JP2003197371A - Manufacturing method for electroluminescent element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method for an electroluminescent element for improving wettability of an interface between a water-soluble polymer and an organic solvent-soluble polymer. <P>SOLUTION: This electroluminescent (EL) element 23, in which a layer having a light emission area is arranged between a positive electrode 2 and the negative electrode 22, is constructed of a lamination structure formed of a hole transporting layer (PEDOT layer) 4 and an electron transporting light emission layer (MEH-PPV layer) 5 using different solvents for paint mutually. In this manufacturing method for the electroluminescent element 23, after the hole transporting layer 4 is formed, the electron transporting light emission layer 5 is formed on it, and in this process, the surface of the hole transporting layer 4 is treated with an organic solvent 42 for the paint 5a for forming the electron transporting light emission layer 5. In this way, wettability of the paint 5a is improved. <P>COPYRIGHT: (C)2003,JPO

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 electroluminescence device suitable as, for example, a self-luminous thin flat display.

[0002]

2. Description of the Related Art Conventionally, research and development of a lightweight and highly efficient flat panel display have been actively carried out for image display of computers and televisions.

One of them is a cathode ray tube (CRT).
Has been used as the most popular display at present due to its high brightness and good color reproducibility, but it has the problems of being relatively heavy, taking up space, and consuming high power.

Therefore, as a light and thin display, a liquid crystal display has been commercialized and is becoming popular nowadays. However, a drawback peculiar to the liquid crystal display is that the viewing angle is narrow and a sufficient response to a high-speed pixel signal is obtained. There is a problem that performance is not obtained. In particular, with respect to the large screen of the display, there are problems that it is difficult to manufacture and the cost is high.

As an alternative to this, there is a display using a light emitting diode, but there are still problems that the manufacturing cost is high and it is difficult to form a matrix structure of the light emitting diode on one substrate.

As a flat panel display capable of solving these problems, attention has recently been paid to an organic electroluminescent device (organic EL device) using an organic light emitting material.
L element). That is, the organic electroluminescent device is expected to realize a flat panel display that is self-luminous, has a high response speed, and has no viewing angle dependency by using an organic compound as a light emitting material.

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
ang et al. disclose an electroluminescent device having a structure in which an organic light emitting layer and a charge transport layer are laminated.

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 transporting property as a light emitting material. In addition, Coumarin derivative and DCM1 (Eastman) are added to Alq ₃ forming the organic light emitting layer.
(Chemicals Co., Ltd.) and the like, and produced a device doped with a fluorescent material, etc., and reported that the emission color changes by proper selection of the dye, and also disclosed that the emission efficiency is increased compared to the undoped one. (Journal of Applied Physi
cs, 65, p. 3610 (1989)).

Following this research, many researches and developments have been carried out, and as a new functional material, fluorescent chelating metal complexes, electron-transporting organic molecules and hole-transporting organic molecules have been developed and used for colorization. Various studies have been made toward this.

FIG. 13 shows an example of a conventional organic electroluminescent device.

This organic electroluminescence (EL) element 73A is
ITO (Indium Tin Oxid) is placed on the transparent glass substrate 51.
e) The transparent pixel electrode (anode) 52, the hole transport layer 4, the light emitting layer 75, the electron transport layer 55, and the cathode 62 are sequentially formed by, for example, a vacuum vapor deposition method.

Then, the organic electroluminescence (EL) device 7
In 3A, when a DC voltage 74 is applied between the ITO transparent pixel electrode 52 which is an anode and the cathode 62, holes as carriers injected from the ITO transparent pixel electrode 52 pass through the hole transport layer 54. On the other hand, the electrons injected from the cathode 62 move through the electron transport layer 55, and recombination of these electron-hole pairs occurs in the light emitting layer 75, and the light emission 76 having a predetermined wavelength is generated therefrom. Can be observed from the transparent glass substrate 51 side.

FIG. 14 shows another conventional organic electroluminescent device 73B. In this organic electroluminescent device 73B, the electron transport layer 55A also serves as a light emitting layer.

This structure is specifically constructed as a laminated structure shown in FIG. That is, ITO transparent pixel electrode (anode)
A hole transport layer 54 is formed on a glass substrate 51 provided with 52, an electron transport light emitting layer 55A is formed on the hole transport layer 54, and a calcium (Ca) layer 63 for improving electron injection properties is formed thereon.
Between the aluminum (Al) layer 60.

Such an organic electroluminescence (EL) device 73
In the layer structure of B, the material of the hole transport layer 54 is poly (3,4) -ethylenedioxythiophene (hereinafter, PE).
Abbreviated as DOT. ), Poly (2-methoxy-5- (2′-ethylhexyloxy)) is used for the electron-transporting light-emitting layer 55A.
-1,4-phenylene vinylene) (hereinafter MEH-PP
Abbreviated as V. ) Is used, and a cathode 62 composed of a calcium (Ca) layer 63 and an aluminum (Al) layer 60 for improving the electron injection property is provided thereon.

FIG. 16 shows the organic electroluminescent device 7 of FIG.
The structural example of the flat display using 3B is shown.

As shown in the figure, the organic laminated structure composed of the electron transport layer 55A and the hole transport layer 54 has a cathode 62 and an anode 5.
3 are arranged in a predetermined pattern. Cathode 62 and anode 5
2 are provided in a stripe shape intersecting with each other,
Brightness signal circuit 84 and shift register built-in control circuit 8
5, the signal voltage is applied. As a result, the organic laminated structure emits light at the position (pixel) where the selected cathode 62 and anode 52 intersect.

