JPH08333568A - Organic thin-film diode and its production - Google Patents

Abstract

PURPOSE: To obtain an organic thin-film light-emitting diode having a hole injection (transfer) layer composed of a specific aromatic compound and having high reliability and long life because the hole injection (transfer) layer does not crystallize over a long period. CONSTITUTION: This organic thin-film diode is provided with a light-emitting layer and a hole injection layer or a hole injection and transfer layer. The hole injection layer or the hole injection and transfer layer is composed of an aromatic compound produced by crosslinking (A) a compound having 1-12 aromatic rings with (B) an N-containing compound capable of forming a hole- transfer functional group. The component A is preferably a compound having 3-8 benzene rings such as triphenylamine of formula. The component B is preferably aniline, nitrogen or ammonia when the component A is triphenylamine. The objective diode is produced by crosslinking the component A with the component B by glow-discharge polymerization (preferably low-temperature plasma polymerization) while introducing the component A and the component B at the same time, thereby forming an aromatic compound constituting the hole injection layer or the hole injection and transfer layer.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing an organic thin film diode, and more particularly to a method for manufacturing an organic thin film diode which performs charge injection and light emission.

[0002]

2. Description of the Related Art In recent years, organic thin film diodes (organic EL)
Is being actively researched. In this method, a hole transport material such as TPD is deposited on a transparent electrode such as ITO to form a thin film, a phosphor such as an aluminum quinolinol complex is laminated as a light emitting layer, and a metal electrode having a small work function such as Mg is formed. It has attracted attention because it is an element having a basic structure and can obtain an extremely high brightness of several thousand cd / cm ² at a voltage of around 10V.

As a charge transport material, particularly a hole transport material, a vapor deposition film of an aromatic amine derivative such as TPD is conventionally known. However, the device using such an aromatic amine derivative has an extremely short emission life. It is considered that this is because the aromatic amine compound such as TPD is very easily crystallized, the uniformity of the thin film is lost, and the charge injection is not successful. In order to prevent such crystallization of the charge transport material, a compound with a large molecular weight such as dimerization of the material, or a star with a large twisted branch called Starburst developed by Osaka University and Shirota Vapor-deposited films of compounds having a shaped structure are used. In addition, vapor-deposited films such as poly or oligothiophene, or TP as a solvent
It has been reported that a method in which a hole transport material such as D and a polymer are dissolved to form a thin film by spin coating, or a spin coat film further laminated with a hole transport material is used. Although the emission lifetime of the device using these methods has been considerably improved, it is still insufficient for practical use. Most of the causes are crystallization of the charge injection layer material at the contact interface with the transparent electrode or the metal electrode, or deterioration of the device during driving due to the inclusion of water and oxygen in the spin coat film. It is thought to be promoted. In addition, these compounds have complicated structures and are relatively difficult to synthesize due to many steps.
Furthermore, purification is difficult because the molecule is large and it is a poorly soluble substance. Since the purity is sensitive to the emission characteristics, establishing a purification method was also an issue. For this reason, consistent film formation in vacuum is desired with charge transport layer materials that do not cause crystallization. If the material itself can be a simple compound,
Practicality is expected to be further enhanced because synthesis and purification will be easier.

Plasma polymerization has been attempted as one of the vacuum film formations (organic EL device development strategy "Science Forum": kido, J., Nagai, K., McBeen, J., and O.
kamoto, Y.). In addition, the prevention of crystallization by plasma treatment such as TPD is reported (Miyake et al., Proceedings of the 41st Joint Lecture on Applied Physics, 1123, 199).
4). However, as described above, these impair the charge transporting functional group, but the crosslinking prevents the aggregation of the charge transporting layer. The problem was

The conventional problem of deterioration of the charge transport layer is solved if the charge transport layer material, particularly the charge injection layer material, does not crystallize at the interface with the transparent electrode or the metal electrode. However, crystallization cannot be prevented by simply increasing the molecular weight of the charge injection layer material as in the prior art, and vapor deposition cannot be performed as it is with a high molecular compound. For this reason, there are restrictions such as decomposing vapor deposition and using a spin coating method. Therefore, a vapor deposition polymerization method in which a low molecular weight compound has a high molecular weight after vapor deposition can be considered, but a functional group for polymerization is required. This functional group is not preferable because it deteriorates the charge transport property of TPD and the like.

