JPH11329751A - Manufacture of organic light emitting element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method capable of manufacturing, with a simple process, an organic light emitting element which can uniformly and stably emit light throughout each picture element region interposed between a first electrode and a second electrode and of which second electrode is hardly damaged. SOLUTION: This manufacturing method for an organic light emitting element wherein an organic electroluminescent layer 7 is formed between first electrodes 2 and second electrodes 6 forms the first electrodes 2 on the main surface of a board, and thereafter forms an insulation layer 8 on the first electrodes 2 and regions among the first electrodes 2 so as to cover the first electrodes 2 in a manner that makes its surface substantially flat, removes the surface of the insulation layer 8 until the clean surfaces of the first electrodes 2 are exposed to make the surface of the insulation layer 8 flush with the surfaces of the first electrodes 2, and thereafter forms an organic electroluminescent layer 7 and the second electrodes 6 on them.

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 light emitting device using an electroluminescence (EL) phenomenon of an organic substance.

[0002]

2. Description of the Related Art Organic electroluminescent elements and inorganic electroluminescent elements are known as electroluminescent (electroluminescent) elements. In particular, organic electroluminescent elements can be driven at a low voltage. It is being used as.

FIG. 4 is a sectional view showing a display using an organic electroluminescent device. A plurality of strip-shaped transparent electrodes 2 extending in a direction perpendicular to the paper surface of FIG. 4 are formed on the glass substrate 1 so as to be parallel to each other. This transparent electrode 2 becomes the first electrode. Substrate 1 including transparent electrode 2
The organic electroluminescent layer 7 is formed on the entire surface of the substrate.
On the organic electroluminescent layer 7, a plurality of strip-shaped second electrodes, ie, rear electrodes 6, are formed so as to cross the transparent electrodes 2. One EL cell is formed by being sandwiched between the transparent electrode 2 and the back electrode 6, and this constitutes one pixel.

[0004] The organic electroluminescent layer 7 is constituted by sequentially laminating an organic hole injecting and transporting layer, a light emitting layer, and an organic electron injecting and transporting layer. Since the thickness of the organic electroluminescent layer 7 is not so large as compared with the thickness of the transparent electrode 2, the organic electroluminescent layer 7 sandwiched between the back electrode 6 and the edge of the transparent electrode 2 as shown in FIG. , That is, the thickness of the portion shown as N in FIG. 4 is reduced. Particularly, when the organic electroluminescent layer 7 is formed by laminating by a dry process such as a vacuum deposition method, the organic electroluminescent layer 7 is formed along the unevenness of the transparent electrode 2, so that the thickness of the N portion is reduced. In the portion M at the center of the transparent electrode 2, the thickness of the organic electroluminescent layer 7 is large and the resistance is large. As a result, a larger current flows in the thin portion N in the pixel region than in the thick portion M. Therefore, the N portion of the organic electroluminescent layer 7 emits light brightly, the light emission becomes non-uniform, and the withstand voltage decreases.

Further, as shown in FIG. 4, since the surface of the back electrode 6 also has irregularities, the projection of the back electrode 6 may be damaged or the back electrode 6 may be cracked.
As a method of solving such a problem, a method of forming an organic electroluminescent layer on a flat surface in which electrodes are embedded can be considered. JP-A-57-185607 discloses a method of forming a pattern electrode having a flat surface.

FIG. 5 is a cross-sectional view showing a manufacturing process of the pattern electrode disclosed in the publication. As shown in FIG. 5A, a transparent electrode 2 is formed on a glass substrate 1. next,
As shown in FIG. 5B, a patterned photoresist 9 is formed on the transparent electrode 2, and as shown in FIG. 5C, the photoresist 9 is masked by a wet process using an etchant. Then, the transparent electrode 2 is patterned by etching.

Next, as shown in FIG. 5D, an insulating layer 8 is applied to the glass substrate 1 on the transparent electrode 2 and other areas.
On top of. The thickness of the insulator layer 8 is formed to be substantially the same as the thickness of the transparent electrode 2.

According to the publication, a photoresist 9 is introduced by infiltrating a stripping solution or by plasma etching or the like.
By removing the insulator layer 8 on the substrate together with the photoresist 9, a pattern electrode having a flat surface as shown in FIG. 5E can be formed.

[0009]

However, in practice, it is considered impossible to remove the insulator layer 8 on the photoresist 9 together with the photoresist 9 by plasma etching for the following reasons.

That is, a photoresist 9 and an insulating layer 8 are laminated on the transparent electrode 2, and the total thickness thereof is equal to the thickness of the insulating layer 8 on the glass substrate 1 on which the transparent electrode 2 is not provided. It becomes thicker than the thickness. Therefore, if both the insulating layer 8 and the photoresist 9 on the transparent electrode 2 are removed by plasma etching, the insulating layer 8 on the glass substrate 1 on which the transparent electrode 2 is not provided is also removed. FIG.
A pattern electrode having a flat surface as shown in (e) cannot be formed.