[0018]

[Problems to be Solved by the Invention]

Next, a manufacturing process of a conventional organic electroluminescence (EL) device will be exemplified.

First, for the transparent glass substrate 51 having a hydrophobic surface, in the substrate cleaning step, ultrasonic cleaning is performed using a cleaning agent manufactured by Fisher, and then cleaning is performed several times with ultrapure water. Repeat twice.

Then, after washing with acetone and isopropyl alcohol, it is dried in a clean oven, further irradiated with ultraviolet-ozone and then IT.
The O transparent pixel electrode (anode) 2 is formed by vacuum deposition or the like and patterning.

Next, as shown in FIG. 17, in the chamber (treatment tank) 59A, the dropping conditions are controlled under the atmosphere, and the coating device 56 is used to transport the holes having the molecular structure shown in FIG. Aqueous PEDOT Aqueous Solution 54a
Is dropped and spin-coated.

Next, this is placed on a hot plate (not shown) in the chamber 59B and baked to form the hole transport layer 54.

As a condition of this step, the application of the aqueous solution 54a of PEDOT which is a hole transporting polymer is performed by, for example, a spin coating method for 2 sec, 600 rpm and 58.
sec and 3000 rpm. In addition, the above-mentioned firing treatment is performed in a treatment tank in an atmospheric state or a reduced pressure state while controlling the firing temperature or the degree of reduced pressure. The temperature of this baking treatment is 120 ° C., and the baking time is 2 hours.

Next, in the chamber 59C, the dropping conditions are controlled in the atmospheric condition, and MEH, which is an electron-transporting polymer having the molecular structure shown in FIG. 11A, is placed on the hole-transporting layer (PEDOT layer) 54. -PPV solution (solution dissolved in organic solvent) 55a is dropped, and spin coating is performed under the same conditions as above.

Then, this is placed on a hot plate (not shown) and subjected to a baking treatment to obtain an electron transporting light emitting layer (M
EH-PPV layer) 55 is formed. This firing treatment is performed in a chamber (treatment tank) 59D in the atmospheric state or a reduced pressure state while controlling the firing temperature or the degree of reduced pressure. The temperature of this baking treatment is 70 ° C., and the baking time is 2 hours.

As described above, general organic electroluminescence (E
L) In the structure of the element, the hole transport layer 54 and the electron transport light emitting layer 55 are separately laminated, and the hole transport layer 54 is formed by applying an aqueous solution 54a of a water-soluble polymer (PEDOT). Then, an organic solvent-soluble (oil-soluble) polymer (MEH-PP) is formed on the layer 54.
The solution 55a of V) is applied to form the electron transporting light emitting layer 55.

In this case, PED, which is a water-soluble polymer
MEH, which is an organic solvent-soluble polymer, is formed on the OT layer 54.
When the -PPV solution 55a is applied, the wettability of the solution 55a is poor, which deteriorates the bondability at the interface between the hole transport layer 54 and the electron transporting light emitting layer 55, and tends to deteriorate the light emission efficiency. .

This is PEDO, which is a water-soluble polymer.
When the solution 55a of MEH-PPV, which is a polymer soluble in an organic solvent, is applied on top of this after applying and drying T,
This is because this solution is essentially hard to be compatible with the surface of the main soluble polymer (poor wettability).

The present invention has been made in view of the above circumstances, and an object thereof is to provide material layers having different physical properties (particularly, a layer composed of a water-soluble polymer) from each other depending on the kind of solvent of the coating liquid. Another object of the present invention is to provide a method for manufacturing an electroluminescence device, which can improve the wettability of the organic solvent-soluble (oil-soluble) polymer and the interface between the layer and the layer, and can enhance the luminous efficiency.

[0031]

That is, the present invention has a layer having a light emitting region between a first electrode and a second electrode, and this layer is a first substance layer having physical properties different from each other. In a method for manufacturing an electroluminescent device having a laminated structure of a first material layer and a second material layer, the material layer is formed on one of the first material layer and the second material layer, and The present invention relates to a method for manufacturing an electroluminescent device, characterized in that when forming the other material layer, a treatment for improving the wettability of the coating liquid for forming the other material layer is performed. . Here, the above-mentioned "different physical properties from each other" means that both solvents are essentially water-soluble and the other is oil-soluble due to the difference in the solvent of the coating liquid used to form each layer. It means that a familiarity defect such as a defect is likely to occur.

According to the present invention, when forming the other material layer on the one material layer, a treatment for improving the wettability of the coating liquid for forming the other material layer is performed. Therefore, it is possible to improve the wettability of the coating liquid of the other substance layer with respect to the one substance layer, improve the bondability between both substance layers, and reliably form a laminated structure with high luminous efficiency.

[0033]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, after forming the one material layer, a solvent used for coating the other material layer is applied thereon, and the other material layer coating liquid is further applied. It is desirable to apply.

Further, it is preferable that the coating liquid for the other substance layer is applied onto the one substance layer under the atmosphere of the solvent used for the coating liquid for the other substance layer.

For example, after the surface of the one substance layer is brought into contact with the atmosphere of the solvent used for the coating liquid of the other substance layer, the coating liquid of the other substance layer is applied onto the one substance layer. Is also desirable.

