JP2002313567A - Organic electroluminescence element and its manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an organic EL element of excellent luminescent performance, able of using the luminescence with high efficiency. SOLUTION: In this organic EL element with an ITO electrode 15, a hole transport layer 14, an electron transportable luminescent layer 13, a Ca layer 12 and an Al electrode 11 laminated in this order on a glass substrate 16, the film of the hole transport layer 14 is formed of a PEDOT aqueous solution, and the film of the electron transportable luminescent layer 13 is formed of an MEH-PPV solution. Both films are formed by baking while controlling baking conditions such as a pressure reduced state or a heating temperature after spin-coating the solutions. Crater-like unevenness is thereby formed in the interface of the hole transport layer 14 and electron transportable luminescent layer 13 or the interface of the electron transportable luminescent layer 13 and Ca layer 12 with the evaporation of the solution during baking, and the luminescent area of the interface is enlarged to improve luminous efficiency.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an organic electroluminescent device suitable for use in, for example, a self-luminous thin flat display and the like and a method of manufacturing the same.

[0002]

2. Description of the Related Art Conventionally, a display panel made of an organic light emitting element (EL) has features of high visibility, excellent display capability, and high-speed response.

In recent years, reports have been made on electroluminescent devices using organic compounds as constituent materials (Applied physics).
letters 51 p.913 (1987)). In this report, C.I. W. T
disclose an electroluminescent device having a structure in which an organic light emitting layer and a charge transport layer are stacked.

Here, an excellent electroluminescent device is obtained by using a tris (8-quinolinol) aluminum complex (hereinafter referred to as Alq ₃ ) having both high luminous efficiency and electron transport as a luminescent material. In addition, a coumarin derivative or DCM1 (Eastman chemi) is added to Alq ₃ forming an organic light emitting layer.
cals), and reported that the emission color was changed by appropriate selection of the dye, and that the luminous efficiency was higher than that of the undoped one. (Journal of Applied physics, 65, p.3610 (198
9)).

Following this research, much research and development has been carried out. As a new functional material, a chelate metal complex having a fluorescent property, an organic molecule having an electron transporting property and an organic molecule having a hole transporting property have been developed. Various investigations have been made toward this.

FIG. 11 shows an example of a conventional organic electroluminescent device.

The organic electroluminescent device 10 includes an ITO (Indium Tin Oxide) transparent electrode 5 on a transparent glass substrate 6.
Hole transport layer 4, light emitting layer 3, electron transport layer 2, and cathode 1
Are sequentially formed by, for example, a vacuum evaporation method.

In this organic electroluminescent device 10, when a DC voltage 8 is applied between the ITO transparent electrode 5 serving as the anode and the cathode 1, holes (holes) as carriers injected from the ITO transparent electrode 5 become holes. On the other hand, electrons injected from the cathode 1 move through the electron transport layer 2 via the transport layer 4, and recombination of the electron-hole pairs occurs in the light-emitting layer 3, from which light emission 9 of a predetermined wavelength occurs. Occurs, which can be observed from the transparent glass substrate 6 side.

FIG. 12 shows another conventional organic electroluminescent device. In this organic electroluminescent device 10A, the electron transport layer 2 also serves as a light emitting layer.

FIG. 13 shows the organic electroluminescent device 10 of FIG.
1 shows a configuration example of a flat panel display using A.

As shown in the figure, an organic laminated structure including an electron transport layer 2 and a hole transport layer 4 is disposed between a cathode 1 and an anode 5. The cathode 1 and the anode 5 are provided in a stripe shape crossing each other, and selected by a luminance signal circuit 34 and a control circuit 35 with a built-in shift register, respectively, to which a signal voltage is applied. Thus, the selected cathode 1 and anode 5
The organic laminated structure at the position (pixel) where the light crosses emits light.

In order to show the interface structure of the organic layer of such a conventional organic electroluminescent device, FIG. 14 shows a main part of a layer structure of still another conventional organic EL device 10B. In the case of this example, PEDOT is used as the material of the hole transporting layer 14, and the electron transporting layer 13 is formed by using MEH-PPV as in FIG. The Ca layer 12 that enhances the electron injection property is made of Al
It is provided between the electrode 11. In each case, as shown in FIG. 14, the interface of the organic layer is formed flat.

[0013]

However, in the conventional display, the half width of the emission spectrum is wide, and high efficiency light emission with a narrow half width that can be perceived brightly by human eyes cannot be obtained. The challenge is to obtain efficient color light emitting displays.

Further, in Japanese Patent Application Laid-Open No. Hei 7-114350, there is a problem that the thickness of the laminated glass substrate is increased, high resolution cannot be obtained, and the glass substrate is easily broken and the yield is low.
Japanese Patent Application Laid-Open No. H11-17894 discloses an electroluminescent display panel in which a color element is formed by laminating a substrate material having a novel configuration capable of being flexible and thin, and which is thin, has a large screen, and is easy to manufacture. Although disclosed, there is still much room for improvement.