Therefore, in order to remove the insulating layer 8 and the photoresist 9 on the transparent electrode 2, it is necessary to use a stripper. When a stripping solution is used, a trace amount of impurities easily remains on the surface of the transparent electrode 2. When an organic charge injecting and transporting layer is formed thereon, charge injection from the transparent electrode to the organic charge injecting and transporting layer is caused by the impurities. There is a problem that the characteristics are hindered and the characteristics are deteriorated. Examples of such impurities include a high molecular weight component contained in the photoresist, moisture and other impurities contained in the stripping solution, and these impurities are physically and / or chemically adsorbed on the surface of the transparent electrode. Is done.

Therefore, in the method disclosed in the above publication,
After forming a flat pattern electrode using a stripping solution, it is necessary to provide a process for removing a small amount of impurities on the surface of the transparent electrode, the manufacturing process of the organic light emitting device becomes complicated,
There was a problem that the cost also increased.

An object of the present invention is to provide an organic light emitting device that can uniformly and stably emit light over the entire region of a pixel sandwiched between a first electrode and a second electrode, and in which the second electrode is hardly damaged. An object of the present invention is to provide a manufacturing method capable of manufacturing an element by a simple process.

[0014]

According to the manufacturing method of the present invention, a plurality of strip-shaped first electrodes are formed on a main surface of a substrate at a distance from each other, and the first electrodes are formed so as to cover the first electrodes. Forming an insulator layer on the surface of the first electrode and the region between the first electrodes so that the surface thereof is substantially flat, and removing the surface of the insulator layer until a clean surface of the first electrode is exposed. Removing, making the surface of the insulator layer coincide with the surface of the first electrode; forming the organic electroluminescent layer on the insulator layer after the removal and the exposed first electrode; Forming a second electrode on the substrate.

In the present invention, the insulator layer is preferably formed from an insulating polymer. As the insulating polymer, a substance which becomes fluid when heated is preferable, and a thermoplastic resin, a thermosetting resin, and a photocurable resin are preferably used. After the organic light-emitting device is manufactured by forming the insulator layer from an insulating polymer, compared to the case of using a low-molecular substance, the insulator layer has less change with time and has a long life. be able to.

As a method of forming an insulating layer made of an insulating polymer, a liquid in which the insulating polymer is melted is applied so as to cover the first electrode, and then the solid is cooled and solidified. A method for forming a layer is given. Specifically, an insulating layer can be formed by casting a liquid obtained by melting a polymer on the first electrode so as to cover the first electrode so as to cover the first electrode.

As another method for forming an insulating layer using an insulating polymer, a solution obtained by dissolving a polymer in a solvent is used.
After casting on the first electrode, the solvent is removed to form an insulator layer.

In the present invention, the refractive index of the insulating layer is
It is preferable that a material forming the insulator layer be selected so that the refractive index is smaller than the refractive index of the transparent electrode. For example, IT
When the transparent electrode formed of O has a refractive index of 1.9, it is preferable to form the insulator layer from a substance having a refractive index of less than 1.9. The refractive index of the insulator layer is preferably 3% or less, more preferably 10% or less, even more preferably 15% or more less than the refractive index of the transparent electrode.

By making the refractive index of the insulating layer smaller than the refractive index of the first electrode, the efficiency with which light emitted from the light emitting layer is guided to the first electrode is improved. In addition, light guided to the first electrode is emitted through the substrate without leaking to the insulating layer, so that light extraction efficiency is improved and an organic light-emitting element with low power consumption can be obtained. .

In the present invention, the step of removing the insulator layer is preferably performed by etching by irradiation with ultraviolet rays in an atmosphere containing oxygen. In such etching, insulators and impurities adhering or adsorbing to the surface of the first electrode can be photo-excited by irradiation with ultraviolet rays, and can be oxidatively decomposed by reacting with oxygen. Therefore, the surface of the first electrode can be made very clean.

It is preferable that the atmosphere at the time of performing the etching by the ultraviolet irradiation or the dry etching such as the plasma etching has an ozone concentration of 0.01 g / m ³ or more. With such an ozone concentration,
Oxidative decomposition of insulators and impurities attached or adsorbed to the surface of the first electrode can be promoted, and the surface of the first electrode can be cleaned at a high speed.

