JP2001052857A - Organic electroluminescent element and manufacture thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stabilize the light emission quality by adhering a first substrate and a second substrate to each other while pinching a spacer and an organic layer. SOLUTION: Mg-Ag as a negative electrode 2 is vacuum-deposited onto an electrode substrate 1a. A spacer 3 is formed on the negative electrode 2 by photolithography. An aluminum quinolinol complex layer 4a as an electron transporting light emitting layer is deposited. On the other hand, ITO as a positive electrode 5 is formed on an electrode substrate 1b by spattering, and continuously, a film of polyvinyl carbazole 6 as a hole transporting layer is formed by spin coating. After heating the electrode substrate 1b under the nitrogen atmosphere, the spacer 3 is pinched for facing, and the electrode substrate 1a is welded for adhesion. With this structure, organic EL element having the predetermined distance between the positive electrode and the negative electrode can be produced with excellent reproducibility, and excellent green light emission can be obtained by applying the direct current voltage to the organic EL element.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an organic electroluminescence device and a method of manufacturing the same, and more particularly, to a color display device in which the thickness of an organic layer and the distance between electrodes are adjusted and multicoloring is easy. The present invention relates to an organic electroluminescent device that can be used and a method for manufacturing the same.

[0002]

2. Description of the Related Art Organic electroluminescent elements (hereinafter referred to as organic EL elements) can respond to electric signals quickly, emit natural light with high visibility, and can be designed in a wide range of molecules because of using organic materials as main raw materials. It has ideal characteristics as a display, such as easy multi-color display, and is being developed for practical use as a color display device.

[0003] Organic EL devices, which are completely solid devices, have excellent impact resistance and are easy to handle, and are being applied to surface light sources, displays, light sources for printers, and the like.

Generally, in an organic EL device, when an organic layer, which is a thin film containing an organic material, is sandwiched between electrodes and current is applied, holes and electrons injected from both electrodes recombine in the organic layer. It is known that a light emission phenomenon occurs due to energy. This luminescence phenomenon occurs when a single organic layer is
It can be seen in the structure sandwiched between two electrodes, but a laminated structure in which a hole transport layer and an electron transport layer are arranged to reduce the energy barrier between the electrode and the organic layer and facilitate carrier transfer to the organic layer is proposed. Have been. As described above, the structure of the organic EL element has a basic structure of anode / light-emitting layer / cathode, anode / hole transport layer / light-emitting layer / cathode, anode / light-emitting layer / electron transport layer / cathode, anode / hole transport. Structures such as layer / light emitting layer / electron transport layer / cathode are known.

[0005] Such an organic EL device is generally produced by sequentially laminating an anode, a hole transport layer, a light emitting layer, an electron transport layer and a cathode on a supporting substrate such as glass. For example, first, a transparent electrode is formed as an anode on a supporting substrate such as glass using a sputtering method, a vacuum evaporation method, or the like.
After patterning the electrode into a predetermined shape, a hole transport layer, a light emitting layer, and an electron transport layer are formed thereon by a vapor deposition method such as a vacuum evaporation method, a coating method such as a spin coating method, an LB method, and screen printing. The layers are sequentially laminated using a known thin film forming method such as Next, a metal film is formed as a cathode by a vacuum evaporation method or a sputtering method. Finally, an external lead wire is attached, and the organic layer is sealed with a sealing agent such as polyethylene, polystyrene, or silicone resin to prevent the organic layer from moisture and heat, thereby obtaining an organic EL element.

In a matrix type organic EL device, patterning of electrodes is indispensable. However, it is very difficult to use a photolithography method using an ultraviolet ray or an organic solvent which may damage the organic layer after forming the organic layer. Difficult. Further, it is difficult to form a fine shape by a method of patterning an electrode using a shadow mask. Therefore, a method has been proposed in which electrodes are formed on two support substrates and each is patterned to form an organic EL element.

