JP2917795B2 - Organic electroluminescence device and method of manufacturing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an organic electroluminescence (EL) device and a method for manufacturing the same.

[0002]

2. Description of the Related Art In light emission of an organic electroluminescence device, holes and electrons injected from electrodes are recombined in a light emitting layer to generate excitons, which excite molecules of a light emitting material constituting the light emitting layer. It is believed to be based on
When a fluorescent dye is used as the light-emitting material, an emission spectrum equivalent to the photoluminescence of the dye molecule can be obtained as electroluminescence light emission.

Recently, an element having two layers, a hole transport layer and an electron transporting light emitting layer, which efficiently emits green light at a low voltage of about 10 V as compared with a conventional organic electroluminescent element having a single layer structure, Proposed by Tang and Vanslyke (CWTang and SAVanSlyke; Appl.Phys.Lett.,
51 (1987) 913]. The device is configured by laminating a hole transport layer, an electron transport light emitting layer, and a cathode in this order on a transparent conductive film of a transparent conductive substrate as an anode.

In the above device, the hole transport layer functions to inject holes from the anode to the electron transporting light emitting layer, and prevents the electrons injected from the cathode from escaping to the anode without recombination with the holes. It also plays the role of confining electrons in the electron transporting light emitting layer. Therefore, due to the electron confinement effect of the hole transport layer, recombination of holes and electrons occurs more efficiently than in a conventional device having a single-layer structure, and a drastic reduction in driving voltage can be achieved.

[0005] Saito et al., In a two-layer device,
In addition to showing that not only the electron transport layer but also the hole transport layer can be a light emitting layer (C. Adachi, T. Tsutsui and S. Saito; Ap
pl. Phys. Lett., 55 (1989) 1489], and proposed an organic electroluminescent device having a three-layer structure in which an organic light emitting layer was sandwiched between a hole transport layer and an electron transport layer [C. Adachi, ST.
okito, T.Tsutsui and S.Saito; Jpn.J.Appl.Phys., 27
(1988) L269].

Saito et al. Have a two-layer structure in which a transparent conductive film of a transparent conductive substrate is used as an anode, and a hole transporting light emitting layer, an electron transporting layer, and a cathode are stacked in this order. Contrary to the above, the electron transport layer functions to inject electrons from the cathode into the hole transporting light emitting layer, and the holes injected from the anode escape to the cathode without recombination with the electrons. And also serves to confine holes in the hole-transporting light-emitting layer. For this reason, the effect of confining holes by the electron transport layer enables a drastic reduction in driving voltage as in the case of the above.

Further, Saito et al.'S three-layer device is described in Tang, supra.
These elements are further improved, and are formed by stacking a hole transport layer, a light emitting layer, an electron transport layer, and a cathode in this order on a transparent conductive film of a transparent conductive substrate as an anode. The hole transport layer functions to confine electrons in the light-emitting layer, and the electron transport layer functions to confine holes in the light-emitting layer. The coupling efficiency is further improved. The electron transporting layer and the hole transporting layer also function to prevent excitons generated by recombination of electrons and holes from escaping by escaping to any of the positive and negative electrodes. Therefore, according to the device having a three-layer structure proposed by Saito et al., The luminous efficiency is further improved.

Further, Japanese Patent Application Laid-Open No. 4-308688 discloses, as an improvement of the above-mentioned device of Tang et al., That heat resistance, thin film forming property and hole-forming property are provided between an anode and a hole transport layer (first hole transport layer). A triphanylamine-based compound having a specific structure with excellent transportability [Y. Shirota, T. Kobata and N. Noma; C
hemistry Letters, pp. 1145-1148, (1989)] and a second hole transport layer is formed.

According to this configuration, the function of the second hole transport layer can further improve the luminous efficiency while improving the durability of the device.
Column 46, line 8 to column 8, line 5.

[0010]

The above-mentioned organic electroluminescence device can expect to emit light with a low voltage and high brightness as compared with a conventional electroluminescence device using an inorganic light emitting material. Each layer can also be formed by a solution coating method, so that it has advantages such as that it is easy to increase the area, and that it is possible to achieve multicolor by the molecular design of organic molecules.