The smaller the difference between the ionization potential of the material of the layer constituting the organic electroluminescent layer (for example, the organic hole injecting and transporting layer) and the ionization potential of the first electrode, the smaller the distance from the first electrode. The fact that it is easy to inject carriers into a layer in the organic electroluminescent layer that is in direct contact with the first electrode is presumed from a general theory of electron transfer between substances. Therefore, the first electrode is etched so that the difference from the ionization potential of the layer in the organic electroluminescent layer directly in contact with the first electrode is reduced, so that the surface of the first electrode is directly in contact with the first electrode. A state suitable for injecting carriers into a layer in the organic electroluminescent layer in contact with the organic light emitting layer can be obtained, and an organic light emitting element having a low driving voltage can be obtained. The difference between the ionization potential of the material of the layer constituting the organic electroluminescent layer such as the organic hole injection / transport layer directly in contact with the first electrode and the ionization potential of the first electrode is preferably 0.3 electron volts or less. , 0.2 electron volts or less.

The etching is preferably performed so that the absolute value of the ionization potential of the first electrode is 4.7 electron volts or more, and more preferably 4.8 electron volts or more. More preferred. The absolute value of the ionization potential of the first electrode is a value when the value of the vacuum order is set to 0 as a reference value.

In the present invention, the insulating layer may be removed by plasma etching. The organic electroluminescent layer in the present invention includes, for example, a light emitting layer, and an organic hole injection / transport layer and / or an organic electron injection / transport layer. Specifically, a three-layer structure in which an organic hole injecting and transporting layer, a light emitting layer, and an organic electron injecting and transporting layer are stacked, a two-layer structure including an organic hole injecting and transporting layer and a light emitting layer, and a light emitting layer 2 consisting of an organic electron injection / transport layer
Those having a layer structure are exemplified. Further, it may have a multilayer structure of four or more layers.

The organic light emitting device of the present invention can employ various known driving methods. For example, a simple matrix system or an active matrix system using TFTs may be used.

In the case of a simple matrix type organic light-emitting device, the first electrode formed on the substrate is formed as a plurality of strip-shaped electrodes. Further, the second electrode is formed to be a plurality of strip-shaped electrodes extending in a direction substantially perpendicular to the first electrode. In this case, after the step of matching the surface of the insulator layer with the surface of the first electrode, a plurality of layers are formed on the substrate with the first electrode exposed according to a known method disclosed in Japanese Patent Application Laid-Open No. 8-315981. May be formed so as to extend in a direction substantially perpendicular to the first electrode, and then the organic electroluminescent layer and the second electrode may be sequentially formed.

In the case of the TFT active matrix system, a first electrode is formed on a substrate on which a thin film transistor (TFT) is formed. In this case, the first electrode may be a drain electrode or a source electrode of the thin film transistor, or may be an electrode connected to the drain electrode or the source electrode. Further, according to a known method, TF
A planarized interlayer insulating film is arranged between T and the first electrode, and the first electrode is electrically connected to a drain electrode or a source electrode of the TFT via a contact hole provided in the interlayer insulating film. It may be configured to do so.

[0028]

FIG. 1 is a sectional view showing a manufacturing process of an organic light emitting device according to a first embodiment of the present invention. Referring to FIG. 1A, a plurality of strip-shaped transparent electrodes 2 are formed by patterning in parallel on a glass substrate 1 which is an insulating substrate. The transparent electrode 2 extends in a direction perpendicular to the paper surface. The thickness of the transparent electrode 2 is, for example, 200 n
m, which can be changed in the range of 80 nm to 2 μm,
Preferably, it can be changed in the range of 100 nm to 1 μm.

In this embodiment, the transparent electrode 2 is formed using indium tin oxide (ITO). As the patterning method, a wet etching method using a hydrochloric acid aqueous solution containing FeCl ₃ can be used, and another known method may be used.

Next, referring to FIG.
An insulating layer 8 is formed on the entire surface of the glass substrate 1 including
You. The density of the insulator layer 8 at 25 ° C. is 0.915 g.
/ Cm ^ThreeMelting point 115 ° C having a long-chain branched molecular structure
From low density polyethylene. Low density polyethylene
Density at 25 ° C. is 0.90 g / cm^Three~ 0.
93g / cm^ThreeMay be changed in the range of. The melting point is
The temperature may be changed in the range of 107 ° C to 120 ° C. This low density
Polyethylene is melted at 190 ° C and the resulting melt is
The insulating layer 8 is formed by casting.
The temperature at which polyethylene is melted is 110 ° C. to 320 ° C.
Can be changed in the range of, preferably 150 ° C. ~ 2
It can be changed in the range of 30 ° C., more preferably
It can be changed in the range of 170 ° C to 210 ° C.