[0006]

SUMMARY OF THE INVENTION It is an object of the present invention to provide an organic thin film diode, which is a light emitting device having a long life, which forms a hole injection layer or a hole injection transport layer that does not cause crystallization for a long period of time. To do.

[0007]

The above objects are achieved by the present invention described in (1) to (6) below. (1) In an organic thin film diode including a light emitting layer and a hole injecting layer or a hole injecting / transporting layer formed integrally with or separately from the light emitting layer, an aromatic compound constituting the hole injecting layer or the hole injecting / transporting layer. An organic thin-film diode, wherein the compound is a compound having 1 to 12 aromatic rings cross-linked by N-containing molecules capable of becoming a hole-transporting functional group. (2) The N-containing molecule that can be the hole-transporting functional group is
Nitrogen, ammonia, primary to tertiary alkyl amines and 1
~ The organic thin film diode of (1) above, which is at least one selected from tertiary arylamines. (3) A method of manufacturing an organic thin film diode comprising a light emitting layer, a hole injecting layer or a hole injecting and transporting layer formed integrally with or separately from the light emitting layer, wherein a compound having an aromatic ring of 1 to 12 and holes By introducing at the same time an N-containing molecule that can become a transportable functional group, the above-mentioned 1
A method for manufacturing an organic thin-film diode, which comprises cross-linking a compound having an aromatic ring of 1 to 12 with the N-containing molecule to form an aromatic compound constituting the hole injection layer or the hole injection / transport layer. (4) The method for producing an organic thin film diode according to (3), wherein the glow discharge polymerization method is a plasma polymerization method using a high frequency power source. (5) The method for producing an organic thin film diode according to (3) above, wherein the glow discharge polymerization method is a plasma polymerization method in which a high frequency power source is used and a negative bias voltage is applied to the film formation substrate. (6) The N-containing molecule that can be the hole-transporting functional group is
Nitrogen, ammonia, primary to tertiary alkyl amines and 1
~ The method for producing an organic thin film diode according to any one of (3) to (5) above, which is at least one selected from tertiary arylamines.

[0008]

In the organic thin film diode of the present invention, the aromatic compound constituting the hole injection layer or the hole injection / transport layer is formed by the N-containing molecule which can be a hole transport functional group. It is a compound having 1 to 12 crosslinked aromatic rings. The compounds each having 1 to 12 aromatic rings are fixed by the above-mentioned cross-linking and the crystallization is suppressed, so that deterioration is less likely to occur, and thus a light emitting device having a long life can be realized. Furthermore, since the above-mentioned cross-linking is performed with N-containing molecules capable of becoming a hole transporting functional group, the aromatic compound constituting the obtained hole injecting layer or hole injecting / transporting layer has a hole transporting function. Will be improved.

The above-mentioned cross-linking can be carried out by a glow discharge polymerization method while simultaneously supplying a compound having an aromatic ring of 1 to 12 and an N-containing molecule which can be a hole-transporting functional group.

[0010]

Specific Structure The specific structure of the present invention will be described in detail below.

An example of the structure of the organic thin film diode of the present invention is shown in FIG. The EL element 1 shown in FIG.
The anode 3, the hole injecting and transporting layer 4, the light emitting layer 5, the electron injecting and transporting layer 6, and the cathode 7 are sequentially provided.

The light emitting layer has a function of injecting holes and electrons, a function of transporting them, and a function of generating excitons by recombination of holes and electrons. The hole injecting and transporting layer has a function of facilitating injection of holes from the anode, a function of transporting holes and a function of hindering electron transport, and the electron injecting and transporting layer is
These layers have the function of facilitating the injection of electrons from the cathode, the function of transporting electrons, and the function of hindering the transport of holes. These layers increase and confine holes and electrons injected into the light-emitting layer. To optimize the recombination region and improve the luminous efficiency. The electron injecting and transporting layer and the hole injecting and transporting layer are
It is provided as necessary in consideration of the functions of electron injection, electron transport, hole injection, and hole transport of the compound used in the light emitting layer. For example, when the compound used for the light emitting layer has a high hole injecting / transporting function or an electron injecting / transporting function, the light emitting layer is not provided with the hole injecting / transporting layer or the electron injecting / transporting layer, and the light emitting layer is the hole injecting / transporting layer or the electron injecting / transporting layer. It can be configured to also serve as a transport layer. Further, in the hole injecting and transporting layer and the electron injecting and transporting layer, a layer having an injecting function (hole injecting layer) and a layer having a transporting function (hole transporting layer) may be separately provided.