However, the above-mentioned organic electroluminescent element may not be able to obtain the luminous luminance as designed or may have a variation in the luminous luminance. There is a possibility that the luminance may be further reduced, and improvement of light emission luminance, light emission life, and stability has become a major issue. The present invention has been made in view of the above circumstances, an organic light emitting device having a high initial light emission luminance and no variation in the light emission luminance, excellent light emission life, and excellent stability, and a method for manufacturing the same. It is intended to provide.

[0012]

Means for Solving the Problems and Actions In order to solve the above-mentioned problems, the present inventors have proposed a method for forming a surface of a transparent conductive film on a transparent conductive substrate as a base on which an organic layer constituting an element is formed. We focused on the state. In a conventional device manufacturing process, the surface of a transparent conductive film of a transparent conductive substrate is subjected to ultrasonic cleaning with, for example, a surfactant, water and an organic solvent in this order, and then used for forming the device.

However, when the inventors evaluated the cleanliness of the surface of the transparent conductive film by the contact angle of water, the cleanliness was about 25 to 30 ° immediately after the washing, and the surface was contaminated, although very slightly. Confirmed that. Further, when the transparent conductive substrate after washing was left in the air, the contact angle of water on the surface of the transparent conductive film gradually increased, so that the contamination of the surface was predicted to progress with time. Then, they have come to think that these may be the causes of the shortage or variation of the light emission luminance of the element, the reduction of the light emission life, and the like.

That is, if a contaminant remains on the surface of the transparent conductive film, the contaminant inhibits injection of holes from the transparent conductive film into the organic layer. If the hole injection is not performed smoothly, and the hole injection is not performed smoothly, abnormal heat generation occurs in the element, and the organic substance constituting the organic layer is easily deteriorated in a short period of time, so that the light emission life and stability are reduced. .

Further, since the surface contamination progresses with time as described above, the light emission luminance varies depending on how much the transparent conductive substrate is left after cleaning and then used for forming an element. Therefore, the present inventors considered that, while using a contact angle of water as a parameter, to maintain the cleanliness of the surface of the transparent conductive film of the transparent conductive substrate at a high level, and to manufacture an element, the present invention led to the present invention. It was completed.

That is, the organic electroluminescent device of the present invention is subjected to a washing treatment so that the contact angle of water is less than 25 °, and is a transparent conductive substrate held in a vacuum or an inert gas. A single or multiple organic layers constituting an element are formed on the surface of the transparent conductive film. Further, in the method for producing an organic electroluminescence element of the present invention, the surface of the transparent conductive film of the transparent conductive substrate is washed so that the contact angle of water is less than 25 ° , and the vacuum is applied.
Held in an inert gas or on the transparent conductive film,
It is characterized in that a single layer or a plurality of organic layers constituting an element are formed.

According to the present invention having the above structure, an element is manufactured by forming an organic layer on the surface of a transparent conductive film having a contact angle of water of less than 25 ° and substantially free of contaminants. It is possible to manufacture an organic electroluminescent device having high initial light emission luminance, no variation in the light emission luminance, and excellent light emission life and stability.

The contact angle of water on the surface of the transparent conductive film is more preferably 20 ° or less even within the above range. Hereinafter, the present invention will be described. Examples of the transparent conductive substrate include those obtained by forming a transparent conductive film on the surface of a transparent substrate.

As the transparent substrate, various conventionally used substrates such as a glass plate can be used. As the transparent conductive film formed on the surface of the substrate, a film made of a transparent conductive material such as ITO (indium-tin-oxide) or SnO ₂ is preferably used. The transparent conductive film can be formed by applying or printing an ink containing the above-described transparent conductive material on a substrate, in addition to being formed by a vacuum evaporation method or a reactive sputtering method.

The surface of the transparent conductive film has a water contact angle of 25 °.
As a cleaning method for cleaning up to a state in which contaminants hardly exist, the cleaning method is not limited to this. First, the surface of the transparent conductive film is first treated with a surfactant, water, and an organic solvent as in the past. After ultrasonic cleaning in order,
Further, there is a method of performing at least one of acid cleaning and plasma treatment.