As shown in FIG. 1B, the thickness of the insulator layer 8 in a region between the adjacent transparent electrodes 2 is D.
In this embodiment, the thickness D is, for example, 1 μm. D can be set in a range exceeding the thickness d of the transparent electrode 2, can be preferably changed in a range of 1.1d to 4d, and more preferably be changed in a range of 1.5d to 3.0d. And most preferably can be changed in the range of 2.4d to 2.6d.

It is preferable that the temperature of the glass substrate 1 at the time of the casting be about 60 ° C. so that polyethylene does not rapidly solidify. The temperature of the glass substrate 1 can be changed in a range of 0 ° C. to 105 ° C., and preferably in a range of 40 ° C. to 80 ° C.

In casting, it is preferable to rotate the glass substrate 1 and to use a centrifugal force so that the thickness of the insulating layer 8 does not become uneven. In addition, the surface of the insulator layer 8 can be made flatter by such rotation.

By performing the casting as described above, the surface tension of the molten liquid of polyethylene acts, and the surface of the insulator layer 8 is naturally formed as a flat surface. The thickness of the insulator layer 8 in the portion on the transparent electrode 2 is (D−
d).

Insulator layer 8 formed using polyethylene
The refractive index of the Fraunhofer line having a wavelength of 589 nm at 20 ° C. with respect to the D line was 1.51. In addition,
Similarly, the refractive index shown below is the refractive index for a wavelength of 589 nm at 20 ° C.

Next, as shown in FIG. 1C, the entire surface of the insulator layer 8 is etched by irradiating it with ultraviolet rays in an atmosphere containing oxygen. This etching is performed until a clean surface of the transparent electrode 2 is exposed. By this etching, the surface of the insulator layer 8 and the surface of the transparent electrode 2 come to coincide. By this etching, the thickness of the insulating layer 8 in a region other than the region where the transparent electrode 2 is provided becomes d, which is the same as the thickness of the transparent electrode 2.

At the time of the above etching, the temperature of the glass substrate 1 was set to 60 ° C. The temperature of the glass substrate 1 is 0 ° C. to 105
° C, preferably between 40 ° C and 8 ° C.
It can be changed in the range of 0 ° C. The etching was performed in an oxygen atmosphere containing ozone (O ₃ ). This oxygen atmosphere was supplied to a surface discharge type ozone generator at a constant flow rate such that pure oxygen was supplied at a flow rate of 3 liters per minute. Obtained by feeding. Also, the ultraviolet light is input power 3
Two low-pressure mercury lamps of 00W are used as light sources, and the wavelength is 185n.
Ultraviolet light having a main peak component at m and a wavelength of 254 nm was irradiated.

The time required until the clean surface of the transparent electrode 2 was exposed was about 15 minutes. At this time, the distance between the lamp tube wall and the top of the substrate surface was 5 mm,
The distance can be set arbitrarily as long as ultraviolet light with sufficient intensity is obtained on the substrate surface.

In this embodiment, the ozone concentration in the vicinity of the insulator layer 8 is 9.8 g / m ³ , but the ozone concentration is 0.01 g / m ^3.
If it is at least / m ³ , the effect of promoting the oxidative decomposition of insulators and impurities by adding ozone can be expected. The concentration is preferably 0.1 g / m ³ or more, more preferably 1 g / m ³ or more, and particularly preferably 5 g / m ³ or more.
g / m ³ or more.

Next, the organic electroluminescent layer 7 was subsequently formed without performing the step of cleaning the exposed portion of the transparent electrode 2. On the organic electroluminescent layer 7, a plurality of strip-shaped electrodes are formed in parallel with the back electrode 6 in a direction crossing the transparent electrode 2. The back electrode 6 was formed by a vacuum deposition method.

FIG. 2 is a cross-sectional view taken along the line AA shown in FIG. As shown in FIG. 2, the organic electroluminescent layer 7
Is formed by sequentially laminating an organic hole injection / transport layer 3, a light emitting layer 4, and an organic electron injection / transport layer 5.

The transparent electrode 2 is made of ITO, tin oxide (Sn
O ₂ ), gold (Au) or the like, but in this embodiment, it is made of ITO. The organic hole injection / transport layer 3 is composed of a triphenylamine derivative,
4 ', 4 "-tris (3-methylphenyl
phenylamino) triphenylamine
e (commonly called “MTDA”). The thickness of the organic hole injecting and transporting layer 3 is 70 nm in the present embodiment, but can be changed within a range of, for example, 10 nm to 80 nm.

The light emitting layer 4 is made of N, N'-Diphenyl.
-N, N'-dibenzyl [1,1'-biphe
nyl] -4,4'-diamine (commonly called "TP
D ") as the main component and 5,6,11,12-T
It can be formed from those containing 5% by weight of ethraphenylnapthacene (commonly referred to as “Rubrene”). The weight ratio of Rubrene can be changed in the range of 0.5% to 15%, and further, it can be changed in the range of 2% to 6%. Light emitting layer 4
Is 20 nm in the present embodiment, for example, 5 nm.
It can be changed in the range of nm to 45 nm.