Japanese Patent Application Laid-Open No. 8-236273 discloses an organic EL device formed by sandwiching an organic layer between electrode substrates under a high degree of vacuum and heating using a vacuum melting apparatus. In the method disclosed in JP-A-8-236273, the distance between the electrodes changes depending on the polymer concentration and viscosity, and the pressure applied to the electrode substrate. Japanese Patent Application Laid-Open No. 8-236273 does not disclose or teach a method for adjusting the thickness of an organic layer and the distance between electrodes.

Japanese Patent Application Laid-Open No. 7-153571 discloses an organic thin-film EL device in which a light-emitting layer is sandwiched between an anode material layer and a cathode material layer, and a moisture absorbing layer and a moisture-proof layer are provided on both sides thereof. The anode material layer and the cathode material layer are formed on another substrate,
The applied light emitting layer is overlaid and thermocompressed. JP-A-7-153571 does not disclose or teach a method of adjusting the thickness of an organic layer and the distance between electrodes.

Japanese Patent Application Laid-Open No. 9-7763 discloses that an anode layer and an organic thin film layer are sequentially laminated on one film, and a cathode layer and an organic thin film layer are sequentially laminated on the other film. It discloses an organic EL element formed by bonding films by thermocompression bonding with facing each other, and bonding or fusion sealing the peripheral portion. Japanese Patent Application Laid-Open No. 9-7763 also does not disclose or teach a method for adjusting the thickness of the organic layer and the distance between the electrodes.

[0010]

In the above-mentioned method for manufacturing an organic EL device, it is generally difficult to uniformly form the thickness of the organic layer. Therefore, it is difficult to provide an organic EL element having a stable luminous quality with good reproducibility.
There is no prior art teaching a method of adjusting the thickness of the organic layer and the distance between the electrodes. The present invention relates to the above conventional organic EL
Organic E with stable performance by improving the device manufacturing method
Provided are an L element and a method for manufacturing the same.

[0011]

SUMMARY OF THE INVENTION The present invention relates to an organic electroluminescent device having an organic layer containing an organic material, the device comprising a first substrate on which a cathode is formed; a second substrate on which an anode is formed. A spacer disposed on at least one of the first and second substrates, each having a bottom area in contact with the substrate on which it is disposed and a top area opposing the bottom area; And an organic layer containing an organic material formed on at least one of the cathode and the anode. The first substrate and the second substrate are closely attached to each other with the spacer and the organic layer interposed therebetween. ing.

The present invention, in one aspect, relates to a method for manufacturing an organic electroluminescent device having an organic layer containing an organic material, the method comprising the steps of forming a cathode on a first substrate; Forming an anode on at least one of the first and second substrates, wherein each of the spacers has a bottom area in contact with the substrate on which the spacer is disposed and a bottom area in contact with the bottom area. Forming an organic layer containing an organic material on at least one of the cathode and the anode; and opposing the first substrate and the second substrate, The method includes a step of sandwiching and adhering the organic layer.

[0013] The spacer has a bottom area in contact with one of the substrates on which it is disposed, and an upper area opposite to the bottom area, and contacts the other opposing substrate through this upper area, Maintain the desired thickness of the organic layer.

[0014] Preferably, the spacer is arranged around the organic layer or at the periphery of the substrate. The position and size of the spacer can be changed according to the desired aperture ratio of the organic EL device and the size of the substrate.

The organic layer is formed by forming an organic layer containing an organic material on at least one of the cathode and the anode, so that the low molecular material is formed on one or both of the cathode and the anode. Alternatively, a polymer material is laminated using a known thin-film forming method such as a vapor deposition method such as a vacuum evaporation method or a coating method such as a spin coating method.

The organic layer may optionally contain a hole and electron injection material, a charge limiting material, for example, an inorganic substance such as LiF. Further, the organic layer can be configured as a multilayer structure in which two or more layers containing the above materials are stacked. This multi-layer structure can be formed as a multi-layer structure by forming the multi-layer structure on one of the first substrate and the second substrate or on each of the two substrates, and then by closely contacting the two substrates.