The solvents used for the coating liquid for the one substance layer and the coating liquid for the other substance layer may be different from each other. For example, the one substance layer is water-soluble and the other substance layer is water-soluble. The layer may be organic solvent soluble (oil soluble).

The application of the organic solvent or water as the solvent or the formation of the one material layer or the other material layer is preferably performed by a thin film forming method such as a spin coating method, a printing method and a casting method. . Printing methods include letterpress printing, intaglio printing, offset printing, lithographic printing, letterpress reverse offset printing, screen printing, gravure printing, and the like.

Further, it is desirable to heat the solvent and subject it to the treatment.

The solvent is cyclohexanone, p-
It is preferable that the organic solvent comprises at least one organic solvent selected from xylene, o-xylene, m-xylene, Mix-xylene (mixed xylene), tetrahydrofuran, toluene, ethylbenzene, cyclohexane, methyl cellosolve and butyl cellosolve.

Further, it is desirable that the treatment is performed by plasma treatment of the one material layer and the plasma treatment is performed by, for example, gas plasma.

It is also preferable that the one material layer is heated to perform the treatment, and the coating liquid is applied onto the one material layer during or after the heating. This heating may be done with a hot plate.

It is also desirable to heat the coating liquid and apply the heated coating liquid onto the one material layer.

Further, it is desirable to carry out the above-mentioned treatment after or before firing the one material layer.

Further, it is preferable that the light emitting region includes a crystallized π-electron conjugated polymer layer.

Further, it is desirable that the one material layer is a hole transport layer and the other material layer is an electron transport layer.

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

First Embodiment FIG. 1 to FIG. 3 and FIG. 6 exemplify a manufacturing process of an organic electroluminescence (EL) element according to the first embodiment.

First, as shown in FIG. 1A, the transparent glass substrate 1 having a hydrophobic surface is ultrasonically cleaned using a cleaning agent manufactured by Fisher in a substrate cleaning process, The process of washing with ultrapure water several times is performed twice.

Then, after washing with acetone and isopropyl alcohol, it is dried in a clean oven, further irradiated with ultraviolet-ozone and then IT.
The O transparent pixel electrode (anode) 2 is formed by vacuum deposition or the like and patterning.

Next, in a chamber (processing tank: not shown here, the same applies hereinafter), the dropping conditions are controlled under the atmosphere, and as shown in FIG. 1 (2), for example, a microsyringe type coating is applied. Using the apparatus 6 and the like, an aqueous solution 4a of hole transporting PEDOT having the molecular structure shown in FIG. 12 is dropped and spin-coated.

Next, as shown in FIG. 1C, this is placed on a hot plate and baked to form a hole transport layer (PEDOT layer) 4.

Here, the hole transport layer (PEDOT layer) 4 formed by dropping the PEDOT aqueous solution 4a has a thickness of 3
0 to 50 nm is preferable. In addition, hole transporting PEDO
The dropping method of the T aqueous solution 4a is not limited to the spin coating method using the coating device 6, and may be any method as long as it has a predetermined effect.

The hole transporting PEDOT aqueous solution 4a is applied by, for example, spin coating for 2 sec.
It shall be performed under the conditions of 00 rpm, 58 sec, and 3000 rpm. In addition, the above-mentioned firing treatment is performed in a treatment tank in an atmospheric state or a reduced pressure state while controlling the firing temperature or the degree of reduced pressure. The temperature of this baking treatment is 12
The temperature is 0 ° C. and the firing time is 2 hours.

Next, in the chamber, the dropping conditions are controlled in the atmospheric condition, and as shown in FIG. 2 (4), the hole transport layer (PEDOT) is applied using the coating device 6 and the like.
A volatile organic solvent 42a is dropped and spin-coated on the layer 4 to form a thin organic solvent layer 42 as shown in FIG.

By the formation of the organic solvent layer 42, the electron transport is carried out on the hole transport layer (PEDOT layer) 4 to the organic solvent (this may be the same as the organic solvent 42a, but may be different). The wettability of the coating liquid with respect to the hole transport layer 4 is improved when the solution in which the luminescent material is dissolved is applied.

The organic solvent 42a is preferably made of at least one selected from highly volatile cyclohexanone, p-xylene, tetrahydrofuran and the like.

The timing of forming the organic solvent layer 42 is preferably after the firing of the hole transport layer 4. That is, the hole transport layer 4 contains a small amount of water immediately after formation, and in this state, since the coatability of the organic solvent 42a is deteriorated, if the water is removed by baking the hole transport layer 4,
This is because the organic solvent 42a can be easily applied onto the hole transport layer 4 by spin coating.

This is especially true when the solvent of the organic EL material solution formed on the hole transport layer 4 is a mixed solvent.
It can be said that it is desirable because the deterioration of wettability may be remarkable.

A wet-on-dry method, in which the organic solvent is applied after firing the hole transport layer 4 as described above, is desirable, but a wet-on method in which the organic solvent is applied without firing the hole transport layer 4 is preferable. It does not matter if the wet method is adopted.

In the chamber, the dropping conditions are controlled under the atmospheric condition, and as shown in FIG. 2 (6), the organic solvent layer 42 on the hole transport layer (PEDOT layer) 4 is placed on the organic solvent layer 42 as shown in FIG. 11 (1). A solution (solution of an organic solvent such as cyclohexanone) 5a of MEH-PPV, which is an electron-transporting light-emitting polymer having the molecular structure shown in (5), is applied by dropping and spin coating. In addition to this, it may be applied in a predetermined pattern by screen printing or an inkjet method.