The organic electron injecting and transporting layer 5 is made of Aluminum
um tris (quinoline-8-olat
e) (commonly called “Alq ₃ ”). The thickness of the organic electron injecting and transporting layer 5 is 60 nm in this embodiment, but can be changed in a range of, for example, 10 nm to 80 nm.

The back electrode 6 is composed of Mg and In in a weight ratio of 9: 9.
It is formed from an alloy co-deposited at a ratio of 1. Back electrode 6
Is 200 nm in the present embodiment, but can be changed in the range of, for example, 50 nm to 500 nm. The content of In is 0.01% to 9% by weight.
It can be changed in the range of 5%, preferably 1% to 7%.
It can be changed in the range of 5%, more preferably in the range of 5% to 25%.

The overall thickness of the organic electroluminescent layer 7 composed of the organic hole injecting and transporting layer 3, the light emitting layer 4, and the organic electron injecting and transporting layer 5 can be changed, for example, in the range of 25 nm to 205 nm.

To drive the above-mentioned organic light emitting display device, a voltage of about 5 to 20 V may be applied between electrodes corresponding to arbitrary pixels. The electrons injected into the light-emitting layer 4 recombine with the holes injected from the organic hole injection / transport layer 3 into the light-emitting layer 4 in the light-emitting layer 4 to emit light.

In the organic electroluminescent display device of the present embodiment, as shown in FIG. 1C, the surface of the transparent electrode 2 and the surface of the insulator layer 8 coincide with each other. Even when the light emitting layer 7 and the back electrode 6 are stacked, the surfaces of the organic electroluminescent layer 7 and the back electrode 6 are flat and do not have an uneven shape. Therefore, the thickness of the organic electroluminescent layer 7 can be made uniform overall. Therefore, when the organic light emitting element is driven, uniform light emission corresponding to the electrode shape can be obtained. Further, since the surface of the back electrode 6 is flat, it is not damaged.

Next, the light emitting characteristics of the organic light emitting device manufactured as described above were evaluated. Evaluation of an organic light-emitting element for an experiment in which the width of the transparent electrode 2 and the width of the back electrode 6 formed so as to intersect with the transparent electrode 2 were each 2 mm, and the area of the light-emitting portion per pixel was 4 mm ^2. did. As a result, when the applied voltage is 3 V, the luminance is 0.6 c.
A green light emission of d / m ² was obtained.

As the applied voltage increases, the luminance also increases. When 5 V is applied, the luminance becomes 80 cd / m ^{2 and the} luminance becomes 10 cd / m ² .
Luminance 5000 cd / m ² becomes the time of the application, was the luminance 54000cd / m ² at the time of 15V is applied.

When the spectrum of the green light emission was analyzed, it coincided with the fluorescence maximum wavelength of Rubrene contained in the light-emitting layer 4 and had a maximum light emission peak at a wavelength of 562 nm. Therefore, the light emission was based on the excited state of Rubrene. Conceivable.

From the initial luminance of 500 cd / m ² , a continuous light emission test was performed by continuously applying a DC voltage to a constant current density of about 5 mA / cm ² using a DC constant current power supply. The luminance half-life, which is the time required for the luminance to decrease by half to reach 250 cd / m ² , was 1300 hours.

When the step shown in FIG. 1C was completed, the ionization potential of the surface of the transparent electrode 2 was measured. As a result, when the vacuum order is set to the reference value of 0,
A measurement of 4.83 electron volts was obtained. The measurement of the ionization potential was performed at room temperature of about 20 ° C. and the amount of ultraviolet light based on the principle of a low-energy electron counting method by irradiating ultraviolet light in the atmosphere using a Riken AC-1 measuring device manufactured by Riken Keiki Co., Ltd. The measurement was performed under the conditions of 650 nW and a counting time of 5 seconds.

MT constituting the organic hole injection / transport layer 3
The ionization potential of DATA was measured. As a sample, a powder of MTDATA that had been purified by sublimation in advance was used, and the ionization potential was measured in the same manner as described above. As a result, a measured value of 5.0 eV was obtained.

According to the widely accepted theory of electron transfer, it is known that charge transfer between two adjacent layers occurs more easily as the difference between the energy levels of the respective layers is smaller. .

Since the value of the ionization potential is an index directly indicating the energy level of the highest occupied electron orbital of the substance, in the organic light emitting device of the above embodiment,
The energy level difference between the transparent electrode 2 and the organic hole injection / transport layer 3 is (5.0-4.83) electron volts, that is, 0.2 electron volts or less, which is a very small value. Accordingly, holes are injected from the transparent electrode 2 into the organic hole injection / transport layer 3 very efficiently, and relatively bright light emission with a luminance of 0.6 cd / m ² is obtained even at a low applied voltage of 3 V. Probably obtained.