As the surfactant, there can be used various activators (for example, semi-coclean etc.) such as a nonionic activator which have been conventionally used for cleaning the surface of the transparent conductive film. The water is preferably pure water or ultrapure water that does not contain impurities that can be a pollutant as much as possible.However, if ultrasonic cleaning with water is repeated several times, the purity should be reduced to pure water or ion-exchanged water. It is economical to gradually raise it.

As the organic solvent, those having excellent degreasing and dehydrating power, high volatility, low cost, and high safety which do not cause environmental destruction and the like are desirable. However, there is no solvent satisfying all of these conditions. The washing may be repeated for each of two or more solvents satisfying some of these conditions. Examples of the organic solvent include, but are not limited to, alcohols such as methanol, ethanol, and isopropanol.

Ideally, both the acid cleaning and the plasma treatment are performed, but the surface of the transparent conductive film has a contact angle of water of 2 μm.
As long as the cleaning can be performed until the temperature becomes less than 5 °, only one of the processes may be performed. Examples of the acid used for the acid washing include sulfuric acid, hydrochloric acid, aqua regia, and chromic acid. In order to prevent the transparent conductive film from being damaged, for example, sulfuric acid, hydrochloric acid, or the like is preferably used after being diluted with water or the like. The acid cleaning is performed by immersing the base material obtained by ultrasonically cleaning the transparent conductive film with the surfactant, water and an organic solvent in the acid for a predetermined time.

As the plasma processing, so-called plasma dry etching in semiconductor manufacturing technology can be applied. That is, chlorine-based or fluorine-based Cl ₂ , CCl ₄ , CCl ₂ F ₂ , CF ₄ ,
Use PCl ₃ , HCl, etc., and further add H ₂ , O ₂
The transparent conductive film of the transparent conductive substrate may be brought into contact with low-temperature plasma generated by applying a high-frequency or direct-current electric field while adding such as an auxiliary gas.

For the plasma treatment, a vacuum evaporation apparatus used for forming an organic layer constituting an element in the next step can be used. Since there is a possibility that the deposition material adheres to the inside and contaminates the surface of the transparent conductive film during the plasma processing, a dedicated plasma processing apparatus different from the vacuum deposition apparatus, for example, a plasma dry etching apparatus such as an asher apparatus or the like is used. It is preferred to use.

The transparent conductive base material after the acid cleaning or plasma treatment, in order to prevent from being contaminated again, not left standing in air, the coercive at or in a vacuum, or an inert gas secondary
Immediately after the treatment, that is, before the contact angle of water of the transparent conductive film does not become 25 ° or more, it must be used for forming a layer in the next step .

According to the present invention, an organic layer constituting an element is formed on the surface of a transparent conductive film of a transparent conductive substrate which has been washed so as to have a contact angle of water of less than 25 ° as described above. The configuration other than the above is not particularly limited. The organic layer constituting the device may have a conventional single-layer structure or a multilayer structure of two or more layers. In short, various layer configurations can be applied.

In the present invention, preferred examples of the organic layer formed on the surface of the transparent conductive film include, for example, an organic layer containing at least a 1,2,4-triazole derivative layer, a transparent conductive film And an organic layer in which the layer immediately above is a hole injection / transport layer made of a hole transport material.

[0029] Among the organic layers described above, 1,
1,2,4 constituting a layer of 2,4-triazole derivative
A triazole derivative is not very effective as a hole transporting material, but when used as an electron transporting material, has better electron transporting properties than other materials conventionally used;
Exhibits hole blocking and exciton generated by recombination of electrons and holes can be efficiently confined in the light-emitting layer, greatly improving the light-emitting layer's luminous efficiency, luminous brightness, and accompanying stability. It is.

Therefore, for example, when the above-mentioned 1,2,4-triazole derivative layer is combined with a light-emitting layer made of a blue light-emitting material having a high hole-transport property, which has conventionally been difficult to emit light, Since the luminous efficiency and luminous luminance of the luminous layer can be improved to a sufficiently practicable range, it is possible to configure a high-luminance blue-light-emitting organic electroluminescent element which has conventionally been difficult to put into practical use.