Then, this was placed on a hot plate and subjected to a baking treatment, and as shown in FIG. 2 (7), MEH-P
The electron transporting light emitting layer 5 made of PV is formed. This firing treatment is carried out in a treatment tank in an atmospheric state or a reduced pressure state while controlling the firing temperature or the degree of reduced pressure.

The temperature, method, time, degree of pressure reduction and the like in this baking treatment may be arbitrary as long as they have a predetermined effect. For example, the baking treatment temperature is 70 ° C. and the baking time is 2 hours. To do.

Next, as shown in FIG. 3 (8), an electron transporting light emitting layer (MEH-PPV layer) 5 is formed by a vacuum vapor deposition method.
A calcium (Ca) layer 13 is formed thereon, and an aluminum (Al) layer 10 serving as an electrode is formed on the calcium layer 13.
Then, a gold-germanium (Au-Ge) layer 9 for protection and external connection is formed on the aluminum layer 10, and patterning is performed.

As a result, the cathode 2 having the three layers of the calcium layer 13, the aluminum layer 10 and the Au-Ge layer 9 is formed.
Form 2. Here, the thickness of the calcium layer 13 is 50
The aluminum layer 10 may have a thickness of 1000 Å, and the Au—Ge layer 9 may have a thickness of 1000 Å.

Next, as shown in FIG. 3 (9), Au-G
The substrate 8 is covered on the e-layer 9, and the side portion is further sealed with the epoxy resin 7 to complete the organic electroluminescence (EL) element 23.

In this organic electroluminescent device 23, in the light emitting region, an oriented crystallized π-electron conjugated polymer layer,
In particular, since the MEH-PPV layer 5 is included, carrier transportability is excellent and luminous efficiency is also good.

Then, in the present embodiment, as shown in FIG. 6, each of the above-described steps is performed by the belt 40 moving on the roller 41 into each of the chambers 39A, 39B, 3B.
While sequentially passing through 9C, 39D, and 39E, each process can be performed in-line with high efficiency and high productivity, and a thin and large-sized organic EL flat panel display can be manufactured.

According to the present embodiment, as described above, when the electron transporting light emitting layer 5 as the second substance layer is formed on the hole transporting layer 4 as the first substance layer, Since the transport layer 4 is treated with the organic solvent 52a in order to improve the wettability of the coating liquid for forming the electron transporting light emitting layer 5, the coating liquid 5a for the electron transporting light emitting layer 5 is used.
The wettability of the layers can be improved, whereby the bondability between the layers 5-4 is improved, and along with this, the film quality, and further the luminous efficiency and luminous brightness of the device are improved.

Further, in this embodiment, since the process for forming the organic layer, particularly the electron-transporting light emitting layer 5, is easy, the organic electroluminescent display (panel) is thin and has a large screen. It is easy to provide and the industrial value is great.

Second Embodiment In the present embodiment, as shown in FIG. 4, a solution 5a of an organic solvent of MEH-PPV is arbitrarily applied by a plurality of coating devices 6 on a hole transport layer (PEDOT layer) 4. It is the same as that of the above-mentioned first embodiment except that the electron-transporting light-emitting layer 5 is formed by applying the above-mentioned pattern.

That is, the organic solvent layer 52a was coated on the hole transport layer 4 in the same manner as the steps described in FIGS. 1 (1), 1 (2) and 3) and 2 (4) and 2 (5). Later, Figure 4
As shown in (1) and (2), various patterns, widths, lengths and thicknesses can be obtained by controlling the amount of the organic EL material solution 5a ejected from the plurality of coating devices 6 and the ejection timing. It is possible to form an electron-transporting light emitting layer 5 such as.

Then, as shown in FIG. 4C, the cathode layers 13, 10 and 9 are laminated in the same pattern.
As shown in (4), the organic electroluminescent device 23 is completed.

Also in this embodiment, the same action and effect as those of the first embodiment can be obtained, and at the same time, the patterning of the electron transporting light emitting layer 5 improves the light emitting efficiency of the pixel, Crosstalk between them can be reduced.

Third Embodiment In the present embodiment, as shown in FIG.
The inside of C is a gaseous organic solvent atmosphere 42b made of an organic solvent used for the MEH-PPV solution 5a, and under this atmosphere, the hole transport layer (PE
The procedure is the same as that of the first embodiment described above, except that the MEH-PPV solution 5a is applied onto the DOT layer) 4 by a spin coating method or the like to form the electron transporting light emitting layer 5.

That is, after performing the steps of (1), (2) and (3) of FIG. 1 in the same manner, the hole transport layer (PEDOT layer) is maintained while the concentration of the gaseous organic solvent 42b in the chamber 39C is kept constant. ) 4 is coated with the MEH-PPV solution 5a, a gaseous organic solvent 42b having a desired concentration is attached onto the hole transport layer (PEDOT layer) 4 to form a ME solution.
It is possible to improve the wettability of the H-PPV coating liquid 5a and obtain the same operation and effect as those of the above-described first embodiment.
Moreover, the chamber 3 in the first embodiment described above is used.
Since 9D can be omitted, the productivity becomes good.

In this embodiment, the MEH-PPV solution 5a is applied by the spin coating method in the atmosphere 42b of the organic solvent, but instead of this, the atmosphere 42b of the gaseous organic solvent 42b is temporarily set in the chamber 39C. And hole transport layer 4
After the gaseous organic solvent 42b is adhered on the upper surface at a predetermined concentration, the gaseous organic solvent 42b is removed from the chamber 39C.
b may be removed, and then the electron transporting light emitting layer 5 may be formed by applying the MEH-PPV solution 5a on the surface of the hole transport layer 4 to which the organic solvent 42b is attached by spin coating or the like.