Preferably, the contacting step is performed by thermocompression bonding. This contacting step can be performed by melting at least one material to be contacted.

Preferably, the region near the surface of the organic layer is made of a polymer material, and the adhesion between the layers is increased in the step of adhering.

Preferably, at least one of the organic layers contains a crosslinkable or polymerizable material near its surface, and the step of bonding includes crosslinking or polymerizing the crosslinkable or polymerizable material with light or heat. And thereby increase the adhesion between the stacked layers.

The above-mentioned step of adhering can be carried out under atmospheric pressure conditions, under vacuum conditions, and under an inert gas atmosphere, preferably, under vacuum conditions and under an inert gas atmosphere. When carried out at atmospheric pressure and under an inert gas atmosphere, preferably a humidity of 40% or less, 100%
The method is performed under the condition of not more than ppm and reduces oxygen remaining in the organic EL element formed thereby, thereby improving the reliability of the organic EL element.

Preferably, the thermocompression bonding is performed at a temperature lower than the melting point or glass transition temperature of the spacer material and higher than the melting point or glass transition temperature of the material near the surface of the organic layer. The deviation of the thickness of the organic layer of the obtained organic EL device from the desired thickness of the organic layer is minimized.

In one embodiment, the step of disposing the spacer is performed by using a photolithography method.

Preferably, the bottom area of the spacer is larger than the top area, thereby minimizing the deviation of the thickness of the organic layer of the organic EL device obtained from the desired organic layer thickness.

In one embodiment, one of the first and second substrates may include a TFT element.

[0025]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The organic EL device of the present invention will be described with reference to FIG.

(1) Electrode Substrate As the electrode support substrates 1a and 1b, any material used in a conventional organic electroluminescence device can be used. A material that is highly moisture-proof and functions as a sealing layer for the organic layer, preventing intrusion of oxygen in the air, a material that has good light extraction efficiency and is transparent in the visible light range, and an organic material that diffuses Joule heat generated when voltage is applied A material having high thermal conductivity for preventing the layer from deteriorating is preferably used. Examples of suitable materials include:
Examples include, but are not limited to, inorganic materials such as quartz and glass, and polymer materials such as polyimide and polyester. The electrode substrate may be a single-layer substrate made of these materials or a laminated substrate in which single layers made of these materials are stacked.

(2) Electrodes The electrodes 2 and 5 formed on the electrode substrate are preferably made of a transparent material having a light transmittance of at least 60% or more, more preferably at least 70% or more in the visible light region. Used. Examples of suitable materials, ITO (indium tin oxide), but SnO ₂ include, but are not limited to. For example, Au, Al, Pt, Cu, M
Metals such as n, Mg, Ag, Ca, Li, and Ba, and alloys composed of two or more of these can also be used as the electrodes. As the anode, an alloy having a work function of 4.5 eV or more or an electrically conductive compound of the alloy and having a high ionization potential and a small electron affinity is preferably used. As the cathode, an alloy having a work function of 4.0 eV or less or an electrically conductive compound of the alloy and having a low ionization potential and a high electron affinity is preferably used. The metal electrode is formed on the electrode substrate using a method known to those skilled in the art, such as a vacuum deposition method, a sputtering method, and screen printing. The formed electrode is patterned by a method known to those skilled in the art, such as a shadow mask method, a photolithography method, and screen printing.

(3) Spacer As the spacer 3, a spacer material used in a conventional liquid crystal device or a resist formed by photolithography can be used. Inorganic and organic materials having excellent heat resistance and insulation properties are preferred. When the spacer also serves as a black matrix, a black or highly light-absorbing material is preferably used. When the distance between the electrode substrates is 5 μm or less, a partition may be formed using a resist material, and the partition may be used as a spacer. Examples of such a resist material include, but are not limited to, polyvinyl cinnamate, photosensitive imide, rubber-based resist, and novolak resin. The cross section of the spacer perpendicular to the electrode substrate can be triangular, trapezoidal, circular,
It can be any shape such as an oval, but the thickness of the organic layer,
In order to minimize the deviation from the desired thickness, a shape in which the top section is smaller than the bottom section is preferably used.