The layer of the 1,2,4-triazole derivative as referred to herein is a layer containing at least one or two or more 1,2,4-triazole derivatives.
In addition to a layer composed of only one or more of the triazole derivatives, a layer in which one or more of the 1,2,4-triazole derivatives are dispersed in a suitable binder is exemplified. Further, the layer of the 1,2,4-triazole derivative may contain other components such as various additives that do not inhibit the function of the 1,2,4-triazole derivative.

The layer of the 1,2,4-triazole derivative can be formed by a vapor phase growth method such as a vacuum evaporation method, or a coating solution obtained by dissolving a material constituting the layer in an appropriate solvent can be formed on a substrate or It can also be formed by a solution coating method of coating and drying on another layer. Various compounds can be used as the 1,2,4-triazole derivative, and in particular, the compound represented by the formula (1):

[0033]

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3- (4-biphenylyl)-represented by
4-phenyl-5- (4-tert-butylphenyl)-
1,2,4-triazole (hereinafter referred to as “TAZ”)
Is most preferably used because of its excellent electron transporting property and hole blocking property. The thickness of the 1,2,4-triazole derivative layer is not particularly limited. However, if the thickness of the above layer is too small, the hole blocking property becomes insufficient, so that the thickness of the layer is desirably somewhat thick. The suitable thickness range of the 1,2,4-triazole derivative layer is not particularly limited. For example, in the case of a TAZ vapor-deposited film represented by the above formula (1), it is necessary to ensure sufficient hole blocking properties. Has a thickness of 10
Preferably it is 0 to 200 ° or more. The upper limit of the film thickness of the above layer is not particularly limited, but if the film thickness is too large, the electron transporting property is reduced. .

As described above, the layer of the 1,2,4-triazole derivative is preferably combined with a hole-transporting light-emitting layer which emits blue light having a high hole-transport property. Examples of the hole-transporting light-emitting material constituting the blue light-emitting hole-transporting light-emitting layer include, for example, Formula (2):

[0036]

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N, N'-diphenyl-N,
N'-bis (3-methylphenyl) -1,1'-biphenyl-4,4'-diamine [hereinafter referred to as "TPD"]
Or or equation (3):

[0038]

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Examples thereof include polyvinyl carbazole (hereinafter referred to as “PVK”) represented by the formula (where n represents the degree of polymerization). Although the polymerization degree n of PVK is not particularly limited,
About 0 to 5000 is preferable. Considering the effect of the layer of 1,2,4-triazole derivative to confine excitons in the hole-transporting light-emitting layer, the hole-transporting light-emitting layer is composed of an anode (transparent conductive film) and a 1,2,4-triazole derivative. It is preferable to interpose between these layers.

In the combination of the 1,2,4-triazole derivative layer and the blue light-emitting hole-transporting light-emitting layer, furthermore, for example, the formula (4) ):

[0041]

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Tris (8-quinolinolate) represented by
When an electron transport layer made of an aluminum (III) complex (hereinafter referred to as “Alq”) or the like is interposed, the electron injecting characteristics into the hole transporting light emitting layer are further improved, the luminous efficiency is further improved, and blue light with high luminous brightness is obtained. Light emission is obtained. Fig. 1 (a)
Shows a layer configuration of an element including the organic layer 2 in which the hole transporting light emitting layer 21, the 1,2,4-triazole derivative layer 22, and the electron transporting layer 23 are combined. In the figure, reference numeral 1 denotes a transparent conductive substrate having a transparent conductive film (anode) 10 formed on the surface, 5 denotes a cathode,
Is a power supply for applying a drive voltage to the element.

The 1,2,4-triazole derivative layer has at least one of holes and electrons depending on its film thickness, in addition to the effect of confining excitons in the hole transporting light emitting layer described above. It also has the function of selectively transporting one. Therefore, in an element having a three-layer structure in which the layer of the 1,2,4-triazole derivative is interposed between the hole transport layer and the electron transport layer, the thickness of the layer of the 1,2,4-triazole derivative is By selecting, one or both of the hole transport layer and the electron transport layer can emit light.

