JPH0711244A - Thin film element emitting light in electric field and method for producing same - Google Patents

Abstract

PURPOSE:To provide the subject element excellent in heat resistance, light emission, durability and adhesivity, and useful for the display of information, etc., by successively forming a specific silicon-based high molecular compound- containing layer and a specific light-emitting layer on a transparent electrode substrate by vacuum deposition polymerization methods, and further forming the other electrode substrate thereon. CONSTITUTION:The objective element is produced by successively forming a silicone polymeric compound-containing layer 3 comprising a silicon polymer and a condensation polymer, a light-emitting layer 4 comprising the polycondensation polymer of a compound having a polyoxadiazole structure, etc., and a layer 5 containing the above silicon-based high molecular compound on one of electrode substrates 1 at least one of which is transparent, and further forming the electrode substrate 2 thereon, the silicon-based high molecular compound being formed by vacuum deposition polymerization of a dicarboxylic chloride of formula I (X is an organic group containing an aromatic ring or hydrocarbon group and containing Si) and a dicarbohydrazide compound of formula II (Y is X) under a vacuum condition.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thin film electroluminescent device and a method for manufacturing the same, and more particularly to a thin film electroluminescent material used for a flat panel display or a backlight in the field of information display or optical information processing, and the same. The present invention relates to a thin film electroluminescent device such as a light emitting device and a display device used and a manufacturing method thereof.

[0002]

BACKGROUND OF THE INVENTION Organic thin film electroluminescent materials have recently attracted attention in the fields of information display, optical information processing and the like.

The organic thin film electroluminescence (EL) element is a complete solid-state element and thus has excellent impact resistance, and also has a feature of high visibility because it has self-luminous property. Currently, it is a flat panel type display. Has been actively researched for use. This organic thin-film electroluminescent device has an organic electroluminescent layer interposed between electrodes, and can emit light (wavelength and intensity) specific to the organic electroluminescent layer by applying a voltage to the electrodes. . Such light emission is generally considered to occur when electrons and holes injected into the organic electroluminescent layer by applying a voltage as described above recombine and relax in the organic electroluminescent layer. ing.

By the way, as the electroluminescent material, there are organic and inorganic materials. As the organic electroluminescent material, single crystal anthracene which causes blue electroluminescence has been known for a long time. Semiconductors are well known as the electroluminescent material of the system.

However, the number of anthracene single crystals is tens.
Since the thickness is as thick as μm to several mm, a driving voltage of several hundreds V is required to emit light from this single crystal. Further, anthracene single crystal is an organic material having a single composition, but there is a problem that charge injection efficiency is low because both hole (+) and electron (-) charges are injected into such a single crystal. It was

Although it is possible to reduce the drive voltage required for light emission of the anthracene single crystal by thinning it, it is difficult to improve the charge injection efficiency.

By the way, Tang et al. Have proposed a laminated (two-layer) type electroluminescent device (EL device) using an organic light emitting material (Appl. Phys. Lett., Vol. 51, No. 12). (1987) p.
913-915). This two-layer type electroluminescent device is an ITO (Indiu
m Tin Oxide) electrode is formed by sequentially depositing a hole injection layer, a light emitting layer having an electron transport function, and an electron injection electrode made of a MgAg alloy, and the hole injection layer and the electron injection layer are different from each other. This two-layer electroluminescent device is made of a material, and when a voltage of several tens of V is applied, electrons and holes are injected into the light emitting layer of the device to emit light.

In this two-layer type electroluminescent device, the luminescent color can be changed by selecting various luminescent materials, and as the luminescent material, for example, an aluminum quinolinol complex (Alq ₃ ) which is a low molecular weight compound is used. Thus, green light emission is obtained.

However, in this two-layer type electroluminescent device, the above-mentioned low molecular weight compound deposited on the light emitting layer is crystallized and peeling occurs between the organic layer (light emitting layer) and the electrode, so that no light is emitted. There was a point. Further, there is a problem that the two-layer type light emitting element generates heat due to light emission and its temperature rises remarkably, resulting in peeling between the organic layer and the electrode and deterioration of the element.

On the other hand, it has been proposed to prevent deterioration or crystallization of these layers by using a polymer thin film as such an electron injection (transport) layer, a light emitting layer or a hole injection (transport) layer. .

For example, a low molecular weight dye-polymer composite material obtained by doping a small amount of a light emitting low molecular weight dye into poly (methylphenylsilane) as a hole transport material is thinly formed by a wet method such as spin coating. By film-forming and vacuum-depositing an electron-transporting material on this thin film to form a two-layer laminated device (Chem. Lett. 1991 p.1267-1270), or
A low molecular weight dye-polymer composite material obtained by adding a light emitting low molecular weight dye and an electron transporting low molecular weight dye to poly (N-vinylcarbazole) as a hole transport material is formed by a wet method such as spin coating. It has been reported that a high performance electroluminescent device can be produced by forming a single layer type device by applying a film (Applied Physics Vol.61 No.10 p.1044-1047).

In an electroluminescent device having a low molecular weight dye-polymer composite thin film produced by such a wet method, crystallization due to heat generation is less likely to occur, and therefore durability is expected to be improved.

However, when the electroluminescent device is manufactured by the wet method, various impurities may be mixed into the thin film and the surface of the thin film may be contaminated when the low molecular dye-polymer composite thin film is manufactured. There was a problem with. Further, in the electroluminescent device produced by such a wet method, although crystallization is less likely to occur, charge injection efficiency is lowered, and peeling occurs between the electrode and the low molecular weight dye-polymer composite thin film. There were times when it happened.

In the case of manufacturing an electroluminescent device by a wet method, when an organic layer (upper layer) is further applied and formed on the organic layer (lower layer) formed by the wet method, the organic material of the lower layer is formed. It is important to prevent the layer from being dissolved or eluted, and for that purpose, when forming the upper organic layer by coating,
The solvent must be chosen so that it does not dissolve the lower layer. Therefore, the materials that can be used when forming the lower layer and the upper layer, or the combination of solvents is naturally limited, and as a result, the materials that can be selected as the polymer material that constitutes the thin film EL device or the contained low-molecular-weight light emitting material, etc. There was a problem that the types became narrow.