Therefore, an object of the present invention is to provide an excellent light emitting performance,
An object of the present invention is to provide an organic electroluminescent device capable of utilizing this light emission with high efficiency and a method of manufacturing the same.

[0016]

That is, according to the present invention, there is provided an organic electroluminescent device in which an organic layer including a light emitting region is provided on a substrate, wherein the organic layer has irregularities at an interface with the adjacent layer. The present invention relates to an organic electroluminescent device (hereinafter referred to as an organic electroluminescent device of the present invention).

According to the organic electroluminescent device of the present invention, since the organic layer has unevenness at the interface with the adjacent layer, the area of the interface of the organic layer is enlarged, and thus the organic electroluminescent device having a high luminous efficiency is obtained. An element can be provided.

Further, the present invention provides an organic electroluminescent device in which an organic layer including a light emitting region is provided on a substrate, wherein the organic layer has irregularities at an interface with the adjacent layer. When manufacturing the organic electroluminescent device, the method for manufacturing the organic electroluminescent device for forming the unevenness by controlling environmental conditions when forming the organic layer (hereinafter, referred to as the manufacturing method of the present invention). It is related.

According to the production method of the present invention, the environmental conditions when forming the organic layer are controlled. Therefore, by controlling the environmental conditions such as the solvent of the solution of the organic material, the sintering temperature, the degree of reduced pressure, etc. An unevenness can be formed at an interface between a layer and an adjacent layer, and a method for manufacturing an organic electroluminescent device with good reproducibility, which can provide the same effect as the organic electroluminescent device of the present invention described above, can be provided.

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the above-described organic electroluminescent device and the method of manufacturing the same according to the present invention, the environmental conditions include:
It is desirable to control the firing conditions of the coating layer of the solution of the organic layer constituting material.

As the environmental condition, it is desirable that irregularities are easily formed at the interface of the organic layer by evaporating and removing the solvent from the applied layer of the solution of the organic layer constituting material by controlling the firing conditions.

At this time, the sintering conditions are controlled by the degree of reduced pressure at the time of sintering of the organic layer, and are controlled at 1 atm (760 m).
mHg) is set to zero (the same applies to the degree of decompression to be described later), and the degree of decompression is from −400 mmHg to −760 mmH.
It is desirable to carry out in the range of g.

The firing conditions are controlled by the firing temperature at the time of firing the organic layer.
By performing in the range of 0 ° C to 150 ° C, the basic temperature is reduced to 7 ° C.
A temperature of 0 ° C. (the molecular structure of the solvent is extended since it has a transition point of 65 ° C. or higher) is preferable because the solvent is not denatured and irregularities are easily formed.

As the calcination conditions, the calcination may be carried out after cooling the coating layer of the solution, or the solution may be cooled and applied to cool the coating layer, and then the solvent may be removed by evaporation under reduced pressure. This is desirable in that irregularities can be formed at the interface of the organic layer.

As the baking conditions, a high-boiling solvent is added to the solution, the coating is baked after coating, and the high-boiling solvent is added in the range of 1 to 10% by weight, so that the interface of the organic layer is uneven. Is desirable in that it can form

As the firing conditions, the above-mentioned firing is performed after adding a thermally decomposable substance to the solution, and 1 to 10% by weight of the thermally decomposed substance is added, whereby irregularities can be formed at the interface of the organic layer. Desirable in terms of,

In this case, by heating at the time of sintering from one surface side of the organic layer or reducing the pressure for evaporating the solvent, unevenness can be effectively formed at the interface of the organic layer. .

The organic layer has a laminated structure in which an organic hole transporting layer and, if necessary, an organic light emitting layer and an organic electron transporting layer are laminated in this order, and at least one of these layers has the unevenness. it is desirable to provide, in this case, irregularities are present 150-300 pieces ² per lcm, the height of the irregularities is what is desired that 80 nm to 100 nm.

Further, by including the oriented and crystallized π-electron conjugated polymer layer in the layer having the unevenness, the unevenness can be effectively formed at the interface of the organic layer.

Then, a transparent electrode, an organic hole transport layer, and if necessary, an organic light emitting layer, an organic electron transport layer and a metal electrode are laminated on an optically transparent substrate to form a suitable element for a color display. can do.

In the present invention, “irregularities” means the surface roughness at the interface of the organic EL layer.

Hereinafter, embodiments of the present invention will be specifically described with reference to the drawings.

FIG. 1 shows two examples of the basic structure of the embodiment of the present invention. That is, in the present embodiment, the transparent glass substrate 16
ITO transparent electrode 15 and hole transport layer (PEDOT) on top
14, electron transporting light emitting layer (MEH-PPV) 13, Ca
An organic electroluminescent device (hereinafter, referred to as an organic EL device) is formed by sequentially laminating a (calcium) layer 12 and a cathode 11 made of Al (aluminum).

