condensation is used.

The specific structure of the tertiary amine compound used in the present invention which contains one or more triarylamine skeletons and at least two of the aryl groups are hydrogen at the para-position is represented by the following chemical formulas (1) to (4). Or a blue hole transporting luminescent material of the following chemical formula (5), a green hole transporting luminescent material of the following chemical formula (6), and a red hole transporting luminescent material of the following chemical formulas (7) to (8): Exemplified by materials.

（式中、Ｒ_１はフェニル基上の水素原子またはメチル基、エチル基、イソプロピル基、ｔ−ブチル基等のアルキル基、メトキシ基等のアルコキシ基、トリル基等のアリール基、−Ｎ_２ ^＋Ｃｌ⁻等のジアゾニウム塩基、−Ｎ_３、−ＳＯ_２Ｎ_３、−ＣＯＮ_３から独立に選ばれる。）

(Wherein, R ₁ represents a hydrogen atom on a phenyl group, an alkyl group such as a methyl group, an ethyl group, an isopropyl group, a t-butyl group, an alkoxy group such as a methoxy group, an aryl group such as a tolyl group, —N ₂ ⁺ Cl ^- or the like of the diazonium _{base, -N 3, -SO 2 N 3} , are independently selected from -CON _3).

　上記化学式（２）〜（３）で示される第３級アミン化合物においてＲ_１はフェニル基上の水素原子またはメチル基、エチル基、イソプロピル基、ｔ−ブチル基等のアルキル基、メトキシ基等のアルコキシ基、ハロゲン原子、トリル基等のアリール基から独立に選ばれ、かつ、分子中少なくとも２カ所以上のフェニル基のパラ位は水素原子である。ｎは繰り返しを表す０から２の整数である。

In the tertiary amine compounds represented by the chemical formulas (2) to (3), R ₁ represents a hydrogen atom on the phenyl group or an alkyl group such as a methyl group, an ethyl group, an isopropyl group, a t-butyl group, a methoxy group or the like. An aryl group such as an alkoxy group, a halogen atom and a tolyl group is independently selected, and at least two or more phenyl groups in the molecule have a hydrogen atom at the para-position. n is an integer from 0 to 2 representing repetition.

（式中、Ｒ_１はフェニル基上の水素原子またはメチル基、エチル基、イソプロピル基、ｔ−ブチル基等のアルキル基、メトキシ基等のアルコキシ基、トリル基等のアリール基から独立に選ばれ、かつ、分子中少なくとも２カ所以上のフェニル基のパラ位は水素原子である。）

(Wherein, R ₁ is independently selected from a hydrogen atom on a phenyl group or an alkyl group such as a methyl group, an ethyl group, an isopropyl group, a t-butyl group, an alkoxy group such as a methoxy group, and an aryl group such as a tolyl group. And the para position of at least two or more phenyl groups in the molecule is a hydrogen atom.)

　上記化学式（５）〜（８）で示される第３級アミン化合物においてＲ_１はメチル基、エチル基、イソプロピル基、ｔ−ブチル基等のアルキル基、メトキシ基等のアルコキシ基、ハロゲン原子、トリル基等のアリール基から独立に選ばれる。

In the tertiary amine compounds represented by the above formulas (5) to (8), R ₁ is an alkyl group such as a methyl group, an ethyl group, an isopropyl group, a t-butyl group, an alkoxy group such as a methoxy group, a halogen atom, a tolyl group. Independently selected from aryl groups such as groups.

カ ル ボ ニ ル The carbonyl compound used as a raw material of the hole transporting condensate of the present invention is exemplified by Chemical Formulas 9 to 15.

（ここで、Ｒは水素原子、またはメチル基、エチル基、イソプロピル基、ｎ−ブチル基、ｔ−ブチル基等のアルキル基、塩素原子等のハロゲン、ジメチルアミノ基、ジエチルアミノ基から選ばれる。ｎは１または２の整数）

(Here, R is selected from a hydrogen atom, an alkyl group such as a methyl group, an ethyl group, an isopropyl group, an n-butyl group and a t-butyl group, a halogen atom such as a chlorine atom, a dimethylamino group, and a diethylamino group. Is an integer of 1 or 2)

　上記化学式（９）〜（１２）で示されるカルボニル化合物において、Ｒは水素原子、またはメチル基、エチル基、イソプロピル基、ｎ−ブチル基、ｔ−ブチル基等のアルキル基、塩素原子等のハロゲン、ジメチルアミノ基、ジエチルアミノ基から選ばれる。

In the carbonyl compounds represented by the above chemical formulas (9) to (12), R represents a hydrogen atom or an alkyl group such as a methyl group, an ethyl group, an isopropyl group, an n-butyl group, a t-butyl group, or a halogen atom such as a chlorine atom. , Dimethylamino group and diethylamino group.