In the first embodiment, the insulating layer
Removal process by ultraviolet irradiation in an oxygen atmosphere
Performed by etching, but instead in an oxygen atmosphere
Example in which insulator layer was removed by plasma etching
Is shown. The temperature of the glass substrate 1 and the chamber is 20 ° C.
And reduce the pressure in the chamber to 0.4 mPa once.
After that, the flow rate is 3.5 SCCM, that is, in the standard state.
3.5cm per minute flow rate ^ThreeWhile introducing pure oxygen
The pressure in the chamber is maintained at 0.5 Pa,
Generates oxygen plasma with a power of 200 W
Ma etching was performed. Until the surface of the transparent electrode 2 is exposed
Took about 2 hours.

In the subsequent steps, an organic light emitting device was prepared in the same manner as in the first embodiment. When the characteristics of the obtained organic light-emitting device were evaluated, no light emission was observed when the applied voltage was 3 V, green light emission having a luminance of 7 cd / m ² was obtained when 5 V was applied, and 3000 cd / m ² when 10 V was applied.
m ² , and a short circuit occurred when a voltage of 15 V was applied, and the element was destroyed.

From the initial luminance of 500 cd / m ² , a continuous light emission test was performed by continuously applying a DC voltage. As a result, the luminance half life was about 600 hours. When the removal of the insulator layer by plasma etching was completed and the state as shown in FIG. 1C was reached, the ionization potential of the surface of the transparent electrode 2 was measured. As a result, a measured value of 4.64 electron volts was obtained as a value when the vacuum rank was set to 0 as a reference value.

The reason why the light emitting device of the embodiment using the above plasma etching could not obtain superior characteristics as compared with the light emitting device of the embodiment using the etching by irradiation of ultraviolet rays, was that the surface of the transparent electrode was sufficiently cleaned. Probably because it was not. That is, the difference in energy level between the surface of the transparent electrode and the organic hole injection / transport layer is (5.0-
4.64) Electron volts, that is, about 0.4 electron volts, which is a large value compared to the case of the first embodiment. Therefore, the efficiency of hole injection from the transparent electrode to the organic hole injection transport layer is reduced,
It is probable that good characteristics were not obtained.

FIG. 3 is a sectional view showing an organic light emitting device according to a second embodiment of the present invention. In this embodiment, the substrate 1a on which the thin film transistor 1b is formed is used. The first electrode 2a is formed on the projection of the substrate 1a. The first electrode 2a is a drain electrode or a source electrode of the thin film transistor 1b, or an electrode connected to the drain electrode or the source electrode.

As in the first embodiment shown in FIG.
After the insulating layer 8 is formed so as to cover the electrode 2a, the surface of the insulating layer 8 is removed by etching with ultraviolet light in an oxygen atmosphere until the surface of the first electrode 2a is exposed. 7 and the back electrode 6 are formed by lamination.

The structure and forming method of the thin film transistor are as follows.
There is no particular limitation.
No. 836 and JP-A-8-234683 can be used. In particular, a bottom-gate thin film transistor using a polycrystalline silicon thin film is preferably used.

As a material for forming the insulating layer 8, low-density polyethylene is used in the above embodiment, but the material is not limited to this. If the insulating layer 8 is a thermoplastic or fusible insulating material, Can be used.

When the insulating material is melted to form the insulating layer 8 by casting, the temperature of the material constituting the insulating layer 8 at the time of casting is set so that appropriate fluidity can be obtained and the substrate and the first electrode can be heated. Any temperature may be used as long as the thermal adverse effect of the above can be avoided. Preferred specific examples of the substance constituting the insulating layer are shown in parentheses with a suitable range of the temperature of the substance at the time of casting.