In this case, similarly to the case of the blue light emission, the hole transport layer or the electron transport layer can be formed with high luminance and high efficiency by the effect of exciton confinement by the 1,2,4-triazole derivative layer. Since light can be emitted, it is possible to improve the luminous efficiency and the luminous brightness, and to thereby improve the stability. For this reason, for example, by using materials having different emission spectra for the hole transport layer and the electron transport layer, light emission of two or more different emission spectra can be achieved with one device, which is, for example, conventionally impossible. In addition, an organic electroluminescence element capable of performing multi-color display using three primary colors of RGB, white light emission, and the like can be configured.

The hole transporting layer and the electron transporting layer among the above layers can be made of various conventionally known hole transporting materials and electron transporting materials. In short, materials having the desired emission spectrum can be used in appropriate combination. Constituting the organic layer of 1, 2, 2,
Each layer other than the layer of the 4-triazole derivative is
Like the 2,4-triazole derivative layer, it can be formed by a vapor phase growth method such as a vacuum evaporation method, or a solution coating method. Each of the above layers is a binder resin,
Other components that are not directly related to the function of the layer, such as various additives, may be included.

In the organic layer, various compounds can be considered as the hole transporting material constituting the hole injecting and transporting layer formed immediately above the transparent conductive film. In particular, the above-mentioned report by Shirota et al. Alternatively, triphenylamine compounds disclosed in European Patent Publication Nos. 0508562 and 0517542, metal phthalocyanines, and the like are preferably used.

Preferred examples of the triphenylamine-based compound among the above hole transporting materials are not limited to these, but for example, 4,4 ',
4 ″ -tris [N- (3-methylphenyl) -N-phenylamino] triphenylamine [hereinafter “MTDAT
A "], 4,4 ', 4" -tris (N, N-diphenylamino) triphenylamine [hereinafter referred to as "TDATA"] represented by the formula (6), and represented by the formula (7) 4,4 ', 4 "-tris (N-carbazolyl) triphenylamine [hereinafter referred to as" TCTA "] and the like.

[0048]

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[0049]

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Preferred examples of the metal phthalocyanines include a copper phthalocyanine represented by the formula (8) [hereinafter referred to as “Cu
PC ”].

[0051]

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As another hole transporting material, for example, a carbazole trimer represented by the formula (9) [hereinafter referred to as “T
CTB "), a phenothiazine trimer represented by the formula (10) [hereinafter referred to as" PTTB "], and a phenoxazine trimer represented by the formula (11) [hereinafter referred to as" POTB "]
And the like.

[0053]

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[0054]

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These hole transporting materials can be used alone or in combination of two or more. Since each of the hole transporting materials exemplified above is excellent in hole transporting ability, the organic layer provided with the hole injecting and transporting layer made of these hole transporting materials has a hole transport property from the transparent conductive film serving as an anode. The injection efficiency is improved, and the light emission efficiency and light emission luminance are further improved.

As described above, since the hole injection / transport layer improves the hole injection efficiency, the organic layer does not generate abnormal heat. In addition, since the hole transporting materials constituting the hole injecting and transporting layer are all excellent in heat resistance, the layers laminated thereon are prevented from being deteriorated due to heat generation during light emission of the device. Therefore, the organic layer provided with the hole injecting and transporting layer further improves the light emission lifetime and stability.

The layer structure of the organic layer other than the hole injecting and transporting layer is not particularly limited, and various conventionally known organic layer structures having a single-layer structure or a multilayer structure can be employed as they are. That is, the organic layer, in the conventionally known organic layers of various layer configurations, in order to improve the efficiency of hole injection from the anode, just above the transparent conductive film as the anode, a hole injection transport layer was interposed. Can be thought of.

For example, FIG. 1 (b)
In the configuration shown in FIG. 1A, which is an example of a device including an organic layer 2 including a 4-triazole derivative layer 22, in the configuration of FIG.
It corresponds to a structure in which a hole injection / transport layer 20 is interposed between 0 and the hole transportable light emitting layer 21. In the above layer configuration,
Since the hole injection / transport layer 20 functions to improve the hole injection efficiency from the anode 10, the luminous efficiency, luminous brightness, luminous life and stability of blue luminescence can be further improved.