[0015]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and is excellent in hole injection / transport properties, light emission properties, electron injection / transport properties, heat resistance, and durability. An object of the present invention is to provide a thin film electroluminescent device having excellent adhesion between an electrode and a light emitting layer. It is another object of the present invention to provide a method for manufacturing a thin film electroluminescent device that can use a wide range of organic polymer materials or a wide range of low molecular weight light emitting materials.

[0016]

SUMMARY OF THE INVENTION A thin film electroluminescent device according to the present invention is a thin film electroluminescent device comprising a pair of electrodes, at least one of which is transparent, and a light emitting layer provided between the pair of electrodes. It is characterized in that a layer containing a silicon-based polymer compound is provided between the layer and the light emitting layer.

In a preferred embodiment of the present invention, the silicon-based polymer compound-containing layer comprises a silicon-based polymer and a polycondensation polymer, and the silicon-based polymer content is from the electrode side to the light emitting layer. It is preferred that the polycondensation type polymer content decreases toward the side and the polycondensation polymer content increases from the electrode side toward the light emitting layer side.

The silicon-based polymer has the following formula (I):
It is preferred that the polycondensation polymer has a silicon-containing polyoxadiazole structure represented by and the polycondensation polymer has a polyoxadiazole structure represented by the following formula (II).

[0019]

[Chemical 7]

[In the formula (I), X and / or Y represents an organic group containing an aromatic ring or a hydrocarbon group and containing Si. ]

[0021]

[Chemical 8]

[In the formula (II), X'and / or Y '
Represents an organic group containing an aromatic ring or a hydrocarbon group and containing no Si. The polyoxadiazole (II) is preferably a polycondensation product of a diacid chloride represented by the following formula (1) and a dicarbohydrazide compound represented by the following formula (2).

[0023]

[Chemical 9]

[In the formula, X'represents an organic group containing an aromatic ring or a hydrocarbon group and containing no Si. ]

[0025]

[Chemical 10]

[In the formula, Y'represents an organic group containing an aromatic ring or a hydrocarbon group and not containing Si. The method for producing a thin-film electroluminescent device according to the present invention comprises the steps of producing a film electroluminescent device having a pair of electrodes, at least one of which is transparent, a light emitting layer, and a silicon-based polymer compound-containing layer. On the electrode substrate, by vapor deposition polymerization, a silicon-based polymer compound-containing layer made of a silicon-based polymer and a condensation-polymerized polymer, a light-emitting layer made of a condensation-polymerized polymer, and a silicon-based polymer compound as described above. It is characterized in that layers are sequentially formed, and then the other electrode substrate is formed.

In a preferred embodiment of the present invention, the silicon-based polymer comprises a diacid chloride represented by the following formula (3) and a dicarbohydrazide compound represented by the following formula (4) under vacuum conditions. It is preferably obtained by vapor deposition polymerization.

[0028]

[Chemical 11]

[0029]

[Chemical 12]

[In the formulas (3) and (4), X and / or Y contains an aromatic ring or a hydrocarbon group, and S
represents an organic group containing i. In a preferred embodiment of the present invention, the polycondensation polymer is a diacid chloride represented by the following formula (1) and a dicarbohydrazide compound represented by the following formula (2) under vacuum conditions. Is preferably obtained by vapor-depositing and polymerizing.

[0031]

[Chemical 13]

[In the formulas (1) and (2), X'and Y '
Represents an organic group containing an aromatic ring or a hydrocarbon group and containing no Si. According to the present invention, there is provided a thin film electroluminescent device which is excellent in hole injection / transport properties, light emission properties, electron injection / transport properties, heat resistance, durability, and adhesion between electrodes and a light emitting medium layer. To be done. Further, according to the present invention, a thin film electroluminescent device can be manufactured using a wide range of organic polymer materials or a wide range of low molecular weight light emitting materials.

[0033]

DETAILED DESCRIPTION OF THE INVENTION The thin film electroluminescent device and the method for manufacturing the same according to the present invention will be specifically described below. [Thin-Film Electroluminescent Device] The thin-film electroluminescent device according to the present invention is, for example, as shown schematically in FIG. 1, a pair of electrodes 1 in which at least one of the two electrodes 1 and 2 is transparent. , 2, a silicon-based polymer compound-containing layer 3 and 5 respectively provided inside the pair of electrodes 1 and 2, and a light-emitting layer 4 provided between the silicon-base polymer compound-containing layers 3 and 5.
It consists of

In a preferred embodiment of the present invention, as shown in FIG.
Preferably contains a silicon-based polymer and a polycondensation-based polymer. Moreover, in this silicon-based polymer compound-containing layer (concentration gradient layer), the silicon-based polymer content is The polymer compound-containing layers 3 and 5 decrease continuously or stepwise from the side in contact with the electrodes 1 and 2 to the side in contact with the light emitting layer 4. Further, the polycondensation polymer content is determined as follows. It is preferable to increase continuously or stepwise from the side in contact with the side toward the side in contact with the light emitting layer 4. Further, as shown in (e) in FIG. 2, it may be composed of only a silicon-based polymer compound, but considering the light emitting function, (a) or (b) is preferable.

In a preferred embodiment of the present invention as described above, the contact surfaces of the silicon-based polymer compound-containing layers 3 and 5 with the electrodes 1 and 2 are made of a silicon-base polymer and contain a silicon-base polymer compound. The contact surfaces of the layers 3 and 5 with the light emitting layer 4 are preferably made of a polycondensation polymer as in the light emitting layer 4 described later.

In such a thin film electroluminescent device 10, the light emitting layer 4 and the silicon-containing polymer compound-containing layers 3 and 5 are usually formed as a continuous layer and integrated. Of the electrodes 1 and 2 of the electroluminescent device 10, known electrodes such as ITO and Au are used as the hole (hole) injection electrode 2, and Mg is used as the electron (negative charge) injection electrode 1.
Known electrodes such as Ag, In, Ca and Al are used.