The spacer is formed on the electrode substrate by a method known to those skilled in the art, such as a vapor deposition method such as a vacuum evaporation method and a sputtering method, and a coating method such as a spin coating method. The spacer is patterned by a method known to those skilled in the art, such as a shadow mask method, a photolithography method, and screen printing.

(4) Organic Layer As the organic layer 4, an organic material selected from any known low-molecular compound and high-molecular compound can be used. Examples of low molecular weight compounds include triphenylamine compounds, 8-hydroxyquinolinol derivatives, coumarin derivatives, butadiene derivatives, quinacdrine derivatives, styrene arylene derivatives, perylene derivatives, oxazole derivatives, oxadiazole derivatives, thiazole derivatives, benzoxazole derivatives, metals Complexes. Examples of the polymer compound include, but are not limited to, polyvinyl carbazole (PVK), a polyphenylenevinylene derivative, and a polythiophene derivative.

The organic layer may optionally include a hole and electron injection material, a charge limiting material, for example, an inorganic material such as LiF. Further, the organic layer is the second layer containing the above material.
It may be a multilayer structure in which one or more layers are stacked. The organic layer can be composed of only the light-emitting layer as a light-emitting layer / electron transport layer, a hole-transport layer / light-emitting layer, and a hole-transport layer / electron transport layer / light-emitting layer.

[0032]

Next, an embodiment of the present invention will be described with reference to the drawings.

(Example 1) FIGS. 1A to 1E are process diagrams showing one example of a method for manufacturing an organic EL device of the present invention. First, on another glass substrate 1a having a thickness of 1.1 mm, a magnesium-silver (10:
1) 2 was formed into a film using a vacuum evaporation method (a). Then
Using a photolithography method, a predetermined pattern was formed as a stripe-shaped electrode. next,
OMR-83 (manufactured by Tokyo Koka) is formed as a photoresist on the cathode by spin coating, and then, using photolithography, a resist width of 100 μm and a height of 2700 ° are formed between the cathodes along the cathode pattern. (Spacer) 3 was formed. At this time, Tg was adjusted to 200 ° C. or higher by adjusting the post-baking temperature. Next, using a vacuum evaporation method, 50
0 ° thick aluminum quinolinol complex layer 4a (A
lq) was deposited (b).

Next, a 1600 ° -thick ITO5 film was formed as an anode on a 1.1 mm-thick glass substrate 1b by sputtering (c), and then hole transport was performed by spin-coating. Polyvinyl carbazole (PVK) 6 having a thickness of 700 ° was formed as a layer (d). The Tg of the PVK used at this time was 160 ° C.

Thereafter, the substrate on which PVK was formed was heated to 180 ° C. in a nitrogen atmosphere, and both laminated plates were opposed to each other with the spacer interposed therebetween. It was bonded by crimping to a plate (e). The distance between the anode and the cathode of the obtained organic EL device was 1100 °. The above steps (a) to (e) are performed using an organic E having a distance between the anode and the cathode of 1100 °.
The L element was produced with good reproducibility. When a DC voltage is applied to the obtained organic EL device, the luminance becomes 2000 cd from Alq.
/ M ² of green light was obtained.

Comparative Example 1 An organic EL device was prepared in the same manner as in Example 1 except that no partition wall (spacer) was provided. The distance between the substrates of the obtained organic EL device was 2300
３3600 °, and a light emitting layer having a uniform thickness could not be obtained. When a DC voltage was applied to the obtained organic EL device, green light emission from Alq was obtained, but this was not uniform light emission. Even if an organic EL device was prepared again by the same method, a light-emitting layer having a uniform thickness could not be obtained.

(Comparative Example 2) An organic EL device was prepared in the same manner as in Example 1, except that the temperature at the time of thermocompression bonding of both laminates was 100 ° C. The obtained device emitted green light with a luminance of 200 cd / m ² from Alq. This emission was not uniform.