　および、化学式（１５）で表される化合物

And a compound represented by the chemical formula (15)

（ここで、Ｒ_１、Ｒ_２は水素原子、またはメチル基、エチル基、イソプロピル基、ｎ−ブチル基等のアルキル基、その他、「機能性高分子シリーズ、感光性高分子（講談社１９７７年刊）」の１５５〜１５６ページ表６．１の感光基を含む基から独立に選ばれる）
　以上に例示した第３級アミン化合物とカルボニル化合物との付加縮合は、１，４−ジオキサン等の有機溶媒中で、パラ−トルエンスルホン酸等の酸を触媒として用い、５０℃〜１５０℃程度の温度で１０分〜２４時間程度反応させ行う。この際、第３級アミン化合物のカルボニル化合物と反応する確率が高いフェニル基上のパラ位の水素が２カ所以上未置換である化合物を用いる。

(Here, R ₁ and R ₂ are a hydrogen atom or an alkyl group such as a methyl group, an ethyl group, an isopropyl group, and an n-butyl group, and others, “Functional polymer series, photosensitive polymer (Kodansha 1977) Pages 155 to 156 of Table 6.1).
The addition condensation of the tertiary amine compound and the carbonyl compound exemplified above is carried out in an organic solvent such as 1,4-dioxane using an acid such as para-toluenesulfonic acid as a catalyst at a temperature of about 50 ° C. to 150 ° C. The reaction is carried out at a temperature for about 10 minutes to 24 hours. At this time, a compound having two or more unsubstituted para-position hydrogens on the phenyl group which has a high probability of reacting with the carbonyl compound of the tertiary amine compound is used.

具体 Specific examples of the obtained hole transporting condensate are shown below.

　上記化学式（１６）〜（１９）で示される本発明の付加縮合物において、ｎは重合度を表す正の整数を示し、Ｒ_１は水素原子または置換基を表し、置換基はメチル基、エチル基、イソプロピル基、ｔ−ブチル基等のアルキル基、メトキシ基等のアルコキシ基、トリル基等のアリール基、−Ｎ_２ ^＋Ｃｌ⁻等のジアゾニウム塩基、−Ｎ_３、−ＳＯ_２Ｎ_３、−ＣＯＮ_３から選ばれる。

In the addition condensate of the present invention represented by the above chemical formulas (16) to (19), n represents a positive integer representing the degree of polymerization, R ₁ represents a hydrogen atom or a substituent, and the substituent is a methyl group, an ethyl group. group, an isopropyl group, an alkyl group of a t- butyl group and the like, an alkoxy group such as methoxy group, aryl groups such as _tolyl, ^-N 2 + Cl ^- or the like of the diazonium _{base, -N 3, -SO 2 N 3} , - CON ₃

The molecular weight of the obtained addition condensate is about 3,000 to 1,000,000, as determined by GPC using styrene gel as a stationary phase and chloroform as a mobile phase, and a number average molecular weight (in terms of standard polystyrene manufactured by Showa Denko). It is more preferable to fractionate 10,000 to 1,000,000 components by removing the low molecular weight components by reprecipitation, dialysis, centrifugation or the like. Further, the terminal of the molecular chain may have an OH group derived from a carbonyl compound such as a methylol group.

In order to be soluble and have a higher molecular weight distribution on the higher molecular weight side, leave two hydrogens at the para-position on the phenyl group on the triarylamine skeleton and prevent other phenyl groups from being gelled by a long reaction. A bifunctional tertiary amine compound obtained by substituting the above para-position hydrogen with an alkyl group such as a methyl group, an ethyl group, an isopropyl group or a t-butyl group, an alkoxy group such as a methoxy group, or an aryl group such as a tolyl group. What is necessary is just to make it react with the exact equivalent carbonyl compound.

When there are three or more hydrogens at the para position on the phenyl group on the triarylamine skeleton, some of the components of the three-dimensional crosslinked structure are included, and gelation may occur due to a long reaction.