The thickness of the electrodes 1 and 2 of such a thin film electroluminescent device 10 is usually about 100 to 2000 angstroms, and the thickness of the silicon-based polymer compound-containing layers 3 and 5 is usually 10 to 2000 angstroms. The thickness of the light-emitting layer 4 is usually 200 to 10000 angstroms, preferably 500 to 5000 angstroms.

First, the silicon-based polymer and the condensation-polymerized polymer contained in the silicon-based polymer compound-containing layers 3 and 5 of the thin film electroluminescent device 10 will be described below. Silicon-based Polymer The silicon-based polymer contained in the silicon-based polymer compound-containing layers 3 and 5 has at least one function of hole injecting / transporting property, electron injecting / transporting property, and light emitting property, and contains Si. There is no particular limitation as long as it is a polymer.

As such a silicon-based polymer, a compound having a polyoxadiazole structure represented by the following formula (I) (π-electron conjugated organic group-containing polymer) is preferable.

[0040]

[Chemical 14]

[In the formula (I), X and / or Y represents an organic group containing an aromatic ring or a hydrocarbon group and containing Si. ] As such a silicon-based polymer-forming monomer material,
It is desirable to use a diacid chloride represented by the following formula (3) and a dicarbohydrazide compound represented by the following formula (4).

[0042]

[Chemical 15]

[In the above formulas (3) and (4), X and / or Y represents an organic group containing an aromatic ring or a hydrocarbon group and containing Si. ] Here, X in the diacid chloride represented by the above general formula (3)
(That is, X in the above general formula (I)) or (4)
Y in the dicarbohydrazide compound represented by (that is, Y in the above general formula (I)) is an electron-transporting group,
It is a group having a function as a hole transporting group or a light emitting group. Further, X and Y may be the same organic group containing Si, or may be different groups as long as one of X and Y contains Si. Such a group is preferably a π-electron conjugated group.

The polymer having the structure represented by the general formula (I) has excellent adhesion to the glass substrate or the metal electrode, and deterioration of the electroluminescent device is unlikely to occur. In the above formula (3), examples of the diacid chloride (3) in which the residue X is an organic group containing an aromatic ring or a hydrocarbon group and containing Si include the following compounds. it can. [Di (p-chlorocarbonylphenyl) -dimethylsilane]:

[0045]

[Chemical 16]

Further, in the above formula (4), examples of the dicarbohydrazide compound (4) in which the residue Y is an organic group containing an aromatic ring or a hydrocarbon group and also containing Si are as follows: Such compounds can be mentioned.

[0047]

[Chemical 17]

In the above formula (3), when the residue X is a diacid chloride (3) which is an organic group containing an aromatic ring or a hydrocarbon group and not containing Si, it will be described later. The diacid chloride (1) used when forming the condensation-polymerized polymer is preferably used. Further, in the above formula (4), when the residue Y is a dicarbohydrazide compound (4) which is an organic group containing an aromatic ring or a hydrocarbon group and containing no Si, a contraction as described below. The dicarbohydrazide compound (2) used when forming a polymer is preferably used.

Polycondensation polymer In the present invention, the polycondensation polymer is contained in the silicon polymer compound-containing layers 3 and 5 and the light emitting layer 4. Of these, the silicon polymer compound-containing layer is included. The polycondensation polymer contained in 3, 5 has at least one function of hole injecting / transporting property, electron injecting / transporting property, and light emitting property,
Further, the polycondensation polymer contained in the light emitting layer 4 is not particularly limited as long as it has a light emitting function, and may have a hole injecting / transporting property or an electron injecting / transporting function. Good.

Examples of such polycondensation polymers include polyimide, polyamide, polyamideimide, polyurea, polyazomethine and the like (Poly.
merPreprints Japan, Vol.136 p1475 (1987), Vol.13
6 p3021 (1987)).

In the present invention, among such polycondensation polymers, a compound having a polyoxadiazole structure represented by the following formula (5) (π-electron conjugated organic group-containing polymer) is preferable.

[0052]

[Chemical 18]

[Wherein X'and Y'represent an organic group containing an aromatic ring or a hydrocarbon group and containing no Si, and X '
And Y'may be the same or different. n is an integer of 1 or more, which represents the degree of polymerization. As such a polyoxadiazole (5) -forming monomer, it is preferable to use a diacid chloride represented by the following general formula (1) and a dicarbohydrazide compound represented by the following general formula (2). .

[0054]

[Chemical 19]

[In the formulas (1) and (2), X'and Y '
Represents an organic group containing an aromatic ring or a hydrocarbon group and containing no Si. ] Here, X'in the diacid chloride represented by the above general formula (1) (that is, X'in the above general formula (5)) or Y'in the dicarbohydrazide compound represented by (2).
(That is, Y'in the above general formula (5)) represents an electron-transporting group, a hole-transporting group, or a light-emitting group, depending on the intended use (light-emitting layer or silicon-based polymer compound-containing layer). It is a functional group, and X ′ and Y ′ may be the same or different. Such a group is preferably a π-electron conjugated group.

When the thin film containing the polymer represented by the general formula (5) is used as a charge (positive or negative) injecting / transporting layer, X'in the general formula (5) (that is, the formula (1)).
X ') or Y'in the general formula (5) (that is, Y'in the formula (2)) is a hole (hole) injection / transport function or an electron (negative charge) injection / transport function. Have.

For example, the above-mentioned polymer thin film is made into an electron (negative charge).
When used as an injecting / transporting layer for organic groups X ', Y'
Specific examples of the group that can be used as include the following groups and groups in which these groups are combined.

[0058]

[Chemical 20]

Here, R ₁ is bonded to any of the ortho, meta and para positions of the aromatic ring, and is a hydrogen atom, a halogen atom, a cyano group, an alkyl group, an aralkyl group, an alkyloxy group, It is a group selected from the group consisting of nitro groups.