In the organic thin film diode of the present invention, the aromatic compound constituting the light emitting layer, the hole injecting layer or the hole injecting / transporting layer formed integrally with or separately from the light emitting layer has a hole transporting property. It is a compound having 1 to 12 aromatic rings bridged by N-containing molecules that can be functional groups.

The aromatic ring in the above-mentioned compound having an aromatic ring of 1 to 12 is a benzene ring, a naphthalene ring, a pyridine ring, a thiazole ring, a carbazole ring, a pyrrole ring,
Examples thereof include a phenothiazine ring, an indole ring, and a thiophene ring.

As described above, the above compound has 1 to 12 aromatic rings, but preferably has 3 to 8 aromatic rings.

As the above-mentioned compound having a benzene ring,
For example, triphenylamine (TPA: the following chemical formula 1),
N, N'-diphenyl-N, N'-bis (3-methylphenyl)-[1,1'-biphenyl] -4,4'-diamine (TPD: the following chemical formula 2), N, N, N ', N′-tetraphenyl-p-phenylenediamine (TPPD: chemical formula 3 below), 1,3,5-tris (diphenylamino) benzene (TDAB: chemical formula 4 below), 1,3,5-tris (3)
-Methylphenylphenylamino) benzene (MTDA
B: the following chemical formula 5), 4,4 ′, 4 ″ -tris (phenothiazinyl) triphenylamine (TPTTA: the following chemical formula 6), 1,3,5-tris (N-phenyl-N-2-thienylamino) Examples thereof include benzene (TPTAB: the following chemical formula 7).

[0017]

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[0018]

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[0019]

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[0020]

[Chemical 4]

[0021]

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[0022]

[Chemical 6]

[0023]

[Chemical 7]

Examples of the compound having a naphthalene ring include N, N'-diphenyl-N, N'-bis (1-naphthyl)-[1,1'-biphenyl] -4,
4'-diamine (PNBPD: the following chemical formula 8) N, N'-
(2-naphthyl) -N, N'-bis (3-methylphenyl)-[1,1'-biphenyl] -4,4'-diamine (Formula 9 below), N, N, N ', N'- Tetra (1-naphthyl)-[1,1'-biphenyl] -4,4'-diamine (the following chemical formula 10), N, N, N ', N'-tetra (2-
Naphthyl)-[1,1'-biphenyl] -4,4'-diamine (the following chemical formula 11) and the like can be mentioned.

[0025]

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[0026]

[Chemical 9]

[0027]

[Chemical 10]

[0028]

[Chemical 11]

The compound having a pyridine ring is
For example, N, N'-bis (4-pyridyl) -N, N'-
Bis (3-methylphenyl)-[1,1'-biphenyl] -4,4'-diamine (BPTBA:
2), 1,3,5-tris- (N-phenyl-N-4-
Pyridyl) triaminobenzene (Chemical Formula 13 below), 4,
4'-bipyridine (Chemical Formula 14 below), N, N'-bis (3
-Methylphenyl) -N, N'-bis (7-quinolyl)
-[1,1'-biphenyl] -4,4'-diamine (the following chemical formula 15) and the like can be mentioned.

[0030]

[Chemical 12]

[0031]

[Chemical 13]

[0032]

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[0033]

[Chemical 15]

Examples of the compound having a thiazole ring include N, N'-diphenyl-N, N'-bis (5-benzothiazolyl)-[1,1'-biphenyl] -4,4 '.
-Diamine (Chemical Formula 16 below), N, N, N ', N'-tetra- (5-benzothiazolyl)-[1,1'-biphenyl] -4,4'-diamine (Chemical Formula 17 below), 4,4 ',
4 ″ -tris (N-benzothiazolyl) triphenylamine (TBTTPA: the following chemical formula 18) and the like can be mentioned.

[0035]

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[0036]

[Chemical 17]

[0037]

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Examples of the compound having a carbazole ring include, for example, 4,4 ′, 4 ″ -tris (N-carbazoyl) triphenylamine (TCTA: the following chemical formula 19),
1,3,5-tris (N-carbazolyl) benzene (the following chemical formula 20) and the like can be mentioned.