Each of the layers including the hole injecting / transporting layer constituting the organic layer is formed by a vapor phase growth method such as a vacuum evaporation method or a solution coating method in the same manner as the respective layers constituting the organic layer. The layers may be formed, and each of the layers may contain other components not directly related to the functions of the layers, such as a binder resin and various additives. As the cathode formed on the organic layer as described above, for example, a normal electrode layer such as a magnesium / silver electrode layer in which magnesium and silver are co-deposited can be used. It is suitable as.

Since the aluminum / lithium electrode layer has a higher electron injection efficiency than other electrode layers, the luminous efficiency and luminous brightness of the device are further improved. Aluminum /
Since the lithium electrode layer has a high electron injection efficiency as described above, abnormal heat generation of the element does not occur, and thus the light emission lifetime and stability of the element are further improved.

[0061]

The present invention will be described below based on examples and comparative examples. Confirmation of cleaning effect An ITO (indium-tin-oxide) -coated glass substrate (made by Asahi Glass Co., Ltd., ITO film thickness 1500 to 1600 の) having a sheet resistance of 15Ω / □ is ultrasonicated with a surfactant, water, isopropanol and methanol in this order. Immediately after washing and drying, the contact angle of water on the surface of the ITO film was measured.
３０30 °.

Then, the ITO-coated glass substrate after the ultrasonic cleaning is successively immersed in dilute sulfuric acid (diluted 5 times with water) at room temperature for 10 minutes to perform acid cleaning, and then acidified with distilled water. Was washed off and dried, and the contact angle of water on the surface of the ITO film could be reduced to 15 to 20 °. On the other hand, instead of the acid cleaning, the ITO-coated glass substrate after the ultrasonic cleaning was plasma-treated (dry-cleaned) for 60 seconds under the following conditions using an asher apparatus as a plasma processing apparatus. The contact angle of water on the surface could be reduced to 5-20 °. <Plasma processing conditions> * Introduced gas pressure O ₂ gas: 0.4 Torr CF ₄ gas: 0.06 Torr * Substrate temperature 120 ° C. * Plasma power 100 W Example 1 Surface activity under the same conditions as in the above-described cleaning effect confirmation test. Agent,
After ultrasonic cleaning with water, isopropanol and methanol in this order, and drying, the ITO-coated glass substrate (contact angle of water on the ITO film surface of 5 to 20 °) plasma-treated (dry-cleaned) using an asher device. Immediately after the treatment, the chamber was set in a chamber of a vacuum evaporation apparatus, and the apparatus was operated to make a vacuum state in the chamber.

Next, the I-coated glass substrate I
On the surface of the TO film (anode), MTDATA represented by the above formula (5) as a hole injection / transport material, TPD represented by the above formula (2) as a hole transporting light emitting material,
TAZ represented by the above formula (1) as a 2,4-triazole derivative, and the above formula as an electron transport material
Alq represented by (4) was formed in this order by a vacuum evaporation method. The size of the light emitting region was a square having a length of 0.5 cm and a width of 0.5 cm. The deposition conditions were as follows: ultimate vacuum degree: 2 × 10 ⁻⁵ Torr, substrate temperature: room temperature, deposition rate: 2 to 4 ° / sec, and the thickness of each layer formed was MTDATA. Layer (hole injection / transport layer) = 200 °,
TPD layer (hole transporting light emitting layer) = 300 °, TAZ layer (layer of 1,2,4-triazole derivative) = 150 °,
Alq layer (electron transport layer) = 350 °.

Then, magnesium and silver were co-deposited on the Alq layer at a deposition rate ratio of 10: 1 to form a film having a thickness of 1500
(4) An Mg / Ag electrode layer (cathode) of Mg / Ag = 10/1 (molar ratio) was formed to obtain an organic electroluminescence device having a layer structure shown in FIG. 1 (b). Using the ITO film of the organic electroluminescence device prepared as described above as an anode and the Mg / Ag electrode layer as a cathode, a DC electric field is applied between the two electrodes at room temperature and in the air to cause the light emitting layer to emit light. Was measured using a luminance meter (LS-100 manufactured by Minolta), and blue light emission with a maximum luminance of 9800 cd / m ² was observed from the TPD layer at a driving voltage of 12 V.