[0060]

[Chemical 21]

Here, R ₂ , R ₃ and R ₄ are bonded to any of the ortho, meta and para positions of the aromatic ring,
Each is independently a group selected from the group consisting of a hydrogen atom, a halogen atom, a cyano group, a nitro group, an alkyl group, an aralkyl group and an alkyloxy group, and R ₂ , R ₃ and R ₄
May be the same or different.

[0062]

[Chemical formula 22]

Here, R ₅ and R ₆ are bonded to any of the ortho, meta and para positions of the aromatic ring, and are independently a hydrogen atom, a halogen atom, a cyano group, an alkyl group or an aralkyl. It is a group selected from the group consisting of a group, an alkyloxy group and a nitro group, and R ₅ and R ₆ may be the same or different.

Of these, X'and Y'are preferably a meta-phenylene group, a para-phenylene group, a 4,4'-biphenylene group or a 2,6-pyridylene group, and particularly para-phenylene group. It is preferably a group.

An organic group having such an electron (negative charge) injection / transport function is represented by X'or Y'in the general formula (5).
When used as, the thin film containing the polymer having the structure represented by the formula (5) can serve as an electron injecting / transporting layer.

In the thin film containing the polymer having the structure represented by the general formula (5), for example, Chem.Mate
r., Vol.3 (1991) pp.709-714 and J.Imag.Sci., Vol.29, N
A low molecular weight compound having an electron injecting / transporting function such as a diphenoquinone derivative and a fluorenone derivative disclosed in o.2 (1985) pp.69-72 may be contained. Here, by adjusting the concentration of the contained low molecular weight compound, the injection / transport performance for electrons in the obtained thin film can be controlled.

When the polymer-containing thin film is used as a hole injecting / transporting layer, X'and Y'in the general formula (5) are various compounds known as electrophotographic photoreceptors. Derivative residues can be used. Examples of such a hole injecting / transporting residue include groups derived from the following compounds.

Aromatic tertiary amine or porphyrin compounds disclosed in JP-A-63-295695, JP-A-53-27033 and JP-A-54-58.
445, JP-A-54-149634, JP-A-54-64299, and JP-A-55-144250.
JP-A-56-119132, JP-A-61
Compounds disclosed in, for example, JP-A-295558 and JP-A-61-98303.

Of these, the organic radicals particularly preferable for the hole injecting / transporting layer include the following groups.

[0070]

[Chemical formula 23]

[0071]

[Chemical formula 24]

When such an organic group having a hole injecting / transporting function is used for the residue X'or Y'in the general formula (5), it has a structure represented by the formula (5). The polymer-containing thin film can be a hole injecting / transporting layer.

In the thin film containing the polymer having the structure represented by (5), for example, Chem. Lett., 1989,
4,4 ', 4''-tris (N, Ndiphenylamino) triphenylamine disclosed in pp.1145 and 4,4', 4 ''-tris [N- (3
A low molecular weight compound having an excellent hole injecting / transporting function such as a triphenylamine derivative such as -methylphenyl) -N-phenylamino] triphenylamine may be contained.

When the polymer-containing thin film is used as a light emitting layer, the organic groups X'and Y'as described above are used as the residue X'or Y'in the general formula (5). it can. That is, the polyoxadiazole represented by the general formula (5) has not only a charge injection / transport function but also a function of emitting fluorescence by itself.

Further, a laser dye residue or a luminescent dye residue known as an organic scintillator can be used as the residue X'or Y'in the general formula (5). Specific examples of such a luminescent dye residue include the following groups.

[0076]

[Chemical 25]

Two or more of these luminescent dye residues may be combined. In addition, when the residue X ′ in the general formula (5) is a 1,4-phenylene group and Y ′ is a 1,3-phenylene group, a heavy chain having a structure represented by the general formula (5) is used. The thin film electroluminescent device using the combined thin film as a light emitting layer emits blue fluorescence having a maximum value at a wavelength of 410 nm. When both X ′ and Y ′ are 1,4-phenylene groups, blue fluorescence having a maximum value at a wavelength of 450 nm is emitted. That is, the polymer-containing thin film having the polyoxadiazole structure represented by the general formula (5) can be a light emitting layer of an electroluminescent device.

Further, in such a polymer-containing thin film,
For example, coumarin 343 known as a laser dye,
A fluorescent low molecular weight compound such as NK757, DCM, NK2929, or an aluminum quinolinol complex may be contained.

As is clear from the above description,
The polymer thin film obtained by using an electron injecting / transporting group as X ′ or Y ′ in the general formula (5) has an electron injecting / transporting function, and is obtained by using a hole injecting / transporting group. The obtained polymer thin film has a hole injecting / transporting function, and has a light emitting function when a light emitting group is used.

As X'or Y'in the general formula (5), an electron transporting group, a light emitting group and a hole transporting group can be used in combination. For example, when an electron transporting group and a light emitting group are independently selected as X ′ or Y ′, the polymer thin film has an electron injecting / transporting light emitting function. In addition, X'or Y'in the general formula (5)
When the hole transporting group and the light emitting group are independently selected as, the polymer thin film has a hole injecting / transporting function and a light emitting function. Furthermore, when an electron-transporting group and a hole-transporting group are independently selected as X ′ or Y ′ in the general formula (5), the polymer thin film is used for electron injection /
It has both transporting function and hole injection / transporting function.

[Manufacture of Thin-Film Electroluminescent Device] The thin-film electroluminescent device according to the present invention includes a pair of electrodes 1 and 2, at least one of which is transparent, as shown in FIG.
In the thin-film light emitting electric field device 10 including the light emitting layer 4 provided between the pair of electrodes 1 and 2, the silicon-based polymer compound-containing layers 3 and 5 are provided between the electrodes 1 and 2 and the light emitting layer 4. The thin film electroluminescent device 1 having such a structure
In manufacturing 0, for example, a silicon-based polymer compound-containing layer 3 containing a silicon-based polymer and a polycondensation polymer is formed on an electrode substrate 1, and then a compression layer having at least a light emitting function is formed. The polymerization type polymer layer 4 is formed, then the above-mentioned silicon type polymer compound containing layer 5 is formed again, and then the other side is formed on the silicon type polymer compound containing layer 5 obtained as described above. The electrode substrate 2 may be formed.