[0039]

[Chemical 19]

[0040]

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Examples of the compound having a pyrrole ring include N, N'-biphenyl-N, N'-bis (2-pyrrolyl)-[1,1'-biphenyl] -4,4'-diamine (BPPBA: Chemical formula 21), 1,3,5-tris (N-phenyl-N-2-pyrrolyl) triaminobenzene (chemical formula 22 below) and the like can be mentioned.

[0042]

[Chemical 21]

[0043]

[Chemical formula 22]

Examples of the compound having a phenothiazine ring include the compounds represented by the above chemical formula 6 and the like.

Examples of the compound having an indole ring include 1,4-bis (N-indolyl) benzene (Chemical Formula 23 below) and the like.

[0046]

[Chemical formula 23]

Of the above, the aromatic ring is particularly preferably a benzene ring, and the compound having such an aromatic ring is preferably the compound represented by the above Chemical Formulas 1 to 7.

On the other hand, N, which can be the above-mentioned hole-transporting functional group,
The contained molecule is preferably at least one selected from nitrogen, ammonia, primary to tertiary alkyl amines, primary to tertiary aryl amines, and the like. In the above-mentioned primary to tertiary alkylamines, the number of carbon atoms is 1 to 12, especially 3
It is preferable that it has from ~ 9 alkyl groups.
In addition, the above-mentioned primary to tertiary arylamines preferably have an aryl group having 6 to 18 carbon atoms.

In the present invention, examples of preferable combinations of the compound having an aromatic ring and the N-containing molecule are as follows.

TPA: aniline TPA: nitrogen TPA: ammonia TPD: triethylamine

The light emitting layer contains a fluorescent substance. Examples of the fluorescent substance include at least one compound selected from compounds such as those disclosed in JP-A-63-264692, such as metal complex dyes, coumarin, quinacridone, rubrene, and styryl dyes. Can be mentioned. Examples thereof include organic phosphors such as tetraphenyl butadiene, anthracene, perylene, coronene, 12-phthaloperinone derivatives, and tris (8-quinolinolato) aluminum.

Further, the light emitting layer may contain a singlet oxygen quencher. Examples of such a quencher include nickel complexes, rubrene, diphenylisobenzofuran, tertiary amines, and the like.

The electron injecting and transporting layer includes an organometallic complex derivative such as tris (8-quinolinolato) aluminum, an oxadiazole derivative, a pyridine derivative, a pyrimidine derivative, a quinoline derivative, a quinoxaline derivative, a diphenylquinone derivative, a perylene derivative, and a fluorene derivative. Etc. can be used.

When the hole injecting and transporting layer is separately formed into the hole injecting layer and the hole transporting layer, preferred combinations can be selected and used from the compounds for the hole injecting and transporting layer. At this time, it is preferable to stack layers of a compound having a small ionization potential in order from the anode (ITO or the like) side. Further, it is preferable to use a compound having a good thin film property on the surface of the anode. This stacking order is the same when two or more hole injecting and transporting layers are provided. By adopting such a stacking order, the driving voltage is lowered, and it is possible to prevent the occurrence of current leakage and the generation / growth of a partial non-light emitting portion (dark spot). In addition, since vapor deposition is used to form a device, a thin film of about 1 to 10 nm can be made uniform and pinhole-free, so that the hole injection layer has a small ionization potential and absorption in the visible region. Even if such a compound is used, it is possible to prevent a decrease in efficiency due to a change in the color tone of the emission color or reabsorption.

When the electron injecting and transporting layer is separately formed into the electron injecting layer and the electron transporting layer, preferred combinations can be selected and used from the compounds for the electron injecting and transporting layer. At this time, it is preferable to stack the compound layers having a large electron affinity value in this order from the cathode side. The stacking order is the same when two or more electron injecting and transporting layers are provided.

The thickness of the light emitting layer, the thickness of the hole injecting and transporting layer, and the thickness of the electron injecting and transporting layer are not particularly limited, and are usually 1 to 1000 nm per layer, although they vary depending on the forming method.
It is preferably about 8 to 200 nm.

The thickness of the hole injecting / transporting layer and the thickness of the electron injecting / transporting layer may be the same as the thickness of the light emitting layer or about 1/10 to 10 times, although it depends on the design of the recombination / light emitting region. . When the electron injection layer and the electron injection layer are separated from the transport layer, it is preferable that the injection layer has a thickness of 1 nm or more and the transport layer has a thickness of 20 nm or more. At this time, the upper limit of the thickness of the injection layer and the transport layer is usually about 100 nm in the injection layer and 100 in the transport layer.
It is about 0 nm. Such a film thickness is the same when two injecting and transporting layers are provided to form the first and second injecting and transporting layers.