In the structure of FIG. 1A, irregularities 20 are formed on the surface of the hole transport layer 14 by controlling the solution application conditions or the baking conditions, which will be described later, when the hole transport layer 14 is formed. By mounting the electron transporting light emitting layer 13, the interface between both layers is formed in an uneven shape. As a result, the bonding area between the organic layers is increased, so that the luminous efficiency is improved.

In the structure shown in FIG. 1B, irregularities 21 are formed on the surface of the electron-transporting light-emitting layer 13 by controlling the solution application conditions or firing conditions in the same manner as described above. By laminating the Ca layer 12 thereon, the interface between the two layers is formed in an uneven shape. As a result, the bonding area of the organic layer with the electrode increases, so that the amount of injected electrons increases, and the luminous efficiency improves.

In order to form the above irregularities, the material of the hole transport layer 14 is shown in FIG. 2 as a poly (3,4) -ethylenedi
Using an oxythiophene (PEDOT) aqueous solution and a poly (phenylene-vinylene) (PPV) solution as the material of the electron transporting light emitting layer 13, controlling the environmental conditions (coating conditions and firing conditions, etc.) when forming these layers. Is done.

In the present invention, the luminous area is enlarged by forming crater-like irregularities at the interface of the organic layer to constitute the organic EL device. Therefore, the thickness of the organic layer forming the irregularities is increased. Thus, by increasing the content of air in the layer, the emission area can be further increased, and the emission efficiency can be improved. For this reason, the thickness of the organic layer is desirably 70 nm to 150 nm.

FIG. 4 shows an outline of a process of manufacturing an organic EL device according to the present embodiment and measuring characteristics.

Firstly, a transparent substrate having a hydrophobic surface, in the substrate cleaning step A _1, the first was subjected to ultrasonic cleaning for 20 minutes using a Fisher Co. detergent, washed several times with ultrapure water, twice Ultrasonic cleaning is performed. Then, after washing with acetone and isopropyl alcohol, drying in a clean oven at 120 ° C., and further, UV-ozo before use.
After irradiating ne for 20 minutes, an ITO transparent electrode is vacuum deposited.

[0040] In the treatment tank 18A performs spin coating A ₂ of PEDOT aqueous solution to control the coating conditions at atmospheric conditions, firing A ₃ is performed by placing them on a hot plate. In the baking, the baking temperature or the degree of decompression is controlled in the processing tank 18A in an atmospheric state or a reduced pressure state.

[0041] In the treatment tank 18B performs a spin coating _{A 4} of MEH-PPV solution to control the coating conditions at atmospheric conditions. At this time, the MEH-PPV coating layer is preferably, for example, about 100 μm thick in order to avoid a short circuit in the recess after the formation of the unevenness. Then, this fired A ₅ put on a hot plate is performed, the calcination is in the processing tank 18B atmospheric conditions or under reduced pressure, the firing temperature or the degree of reduced pressure is controlled.

[0042] After completion of the above steps, Ca, a metal electrode as a cathode by performing a vacuum deposition A ₆ of Al is formed.

[0043] Then, the luminous efficiency of the organic EL devices fabricated as described above efficiency measurement A ₇ is performed.

By the above-described process, the organic EL element 25A having the structure shown in FIG. 1A and the organic EL element 25B having the structure shown in FIG. 1B are manufactured. 5 and 6 and FIGS. 7 and 8
Shown in

FIGS. 5 and 6 show the manufacturing process of the organic EL element 25A (forming irregularities at the interface of the PEDOT layer) shown in FIG. 1A. First, as shown in FIG.
The cleaning process shown in FIG. 4 is performed on the glass substrate 16 formed as a substrate.

Next, as shown in FIG. 5 (b), ITO was deposited on the glass substrate 16 whose surface was cleaned by vacuum evaporation.
The transparent electrode 15 is laminated, and as shown in FIG. 5C, a PEDOT aqueous solution is spin-coated mainly in the treatment tank 18A in FIG. 4, and the hole transport layer 14 is laminated. At this time, the application conditions of the PEDOT aqueous solution are as follows: application in the air, application in a cold room, application by cooling the application solution,
Alternatively, a coating is selected by adding a thermally decomposable substance.

Next, as shown in FIG.
In 8A, a glass substrate 16 on which PEDOT is laminated as a hole transport layer 14 is placed on a hot plate 17 and baked. As the firing conditions, the degree of air pressure or the degree of pressure reduction and the temperature are controlled. As a result, the heating temperature during this firing is thermally conducted from below to above, so that PE
Gas escapes as the DOT aqueous solution evaporates,
Crater-like irregularities 20 are generated on the surface of the hole transport layer 14, and the light emitting area at the interface is enlarged.

[0048] Such a phenomenon is caused by PEDO in a cold room or the like.
The evaporation of the gas may be suppressed by applying a T aqueous solution, and the gas may be exposed to a sudden high temperature or reduced pressure during firing, or may be achieved by adding a small amount of a thermally decomposable substance to the application liquid. .