(Example 2) On another glass substrate having a thickness of 1.1 mm, a magnesium film having a thickness of 1000 mm was formed as a cathode.
After silver (10: 1) was formed by a vacuum evaporation method, the film was patterned into a predetermined stripe pattern by a photolithography method. Next, OMR-83 (manufactured by Tokyo Kagaku) is formed as a photoresist by spin coating, and a barrier having a resist width of 100 μm and a height of 2700 ° is formed between the cathodes along the cathode pattern using photolithography. Formed. Next, an aluminum quinolinol complex (Alq) having a thickness of 500 ° was deposited as an electron transporting light emitting layer using a vacuum evaporation method, and 30 wt% TP was further formed thereon using a spin coating method.
D (hole transport material) and 5 wt% styrylpyridinium (sensitizer) were dispersed.

Next, a 1600-mm thick ITO film is formed as an anode on a 1.1-mm-thick glass substrate by sputtering, and then patterned into a predetermined stripe-like pattern by photolithography. did. Then, using a spin coating method, 30 wt% of TPD (hole transport material) having a thickness of 300 ° and 5 wt.
A film of polyvinyl cinnamate (photocrosslinkable photopolymer) in which styrylpyridinium (sensitizer) was dispersed in wt% was formed.

Then, under a nitrogen atmosphere, both laminates were thermocompression-bonded at room temperature with the above-mentioned partition wall sandwiched therebetween, and exposed to light of 340 nm for 2 minutes to produce an organic EL device. The distance between the anode and the cathode of the obtained organic EL device was 1100 °. The above-mentioned steps (a) to (e) are performed by an organic EL having an anode-cathode distance of 1100 °
The device was produced with good reproducibility. In the obtained organic EL device,
When a DC voltage is applied, the luminance is changed from Alq to 500 cd / m ^2.
Green light was obtained.

Comparative Example 3 An organic EL device was formed in the same manner as in Example 2 except that polymethyl acrylate (PMMA) was used instead of polyvinyl cinnamate.
The obtained organic EL element was peeled off immediately because of low adhesion between the two laminates.

(Example 3) On another glass substrate having a thickness of 1.1 mm, a magnesium film having a thickness of 1000 mm was formed as a cathode.
After silver (10: 1) was formed by a vacuum evaporation method, the film was patterned into a predetermined stripe pattern by a photolithography method. Next, OMR-83 (manufactured by Tokyo Kagaku) is formed as a photoresist by spin coating, and a barrier having a resist width of 100 μm and a height of 2700 ° is formed between the cathodes along the cathode pattern using photolithography. Formed. Next, using a vacuum deposition method, a 500- [mu] thick aluminum quinolinol complex (Alq) is deposited, and a 300 [deg.]-Thick TP is deposited thereon.
D, a co-evaporated film of paraphenylenediamine and a biphenyl epoxy compound was laminated.

Next, a 1600-mm thick ITO film is formed as an anode on a 1.1-mm-thick glass substrate by sputtering, and then patterned into a predetermined stripe pattern by photolithography. did. Next, a co-evaporated film of TPD, paraphenylenediamine, and biphenyl epoxy compound having a thickness of 300 ° was laminated by an evaporation method.

Thereafter, under a nitrogen atmosphere, both laminates were thermocompression-bonded at 150 ° C. with the above-mentioned partition wall sandwiched therebetween to obtain an organic EL device. The distance between the anode and the cathode of the obtained organic EL device was 1100 °. Organic E obtained
When a DC voltage is applied to the L element, the luminance becomes 500 from Alq.
Green light emission of cd / m ² was obtained. Comparative Example 4 An organic EL device was formed in the same manner as in Example 3 except that no paraphenylenediamine and biphenyl epoxy compound were used. The obtained organic EL element was peeled off immediately because of low adhesion between the two laminates.