Further, the recombination is performed by controlling the film thickness while considering the carrier mobility and carrier density (determined by the ionization potential and electron affinity) of the light emitting layer, electron injecting and transporting layer and hole injecting and transporting layer to be combined. It is possible to freely design the area and the light emitting area, and it is possible to design the light emitting color, control the light emitting luminance and the light emitting spectrum by the interference effect of both electrodes, and control the spatial distribution of light emission.

At least one of the electrodes must be transparent or semi-transparent in order to allow the EL element to emit surface light.
Since the material of the cathode is limited as described above, it is preferable to determine the material and the thickness of the anode so that the transmittance of emitted light is 80% or more. In particular,
For example, ITO, SnO ₂ , Ni, Au, Pt, Pd,
It is preferable to use polypyrrole doped with a dopant for the anode. The thickness of the anode is 10-500 nm
It is preferable to set the degree. In addition, it is necessary that the driving voltage is low in order to improve the reliability of the device, but ITO of 10 to 30 Ω / □ is preferable.

The substrate material is not particularly limited, but in the illustrated example, a transparent or semitransparent material such as glass or resin is used in order to take out emitted light from the substrate side. Further, a color filter film or a dielectric reflection film may be used on the substrate to control the emission color.

When an opaque material is used for the substrate, the stacking order shown in FIG. 1 may be reversed.

Next, a method of manufacturing the hole injecting layer or the hole injecting and transporting layer composed of the above aromatic compound, which is a characteristic part of the organic thin film diode of the present invention, will be described. Hereinafter, the hole injection layer or the hole injection transport layer will be described as the hole injection transport layer.

The aromatic compound constituting the hole injecting and transporting layer of the present invention can serve as the hole transporting functional group together with the compound having an aromatic ring of 1 to 12 (hereinafter sometimes referred to as a monomer). It can be obtained by cross-linking the monomer with the N-containing molecule by a glow discharge polymerization method, particularly a plasma polymerization method while introducing the N-containing molecule.

As described above, the aromatic compound obtained by glow discharge polymerization, particularly plasma polymerization, has the effect of the present invention because crystallization is suppressed.

That is, for example, rather than glow discharge polymerization of TPD itself, by positively introducing and polymerizing a molecule such as an amino group that can be a functional group responsible for hole transport, the hole injection characteristics and the hole characteristics can be improved. The crystallinity can be completely lost with almost no decrease.

The glow discharge polymerization method includes a direct current method, an alternating current method, and a high frequency method depending on the type of power source for causing glow discharge, but any method may be used. Also, a direct method of forming a polymer film directly on an electrode, an indirect method of forming a film on a portion other than a discharge electrode, a three-pole method combining both, and a kind of indirect method, a coil wound on the outside of a glass tube. The method can be classified into a non-polar method in which a high-frequency current is applied to polymerize, but any of these methods may be used.

Glow discharge polymerization is carried out by C--C, C = C, C≡
Most organic monomer compounds having C bonds, aromatics, heterocycles, etc. as monomer molecules are subjected to electron impact by discharge to become various free radicals, excited radicals, ion radicals, and ions, and these become active species. Then, the polymerization reaction proceeds. In general, the obtained polymerized film can control the film thickness with an accuracy of about 10 A in the film thickness range of several hundred A to several thousand A. The degree of vacuum during polymerization is usually 10 ^-1.
It should be around 1 Torr.

In the present invention, it is particularly preferable to use a low temperature plasma polymerization method using a high frequency power source.

An example of a plasma polymerization apparatus 10 for carrying out such a low temperature plasma polymerization method is shown in FIG.

In FIG. 2, reference numeral 11 is a vacuum chamber, and in this chamber 11, a cathode plate 12 and an anode plate 13 are arranged so as to face each other. A high frequency power source 14 is connected to the anode plate 13 so that a high frequency current is applied thereto, and the cathode plate 12 is grounded. Substrate 2
Are usually installed on the cathode plate 12. The substrate 2 is preferably rotated so that the film formation is more uniform. At this time, the substrate 2 is, as shown in FIG.
A negative bias voltage (DC) is preferably applied by the bias power supply (DC) 15. The voltage is -5
The voltage is in the range of -500V, preferably -10 to -100V, and more preferably -20 to -60V. The purpose of applying a negative voltage to the substrate is to promote stabilization by crosslinking. Alternatively, the substrate 2 may be placed on the anode plate 13 and its self-bias may be utilized. In FIG. 2, E indicates an electric field and P indicates plasma.