Next, as shown in FIG.
After the MEH-PPV solution is spin-coated on the hole transport layer 14 on which is formed in the processing tank 18B in FIG. 4 in the air state, the MEH-PPV solution is baked in the processing tank 18B to form the electron transporting light-emitting layer 13. . At this time, as a firing condition of the MEH-PPV, the degree of decompression or the temperature is controlled in the air or under reduced pressure. Therefore, the interface between the electron transporting light emitting layer 13 and the hole transporting layer 14 is formed in the shape of the irregularities 20.

Next, as shown in FIG. 6 (f), after a Ca layer 12 is formed thereon to improve the electron injecting property, an Al electrode 11 as a cathode is formed as shown in FIG. 6 (g).
Are stacked, and the manufacturing process ends.

In the organic EL device of the present invention, since the organic layer has irregularities at the interface with the adjacent layer, the area of the interface between the organic layers is enlarged, so that the luminous efficiency is improved. This is because the uneven organic layer made of PEDOT contains the oriented and crystallized π-electron conjugated polymer compound, so that the light emitting property is good, and the light emitting area is enlarged by the unevenness.
This is because it further contributes to the improvement of luminous efficiency. This is the same in an organic EL element 25B, which will be described later, in which unevenness is formed in an organic layer made of MEH-PPV.

FIGS. 7 and 8 show a process of manufacturing the organic EL element 25B (forming irregularities at the interface of the MEH-PPV layer) shown in FIG. 1B. First, FIGS. 7A to 7
(C) is performed in the same manner as in the above-described organic EL element 25A.

In the case of the organic EL element 25B, as shown in FIG. 7D, the application condition of MEH-PPV is selected, and the organic EL element 25B is spin-coated mainly in the processing tank 18B in FIG. Layer 13 is laminated. That is,
As the application conditions, any one of application in the atmosphere, application in a cold room, application by cooling the application liquid, or addition of a high boiling point solvent to the polymer solution is selected.

Next, as shown in FIG. 8E, MEH-PPV was formed as the electron transporting light emitting layer 13 in the processing tank 18B.
Is placed on a hot plate 17 for firing. As the firing conditions, the degree of vacuum or the firing temperature is controlled in the air or under reduced pressure. Therefore, also in this case, as in the case of the organic EL element 25A, unevenness 21 is generated on the crater on the surface of the electron-transporting light-emitting layer 13 when the gas escapes due to the evaporation of the MEH-PPV solution due to heating from below, thereby causing light emission. The area increases.

[0055] Such a phenomenon is caused by MEH-
It is also generated by applying a PPV solution to suppress gas evaporation and exposing it to a sudden high temperature or reduced pressure during baking, or by adding a high boiling solvent to the polymer solution. Can be done.

Next, as shown in FIG.
By forming a Ca layer 12 on the electron transporting light emitting layer 13 on which the electron transporting light emitting layer 1 is formed in order to improve the electron injecting property, the interface between the Ca layer 12 and the electron transporting light emitting layer 13 has the unevenness. 21 is formed.

Thereafter, the Al electrode 11 shown in FIG. 8 (g) is formed in the same manner as the above-mentioned organic EL element 25A.
The manufacturing process of the electrons 25B ends.

[0058]

EXAMPLES Based on the above-described embodiment, an organic EL device was manufactured by changing the application conditions and baking conditions of the organic layer solution, and the same materials as in the examples were used to compare the luminous efficiency with the organic EL device. And organic E by a conventional method.
An L element was produced as a comparative example. First, a comparative example will be described.

[0059] On the ITO electrode 15 laminated on a transparent substrate 16 having a comparative example hydrophobic surface, PEDOT aqueous solution 4000 rpm / 1 m
After spin coating under the conditions of “in”, the temperature was set to 120 ° C. on a hot plate, and firing was performed for 2 hours to laminate the hole transport layer 14. Similarly, the MEH-PPV solution is 3
After spin coating under the condition of 000 rpm / 1 min,
Baking was performed at 70 ° C. for 3 hours, and the electron transporting light emitting layer 13 was laminated. All tests were performed in the atmosphere. Ca layer 1 on this
2 and an Al electrode 11 to form a cathode,
An element was manufactured. Ca layer 1 vacuum-deposited as this cathode
2 has a thickness of 500 ° and the Al electrode 11 has a thickness of 1000 °, which is the same in each embodiment described later.

Example 1 According to the above-described manufacturing process, a PEDOT aqueous solution was spin-coated on the ITO electrode 15 mounted on the transparent substrate 16 having a hydrophobic surface under the condition of 4000 rpm / 1 min using the processing bath 18A shown in FIG. After that, the degree of decompression was reduced to -400 mmHg and -600 mmH in the treatment tank 18A.
g, -760 mmHg, hot plate 1
7 was set at 120 ° C., and baked for 2 hours to laminate the hole transport layer 14. Similarly, in the treatment tank 18B, the MEH-PPV solution is supplied at 3000 rpm / 1 min.
After spin-coating under the conditions described above, baking was performed at 70 ° C. for 3 hours in the same reduced pressure state as described above to obtain the electron transporting light-emitting layer 1.
3 were stacked. As described above, the hole transport layer 14 and the electron transporting light emitting layer 13 were formed by controlling the degree of pressure reduction, and the Ca layer 12 and the Al electrode 11 were vacuum-deposited thereon to produce an organic EL device 25A.