In this case, the solution 5a can be applied after sufficient treatment with the organic solvent 42b.

Fourth Embodiment In this embodiment, as shown in FIGS. 5 (1) and 8,
A solution for forming the electron transporting light emitting layer (MEH-PPV layer) 5 on the hole transporting layer 4 after firing the hole transporting layer 4 instead of forming the organic solvent layer 42 on the hole transporting layer (PEDOT layer) 4. Similar to the first embodiment described above except that the entire substrate 1 including the hole transport layer 4 is heated before or during the application of 5a to improve the wettability of the solution 5a with respect to the hole transport layer 4. Is.

As the heating conditions, for example, the heating temperature is preferably 40 ° C to 80 ° C. Because, if the heating temperature is lower than 40 ° C., it is difficult to effectively heat the entire substrate 1 including the surface of the hole transport layer 4, and the hole transport layer 4
It is difficult to improve the wettability of the surface and the heating temperature is 80 ℃
When it exceeds, the whole substrate 1 is overheated, the wettability of the solution 5a is deteriorated due to evaporation of the solvent of the solution 5a, and the coating is likely to be difficult.

A heating time of at least 10 minutes is desirable for uniform heating of the entire substrate.

As the heating means, the hot plate 4
3 or heated air can be used.

According to this embodiment, since the surface of the hole transport layer 4 is heated, the solution 5a applied thereon is heated.
Since the conformability (wettability) is improved, the bondability between the electron-transporting light emitting layer 5 and the hole-transporting layer 4 formed as shown in FIG. 5B is enhanced. Then, the same operation and effect as those of the above-described first embodiment can be obtained.

Fifth Embodiment In the present embodiment, in the above fourth embodiment,
Instead of, or simultaneously with, heating the substrate 1, the solution 5
By heating and applying a itself, the wettability of the solution 5a with respect to the hole transport layer 4 can be improved, and the same effect can be obtained.

At this time, considering the boiling point of the solution 5a,
The heating temperature of the solution 5a is preferably 80 ° C. or lower (70 ° C. or lower in the case of MEH-PPV solution).

Sixth Embodiment In this embodiment, as shown in FIG. 9, instead of forming the organic solvent layer 42 on the hole transport layer (PEDOT layer) 4, electron transport is performed on the hole transport layer 4. The chamber 39C before or during the application of the solution 5a for forming the luminescent layer 5.
The same as the above-described first embodiment, except that the inside is set to a heating atmosphere 80 of 40 to 80 ° C., for example, 70 ° C. to improve the wettability of the solution 5a to the surface of the hole transport layer 4.

The heating condition is preferably 40 to 80 ° C. for the same reason as described above, and the heating time may be at least 10 minutes, for example, 30 minutes like the coating time. As the heating means, heated air or the like can be used.

Also in this case, the solution 5a for forming the electron transporting light emitting layer 5 may be heated. At this time,
Considering the boiling point temperature of the solution 5a, the heating temperature is 80 ° C or lower,
In particular, it is preferably 70 ° C or lower.

Also according to this embodiment, the hole transport layer 4
Since the surface and / or the solution 5a are heated, the compatibility (wettability) of the solution 5a applied thereon is improved, and the bondability between the hole transport layer 4 and the electron transport light emitting layer 5 is enhanced. Further, the same operation and effect as those of the above-described first embodiment can be obtained.

Seventh Embodiment In the present embodiment, as shown in FIG. 10, the organic solvent layer 42 is not formed on the hole transport layer (PEDOT layer) 4 but the electron is formed on the hole transport layer 4. Transport (organic EL emission)
Before or at the time of applying the organic EL material solution 5a for forming the layer 5, the surface of the hole transport layer 4 is irradiated with plasma 81 in the chamber 39C ′ to activate and wet the surface of the hole transport layer 4. The characteristics are the same as those in the first embodiment except that the property is improved.

Irradiation of this plasma may be performed by gas plasma using hydrogen gas, for example, and the irradiation time may be about 10 minutes.

According to the present embodiment, the surface of the hole transport layer 4 is activated by the plasma, the compatibility (wettability) with the solution 5a applied thereon is improved, and the hole transport layer 4 and the electron transport property are improved. The bondability with the light emitting layer 5 is enhanced. Further, the same operation and effect as those of the above-described first embodiment can be obtained.

[0092]

EXAMPLES Examples of the present invention will be described below.

Example 1 <Fabrication of Organic Electroluminescent Device> Using the apparatus shown in FIG. 6, first, a glass substrate coated with ITO and patterned with an ITO transparent pixel electrode was irradiated with UV ozone, and then a PEDOT aqueous solution was used. Was spin-coated at 600 rpm for 2 seconds and 3000 rpm for 58 seconds.

After completion of this spin coating, it was baked on a hot plate at 120 ° C. for 10 minutes to form a hole transport layer (PEDOT).
Layers) were formed.

Next, after completion of the firing, the hole transport layer (P
On the EDOT layer), organic solvents cyclohexanone, p-xylene, and tetrahydrofuran were applied by a spin coating method at 3000 rpm and 10 sec, respectively, to obtain three kinds of samples.