The frequency of the high frequency power source used for plasma polymerization is preferably in the range of 1K to 100GHz. rf
13.56MH, which is often used for power supply and MW power supply
z and 22.4 GHz are included.

An introduction passage 16 is provided in the chamber 11, and the monomer and N 2 are introduced from the introduction passage 16.
Chamber 11 containing molecules in gas or liquid state
Introduced within. As described above, the monomer and the N-containing molecule introduced into the chamber 11 are subjected to the action of the plasma generated between the electrodes, and the monomer is cross-linked by the N-containing molecule to form a film on the substrate. To be done.

By the above-mentioned crosslinking, crystallization of the film material can be completely prevented, and most of the charge transporting functional group structure can be left, so that the charge transporting property is almost the same as the vapor deposition film of the monomer itself. Can be held.

The method of introducing the monomer is relatively easy as long as it is a gas or a liquid, and it may be introduced as it is or after it is heated to be vaporized and introduced into the chamber. For example,
Aromatic amines having a relatively high vapor pressure alone or a mixed vapor with other aromatic compounds may be introduced. However, when using TPD or the like, which is less likely to become vapor, as a monomer, it may be introduced by sublimation by heating as necessary. At this time, it is necessary to keep the temperature of the introduction path at a certain temperature or higher.

The crosslinked structure in the film thus obtained is not constant and is generally difficult to identify. That is, the entire film becomes an integral structure due to the crosslinking reaction. However, due to the infrared absorption spectrum, 1250
Since strong absorption of aromatic amines is widely observed at ˜1360 cm ⁻¹ , it is presumed that the above-mentioned crosslinked structure intended by the present invention is formed.

The device thus manufactured can maintain a uniform thin film without being crystallized for a long period of time even if heat is generated by a current for light emission. Therefore,
A light-emitting element in which a light-emitting material such as an aluminum quinolinol complex is laminated on such a plasma-polymerized thin film, an AgMg electrode is further laminated, and finally a SiO ₂ film or the like is formed as a protective film by sputtering is extremely stable. You can get quality.

The organic thin film diode of the present invention is usually used as a direct current drive type EL element, but it can be driven by alternating current or pulse drive. The applied voltage is usually
It is about 2 to 20V.

[0078]

EXAMPLES The present invention will be described in more detail below by showing specific examples of the present invention.

Example 1 A transparent electrode (ITO) on a transparent polycarbonate sheet
The compound having an aromatic ring and the N-containing molecule are selected as shown in Table 1, and a thickness of 8 is formed on the substrate by using the plasma polymerization apparatus having the structure shown in FIG.
An aromatic ring compound layer as a hole injecting and transporting layer having a thickness of about 0 nm was formed.

First, the substrate was set on the rf counter electrode.
After vacuum suctioning the apparatus to 2 × 10 ⁻³ Torr, ³ SCCM of the compound having an aromatic ring and 2 SC of the N-containing molecule shown in Table 1 were used.
CM and was introduced, and the inside of the apparatus was adjusted to 0.075 Torr. In this state, an rf power source of 13.56 MHz was applied at 50 W for plasma discharge to form an aromatic ring compound layer crosslinked with N-containing molecules of Sample Nos. 1 to 36. These were left in an environment of 40 ° C and 90%, but all 1000
It did not crystallize after hours. On the other hand, for comparison, sample No. 3 in which N-containing molecules were not introduced was sample No. 37, TPD was formed by vapor deposition as sample No. 38, and the sample was left in the same environment as above. , Both crystallized within 24 hours.

[0081]

[Table 1]

Tris (8-quinolinolato) aluminum was vapor-deposited as a light emitting layer on the hole injecting and transporting layer produced as described above while maintaining a vacuum. Furthermore, Ag and Mg were vapor-deposited as a cathode, the whole was covered with SiN, and the organic thin film diode of sample No. 1-36 of an Example and sample No. 37 and 38 of a comparative example was formed as a protective film. For these organic thin film diodes,
The device was driven at a constant current of 10 mA, and the initial emission luminance and the luminance half-life were measured. The results are shown in Table 1 above.