The comparative example was performed except that only the hole transporting layer 14 formed with a PEDOT aqueous solution or the electron transporting light emitting layer 13 formed with a MEH-PPV solution was formed under the same film forming conditions as in Example 1. In the same manner as in the above, an organic EL element 25A was manufactured in the former, and an organic EL element 25B was manufactured in the latter.

Example 2 According to the above-described manufacturing process, the PEDOT aqueous solution was spin-coated on the ITO electrode 15 laminated on the transparent substrate 16 having a hydrophobic surface under the condition of 4000 rpm / 1 min using the processing bath 18A shown in FIG. After that, the pressure reduction degree was kept at -760 mmHg in the same treatment tank 18A, the temperature of the hot plate 17 was set to 100 ° C or 150 ° C, and calcination was performed for 2 hours to laminate the hole transport layer 14. Similarly,
The MEH-PPV solution was placed in the processing tank 18B for 300 hours.
After spin-coating under the condition of 0 rpm / 1 min, baking was performed at 100 ° C. or 150 ° C. for 3 hours in the same reduced pressure state as above, and the electron transporting luminescence 13 was laminated. As described above, the hole transporting layer 14 and the electron transporting light emitting layer 13 were formed by controlling the firing temperature, and the Ca layer 12 and the Al electrode 11 were vacuum-deposited thereon to produce the organic EL element 25A.

It should be noted that only the hole transport layer 14 formed of the PEDOT aqueous solution or the electron transportable light emitting layer 13 formed of the MEH-PPV solution was formed under the same film forming conditions as in Example 2. In the same manner as in the example, an organic EL element 25A was manufactured in the former and an organic EL element 25B was manufactured in the latter.

Example 3 In the above-described manufacturing process, when the PEDOT aqueous solution and the MEH-PPV solution were spin-coated on the ITO electrode 15 laminated on the transparent substrate 16 having a hydrophobic surface, the spin-coating was performed in a cool room. Solvent evaporation at the time was suppressed. The spin coating conditions and the firing conditions were the same as in Example 1. After the hole transport layer 14 and the electron transporting light emitting layer 13 were stacked, the Ca layer 12 and the Al electrode 11 were vacuum-deposited thereon to form the organic EL device 25A. It was created.

It should be noted that only the hole transport layer 14 formed with the PEDOT aqueous solution or the electron transportable light emitting layer 13 formed with the MEH-PPV solution was formed under the same film forming conditions as in Example 3. In the same manner as in the example, an organic EL element 25A was manufactured in the former and an organic EL element 25B was manufactured in the latter.

Example 4 By the above-described manufacturing process, the PEDOT aqueous solution was spin-coated on the ITO electrode 15 laminated on the transparent substrate 16 having a hydrophobic surface under the condition of 4000 rpm / 1 min using the processing bath 18A shown in FIG. After that, the temperature of the hot plate 17 is set to 120 ° C. in the processing tank 18B in the atmospheric state.
And firing was performed for 2 hours to laminate the hole transport layer 14. Next, MEH-PPV was placed in the same treatment tank under the same conditions.
The solvent of the solution was changed from cyclohexanone to nitrobenzene, and the added amount was changed to 3 w%, 5 w% or 10 w%,
Spin coating was performed at 000 rpm / 1 min, and the effect in a high boiling point solvent was attempted. Further, the temperature of the hot plate 17 was set at 200 ° C., and the mixture was baked for 3 hours to laminate the electron transporting light emitting layer 13. The Ca layer 12 and the Al electrode 11 were vacuum-deposited thereon to produce an organic EL device 25B.

Example 5 According to the above-described manufacturing process, a thermally decomposable ammonium carbonate (pyrolyzed at 70 ° C.) was added to an aqueous PEDOT solution on an ITO electrode 15 laminated on a transparent substrate 16 having a hydrophobic surface.
w%, 7 w%, or 10 w%, and spin-coated at 4000 rpm / 1 min in the processing bath 18A shown in FIG.
The temperature was set to 0 ° C., and the mixture was baked for 2 hours to laminate the hole transport layer 14. Similarly, the MEH-PPV solution also contains ammonium carbonate, spin-coated at 3000 rpm / 1 min, set the temperature of the hot plate 17 at 200 ° C., baked for 3 hours, and laminated the electron transporting light emitting layer 13. did. A Ca layer 12 and an Al electrode 11 were vacuum-deposited thereon to produce an organic EL device 25A.

It should be noted that only the hole transport layer 14 formed of a PEDOT aqueous solution or the electron transportable light emitting layer 13 formed of a MEH-PPV solution was formed under the same film forming conditions as in Example 5. In the same manner as in the example, an organic EL element 25A was manufactured in the former and an organic EL element 25B was manufactured in the latter.