10 to 20 after the application of the organic solvent.
Within seconds (with the organic solvent wet without evaporation), M
A solution prepared by dissolving 0.7% by weight of EH-PPV in cyclohexanone is used as each hole transport layer (PEDOT layer).
On top, 600 rpm, 2 sec and 3000 rpm, 5
It was spin-coated for 8 seconds.

After completion of this coating, baking was carried out at 70 ° C. for 2 hours to form an electron transporting light emitting layer (MEH-PPV layer).

After this firing, calcium was added to a thickness of 500 Å, aluminum was added to a thickness of 1000 Å, and Au-Ge was added to a thickness of 10 Å.
After vacuum deposition to a thickness of 00Å, patterning was performed to form a cathode. After that, sealing with epoxy resin,
An organic electroluminescent device was produced.

<Evaluation of Luminescent Properties> The results of measuring the luminous efficiency and the luminous brightness of each organic electroluminescent device of this example are shown in Table 1 below. For comparison, the same table shows the luminous efficiency and the luminous brightness at a certain constant current value for the sample spin-coated with the MEH-PPV solution in the state where the organic solvent was not applied after the formation of the hole transport layer (completion of firing). The measurement results are also shown (the same applies below).

[Table 1] Table 1

According to the above table, in each organic electroluminescent device of this example, since the organic solvent was applied onto the hole transport layer before the application of the electron transporting light emitting material solution, the organic solvent was applied. The emission intensity and the emission brightness were greatly improved as compared with the case where the emission was not performed, and favorable emission characteristics were exhibited.

Example 2 On each hole transport layer in a state where the hole transport layer (PEDOT layer) was not baked (a state in which water was present in the layer),
Example 1 was repeated except that the organic solvents cyclohexanone, p-xylene, and tetrahydrofuran were applied by the spin coating method.

The luminous efficiency and luminous brightness of each organic electroluminescent device of this example are shown in Table 2 below.

[0103]

[Table 2] Table 2

According to the above table, each organic electroluminescent device of this example was coated with the organic solvent without firing the hole transport layer, even though the organic solvent was coated on the hole transport layer. The emission intensity and emission brightness are improved compared to the case without
It showed good emission characteristics.

Example 3 Using the apparatus shown in FIG. 7, one hole transport layer (PEDOT layer) was applied onto a substrate in the same manner as described in Example 1.
After firing at 10 ° C. for 10 minutes, MEH-PP was deposited on the hole transport layer under each atmosphere (in vapor) of cyclohexanone, p-xylene, and tetrahydrofuran, which are organic solvents.
The same procedure as in Example 1 was carried out except that a 0.7 wt% cyclohexanone solution of V was spin-coated.

The luminous efficiency and luminous brightness of each organic electroluminescent device of this example are shown in Table 3 below. For comparison, the same table also shows the measurement results of the emission efficiency and the emission luminance of the sample spin-coated with the MEH-PPV solution without using the organic solvent atmosphere.

[0107]

[Table 3] Table 3

According to the above table, in each organic electroluminescent device of this example, the hole transport layer was placed in an organic solvent atmosphere before coating the solution of the electron transporting light emitting material, and the solution was coated in this state. Therefore, the emission intensity and the emission brightness were significantly improved as compared with the case where the organic solvent atmosphere was not used, and the favorable emission characteristics were exhibited.

Example 4 After using the apparatus shown in FIG. 10 to form a hole transport layer (PEDOT layer) in the same manner as described in Example 1, hydrogen plasma was introduced into the chamber, and the hole transport layer was formed. Three
Example 1 was repeated, except that hydrogen plasma of 50 mW / cm ² was irradiated for 10 minutes, and a 0.7 wt% cyclohexanone solution of the electron transporting light emitting material solution was spin-coated.

The luminous efficiency and luminous brightness of the organic electroluminescent device of this example are shown in Table 4 below. For comparison, the table also shows the measurement results of the emission efficiency and the emission luminance of the sample spin-coated with the cyclohexanone solution of MEH-PPV without plasma irradiation.

[0111]

[Table 4] Table 4

According to the above table, in the organic electroluminescent device of this example, the hole transport layer was plasma-treated and the electron transporting light emitting material was further coated before the application of the electron transporting light emitting material solution. Therefore, the light emission intensity and the light emission luminance were significantly improved as compared with the case where the plasma treatment was not performed, and the good light emission characteristics were exhibited.

Example 5 After using the apparatus shown in FIG. 8 to form a hole transport layer (PEDOT layer) in the same manner as described in Example 1, the entire substrate including the hole transport layer is hotplated in the chamber. By heating at 50 ° C., 70 ° C. and 100 ° C. for 30 minutes respectively, and spin-coating a 0.7 wt% cyclohexanone solution of MEH-PPV on the hole transport layer of each of these three types of samples. Same as 1.

The luminous efficiency and luminous brightness of each organic electroluminescent device of this example are shown in Table 5 below. For comparison, the table also shows the measurement results of the luminous efficiency and the luminous brightness when the MEH-PPV solution was applied at room temperature (25 ° C.).

[0115]

[Table 5] Table 5

According to the above table, in each organic electroluminescent device of this example, the hole transport layer was heated before the application of the electron transporting light emitting material solution, and the electron transporting light emitting material was further applied. Therefore, the emission intensity and the emission brightness were improved, and good emission characteristics were exhibited. The heating temperature range is preferably 40 ° C. to 80 ° C., more preferably 50 ° C. to 70 ° C., from the viewpoint of light emission characteristics.