These hole-transporting condensate compounds of the present invention have a triarylamine compound in the main chain skeleton, have high hole-transport performance, and have a higher glass transition temperature than a low-molecular compound because they are polymers. The heat resistance of the element can be increased. Specifically, in the chemical formulas (16) to (19), when R is a hydrogen atom, Tg is 148 ° C., 141 ° C., 190 ° C., 157 ° C. (the temperature is raised at a rate of 10 ° C./min by the DSC method). Measurement).

The thin film can also be easily formed by dissolving in an organic solvent such as toluene or chloroform, and by a wet method such as a spin coating method or a blade coating method.

Further, in the layer of the hole-transporting condensate of the present invention, the step of the work function value between the anode and the light-emitting layer is reduced to improve the hole injection efficiency, improve the adhesion between layers, prevent deterioration, adjust the color tone, etc. For the purpose of the above, other known aromatic tertiary amine-based materials, known phthalocyanines such as CuPc, chlorinated copper phthalocyanine, tetra (t-butyl) copper phthalocyanine, and non-metallic phthalocyanines such as quinacridone A hole injecting / transporting material or a polymer hole transporting material such as poly (para-phenylenevinylene) or polyaniline is mixed with the compound represented by the formula (1) and used as a hole injecting / transporting layer, or as shown in FIG. As described above, the hole transporting material insoluble in the solvent at the time of forming the second hole injecting and transporting layer (12) is used as the first hole injecting and transporting layer (11) and as the second hole injecting and transporting layer (12). Hole transport according to the invention Condensates of it is possible to form the hole injection transport layer of the multilayer with. Further, it is also possible to form a multilayer hole transport layer having three or more layers. The layer of the hole transporting condensate of the present invention can crosslink molecular chains to increase heat resistance and to insolubilize in an organic solvent.

Specifically, a photosensitive group such as an azide group, a sulfonyl azide group, or a carbonyl azide group is introduced into a substituent in a tertiary amine compound, or a cinnamyl group, a stilbene group, a vinyl group, or the like is added to a carbonyl compound. Sensitization of benzophenone or the like by introducing a photosensitive group of the formula (1) and photocrosslinking, or by introducing a group from which a hydrogen radical such as an ethyl group or an isopropyl group is easily extracted as a substituent in a tertiary amine compound or a carbonyl compound. Add a material and photocrosslink.

The photocrosslinking is performed by irradiating ultraviolet rays in a vacuum or in an inert gas such as argon while heating to Tg or more.

た め In order to perform crosslinking sufficiently, it is also possible to perform crosslinking with a formaldehyde gas in an atmosphere of an acid such as hydrochloric acid or formic acid after film formation and photocrosslinking.

The hole-transporting condensate of the present invention comprises a tertiary amine used as a raw material, alone or mixed with a hole-transporting luminescent material having a fluorescence spectrum peak in a visible light region as represented by chemical formulas (5) to (8). Or as a mixture with a hole transporting material represented by chemical formulas (1) to (4) to function as an organic hole transporting light emitting layer (6), and can be any of blue, green, red, white, etc. Luminescent color is obtained.

In the case of forming a pattern of the hole transporting condensate of the present invention, a desired negative pattern can be formed by forming a film, exposing the film to a mask, and developing the film with an organic solvent such as toluene.

In addition, a negative pattern can be obtained by introducing a diazonium salt into a substituent in a tertiary amine compound, forming a film, exposing the film to a mask, and developing with an aqueous alkali solution. By patterning the hole transporting condensate of the present invention having blue, green, and red fluorescence three times and arranging the blue, green, and red patterns two-dimensionally on the substrate, as shown in FIG. It is possible to obtain a patterned hole transporting light emitting layer (13) corresponding to a suitable color display.

(4) The thickness of the organic hole injecting and transporting layer (3) and the organic hole transporting and emitting layer (6) is 100 nm or less, preferably 5 to 70 nm, even when they are formed as a single layer or a stacked layer.

Next, the case where the organic light emitting layer (4) is formed on the organic hole injection / transport layer (3) or the second hole injection / transport layer (12) as shown in FIGS. 1 and 3 will be described.

The organic light-emitting layer (4) is a layer containing one or more kinds of arbitrary phosphors having strong fluorescence in a visible region. Although the organic light emitting layer (4) can be formed only by the body, if the fluorescence is quenched in a solid state or a smooth film cannot be formed, the material may be used in a hole injection / transport material, an electron injection / transport material, or an appropriate resin. It can be used by dispersing it at an appropriate concentration in a binder.