Example 6 In the above-described manufacturing process, a PEDOT aqueous solution cooled in a refrigerator or the like was applied to the ITO electrode 15 laminated on the transparent substrate 16 having a hydrophobic surface under the condition of 4000 rpm / 1 min. After spin-coating in 18B, the pressure reduction degree was maintained at -760 mmHg in the same treatment tank, the temperature was set to 120 ° C, and firing was performed for 2 hours to laminate the hole transport layer 14. MEH-PP cooled similarly
V solution and 3000 rpm in the processing tank 18A.
After spin coating under the condition of / 1 min, the same treatment tank 18 was used.
In B, baking was performed at 100 ° C. for 3 hours, and the electron transporting light emitting layer 13 was laminated. A Ca layer 12 and an Al electrode 11 were vacuum-deposited thereon to produce an organic EL device 25A.

It should be noted that only the hole transport layer 14 formed with the PEDOT aqueous solution or the electron transportable light emitting layer 13 formed with the MEH-PPV solution was formed under the same film forming conditions as in Example 6. In the same manner as in the example, an organic EL element 25A was manufactured in the former and an organic EL element 25B was manufactured in the latter.

The luminous efficiency of each of the organic EL devices of the comparative example and each of the examples was measured. The measurement is
A BM5A luminance meter manufactured by TOPCOM was used. The following table shows the measurement data for each example based on the measurement results.

[0072]

[Table 1]

[0073]

[Table 2]

[0074]

[Table 3]

From Tables 1, 2 and 3, in each table,
By baking PEDOT and / or MEH-PPV under reduced pressure, the luminous efficiency is significantly improved as compared with the comparative example, and the effect is higher as the degree of reduced pressure is higher. Have been. This is PEDO
In Table 1 where both T and MEH-PPV are depressurized during firing, in Table 2 where only PEDOT is depressurized during firing, M
This is common to any of Table 3 in which only EH-PPV is depressurized at the time of firing, and even if any one of the pressures is depressurized and fired, the MEH-PPV is depressurized during firing rather than PEDOT. Has a large effect.
From these results, it can be proved that by reducing the pressure during firing, irregularities are effectively formed at the interface between the hole transporting layer 14 and the electron transporting light emitting layer 13, which contributes to the improvement of the luminous efficiency.

[0076]

[Table 4]

[0077]

[Table 5]

[0078]

[Table 6]

From Tables 4, 5, and 6, in each table,
By sintering both or any of PEDOT and MEH-PPV by controlling the sintering temperature, the luminous efficiency tends to be higher than that of the comparative example, and the higher the sintering temperature, the higher the luminous efficiency. It is noticeable. This is because in Table 4 where both PEDOT and MEH-PPV are temperature controlled during firing, and in Table 5 where only PEDOT is temperature controlled during firing, MEH-
The results are common to all of the cases of Table 6 in which only PPV is temperature-controlled during firing. From these results, by setting the temperature high during firing, the interface between the hole transport layer 14 and the electron transporting light-emitting layer 13 can be obtained. It can be proved that the irregularities are effectively formed and contribute to the improvement of the luminous efficiency.

[0080]

[Table 7]

[0081]

[Table 8]

[0082]

[Table 9]

From Tables 7, 8, and 9, in each table,
By applying both or any of PEDOT and MEH-PPV in a cold room, the effect of increasing the luminous efficiency as compared with the comparative example is remarkably exhibited. This is PEDOT
In the case of Table 7 in which both PEMOT and MEH-PPV are applied in the cold room, in the case of Table 8 in which only PEDOT is applied in the cold room,
It is common to any of the cases of Table 9 in which only MEH-PPV is applied in a cold room. From these results, if spin coating is performed in a low-temperature atmosphere such as a cold room, a sharp rise in temperature during firing causes It can be proved that the unevenness is effectively formed at the interface between the hole transport layer 14 and the electron transporting light emitting layer 13 and contributes to the improvement of the luminous efficiency.

[0084]

[Table 10]

From Table 10, it can be seen that the addition of the high boiling solvent to the MEH-PPV solution has a remarkable effect of increasing the luminous efficiency as compared with the comparative example.
It can be seen that the more the amount is in the range of 0%, the more the luminous efficiency is improved. Therefore, it can be proved that by adding a high boiling point solvent to the MEH-PPV solution, irregularities are effectively formed at the interface of the electron transporting light emitting layer 13, which contributes to improvement of luminous efficiency.

[0086]

[Table 11]

[0087]

[Table 12]

[0088]

[Table 13]

From Tables 11, 12 and 13, the addition of thermally decomposable ammonium carbonate to PEDOT and / or MEH-PPV in each table gives
A remarkable effect of improving the luminous efficiency as compared with the comparative example is exhibited. Furthermore, the result that the luminous efficiency is improved as the added amount is larger in the range of 3 w% to 10 w% is obtained. This is the same as Table 11 in which ammonium carbonate is added to both PEDOT and MEH-PPV, Table 12 in which ammonium carbonate is added only to PEDOT, and Table 13 in which ammonium carbonate is added only to MEH-PPV. From these results, it is proved that the addition of ammonium carbonate effectively forms irregularities at the interface between the hole transporting layer 14 and the electron transporting light emitting layer 13 and contributes to the improvement of luminous efficiency. it can.