In a preferred embodiment of the present invention, electrode 1
At least one step of forming a layer, forming silicon-containing polymer compound-containing layers 3 and 5, forming light-emitting layer 4, and forming counter electrode 2 and element sealing layer (not shown) Is preferably performed by a vapor deposition polymerization method (dry method), and all these steps are continuously performed under vacuum conditions. As a method for forming a polymer thin film by vapor deposition polymerization method (dry method), various conventionally known methods can be used, for example, J. Vac. Sci. Technol., A4 (1985) 437, J. Vac. S
The method disclosed in ci.Technol., A5 (1987) 2253 can be used.

The silicon-based polymer compound-containing layers (concentration gradient layers) 3 and 5 are, under vacuum conditions, a diacid chloride represented by the above formula (3) and a dicarbohydrazide represented by the above formula (4). The compound is preferably vapor-deposited and polymerized, and the diacid chloride represented by the formula (1) and the dicarbohydrazide compound represented by the formula (2) are preferably vapor-deposited and formed.

Further, the light emitting layer comprising the above-mentioned polycondensation polymer is subjected to vapor deposition polymerization of the diacid chloride represented by the above formula (1) and the dicarbohydrazide compound represented by the above formula (2) under vacuum conditions. It is preferable to form it.

If a silicon-containing polymer compound-containing layer made of a polymer thin film is formed on the substrate on which the electrode is formed by a vapor deposition polymerization method, the vacuum condition is released and the vapor deposition chamber is returned to atmospheric pressure. And a small amount of dust in the air adheres to the polymer thin film surface. Therefore, even if the inside of the chamber is decompressed and the polymer thin film having the light emitting layer function and the upper electrode are formed by the vapor deposition method, the interface between the silicon-based polymer compound-containing layer and the light-emitting layer or the silicon-based polymer compound-containing layer and the upper electrode is formed. The interface with the electrode becomes non-uniform, which causes deterioration of the device. In addition, moisture and oxygen in the air are adsorbed in the polymer thin film due to returning the pressure in the chamber to the atmospheric pressure,
When the obtained device is driven, an oxidation reaction of the electrodes is caused, which causes deterioration of the device earlier.

That is, in the present invention, it is preferable to continuously perform all steps of the above-mentioned element manufacturing process without breaking the vacuum. By such a method, a thin film having further excellent luminous efficiency and durability. EL devices can be manufactured.

In a particularly preferred embodiment of the present invention, the silicon-containing polymer compound-containing layer of the thin film electroluminescent device as described above is of the Si-containing type represented by the formulas (3) and (4) as described above. Vapor deposition polymerization of π-electron conjugated organic group-containing polymer forming monomer and vapor deposition polymerization of Si-free type π-electron conjugated organic group-containing polymer forming monomer as represented by formulas (1) and (2). It is formed by performing.

The light emitting layer is formed by vapor deposition polymerization of a Si-free type π-electron conjugated organic group-containing polymer-forming monomer. More specifically, in the present invention, these monomers may be added, for example, in advance to ITO or Au.
The substrate with the hole injecting electrode such as the above is placed in the vapor deposition source in the vacuum vapor deposition apparatus. Then, inside the device, usually 1
0 ^over 4 torr or less, preferably under reduced pressure of less than 10 ^@ 5 torr, is set to a temperature of about -10 to + 200 ° C., S
The i-containing type π-electron conjugated organic group-containing polymer-forming monomer is usually 0.1 to 10 angstroms / sec, preferably 1 to 4 angstroms / sec (thickness) at an ITO electrode on the substrate. Vapor deposition. Thus, the film thickness is 10 to 100 angstroms, preferably 5
A vapor deposition film [i] of about 0 to 500 angstrom is formed on the electrode. Then, under the same reduced pressure and temperature conditions as described above, a Si-free type π
The electron-conjugated organic group-containing polymer-forming monomer is usually added in an amount of 0.
The vapor deposition is performed at a rate of 1 to 10 Å / sec, preferably 1 to 4 Å / sec (thickness). In this way, a vapor deposition film [ii] having a film thickness of 200 to 10000 angstrom, preferably 500 to 5000 angstrom, is formed on the electrode. This deposited film [i
A part of i] functions as a monomer for forming a silicon-based polymer compound-containing layer together with the vapor deposition film [i], and the rest of the vapor deposition film [ii] functions as a monomer for forming a light emitting layer.

When forming the silicon-containing polymer compound-containing layer, as described above, the Si-containing π-electron conjugated organic group-containing polymer-forming monomer (silane compound) is used.
And the supply of the Si-free type π-electron conjugated organic group-containing polymer-forming monomer (non-silane monomer) are switched. Examples of such a method of switching the raw material monomer include Evaporation method (a), in which the evaporation of the silane-based compound is suddenly stopped by closing the shutter above the evaporation source, and then the non-silane-based monomer having the charge injection / transport or light-emitting function is immediately evaporated, or While gradually decreasing and stopping the evaporation rate of silane compounds, the stepwise evaporation method (b), etc., which gradually increases the evaporation rate of non-silane monomers having charge injection / transport or light emitting functions It can be appropriately selected depending on the type or the type of monomer material.

The non-Si-based monomer for forming the silicon-based polymer compound-containing layer and the non-Si-based monomer for forming the light emitting layer may be the same or different. When the same monomer is used, the monomer deposition can be performed efficiently, and the silicon-based polymer compound-containing layer and the light emitting layer of the obtained thin film light emitting electric field element are continuously integrated, and delamination hardly occurs. That is desirable.