Examples of phosphors that can be used in the EL device of the present invention include 9,10-diarylanthracene derivatives, salicylates, pyrene, coronene, perylene, rubrene, tetraphenylbutadiene, 9,10-bis (phenylethynyl) anthracene , 8-quinolinolate lithium, Alq, tris (5,7-dichloro-8-quinolinolate) aluminum complex, tris (5-chloro-8-quinolinolate) aluminum complex, bis (8-quinolinolate) zinc complex, tris (5 -Fluoro-8-quinolinolate) aluminum complex, tris (4-methyl-5-trifluoromethyl-8-quinolinolate) aluminum complex, tris (4-methyl-5-cyano-8-quinolinolate) aluminum complex, bis (2-methyl-5-trifluorome) 8-quinolinolate) [4- (4-cyanophenyl) phenolate] aluminum complex, bis (2-methyl-5-cyano-8-quinolinolate) [4- (4-cyanophenyl) phenolate] aluminum complex, tris (8-quinolinolate) scandium complex , Bis [8- (paratosyl) aminoquinoline] zinc complex and cadmium complex, 1,2,3,4-tetraphenylcyclopentadiene, pentaphenylcyclopentadiene, poly-2,5-diheptyloxy-para-phenylenevinylene, Alternatively, a fluorescent substance, N, or the like mentioned in Japanese Patent Application Laid-Open No. 4-31488, filed by Idemitsu Kosan, and US Pat. Nos. 5,141,671 and 4,769,292 of Eastman Kodak Company. N 'diaryl-substituted pyrrolopyrrole compounds, etc. And the like.

成膜 These organic light emitting layer materials can be formed by vacuum evaporation, spin coating, blade coating or the like.

(4) The thickness of the organic light emitting layer (4) is 100 nm or less, preferably 5 to 70 nm, even when it is formed as a single layer or a laminate.

The phosphor in the organic light emitting layer (4) is described in, for example, a laser die catalog of Lambda Fizzic Co. or Eastman Kodak Co., USA for conversion of emission wavelength, expansion of emission wavelength, improvement of emission efficiency, and the like. One or more phosphors such as coumarin-based, quinacridone-based, perylene-based, and pyran-based phosphors may be doped into the host light-emitting matrix as one or more guest light-emitting members, or two or more light-emitting layers of various types of phosphors may be laminated. One of them may show fluorescence in an infrared region or an ultraviolet region. Further, the phosphor of the light emitting layer may be an inorganic substance.

Next, when an organic electron injecting and transporting layer (7) is laminated on the organic light emitting layer (4) or the organic hole transporting and emitting layer (6) as shown in FIGS. Preferred conditions for the material are such that the electron mobility is high, the LUMO state density is high, and the LUMO energy level is between the same as the LUMO energy level of the organic light emitting layer material and the Fermi level (work function) of the cathode material. In addition, the ionization energy is larger than that of the organic light emitting layer material, and the film formability is good. Further, in an element in which the anode (2) is opaque and light is extracted from the transparent or translucent cathode (5), the anode (2) needs to be substantially transparent at least in the fluorescent wavelength region of the organic light emitting layer material.

Examples of the organic electron injecting and transporting layer include BPBD, 2,5-bis (1-naphthyl) -1,3,4-oxadiazole, and an oxadiazole derivative synthesized by Hamada et al. (The Chemical Society of Japan, p. 1540) 1991) and bis (10-hydroxybenzo [h] quinolinolato) beryllium complex, triazole compounds described in JP-A-7-90260, and Marco Strukelj et al., Described in Science 267, p. 1969 (1995). Dehydrofluorinated condensation polymer of 1,2-Bis (3-hydroxy) phenyl-4- (3-trifluoromethylphenyl) -triazole and Decafluorobiphenyl provided on Poly (p-phenylenevinylene) light emitting layer, etc. Compounds, other silicon carbide, inorganic semiconductor or photoconductive layer of the amorphous silicon film and the like. In the case where a light emitting layer is formed by doping a guest light emitting body into a host light emitting base, the host light emitting base can be used as an organic electron injection / transport layer.

The organic electron injecting and transporting layer (7) is formed by a coating method such as a spin coating method or a vacuum evaporation method, a CVD method, a cumulative film method or the like, and is formed into a single layer having a thickness of 1 nm to 1 μm. Or a multilayer film.