[0090]

[Table 14]

[0091]

[Table 15]

[0092]

[Table 16]

From Tables 14, 15 and 16, it is found that PEDO
By applying both and / or TH and / or MEH-PPV by cooling in advance in a refrigerator, a remarkable improvement in luminous efficiency is obtained as compared with the comparative example. Therefore, this corresponds to Table 14 in which both PEDOT and MEH-PPV were cooled in a refrigerator, Table 15 in which only PEDOT was cooled in a refrigerator, and Table 16 in which only MEH-PPV was cooled in a refrigerator. From these results, it can be seen from these results that when the coating material is cooled, then coated and fired, the temperature rises sharply during firing, so that irregularities are effectively formed at the interface between the hole transport layer 14 and the electron transportable light emitting layer 13. Formed in
It can be proved that it contributes to the improvement of the luminous efficiency.

According to each of the above embodiments, when the hole transporting layer 14 made of the PEDOT aqueous solution and the electron transporting light emitting layer 13 made of the MEH-PPV solution are laminated on the ITO electrode 15 laminated on the transparent substrate 16, At the time of firing after spin coating the PEDOT aqueous solution and MEH-PPV solution,
By heating from below under reduced pressure, when the air contained in the layer evaporates, crater-like irregularities are formed at the interface, whereby the interface is enlarged, the light emitting area is enlarged, and the luminous efficiency is increased. An improved organic EL device can be manufactured.

Further, a PEDOT aqueous solution and MEH-PP
By applying the V solution after cooling beforehand or by applying it in a cold room, the effect is further enhanced by suddenly exposing it to a high temperature during firing, and MEH-PP
The effect can be further enhanced by adding a high boiling point solvent to the V solution or adding a thermally decomposable substance to the PEDOT aqueous solution.

As is apparent from Tables 1 to 16, the most effective method for improving the luminous efficiency is to control the firing conditions by the degree of reduced pressure. It can be said that the effect is obtained in the order of adding the thermally decomposable substance to the solvent and controlling the temperature.

Further, the MEH-PPV is more effective than the case where the above film forming conditions such as the degree of pressure reduction or temperature are applied only to PEDOT.
When applied to only PEDOT and MEH-PPV, more effective results are obtained. Therefore, it can be said that the more the film is formed under common conditions, the more effective it is.

Further, since the process for forming the organic layer is easy, an organic EL device which is thin and has a large screen is provided, and this result has great industrial value.

The above-described embodiments and examples can be modified based on the technical idea of the present invention.

For example, in the above-described embodiment, the unevenness 20, 2,
Although 1 was formed, as shown in FIG. 9, irregularities 20 and 21 could also be formed at the interface between the two, thereby increasing the junction area between the organic layer and the electrode and increasing the amount of injected electrons. , Can further contribute to the improvement of the luminous efficiency.

As shown in FIG. 10, irregularities 23 are formed at the interface of the light emitting layer 22 composed of a single organic layer using a material having electron transporting performance and hole transporting performance. The organic EL element can also be manufactured by laminating the electrodes 11.

The method of applying the organic layer may be any suitable method other than spin coating, such as printing.
The degree of pressure reduction, the firing temperature, the heating method, and the like may be appropriate other than the examples, and the substance to be added to the solution may be a substance exhibiting an equivalent effect other than nitrobenzene and ammonium carbonate.

[0103]

As described above, according to the organic electroluminescent device of the present invention and the method of manufacturing the same, unevenness is formed at the interface between the organic layer and the adjacent layer, and the light emitting area at the interface of the organic layer is enlarged. The luminous efficiency of the organic electroluminescent device can be increased.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing a basic configuration of an organic EL device according to an embodiment of the present invention.

FIG. 2 is a view showing a chemical structure of PEDOT used in the organic EL device.

FIG. 3 is a view showing a chemical structure of MEH-PPV used in the organic EL device.

FIG. 4 is a view showing a process of manufacturing an organic EL device and measuring efficiency thereof.

FIG. 5 is a schematic cross-sectional view showing one example of a manufacturing process of the organic EL element.

FIG. 6 is a schematic cross-sectional view showing one example of a manufacturing process of the organic EL element.

FIG. 7 is a schematic sectional view showing an example of another manufacturing process of the organic EL element.

FIG. 8 is a schematic sectional view showing an example of another manufacturing process of the organic EL element.

FIG. 9 is a schematic sectional view showing a modified example of the organic EL element.

FIG. 10 is a schematic sectional view showing another modified example of the organic EL element.

FIG. 11 is a schematic sectional view showing an example of an organic EL device according to a conventional example.

FIG. 12 is a schematic sectional view showing another example of the same organic EL element.