Further, the above device was continuously lit at an initial luminance of 100 cd / m ² in a nitrogen gas inert atmosphere at room temperature, and the half-life of the luminous luminance (the time until the luminance reached 50 cd / m ²⁾ ) Was 200 hours. Example 2 As a material constituting the hole injection transport layer, MTDATA was used.
Instead of using TCTA represented by the formula (7), an organic electroluminescent device having a layer structure shown in FIG. 1B was produced in the same manner as in Example 1. The thickness of each layer is TCTA layer (hole injection transport layer) = 150
Å, TPD layer (hole transporting light emitting layer) = 400Å, TA
Z layer (layer of 1,2,4-triazole derivative) = 150
{Alq layer (electron transport layer) = 300}.

When the above device was made to emit light in the same manner as in Example 1, blue light emission with a maximum luminance of 11000 cd / m ² was observed from the TPD layer at a driving voltage of 12 V. The half-life of the light emission luminance of the device was measured in the same manner as in Example 1, and it was 240 hours. Example 3 As a material constituting the hole injection transport layer, MTDATA was used.
Instead of using CuPC represented by the above formula (8), an organic electroluminescence device having a layer structure shown in FIG. 1B was produced in the same manner as in Example 1. The thickness of each layer is CuPC layer (hole injection transport layer) = 150
Å, TPD layer (hole transporting light emitting layer) = 400Å, TA
Z layer (layer of 1,2,4-triazole derivative) = 150
{Alq layer (electron transport layer) = 300}.

When the above device was made to emit light in the same manner as in Example 1, blue light emission with a maximum luminance of 8000 cd / m ² was observed from the TPD layer at a driving voltage of 12 V. The half-life of the light emission luminance of the device was measured in the same manner as in Example 1, and found to be 140 hours. Example 4 Instead of the Mg / Ag electrode layer, aluminum and lithium were co-deposited on the Alq layer at a deposition rate ratio of 100: 1 to form a film having a thickness of 1500 ° and Al / Li = 100/1 (molar ratio). An organic electroluminescent device having a layer structure shown in FIG. 1B was produced in the same manner as in Example 2 except that an Al / Li electrode layer was formed. The thickness of each layer is TCTA layer (hole injecting and transporting layer) = 150 °, TPD layer (hole transporting light emitting layer)
= 450 °, TAZ layer (layer of 1,2,4-triazole derivative) = 150 °, Alq layer (electron transport layer) = 250
Was Å.

When the above device was made to emit light in the same manner as in Example 1, blue light emission with a maximum luminance of 14000 cd / m ² was observed from the TPD layer at a driving voltage of 12 V. When the half-life of the light emission luminance of the device was measured in the same manner as in Example 1, the half-life did not reach half even after 1000 hours,
High emission luminance was maintained. Comparative Example 1 A surfactant, under the same conditions as in the test for confirming the cleaning effect,
An ITO-coated glass substrate (ITO) dried by ultrasonic cleaning in this order with water, isopropanol and methanol and dried.
An organic electroluminescent device having a layer structure shown in FIG. 1B was produced in the same manner as in Example 1 except that the contact angle of water on the film surface was 25 to 30 °).

When the device was made to emit light in the same manner as in Example 1, blue light emission with a maximum luminance of 4000 cd / m ² was observed from the TPD layer at a driving voltage of 12 V. The half-life of the light emission luminance of the device was measured in the same manner as in Example 1. The half-life was reduced by only 20 hours. Example 5 An organic electroluminescent device having a layer structure shown in FIG. 1A was produced in the same manner as in Example 1 except that the MTDATA layer was omitted. The thickness of each layer is as follows: TPD layer (hole transporting light emitting layer) = 400 °, TAZ layer (1, 2, 4
-Triazole derivative layer) = 150 ° and Alq layer (electron transport layer) = 400 °.