Example 6 After using the apparatus shown in FIG. 9 to form a hole transport layer in the same manner as described in Example 1, a heating gas (heating air) introduced at 70 ° C. was introduced into the chamber. In the same manner as in Example 1 except that the entire substrate including the hole transport layer was heated for 30 minutes in the atmosphere and the 0.7 wt% cyclohexanone solution of MEH-PPV was spin-coated within this heating time.

The luminous efficiency and luminous brightness of the organic electroluminescent device of this example are shown in Table 6 below. For comparison, the table also shows the measurement results of the luminous efficiency and the luminous brightness when the MEH-PPV solution was applied without using a heating atmosphere.

[0119]

[Table 6] Table 6

According to the above table, in the organic electroluminescent device of this example, the electron transporting light emitting material was prepared by heating the hole transporting layer in the heating gas atmosphere before the application of the electron transporting light emitting material solution. As compared with the case where no heating atmosphere was used, the emission intensity and emission brightness were improved, and good emission characteristics were exhibited.

Example 7 In the same manner as in Example 1 except that the hole transport layer (PEDOT layer) was applied and then the polymer layer: electron transporting light emitting layer (MEH-PPV layer) was applied by a printing method by letterpress printing. went. At that time, before and after applying the polymer layer, with and without the application of an organic solvent,
The light emission efficiency and the light emission brightness of the produced organic electroluminescence device are shown in Table 7 below.

[0122]

[Table 7] Table 7

According to the above table, in each organic electroluminescent device of this example, since the organic solvent was applied onto the hole transport layer before the application of the electron transporting light emitting material solution, the organic solvent was applied. The emission intensity and the emission brightness were greatly improved as compared with the case where the emission was not performed, and favorable emission characteristics were exhibited.

Example 8 The same procedure as in Example 1 was carried out except that after coating the hole transport layer (PEDOT layer), the polymer layer: electron transporting light emitting layer (MEH-PPV layer) was coated by the casting method. At that time, the luminous efficiency and the luminous brightness of the organic electroluminescence device produced were compared between the case where the organic solvent was applied before the application of the polymer layer and the case where it was not applied, as shown in Table 8 below.
Shown in.

[0125]

[Table 8] Table 8

According to the above table, in each organic electroluminescent device of this example, since the organic solvent was coated on the hole transport layer before the application of the electron transporting light emitting material solution, the organic solvent was coated. The emission intensity and the emission brightness were greatly improved as compared with the case where the emission was not performed, and favorable emission characteristics were exhibited.

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

For example, as the treatment for improving the wettability of the electron transporting light emitting material solution, the solution itself may be heated and applied in addition to the above treatment. Alternatively, it is also possible to combine the treatments of the above-mentioned respective embodiments and apply the organic solvent in a state where the substrate is heated, or place the substrate in an organic solvent atmosphere, for example.

The treatment is preferably performed after firing the hole transport layer, but the treatment may be performed before firing.

Further, the organic solvent used for improving the wettability is the same as the organic solvent of the electron transporting light emitting material solution, and the effect of improving the light emitting property is better (see Table 1 above).
However, it does not matter if they are different. The organic solvent that can be used is preferably cyclohexanone, p-xylene, tetrahydrofuran, etc. described above, but other organic solvents may be used and can be appropriately changed depending on the material to be applied.

In the above example, since the organic electron-transporting light-emitting layer was laminated on the water-soluble hole transporting layer, the lower layer was treated with the organic solvent. It is also possible that a lower layer soluble in an organic solvent is treated with water and then a water-soluble upper layer is formed by coating.

Then, the type and concentration of the organic solvent, the coating method, the coating amount, the thickness, etc., the concentration of the organic solvent atmosphere, the introduction method, the heating method for the substrate and the hole transport layer, the heating temperature, the heating time, etc. The treatment time in the gas plasma treatment, the type of gas plasma used, and the like may be arbitrary as long as they have a predetermined effect.

Further, the electron-transporting light-emitting layer is provided on the entire substrate as in the above-mentioned example.
It may be provided by patterning (for example, in a matrix) by printing or the like.

The electron-transporting light-emitting material is shown in FIG.
Other than MEH-PPV shown in Fig. 11 (2).
The PPV derivative such as CN-PPV shown in FIG. 11 or the PPV shown in FIG. Hole transport material is also PED
It may be selected from known materials other than OT.

[0135]

As described above, according to the present invention, when the other substance layer is formed on the one substance layer, the wettability of the coating liquid for forming the other substance layer is improved. Since it is subjected to a treatment for improving the wettability of the coating liquid of one substance layer to the other substance layer, it is possible to improve the bondability between both substance layers, and form a laminated structure with high luminous efficiency. can do.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a manufacturing process of an organic electroluminescent device according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view showing a manufacturing process of the same organic electroluminescent element.

FIG. 3 is a cross-sectional view showing a manufacturing process of the same organic electroluminescent element.

FIG. 4 is a cross-sectional view showing a manufacturing process of an organic electroluminescent device according to another embodiment of the present invention.

FIG. 5 is a cross-sectional view showing a manufacturing process of an organic electroluminescent device according to still another embodiment of the present invention.

FIG. 6 is a cross-sectional view showing an apparatus used for manufacturing an organic electroluminescence device according to an embodiment of the present invention.

FIG. 7 is a cross-sectional view showing an apparatus used for manufacturing an organic electroluminescent device according to another embodiment of the present invention.