FIG. 13 is a schematic view showing a configuration example of a flat display using an organic EL element.

FIG. 14 is a schematic sectional view showing still another example of the organic EL device.

[Explanation of symbols]

11 ... Al electrode (cathode), 12 ... Ca layer, 13 ... Electron transporting light emitting layer (MEH-PPV), 14 ... Hole transporting layer (PEDOT), 15 ... ITO electrode, 16 ... Glass substrate, 17 ... Hot plate, 18A, 18B ... processing tank,
20, 21, 23: unevenness, 22: light emitting layer (hole transporting property, electron transporting property), 25A, 25B: organic EL element, A
₁ ~A ₇ ... process

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[Procedure amendment]

[Submission date] September 3, 2001 (2001.9.3)

[Procedure amendment 1]

[Document name to be amended] Drawing

[Correction target item name] Figure 3

[Correction method] Change

[Correction contents]

FIG. 3

Continuation of the front page (72) Inventor Shinichiro Tamura 6-35 Kita Shinagawa, Shinagawa-ku, Tokyo Sony Corporation F-term (reference) 3K007 AB03 AB18 BA06 CB01 DA01 DB03 EB00 FA01

Claims (23)

[Claims] 1. An organic electroluminescent device in which an organic layer including a light emitting region is provided on a substrate, wherein the organic layer has irregularities at an interface with an adjacent layer. element. 2. The organic layer has a laminated structure in which an organic hole transporting layer, an organic layer, and if necessary, an organic light emitting layer and an organic electron transporting layer are laminated in this order, and at least one of these layers is formed. The organic electroluminescent device according to claim 1, wherein the organic electroluminescent device has the irregularities. 3. The organic electroluminescent device according to claim 1, wherein the layer having irregularities includes an oriented and crystallized π-electron conjugated polymer layer. 4. The organic electroluminescent device according to claim 1, wherein a transparent electrode, an organic hole transport layer, an organic light emitting layer, an organic electron transport layer and a metal electrode are laminated on an optically transparent substrate. . 5. The organic electroluminescent device according to claim 1, which is configured as a device for a color display. 6. An organic electroluminescent device in which an organic layer including a light emitting region is provided on a substrate, wherein the organic layer has irregularities at an interface with an adjacent layer. A method for manufacturing an organic electroluminescent device, wherein the unevenness is formed by controlling environmental conditions when forming the organic layer when manufacturing the device. 7. A sintering condition of a coating layer of a solution of an organic layer constituting material is controlled as the environmental condition.
3. The method for producing an organic electroluminescent device according to 1.). 8. The method for manufacturing an organic electroluminescent device according to claim 6, wherein the solvent is evaporated from the coating layer of the solution of the organic layer constituent material as the environmental condition. 9. The method for manufacturing an organic electroluminescent device according to claim 7, wherein the firing conditions are a degree of reduced pressure at the time of firing the organic layer. 10. When one atmospheric pressure (760 mmHg) is set to a pressure reduction degree of zero, the pressure reduction degree is -400 mmHg to -76 mm.
The method for producing an organic electroluminescent device according to claim 9, wherein the pressure is 0 mmHg. 11. The method for manufacturing an organic electroluminescent device according to claim 7, wherein the firing condition is a firing temperature at the time of firing the organic layer. 12. The method according to claim 11, wherein the sintering temperature is 70 ° C. to 150 ° C. 13. The method for manufacturing an organic electroluminescent device according to claim 7, wherein the baking is performed after cooling the coating layer of the solution. 14. The method according to claim 8, wherein, as the environmental condition, the solvent is evaporated and removed under reduced pressure after cooling the coating layer of the solution. 15. The method according to claim 7, wherein the baking is performed after adding a high boiling point solvent to the solution as the baking condition. 16. The method according to claim 15, wherein the high boiling point solvent is added in an amount of 1 to 10% by weight. 17. The method for manufacturing an organic electroluminescent device according to claim 7, wherein the baking is performed after adding a thermally decomposable substance to the solution as the baking condition. 18. The method according to claim 17, wherein the pyrolytic substance is added in an amount of 1 to 10% by weight. 19. The method for manufacturing an organic electroluminescent device according to claim 7, wherein heating during firing is performed from one surface side of the organic layer, or pressure reduction for evaporating a solvent is performed. 20. The organic layer has a laminated structure in which an organic hole transporting layer and, if necessary, an organic light emitting layer and an organic electron transporting layer are laminated in this order, and the unevenness is provided on at least one of these layers. A method for manufacturing an organic electroluminescent device according to claim 6. 21. The method for manufacturing an organic electroluminescent device according to claim 6, wherein the layer provided with the unevenness includes an oriented and crystallized π-electron conjugated polymer layer. 22. The organic electroluminescent device according to claim 6, wherein a transparent electrode, an organic hole transport layer, an organic light emitting layer, an organic electron transport layer and a metal electrode are laminated on an optically transparent substrate. Production method. 23. The method for manufacturing an organic electroluminescent device according to claim 6, which is configured as a device for a color display.