Next, a cathode (5) is formed on the organic light emitting layer (4) or the organic electron injection / transport layer (7). For the cathode, it is more effective to use a material having a low work function on the surface in contact with the organic light emitting layer (4) or the organic electron injection transport layer (7) in order to perform electron injection effectively. The material constituting the cathode is a single metal such as Mg, Al, or Yb, or Li, Mg, Ca, Sr, La, Ce, Er, Eu, Sc, or the like having a low work function in order to achieve both a low work function and stability. An alloy or a laminate of one or more metals such as Y and Yb and a stable metal element such as Ag, Al, In, Sn, Zn, Mn, Ti and Zr is used.

Depending on the material, the cathode can be formed by a resistance heating evaporation method, an electron beam evaporation method, a reactive evaporation method, an ion plating method, or a cathode film can be formed by a sputtering method using an alloy target. . The cathode has a thickness of about 10 nm to 1 μm.

Next, a sealing layer (8) is formed on the element in order to prevent oxidation of a layer made of an organic substance and an electrode of the element. The sealing layer (8) is formed immediately after the formation of the cathode (5). Examples of the sealing layer material include oxides such as SiO ₂ , SiO, GeO, MgO, CaO, Al ₂ O ₃ , B ₂ O ₃ , TiO ₂ , ZnO, and SnO. And oxygen compounds such as sulfides such as MgF ₂ , LiF, BaF ₂ , and AlF ₃ , sulfides such as ZnS, and inorganic compounds having a high water vapor barrier property, but are not limited to the above examples. It is not done. These are formed as a single substance, a composite substance, or a multilayer substance by a vapor deposition method, a reactive vapor deposition method, a CVD method, a sputtering method, an ion plating method, or the like.

Furthermore, in order to prevent moisture from entering, the substrate of the EL element is sealed in a vacuum with a hermetic seal, or a commercially available low moisture-absorbing photo-curable adhesive, epoxy-based adhesive, silicone-based adhesive, cross-linked ethylene-vinyl acetate Using an adhesive resin such as a copolymer adhesive sheet or an adhesive material (9) such as low melting point glass, the periphery or the entire surface of a sealing plate (10) such as a glass plate is adhered and sealed. In addition to a glass plate, a metal plate, a plastic plate, or the like can be used. A desiccant such as silica gel or zeolite may be mixed in the adhesive material (9), or a desiccant such as silica gel, zeolite, or calcia may be formed on the sealing layer (8) or the inner surface of the sealing plate (10). Alternatively, a layer of a getter material including alkali metal, alkaline earth metal, rare earth, or the like may be formed.

The organic thin-film EL device thus configured emits light when the organic hole injecting and transporting layer (3) is connected to the power supply (14) with the lead wire (15) and the DC voltage is applied while the organic hole injection / transport layer (3) side is positive. Even when a voltage is applied, light is emitted while the anode (2) is positively applied with a voltage.

In a nitrogen atmosphere, 10 ml of 1,4-dioxane was added to 10.0 g of triphenylamine and 5.42 g of cinnamoylaldehyde, and 0.75 g of paratoluenesulfonic acid was added thereto. The mixture was heated at an oil bath temperature of 120 ° C. for 15 hours. The mixture was stirred and reacted. This was poured into methanol for precipitation. The polymer was reprecipitated and purified with chloroform / methanol = 2/1 and chloroform / acetone = 3/1 to remove low molecular weight substances. The hole transport in the form of pale yellow-green powder represented by chemical formula (18) and R ₁ = H was obtained. 13.4 g of an acidic condensate was obtained.

For this hole transporting condensate, 880-PU manufactured by JASCO Corporation was used as a pump, a differential refractometer 830-RI manufactured by JASCO Corporation was used as a detector, styrene gel was used as a stationary phase, and chloroform was moved. GPC measurement as a phase revealed a number average molecular weight of 10,000 and a weight average molecular weight of 51,000 (standard polystyrene equivalent, manufactured by Showa Denko KK).

Next, regarding this hole transporting condensate, the glass transition point (Tg) was determined at a rate of temperature increase of 10 ° C./min under a nitrogen atmosphere using DSC220 manufactured by Seiko Denshi Kogyo Co., Ltd. Met. The ionization energy measured by a surface analyzer AC-1 manufactured by Riken Keiki Co., Ltd. was 5.8 eV.

(4) As a transparent insulating substrate (1), a blue glass plate having a thickness of 1.1 mm was used, and 120 nm of ITO was coated thereon by a sputtering method to form an anode (2). This transparent conductive substrate was sufficiently washed with water and plasma before use.