In the embodiment of the present invention, the emission brightness is 2
It was about 00 cd / cm ² or more, and the brightness half-life was about 140 hours or more. Sample No. 3, which was obtained by glow discharge polymerization of TPD with triethylamine, had an initial emission luminance of 208 cd / cm ² and a luminance half-life of 320 hours.
On the other hand, in the sample Nos. 37 and 38 of the comparative example, the initial light emission luminance of the sample No. 38 was 290 cd / cm ^2, which was higher than the initial light emission luminance of the sample No. 3, but the luminance half time was 150 in each case. It was less than half of Sample No. 3 in less than time.

Example 2 Also, the above sample Nos. 2, 3, 5, 12, 13, 2
0, 23, 25, 29 and 36 have D on the counter electrode
Sample Nos. 41, 42, 43, 4 of Table 2 were prepared in the same manner as above except that -40 V was applied by the C bias power source.
Hole-injecting and transporting layers of 4, 45, 46, 47, 48, 49 and 50 crosslinked aromatic compounds were deposited by plasma polymerization.

These were left in an environment of 40 ° C. and 90%, but all did not crystallize even after 1000 hours.

Using these samples, the organic thin film diodes of the respective samples were produced in the same manner as above, and the initial emission luminance and the luminance half-life were measured in the same manner as above. The results are shown in Table 2.

[0087]

[Table 2]

As can be seen from this table, the sample obtained by plasma polymerization with a bias voltage applied,
Both the initial emission luminance and the luminance half-life were improved as compared with the case where no voltage was applied.

[0089]

The effects of the present invention are as follows. Since a simple compound can be used, there is no need for a new and complicated synthesis, and the material cost can be suppressed. Purification is easy because it is a simple compound. Since a film can be formed in a consistent vacuum device, deterioration from water, oxygen, etc. can be prevented. By having a cross-linked structure, crystallization can be prevented and thus reliability is improved. By introducing a charge transporting functional group, the original performance can be maintained and low voltage driving becomes possible.

[Brief description of drawings]

FIG. 1 is a diagram showing a layer structure of an organic thin film diode of the present invention.

FIG. 2 is a schematic view of a preferable plasma polymerization apparatus used in the method for manufacturing an organic thin film diode of the present invention.

[Explanation of symbols]

 1 Organic Thin Film Diode 2 Substrate 3 Anode 4 Hole Injecting and Transporting Layer 5 Light Emitting Layer 6 Electron Injecting and Transporting Layer 7 Cathode 10 Plasma Polymerization Device 11 Vacuum Chamber 12 Cathode Plate 13 Anode Plate 14 High Frequency Power Supply 15 Bias Power Supply (DC)

Claims (6)

[Claims] 1. An organic thin film diode comprising a light emitting layer and a hole injecting layer or a hole injecting and transporting layer formed integrally with or separately from the light emitting layer, wherein the hole injecting layer or the hole injecting and transporting layer is formed. An organic thin-film diode, wherein the aromatic compound is a compound having 1 to 12 aromatic rings bridged by N-containing molecules capable of becoming a hole-transporting functional group. 2. The N-containing molecule that can be the hole-transporting functional group is at least one selected from nitrogen, ammonia, primary to tertiary alkyl amines, and primary to tertiary aryl amines. Organic thin film diode. 3. A method of manufacturing an organic thin film diode comprising a light emitting layer, a hole injection layer or a hole injection transport layer formed integrally with or separately from the light emitting layer, and a compound having 1 to 12 aromatic rings, A compound having an aromatic ring of 1 to 12 is cross-linked by the N-containing molecule by a glow discharge polymerization method while simultaneously introducing an N-containing molecule that can be a hole-transporting functional group, and the hole-injecting layer or positive A method for manufacturing an organic thin film diode, which comprises forming an aromatic compound constituting a hole injecting / transporting layer. 4. The method for producing an organic thin film diode according to claim 3, wherein the glow discharge polymerization method is a plasma polymerization method using a high frequency power source. 5. The method for manufacturing an organic thin film diode according to claim 3, wherein the glow discharge polymerization method is a plasma polymerization method in which a high frequency power source is used and a negative bias voltage is applied to the film formation substrate. 6. The N-containing molecule that can be the hole-transporting functional group is at least one selected from nitrogen, ammonia, primary to tertiary alkyl amines, and primary to tertiary aryl amines. 5. A method for manufacturing an organic thin film diode according to any one of 1 to 5.