When the above device was made to emit light in the same manner as in Example 1, blue light emission with a maximum luminance of 6000 cd / m ² was observed from the TPD layer at a driving voltage of 12 V. The half-life of the light emission luminance of the device was measured in the same manner as in Example 1, and it was 90 hours. Example 6 A surfactant, under the same conditions as in the test for confirming the cleaning effect,
Ultrasonic cleaning with water, isopropanol and methanol in this order, followed by immersion in dilute sulfuric acid (diluted 5 times with water) for 10 minutes at room temperature, followed by acid cleaning, then washing off the acid with distilled water and drying An organic electroluminescent device having a layer structure shown in FIG. 1 (b) in the same manner as in Example 1 except that the ITO-coated glass substrate (contact angle of water on the ITO film surface of 15 to 20 °) was used. Was prepared.

When the device was made to emit light in the same manner as in Example 1, blue light emission with a maximum luminance of 7800 cd / m ² was observed from the TPD layer at a driving voltage of 12 V. The half-life of the light emission luminance of the device was measured in the same manner as in Example 1, and it was 160 hours. Example 7 In the same manner as in Example 6, after washing with acid and washing off the acid with distilled water, the dried ITO-coated glass substrate was subsequently subjected to plasma treatment using an asher device under the same conditions as in Example 1 ( Dry cleaning). The contact angle of water on the surface of the ITO film was 5 to 15 °.

Immediately after the treatment, the ITO-coated glass substrate was set in a chamber of a vacuum deposition apparatus, and the apparatus was operated to make the inside of the chamber vacuum. Then, in the same manner as in Example 1, an organic electroluminescence device having a layer structure shown in FIG. When the above device was made to emit light in the same manner as in Example 1, the TPD layer
Blue light emission with a maximum luminance of 9600 cd / m ² was observed at a driving voltage of 12 V.

The half-life of the light emission luminance of the device was measured in the same manner as in Example 1, and it was 190 hours.

[0074]

As described in detail above, according to the present invention,
Washed so that the contact angle of water is less than 25 °,
On the surface of the transparent conductive film of the transparent conductive substrate, a single or multiple organic layers constituting the element are formed, so that the initial light emission luminance is high and the light emission luminance does not vary, and the light emission lifetime, An organic electroluminescence device having excellent stability can be manufactured.

[Brief description of the drawings]

FIG. 1A is a cross-sectional view showing an example of a layer configuration of an organic electroluminescence device of the present invention, and FIG. 1B is a cross-sectional view showing another example of a layer configuration.

[Description of sign]

 DESCRIPTION OF SYMBOLS 1 Transparent conductive base material 2 Organic layer 10 Transparent conductive film

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Yasuko Torii 1-3-1 Shimaya, Konohana-ku, Osaka Sumitomo Electric Industries, Ltd. Osaka Works (56) References JP-A-4-349388 (JP, A) JP-A-5-179034 (JP, A) JP-A-6-252178 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) H05B 33/14 H05B 33/10

Claims (6)

(57) [Claims] An element constituting a device is cleaned on a surface of a transparent conductive film of a transparent conductive substrate held in a vacuum or in an inert gas by a washing treatment so that a contact angle of water is less than 25 °. An organic electroluminescent device, wherein a layer or a plurality of organic layers are formed. 2. The organic electroluminescent device according to claim 1, wherein the organic layer includes at least a layer of a 1,2,4-triazole derivative. 3. The method according to claim 1, wherein the layer directly above the transparent conductive film among the organic layers is
The organic electroluminescence device according to claim 1, wherein the organic electroluminescence device is a hole injection / transport layer made of a hole transport material. 4. The organic electroluminescence device according to claim 1, wherein an aluminum / lithium electrode layer is formed on the organic layer. 5. A cleaning process for cleaning the surface of the transparent conductive film of the transparent conductive substrate so that the contact angle of water is less than 25 ° ,
Held in an inert gas or on the transparent conductive film,
A method for producing an organic electroluminescence device, comprising forming a single layer or a plurality of organic layers constituting the device. 6. The surface of the transparent conductive film of the transparent conductive substrate is subjected to ultrasonic cleaning with a surfactant, water and an organic solvent in this order, and further subjected to at least one of acid cleaning and plasma treatment. 6. The method for manufacturing an organic electroluminescence device according to claim 5, wherein a contact angle of water on the surface of the transparent conductive film is less than 25 °.