Polyolefins (140 ° C. to 320 ° C.) such as polypropylene (190 ° C. to 290 ° C.) and polybutylene (140 ° C. to 190 ° C.), methylpentene resin (27
0 ° C to 320 ° C), EVA resin (180 ° C to 220 ° C)
° C), AS resin (180 ° C to 290 ° C), ABS resin (190 ° C to 270 ° C), methyl methacrylate-styrene copolymer (170 ° C to 260 ° C), polystyrene (1
Polyarene such as 80 ° C to 270 ° C), polyethylene terephthalate (270 ° C to 320 ° C), polyester (220 ° C to 410 ° C), polymethyl methacrylate (1
60 ° C to 260 ° C), polycarbonate (280 ° C to 3 ° C)
00 ° C), polyacetal (180 ° C to 240 ° C), polyphenylene ether (220 ° C to 350 ° C), polyetherketone, polyallyletherketone (380 ° C to
430 ° C), polyetheretherketone (350 ° C ~
400 ° C), thermoplastic polyimide (340 ° C to 425
C), polyacrylonitrile (180-210 C),
Polyamide imide (320 ° C. to 370 ° C.), polyether imide (340 ° C. to 430 ° C.), polyamide (230
C. to 300 C.), polyurethane (220 C. to 270 C.)
℃), fluorine resin such as polychlorotrifluoroethylene and polyvinylidene fluoride (180 ℃ ~ 310
° C), polyvinyl chloride (150 ° C to 210 ° C), polyvinylidene chloride (150 ° C to 200 ° C), chlorinated polyethylene (150 ° C to 200 ° C), polysulfone (330 ° C)
~ 400 ° C), polyether sulfone (310 ° C ~ 40
0 ° C.), polyphenylene sulfide (310 ° C. to 340
° C), silicon resin, polysiloxane, polysiloxanyl methacrylate (170 ° C to 290 ° C).

In order to make the organic light-emitting element have heat resistance, the material constituting the insulator layer 8 must have a melting point of 100.
It is preferable to use one having a temperature of not lower than ° C. Also, the insulator layer 8
It is preferable to use a substance having a small heat shrinkage as a material constituting the above.

In order to improve the light emission efficiency of the organic light emitting device, it is preferable to use a material having a smaller light refractive index than that of the transparent electrode 2 as a material constituting the insulating layer 8.

The refractive index of the transparent electrode made of ITO used in the embodiment of the present invention was 1.9 with respect to the D line having a wavelength of 589 nm. Preferable specific examples of the substance constituting the insulator layer 8 having a small refractive index are shown below, with typical values of the refractive index added in parentheses.

Fluororesin (1.40), polymethyl methacrylate (1.49), polycarbonate (1.5
9), polystyrene (1.59), polysiloxane (1.4 to 1.9).

Next, the manufacture of the organic light emitting device according to the third embodiment of the present invention will be described. An organic light-emitting device was produced in the same manner as in the first embodiment except that the insulating layer 8 was formed using polyvinylidene chloride having a melting point of 155 ° C. instead of polyethylene. The polyvinylidene chloride has a melting point in the range of 150 ° C to 205 ° C.
It is preferable to use a homopolymer of polyvinylidene chloride or a copolymer containing acrylonitrile or the like. The temperature of polyvinylidene chloride during casting is 230 ° C
And The temperature during this casting is, for example, 150
The temperature can be changed in the range of from ℃ to 335 ° C, preferably in the range of from 180 ° C to 300 ° C, and more preferably in the range of from 205 ° C to 265 ° C.

The temperature of the glass substrate 1 during casting was 100 ° C. The temperature of this glass substrate is 0 ° C.
145 ° C., preferably 4 ° C.
The temperature can be changed in the range of 0 ° C to 130 ° C, and more preferably in the range of 70 ° C to 115 ° C. The refractive index of the insulator layer 8 formed using polyvinylidene chloride with respect to the D line at a wavelength of 589 nm was 1.95.

Next, the light emitting characteristics of the organic light emitting device thus obtained were evaluated. The luminance at the time of applying 5 V is 70 cd
/ M ² and the luminance when 10 V is applied is 4500 cd / m
^{Was 2} . Therefore, the luminance was reduced by about 10% as compared with the first embodiment. This is because the refractive index of polyvinylidene chloride is 1.95, which is larger than the refractive index of the transparent electrode made of ITO, which is 1.9. This is presumably because the efficiency of radiation to the outside was reduced, and the ratio of loss due to absorption while repeating reflection inside the polyvinylidene chloride layer was increased. The refractive index of TPD and Alq ₃ constituting the organic electroluminescent layer 7 was 1.7.

In the above embodiment, the insulator layer 8 is formed by melting and casting the material constituting the insulator layer, but the present invention is not limited to this. For example, the insulating layer may be formed by casting a solution in which a substance included in the insulating layer is dissolved using a solvent, and then drying the solvent. In this case, it is preferable to use a solvent that has been carefully purified so as not to contain impurities such as moisture. It is preferable to use a weakly acidic substance as the solvent.

As a preferred specific example of the substance constituting the insulating layer using the solution dissolved in the solvent as described above, EVA is used.
Resin, polystyrene, AS resin, ABS resin, polymethyl methacrylate, polycarbonate, polyphenylene ether, polysulfone, and the like can be given.