Then, the obtained ITO electrode substrate with a vapor deposited film ([i] [ii]) is usually used at 100 to 350 ° C., preferably 2
Each polymerization reaction is completed by heat treatment at a temperature of 00 to 300 ° C. for usually 10 to 240 minutes, preferably 60 to 120 minutes.

By increasing the concentration ratio of the silane-based polymer to the non-silane-based polymer (silane-based polymer / non-silane-based polymer) on the surface in contact with the electrode, the adhesion with the electrode can be improved. You can Note that this concentration ratio varies from the surface of the silicon-containing polymer compound-containing layer in contact with the electrode to the light-emitting layer as shown in FIG.
It may be continuously changed as shown in (c) or may be changed stepwise as shown in (b) and (d) of FIG.

Thus, the Si-containing π-electron conjugated organic group-containing polymer mainly formed in the portion of the silicon-containing polymer compound-containing layer which is in contact with the electrode is represented by the general formula (I). In addition, a Si-free type π-electron conjugated organic group-containing group such as poly (1,4-phenylene-2,5-oxadiazolylene), which is mainly formed in a portion of the silicon-containing polymer compound-containing layer that is in contact with the light-emitting layer The polymer is represented by the general formula (II).

When forming a silicon polymer compound-containing layer or a light emitting layer by vapor deposition polymerization, a low molecular compound having an electron injecting / transporting function such as a diphenoquinone derivative or a fluorenone derivative as described above is co-evaporated. By doing so, a low molecular weight compound having such a function can be contained in the polymer thin film. A low molecular weight compound having such an electron injecting / transporting function is usually 1 mo
It is desirable to be co-deposited in the polymer thin film in an amount of 1% or more, preferably 10 mol% or more.

Further, when forming a polymer thin film by vapor deposition polymerization, a low molecular weight compound having an excellent hole injecting / transporting function such as a triphenylamine derivative is co-evaporated to obtain such a polymer thin film. A low molecular weight compound having a function can be contained. The low molecular weight compound having such hole injection / transport function is usually 1 mol%
Above, preferably 10 mol% or more is desirable to be co-deposited in the polymer thin film.

Further, when a polymer thin film is formed by vapor deposition polymerization, the fluorescent low molecule (for example, coumarin 34) as described above is used.
3, NK757, DCM, NK2929, aluminum quinolinol complex, etc.) can be co-evaporated to contain these fluorescent low molecular weight compounds in the polymer thin film. Such a low molecular weight compound is usually 0.01 to 1
It is desirable to co-deposit in a polymer thin film in an amount of 0 mol%, preferably 0.01-5 mol%.

The polymer thin film formed by such a vapor deposition polymerization method is excellent in thin film properties such as an extremely flat surface,
It has no pinholes and has excellent adhesion to glass substrates or metal electrodes.

An electron injecting electrode is vapor-deposited on the substrate with the hole injecting electrode on which the polymer thin film for the silicon-containing polymer compound-containing layer and the polymer thin film for the light emitting layer are thus formed.
Electron injection electrode materials include Mg, Ag, In, Ca, Al
Known electrode materials such as the above are used alone or in combination of two or more kinds.

A protective film such as an antioxidant film may be laminated on the electron injecting electrode or the hole injecting electrode of this organic thin film electroluminescence (EL) element by a method such as a spin coating method or a vapor deposition method. . In the electroluminescent device provided with such a protective film, the stability of the electrode is increased, and the practicability and durability of the device are improved. Examples of such a protective film include those using a metal or epoxy-based adhesive having a large work function, a silicone-based or a fluorine-based sealant.

The thin film electroluminescent device thus obtained can emit light by applying a voltage between the electron injecting electrode and the hole injecting electrode. The applied voltage is not limited to a direct current (DC) voltage, and it is also possible to emit light by a drive voltage having a waveform such as a pulse or a triangular wave. In particular, when the pulse is used, the power consumption is remarkably reduced as compared with the DC voltage application, and the life of the element can be improved. By thus driving the EL element with a voltage having a specific waveform, the EL element can be used as a display element.

Further, the thin film electroluminescence (EL) device of the present invention has a backlight integrated with a liquid crystal which is driven by applying a pattern such as a matrix electrode or a thin film transistor (TFT) electrode as an electron injection electrode and a hole injection electrode. Alternatively, it can be used as a display element of a flat panel display or the like.

[0102]

EFFECTS OF THE INVENTION According to the present invention, hole transportability, light emission, electron transportability and heat resistance are excellent, durability is excellent, and adhesion between the metal electrode or glass substrate and the light emitting medium layer is excellent. Such a thin film electroluminescent device is provided.
Further, according to the present invention, there is provided a method for manufacturing a thin film electroluminescent device which can use a wide range of organic polymer materials or a wide range of low molecular weight light emitting materials.

[0103]

EXAMPLES Next, the present invention will be described more specifically by way of examples, but the present invention is not limited to these examples.

[0104]

[Example 1]

[0105]

[Chemical formula 26]

Silane-based monomer represented by the above formula:
[Di (p-chlorocarbonylphenyl) -dimethylsilane] was charged into the first vapor deposition source of the vapor deposition polymerization apparatus, and commercially available terephthalic acid dichloride (manufactured by Tokyo Kasei) and terephthalic acid dicarbohydrazide (manufactured by Wako Pure Chemical Industries, Ltd.). ) Was filled in the second and third vapor deposition sources, respectively. In addition, the thickness of the substrate
Prepare glass (HOYA) with 1000 angstrom ITO (Indium Tin Oxide) electrode, and use this electrode glass substrate with acetone, ultrapure water, substrate cleaning agent (semi-coclean EL grade, Furuuchi Chemical), ultrapure water Then, ultrasonic cleaning was performed using isopropyl alcohol (IPA) in this order, and then the product was taken out from the isopropyl alcohol vapor and dried. The thus-cleaned glass substrate with electrodes was placed in a substrate holder in a vapor deposition polymerization apparatus whose temperature was controllable.