(Example 4) On another glass substrate having a thickness of 1.1 mm, a magnesium film having a thickness of 1000 mm was formed as a cathode.
After silver (10: 1) was formed by a vacuum evaporation method, the film was patterned into a predetermined stripe pattern by a photolithography method. Next, OMR-83 (manufactured by Tokyo Kagaku) is formed as a photoresist by spin coating, and a barrier having a resist width of 100 μm and a height of 2700 ° is formed between the cathodes along the cathode pattern using photolithography. Formed. Next, using a vacuum deposition method, a 500-mm-thick aluminum quinolinol complex (Alq) was deposited, and a 300-mm-thick 40 wt% biphenyl epoxy compound-dispersed PV was further deposited thereon.
K was laminated.

Next, a 1600-mm thick ITO film is formed as an anode on a 1.1-mm-thick glass substrate by sputtering, and then patterned by photolithography into a predetermined stripe pattern. did. Next, a PVK film having a thickness of 3000 mm and 40 wt% of paraphenylenediamine dispersed therein was formed.

Thereafter, under a nitrogen atmosphere, both laminates were thermocompression-bonded at 180 ° C. with the above-mentioned partition wall sandwiched therebetween, and the laminate was exposed to light of 340 nm for 2 minutes to produce an organic EL device. The distance between the anode and the cathode of the obtained organic EL device was 1100 °. When a DC voltage is applied to the obtained organic EL device, a luminance of 500 cd /
A green emission of m ² was obtained.

[0048]

According to the present invention, since the substrate on which the electrodes are formed is brought into close contact with the spacer and the organic layer, the film of the organic layer containing the luminescent material can be formed by selecting the size of the spacer. The thickness can be adjusted to a desired thickness. Since there is no step of forming a metal electrode after forming the organic layer, an organic EL element having stable light emission quality is provided without damaging the organic layer.

[Brief description of the drawings]

FIG. 1 is a sectional view of an organic EL device of the present invention.

FIG. 2 is a diagram illustrating a method for manufacturing an organic EL device of the present invention.

[Explanation of symbols]

 1a, 1b Electrode substrate 2 Cathode 3 Spacer 4 Organic layer 5 Anode

Claims (9)

[Claims] 1. An organic electroluminescence device comprising an organic layer containing an organic material, wherein: a first substrate on which a cathode is formed; a second substrate on which an anode is formed; at least one of the first and second substrates A spacer disposed on one of the spacers, each of the spacers having a bottom area in contact with a substrate on which it is disposed and a top area opposite the bottom area; and at least one of the cathode and the anode. An organic layer containing an organic material formed on the first substrate and the second substrate, wherein the first substrate and the second substrate are adhered to each other with the spacer and the organic layer interposed therebetween. 2. A method for manufacturing an organic electroluminescence device including an organic layer containing an organic material, comprising: forming a cathode on a first substrate; forming an anode on a second substrate; Disposing a spacer on at least one of the first and second substrates, each of the spacers having a bottom area in contact with the substrate on which it is disposed and a top area opposite the bottom area. ;
Forming an organic layer containing an organic material on at least one of the cathode and the anode; and the first substrate and the second
And a step of sandwiching and closely adhering the spacer and the organic layer. 3. The method according to claim 2, wherein the spacer is disposed around the organic layer or at the periphery of the substrate. 4. The method according to claim 2, wherein said contacting step is performed by thermocompression bonding. 5. The method of claim 1, wherein at least one of the organic layers includes a crosslinkable or polymerizable material near a surface thereof, and the step of bonding includes crosslinking or polymerizing the crosslinkable or polymerizable material with light or heat. The method of claim 4. 6. The thermocompression bonding is performed at a temperature lower than a melting point or a glass transition temperature of a material of the spacer and higher than a melting point or a glass transition temperature of a material near a surface of the organic layer. The method described in. 7. The method according to claim 2, wherein the step of disposing the spacer is performed using a photolithography method. 8. The method of claim 2, wherein the bottom area of the spacer is greater than the top area. 9. The method of claim 2, wherein one of said first and second substrates comprises a TFT element.