[0076]

According to the present invention, the surface of the insulator layer and the first
The organic electroluminescent layer can be formed on the pattern electrode having the same surface as the electrode. Therefore, no unevenness is formed on the organic electroluminescent layer, and the organic electroluminescent layer can be formed with a uniform thickness. Therefore, when driving the organic light emitting element, it is possible to emit light uniformly. In addition, since no irregularities are formed on the surface of the second electrode, the surface of the second electrode is not damaged.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment according to the present invention.

FIG. 2 is a sectional view taken along the line AA shown in FIG.

FIG. 3 is a sectional view showing another embodiment according to the present invention.

FIG. 4 is a sectional view showing a conventional organic light emitting device.

FIG. 5 is a cross-sectional view showing a conventional method for manufacturing a pattern electrode having a flat surface.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Glass substrate 2 ... Transparent electrode 6 ... Back electrode 7 ... Organic electroluminescent layer 8 ... Insulator layer

Claims (22)

[Claims] A step of forming a plurality of first electrodes on a main surface of a substrate at a distance from each other; and forming a plurality of first electrodes on an area between the first electrodes so as to cover the first electrodes. Forming an insulator layer so that the surface thereof is substantially flat; removing the surface of the insulator layer until a clean surface of the first electrode is exposed; A step of matching a surface with a surface of the first electrode; a step of forming an organic electroluminescent layer on the insulator layer after the removal and the exposed first electrode; Forming a second electrode. 2. The method according to claim 1, wherein the insulator layer is formed of a substantially insulating polymer. 3. The method according to claim 2, wherein the substantially insulating polymer is a substance having fluidity in a heated state. 4. The step of forming the insulator layer comprises applying a liquid obtained by melting the substantially insulating polymer so as to cover the first electrode, and cooling and solidifying the liquid. The method for manufacturing an organic light-emitting device according to claim 2, which is a step of forming an object layer. 5. The organic light emitting device according to claim 4, wherein a liquid in which the substantially insulating polymer is melted is cast on the first electrode so as to cover the first electrode. Manufacturing method. 6. The insulating layer is formed by casting a solution obtained by dissolving the substantially insulating polymer with a solvent on the first electrode, and then removing the solvent. 3. The method for producing an organic light-emitting device according to item 1. 7. The organic light emitting device according to claim 1, wherein a material forming the insulator layer is selected such that a refractive index of the insulator layer is smaller than a refractive index of the first electrode. Method. 8. The method according to claim 7, wherein a refractive index of the insulator layer is smaller than a refractive index of the first electrode by 3% or more. 9. The method according to claim 7, wherein the insulator layer is formed of a material having a refractive index of less than 1.9. 10. The method for manufacturing an organic light emitting device according to claim 1, wherein the step of removing the insulator layer is performed by etching by ultraviolet irradiation in an atmosphere containing oxygen. 11. The method for manufacturing an organic light-emitting device according to claim 10, wherein an atmosphere in which the etching is performed has an ozone concentration of 0.01 g / m ³ or more. 12. The method according to claim 10, wherein the etching is performed so that an absolute value of an ionization potential of the first electrode is equal to or more than 4.7 electron volts. 13. The etching according to claim 1, wherein a difference between an ionization potential of a material of a constituent layer of the organic electroluminescent layer in direct contact with the first electrode and an ionization potential of the first electrode is 0.3 electron volts or less. The method for manufacturing an organic light-emitting device according to claim 10, wherein the method is performed. 14. The method according to claim 1, wherein the step of removing the insulator layer is performed by plasma etching. 15. The method for manufacturing an organic light-emitting device according to claim 14, wherein an atmosphere in which the etching is performed has an ozone concentration of 0.01 g / m ³ or more. 16. The method according to claim 14, wherein the etching is performed so that an absolute value of an ionization potential of the first electrode is equal to or more than 4.7 electron volts. 17. The method according to claim 17, wherein a difference between an ionization potential of a material of a constituent layer of the organic electroluminescent layer in direct contact with the first electrode and an ionization potential of the first electrode is 0.3 electron volts or less. The method for manufacturing an organic light emitting device according to claim 14, wherein the method is performed. 18. The method according to claim 1, wherein the organic electroluminescent layer comprises a light emitting layer, and an organic hole injecting and transporting layer and / or an organic electron injecting and transporting layer. 19. The method according to claim 1, wherein the first electrode is a plurality of strip-shaped electrodes. 20. The method according to claim 19, wherein the second electrode is a plurality of strip-shaped electrodes extending in a direction substantially perpendicular to the first electrode. 21. The method according to claim 1, wherein the substrate is a substrate on which a thin film transistor is formed, and the first electrode is a drain electrode or a source electrode of the thin film transistor. 22. The method according to claim 1, wherein the substrate is a substrate on which a thin film transistor is formed, and the first electrode is an electrode connected to a drain electrode or a source electrode of the thin film transistor. .