Then, the total pressure in the vapor deposition polymerization apparatus is 1 × 10.
^The pressure was reduced using an oil diffusion pump until it became ^-5 Torr or less.
First, each of the vapor deposition sources was heated by a resistance heating method with a shutter provided on the front surface of the substrate, which shuts off the substrate from the vapor deposition sources, being closed.

Next, the temperature of each evaporation source was set while monitoring the evaporation rate of each monomer material from each evaporation source. Next, the shutter of the vapor deposition source was opened, and the silane-based monomer and terephthalic acid dicarbohydrazide were simultaneously vaporized at a rate of 4 angstrom / second,
It controlled so that it might vapor-deposit on a glass substrate with an electrode.

When the film thickness of the vapor deposited film [a] on the above substrate was measured by a crystal oscillator film thickness meter to show a thickness of 150 Å, the shutter for the silane-based monomer was closed again.

At the same time, the shutter of the terephthalic acid dichloride vapor deposition source was opened to start evaporation. At this time,
The evaporation rates of terephthalic acid dicarbohydrazide and terephthalic acid dichloride were each set to 2 angstrom / sec. When the vapor deposition film [b] having a thickness of 600 angstrom was formed on the vapor deposition film [a], only the shutter of the terephthalic acid dichloride vapor deposition source was closed and the shutter of the silane-based monomer vapor deposition source was opened again.

100 Å thick evaporated film [C]
When the film was formed, the shutters of all vapor deposition sources were closed. Then, the temperature of the substrate holder was heated to 300 ° C. and the above vapor deposition films ([A], [B] and [C]) were heat-treated for 30 minutes to complete each polymerization reaction. [Terephthalic acid dichloride and terephthalic acid dicarbohydrate
Polymerization reaction with dorazide [poly (1,4-phenylene-
Confirmation that 2,5-oxadiazolylene) has been produced] By using an Al plate having a thickness of 0.5 mm as a substrate and performing the same operation as the vapor deposition of terephthalic acid dichloride and terephthalic acid dicarbohydrazide, a film thickness can be obtained. A 1 μm vapor-deposited polymerized film (sample) was formed.

[0112] was measured for FT-IR spectrum of the sample by a reflection method, characteristic absorption due to the hydrazide group 3212Cm ^-1 and (N-H stretching vibration), 1666 cm ^-1
C = O stretching vibration of the carbonyl group of
H of 2857 cm ^-1 ,> C = N- or> C = C <of 1
428 to 1560 cm ^-1 , = COOC = 1000-
Absorption at 1025 and 952 to 975 cm ⁻¹ appeared, and it was confirmed that an oxadiazole ring was formed.

From this fact, the polymerization reaction of terephthalic acid dichloride and terephthalic acid dicarbohydrazide gives
It was confirmed that poly (1,4-phenylene-2,5-oxadiazolylene) was produced. [The above silane-based monomer: di (p-chlorocarbonyl)
Phenyl) -dimethylsilane and dicarboterephthalate
That the polymer was formed by the polymerization reaction with the dorazide
When a sample was prepared by the same method as described in [ Confirmation] and the FT-IR spectrum was measured by a reflection method, N—H stretching vibration due to a hydrazide group at 3212 cm ⁻¹ and 1795 cm were obtained.
^-1 C-O stretching vibration of the carbonyl group disappears and aromatic C
-H of 2857 cm ^-1 ,> C = N- or> C = C <of 1428 to 1560 cm ^-1 , = COC = 1000 of
Absorption of -1025, 952-975 cm ^-1 appears,
It was confirmed that an oxadiazole ring was formed.

From this, it was confirmed that a polymer was produced by the polymerization reaction of di (p-chlorocarbophenyl) dimethylsilane and terephthalic acid dicarbohydrazide.

When each monomer material is evaporated, the evaporation rate of each monomer material is adjusted so that a thin film is stoichiometrically formed, and the total number of moles of the silane-based monomer and terephthalic acid dichloride and terephthalic acid are adjusted. The number of moles of dicarbohydrazide was controlled to be equal.

When the surface of each vapor-deposited film thus formed was observed with a scanning electron microscope (SEM), it was confirmed that the film was extremely flat and had no pinholes.

An Ag: Mg electrode to be an electron injection electrode was formed by co-evaporation on the light emitting medium layer formed on the electrode-attached glass substrate to prepare an electroluminescent device. During this co-deposition, the Mg deposition rate should be 10 Å / sec, and the Ag deposition rate should be 1 Å / sec.
Each was set to be seconds.

ITO was added to this electroluminescent device (sample).
When the electrode side was positively connected and the Ag: Mg electrode side was negatively connected and a direct current voltage of 8 V was applied, 4
Electroluminescence (EL) with a peak wavelength at 50 nm occurred. When this electroluminescent device was continuously driven at room temperature for 50 hours, no peeling occurred at any interface of the light emitting layer / silicon-based polymer compound-containing layer / electrode.

In the above electroluminescent device, the layer containing silicon-based polymer compound (concentration: concentration between the ITO electrode and the light emitting layer composed of [poly (1,4-phenylene-2,5-oxadiazolylene)]) The thickness of the inclined layer) is 150 angstroms, and the thickness of the light emitting layer made of [poly (1,4-phenylene-2,5-oxadiazolylene)] is 600 angstroms. The silicon-containing polymer compound-containing layer provided between the light emitting layers has a thickness of 100 Å, and the Ag: Mg electrode has a thickness of 1000.
It was Angstrom.

[0120]

Example 2 [Production Example of Thin-Film Electroluminescent Device of Type in which Component Ratio of Silicon Polymer to Polycondensation Polymer in Layer of Light-Emitting Medium Layer is Stepwise Change]

[0121]

[Chemical 27]

A vapor deposition source was filled with the silane-based monomer represented by the above formula [di (p-carbohydrazidepyridyl) silane], terephthalic acid dichloride and terephthalic acid dicarbohydrazide.