The hole injecting and transporting layer is prepared by first vacuum-depositing Aldrich copper phthalocyanine to a thickness of 10 nm as a first hole injecting and transporting layer (11), and forming a hole transporting condensate of the present invention as a second hole injecting and transporting layer (12). A toluene solution of the compound [Chemical formula (18), R ₁ = H] was spin-coated to form a film having a thickness of 40 nm.

Next, Alq was vapor-deposited as an organic light emitting layer (4) to a thickness of 50 nm, and Mg and Ag were vapor-deposited as a cathode (5) on the upper surface thereof at a vapor deposition rate of 10: 1 to a thickness of 220 nm. Finally, GeO was ion-plated as a sealing layer (8) by 1 μm, and a glass plate (10) was adhered and sealed with a photocurable resin (9).

This device emitted stable green light at a DC voltage of 4 V or more, had a luminance of 7766 cd / m ^{2 at} 15 V, and a current density of 471 mA / cm ² . Even after heating to 100 ° C., light was emitted similarly.

After spin-coating the hole transporting condensate of Example 2, the substrate was irradiated with ultraviolet light from a 150 W deuterium lamp [L1835 manufactured by Hamamatsu Photonics KK] from a distance of about 30 cm on a hot plate heated to 250 ° C. in vacuum. Irradiation was carried out for 20 minutes for crosslinking. The membrane was insoluble in toluene. Thereafter, an EL element was manufactured in the same manner as in Example 2.

This device emitted green light stably at a DC voltage of 4 V or more, had a luminance at 14 V of 8543 cd / m ² and a current density of 678 mA / cm ² .

After depositing copper phthalocyanine in the same manner as in Example 2, spin-coating the hole-transporting condensate of Example 1 with a thickness of 90 nm, mask exposure to ultraviolet light under heating at 250 ° C., and line / space (1 mm / 1 mm) stripes by toluene development. A pattern was formed. Further, a hole transporting condensate obtained by performing a reaction in the same manner as in Example 1 using triphenylamine containing 30% of a green phosphor [chemical formula (6) R ₁ = methoxy] as a raw material is spin-coated to a thickness of 90 nm. A pattern was formed in the form of a stripe in the space portion of the pattern composed of the hole transporting condensate of Example 1 by mask exposure to ultraviolet light at 250 ° C. and development with toluene.

{Circle around (2)} Mg and Ag were deposited as a cathode (5) on the upper surface at a deposition rate ratio of 10: 1 to 220 nm. Finally, GeO was ion-plated as a sealing layer (8) by 1 μm, and a glass plate (10) was adhered and sealed with a photocurable resin (9).

The device emitted stripe-shaped green light stably even when heated to 150 ° C.

FIG. 3 is an explanatory view showing one embodiment of the EL element of the present invention. FIG. 3 is an explanatory view showing one embodiment of the EL element of the present invention. FIG. 3 is an explanatory view showing one embodiment of the EL element of the present invention. FIG. 3 is an explanatory view showing one embodiment of the EL element of the present invention. FIG. 3 is an explanatory view showing one embodiment of the EL element of the present invention.

Explanation of reference numerals

(1) substrate (2) anode (3) organic hole injecting and transporting layer (4) organic light emitting layer (5) cathode (6) organic hole transporting and emitting layer (7) organic electron injecting and transporting Layer (8) Sealing layer (9) Adhesive material layer (10) Glass plate (11) First hole injection transport layer (12) Second hole injection transport layer (13) Pattern formation Hole transporting light emitting layer (14) Power supply (15) Lead wire (16) Cathode outlet

Claims (6)

A hole transporting condensate obtained by addition condensation of a tertiary amine compound containing one or more triarylamine structures and having at least two para groups on the aryl group a hydrogen at the para-position with a carbonyl compound. An EL device, comprising a layer containing the same. The EL device according to claim 1, wherein the carbonyl compound has a crosslinking group containing one or more carbon-carbon double bonds. The EL device according to claim 1, wherein the layer containing the hole-transporting condensate is cross-linked. 4. The EL device according to claim 3, wherein the layer containing the hole transporting condensate is patterned by exposure and development. 4. The EL device according to claim 3, wherein the layer containing the hole transporting condensate contains an organic light emitting material having fluorescence in a visible region. A tertiary amine compound containing one or more triarylamine structures and at least two of the aryl groups at the para-position being hydrogen, obtained by addition condensation with a carbonyl compound; A hole transporting condensate.

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