FIG. 8 is a sectional view showing an apparatus used for manufacturing an organic electroluminescent device according to another embodiment of the present invention.

FIG. 9 is a cross-sectional view showing an apparatus used for manufacturing an organic electroluminescent device according to another embodiment of the present invention.

FIG. 10 is a cross-sectional view showing an apparatus used for manufacturing an organic electroluminescent device according to still another embodiment of the present invention.

FIG. 11 is a molecular structure diagram of various electron-transporting light emitting materials that can be used in the present invention.

FIG. 12 is a molecular structure diagram of the hole transport material.

FIG. 13 is a schematic cross-sectional view showing an example of a conventional organic electroluminescent device.

FIG. 14 is a schematic cross-sectional view showing another example of the organic electroluminescent element.

FIG. 15 is a schematic cross-sectional view showing an example of a specific layer structure of the organic electroluminescent element.

FIG. 16 is a schematic diagram showing a configuration example of a flat display using the same organic electroluminescent element.

FIG. 17 is a cross-sectional view showing an apparatus used for manufacturing the organic electroluminescence element of the same.

[Description of Reference Signs] 1, 8, 51 ... Glass substrate, 2 ... ITO transparent pixel electrode (anode), 4, 54 ... Hole transport layer (PEDOT layer),
4a ... PEDOT aqueous solution, 5, 55 ... Electron transporting light emitting layer (MEH-PPV layer), 5a, 55a ... MEH-PPV
Solution, 6 ... Coating device, 7 ... Epoxy resin, 9 ... Au-G
e layer, 10 ... Aluminum layer, 13 ... Calcium layer, 2
2 ... Cathode, 23 ... Organic electroluminescent device, 39A, 39B,
39C, 39C ', 39D, 39E, 59A, 59B,
59C, 59D ... Chamber (treatment tank), 40 ... Belt, 41 ... Roller, 42 ... Organic solvent layer, 42a ... Organic solvent, 42b ... Organic solvent atmosphere, 43 ... Hot plate,
80 ... Heating gas atmosphere, 81 ... Plasma irradiation

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Yasunori Onijima             6-735 Kita-Shinagawa, Shinagawa-ku, Tokyo Soni             -Inside the corporation F-term (reference) 3K007 AB03 AB04 AB15 DB03 FA01                       FA03

Claims (17)

[Claims] 1. A laminated structure having a layer having a light emitting region between a first electrode and a second electrode, the layer having a first material layer and a second material layer having different physical properties. In the method for manufacturing an electroluminescent element, which comprises: forming a material layer of either one of the first material layer and the second material layer, and then forming the other material layer thereon. A method for manufacturing an electroluminescent device, characterized in that a treatment for improving the wettability of a coating liquid for forming the other substance layer is performed. 2. The method according to claim 1, wherein after forming the one material layer, a solvent used for a coating liquid of the other material layer is applied thereon, and further a coating liquid of the other material layer is applied. A method for manufacturing the electroluminescent device as described above. 3. The electroluminescent device according to claim 1, wherein the coating liquid for the other material layer is applied onto the one material layer in an atmosphere of a solvent used for the coating liquid for the other material layer. Production method. 4. The coating liquid for the other material layer is applied onto the one material layer after the surface of the one material layer is brought into contact with the atmosphere of the solvent used for the coating liquid for the other material layer. The method for manufacturing an electroluminescent device according to claim 3. 5. The method of manufacturing an electroluminescent element according to claim 1, 2 or 3, wherein the solvents used for the coating liquid for the one material layer and the coating liquid for the other material layer are different from each other. 6. The method for manufacturing an electroluminescent element according to claim 5, wherein the one material layer is water-soluble and the other material layer is soluble in an organic solvent. 7. The method of applying an organic solvent or water as the solvent, or forming the one material layer or the other material layer by a thin film forming method such as a spin coating method, a printing method and a casting method. 2. The method for manufacturing an electroluminescent element according to 2. 8. The method for manufacturing an electroluminescent element according to claim 2, wherein the solvent is heated. 9. The solvent is cyclohexanone, p-xylene, o-xylene, m-xylene, Mix-xylene, tetrahydrofuran, toluene, ethylbenzene,
The method for manufacturing an electroluminescent device according to claim 2, comprising at least one selected from cyclohexane, methyl cellosolve, and butyl cellosolve. 10. The method for manufacturing an electroluminescent device according to claim 1, wherein the treatment is performed by plasma treatment of the one material layer. 11. The method for manufacturing an electroluminescent device according to claim 10, wherein the plasma treatment is performed by gas plasma. 12. The method for manufacturing an electroluminescent element according to claim 1, wherein the one material layer is heated to perform the treatment, and the coating liquid is applied onto the one material layer during or after the heating. . 13. The method for manufacturing an electroluminescent element according to claim 1, 5 or 6, wherein the coating liquid is heated and the heated coating liquid is applied onto the one material layer. 14. The method for manufacturing an electroluminescence device according to claim 12, wherein the heating is performed by a hot plate. 15. The method for manufacturing an electroluminescent element according to claim 1, wherein the treatment is performed after or before firing the one material layer. 16. The method for manufacturing an electroluminescent device according to claim 1, wherein the light emitting region includes a crystallized π-electron conjugated polymer layer. 17. The method of manufacturing an electroluminescent device according to claim 1, wherein the one material layer is a hole transport layer, and the other material layer is an electron transport layer.