The electrode-cleaned glass substrate washed in the same manner as in Example 1 was placed on a temperature-controllable substrate holder in the vapor deposition polymerization apparatus, and the oil diffusion pump was used until the total pressure in the apparatus became 1 × 10 ⁻⁵ Torr or less. Was used to reduce the pressure.

First, with the shutter provided on the entire surface of the substrate, which shuts off the substrate and the vapor deposition sources closed, the vapor deposition sources were heated by the heating resistance method. Next, the temperature of each vapor deposition source was set while monitoring the vapor deposition rate of each monomer material from each vapor deposition source.

Next, the evaporation source shirt was opened, and the silane-based monomer and terephthalic acid dichloride were each added to 4 times.
It was controlled to evaporate simultaneously at a rate of angstrom / sec and deposit on a glass substrate with an electrode.

When the film thickness of the vapor-deposited film [a] on the above-mentioned substrate was 200 angstrom when measured by a crystal oscillator type film thickness meter, all the shutters were closed again. Then, the total number of moles of the silane-based monomer and terephthalic acid dicarbohydrazide was controlled to be equal to the number of moles of terephthalic acid dichloride, and then the shutters of all vapor deposition sources were opened. When a vapor deposition film [b] having a thickness of 800 angstrom was formed on the vapor deposition film [a], all the shutters were closed again.

Next, after adjusting the vapor deposition rates of terephthalic acid dichloride and terephthalic acid dicarbohydrazide, these shutters were opened, and when a vapor deposition film [C] having a thickness of 150 Å was formed, the shutter of the vapor deposition source was released. Closed.

Then, the temperature of the substrate holder is heated to 300 ° C. and the above vapor deposition films ([A], [B] and [C]).
Was heat-treated for 30 minutes to complete each polymerization reaction. The confirmation that the polymer was formed was performed by using the same method as in Example 1.

On the light emitting medium layer formed on the electrode-attached glass substrate, an Ag: Mg electrode to be an electron injecting electrode was co-evaporated to form an electroluminescent device. When the ITO electrode side was positively connected and the Ag: Mg electrode side was negatively connected to this electroluminescent device (sample) and a DC voltage of 10 V was applied, electroluminescence having a peak wavelength at 450 nm from the light emitting medium layer was observed. (EL) occurred. When this electroluminescent device was continuously driven at room temperature for 40 hours, no peeling occurred at any interface of the light emitting layer / silicon polymer compound-containing layer / electrode.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view of a thin film electroluminescent device according to the present invention.

FIG. 2 is an explanatory diagram of a composition distribution of a silicon-based polymer and a polycondensation-based polymer in a silicon-based polymer compound-containing layer forming the thin film electroluminescent device shown in FIG.

FIG. 3 is a diagram illustrating an organic thin film electroluminescence (E) according to a conventional example.
L) is a sectional view of the element.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Electron injection electrode 2 ... Hole injection electrode 3 ... Silicon type high molecular compound containing layer 4 ... Light emitting layer 5 ... Silicon high molecular compound containing layer 6 ... Light emitting medium layer 7 ... Hole transport layer 8 ... Electron injection light emitting layer

Claims (7)

[Claims] 1. A thin-film light emitting electric field device comprising a pair of electrodes, at least one of which is transparent, and a light emitting layer provided between the pair of electrodes, wherein a silicon-based polymer is provided between the electrodes and the light emitting layer. A thin-film electroluminescent device comprising a compound-containing layer. 2. The silicon-based polymer compound-containing layer comprises a silicon-based polymer and a condensation-polymerized polymer, and the silicon-based polymer content decreases from the electrode side toward the light emitting layer side. ,
The thin film electroluminescent device according to claim 1, wherein the polycondensation polymer content increases from the electrode side toward the light emitting layer side. 3. The silicon-containing polymer has a silicon-containing polyoxadiazole structure represented by the following formula (I), and the polycondensation polymer is a polyoxadiazole structure represented by the following formula (II). The thin film electroluminescent device according to claim 1 or 2, further comprising: [Chemical 1] [In the formula (I), X and / or Y represents an organic group containing an aromatic ring or a hydrocarbon group and containing Si. ] [Chemical 2] [In the formula (II), X ′ and / or Y ′ represents a group containing an aromatic ring or a hydrocarbon group and containing no Si. ] 4. The polyoxadiazole (II) is
The thin film electroluminescent device according to claim 3, which is a polycondensation product of a diacid chloride represented by the following formula (1) and a dicarbohydrazide compound represented by the following formula (2). [Chemical 3] [In the formula, X'includes an aromatic ring or a hydrocarbon group, and S '
represents an organic group not containing i. ] [Chemical 4] [In the formula, Y'includes an aromatic ring or a hydrocarbon group, and S
represents an organic group not containing i. ] 5. When manufacturing a membrane electroluminescent device having a pair of electrodes, at least one of which is transparent, a light emitting layer, and a silicon-containing polymer compound-containing layer, vapor deposition polymerization is performed on one of the electrode substrates, A silicon-based polymer compound-containing layer comprising a silicon-based polymer and a polycondensation polymer,
A method of manufacturing a thin-film electroluminescent device, which comprises sequentially forming a light-emitting layer made of a condensation-polymerized polymer and a layer containing the silicon-based polymer compound as described above, and then forming the other electrode substrate. 6. The silicon-based polymer is formed by vapor deposition polymerization of a diacid chloride represented by the following formula (3) and a dicarbohydrazide compound represented by the following formula (4) under vacuum conditions. The method for manufacturing a thin film electroluminescent device according to claim 5, wherein: [Chemical 5] [In the formulas (3) and (4), X and / or Y represents an organic group containing an aromatic ring or a hydrocarbon group and containing Si. ] 7. The polycondensation polymer is formed by vapor deposition polymerization of a diacid chloride represented by the following formula (1) and a dicarbohydrazide compound represented by the following formula (2) under vacuum conditions. The method for manufacturing a thin film electroluminescent device according to claim 5, wherein [Chemical 6] [In the formulas (1) and (2), X'and Y'represent an organic group containing an aromatic ring or a hydrocarbon group and containing no Si. ]