JPH09330790A - Manufacture of organic electroluminescent element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stabilize an organic thin film shape for a long period and improve heat resistance in particular by performing a photoirradiation in a non-oxide atmosphere after an organic light emitting layer is formed. SOLUTION: A positive electrode 2 is provided on a substrate 1 and an organic light emitting layer 3 is provided on the electrode 2. A layer 3 is formed by a hole transfer material injected from the electrode 2 and a material which recouples electrons injected from a negative electrode 4 by efficiently transferring electrons and efficiently emits light by the recoupling, between electrodes to which an electric field is given. In this case, the layer 3 is divided into hole transfer layer 3a and an electron transfer layer 3b to improve light emission efficiency. By irradiating these layers 3a and 3b with light in a non-oxidizing atmosphere after the layers 3a and 3b are laminated on the electrode 2 and formed by a coating method or a vacuum deposition method, the thin film shapes are remarkably stabilized. The wavelength range of the light source for light irradiation is set to be in the range of 300 to 750nm and the optical intensity of the light irradiation is set to be in the range of 0.1 to 100mW/cm<2> . Thus, the layers have the stable thin film shapes for a longer period and heat resistance in particular can be improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing an organic electroluminescence device, and more particularly to a method for manufacturing a thin film type device which emits light by applying an electric field to a light emitting layer made of an organic compound. .

[0002]

2. Description of the Related Art Conventionally, as a thin film type electroluminescent (EL) element, Zn, which is a group II-VI compound semiconductor of an inorganic material, is used.
In general, S, CaS, SrS, etc., doped with Mn or a rare earth element (Eu, Ce, Tb, Sm, etc.), which is a luminescent center, are used. ) AC drive is required (50-1000Hz),
There are problems that (2) the driving voltage is high (up to 200 V), (3) it is difficult to realize full color (especially, blue is a problem), and (4) the cost of the peripheral driving circuit is high.

However, in recent years, in order to improve the above problems,
Development of EL devices using organic thin films has been started. In particular, in order to improve the light emission efficiency, the type of electrode is optimized for the purpose of improving the efficiency of carrier injection from the electrode, and the organic hole transport layer made of an aromatic diamine and the organic light emission made of an aluminum complex of 8-hydroxyquinoline. Of an organic electroluminescent device provided with a layer (Appl. Phy
s. Lett. , Vol. 51, p. 913, 1987), the luminous efficiency is greatly improved as compared with a conventional EL device using a single crystal such as anthracene, and the practical characteristics are approached.

In addition to the electroluminescence device using the low molecular weight material as described above, poly (p-phenylene vinylene) (Nature, 347, 539) is used as a material for the organic light emitting layer.
P., 1990, etc.), poly [2-methoxy-5- (2-
Ethylhexyloxy) -1,4-phenylene vinylene] (Appl. Phys. Lett., 58, 19
82, etc.), poly (3-alkylthiophene) (Jp
n. J. Appl. Phys., Vol. 30, L1938, etc.) and the development of an electroluminescent device using a polymer material, and a device in which a low molecular light emitting material and an electron transfer material are mixed with a polymer such as polyvinyl carbazole (Applied Physics, Vol. 61) , 10
Page 44, 1992) is also under development.

[0005]

The biggest problem of the organic electroluminescent device is the service life during driving. There are several factors that shorten the life of the device, but the dominant factor is deterioration of the thin film shape of the organic light emitting layer. It is considered that the deterioration of the shape of the thin film is due to crystallization (or aggregation) of the organic amorphous film due to heat generated when the device is driven. Organic thin films formed from low molecular weight (molecular weight of about 400 to 600) molecules crystallize through Van der Waals forces during or after thin film formation, resulting in an island-like aggregate structure. There are many.

Several attempts have been made to prevent this crystallization. Usually, an organic electroluminescence device is manufactured by a vacuum vapor deposition method, but a stable crystalline thin film is obtained during vacuum vapor deposition (Japanese Patent Laid-Open No. 3-173095), or a substrate is cooled to obtain a uniform thin film. (Jpn. J. App
l. Phys. , 30, L864, 1991),
Heating the substrate when depositing phthalocyanine as a hole transport layer (85 ° C., 100 ° C.) (JP-A-2-127)
However, the improvement of the thin film state of the organic light emitting layer was insufficient. Although the light emitting layer and the charge transport layer are thinned while irradiating light (Japanese Patent Laid-Open No. 4-167395), the vacuum vapor deposition apparatus becomes complicated and sufficient for irradiating from the substrate side. It wasn't effective.

Attempts have been made to use a polymer material as a light emitting layer of an organic electroluminescence device instead of a low molecular weight material as described above. However, since a thin film is formed by a wet method such as coating, impurities are contained. Is difficult to control, and currently the luminous efficiency is insufficient. For the above-mentioned reason, the practical life of the organic electroluminescence device has a serious problem in the driving life of the device, and it is a large light source for a backlight of a facsimile, a copying machine, a liquid crystal display or the like. This is a problem and is a characteristic that is not desirable as a display element such as a flat panel display. .

[0008]

In view of the above situation, the inventors of the present invention have conducted extensive studies for the purpose of providing an organic electroluminescent device which exhibits stable emission characteristics over a long period of time.
After forming the organic light emitting layer, it was found that the shape of the organic thin film was stabilized by irradiating with light in a non-oxidizing atmosphere, and the present invention was completed.

That is, the gist of the present invention is to manufacture an organic electroluminescent device in which an anode, at least an organic light emitting layer, and a cathode are sequentially laminated on a substrate, and after the organic light emitting layer is formed, in an non-oxidizing atmosphere. It exists in the manufacturing method of the organic electroluminescent element characterized by irradiating light.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a method for manufacturing an organic electroluminescent device according to the present invention will be described with reference to the drawings. FIG. 1 is a cross-sectional view schematically showing a structural example of a general organic electroluminescent device used in the present invention, where 1 is a substrate, 2 is an anode, 3 is an organic light emitting layer, and 4 is a cathode.

The substrate 1 serves as a support for the organic electroluminescent device, and is made of a quartz or glass plate, a metal plate or a metal foil, a plastic film or a sheet, or the like. Particularly, a glass plate or a plate of a transparent synthetic resin such as polyester, polymethacrylate, polycarbonate, and polysulfone is preferable. When using a synthetic resin substrate, it is necessary to pay attention to gas barrier properties. If the gas barrier property of the substrate is too low, the organic electroluminescent element may deteriorate due to the outside air passing through the substrate, which is not preferable. Therefore, a method of providing a dense silicon oxide film or the like on at least one surface of the synthetic resin substrate to secure the gas barrier property is also a preferable method.

An anode 2 is provided on the substrate 1, and the anode 2 plays a role of injecting holes into the organic light emitting layer. This anode is usually a metal such as aluminum, gold, silver, nickel, palladium, platinum, a metal oxide such as an oxide of indium and / or tin, a halogenated metal such as copper iodide, carbon black, or poly. (3-
Methylthiophene), polypyrrole, polyaniline, and other conductive polymers. Usually, the formation of the anode 2 is often performed by a sputtering method, a vacuum evaporation method, or the like. In the case of fine metal particles such as silver, fine particles such as copper iodide, carbon black, conductive metal oxide fine particles, or conductive polymer fine powder, they are dispersed in a suitable binder resin solution and To form the anode 2. Further, in the case of a conductive polymer, a thin film may be directly formed on the substrate 1 by electrolytic polymerization, or the conductive polymer may be applied on the substrate 1 to form the anode 2 (Appl. Phys. Lett. , 6
0, 2711, 1992). The anode 2 can be formed by laminating different materials. The thickness of the anode 2 depends on the required transparency. When transparency is required, the visible light transmittance is usually 60% or more, preferably 80% or more. In this case,
The thickness is usually 5 to 1000 nm, preferably 10 to 5
It is about 00 nm. If opaque, the anode 2 may be the same as the substrate 1. Further, it is also possible to laminate a different conductive material on the anode 2.

An organic light emitting layer 3 is provided on the anode 2. The organic light emitting layer 3 efficiently transports and recombines the holes injected from the anode 2 and the electrons injected from the cathode 4 between the electrodes to which an electric field is applied, and emits light efficiently by the recombination. Formed from material. Usually, in order to improve the luminous efficiency, the organic light emitting layer 3 is divided into a hole transporting layer 3a and an electron transporting layer 3b so as to have a function separation type (Appl. Phys). . Le
tt. , 51, 913, 1987).

In the above-mentioned function-separated device, the material of the hole transport layer 3a is a material having a high hole injection efficiency from the anode 2 and capable of efficiently transporting the injected holes. It is necessary. For that purpose, it is required that the ionization potential is small, the hole mobility is large, the stability is excellent, and the impurities serving as traps are not easily generated during manufacturing or use.

As such a hole transport material, for example, an aromatic diamine compound in which a tertiary aromatic amine unit such as 1,1-bis (4-di-p-tolylaminophenyl) cyclohexane is linked (Japanese Patent Application Laid-Open No. 2000-242242) Sho 59-19439
3), 4,4'-bis [N- (1-naphthyl)-
Aromatic amines containing two or more tertiary amines represented by N-phenylamino] biphenyl and having two or more condensed aromatic rings substituted with nitrogen atoms (Japanese Patent Laid-Open No. 5-234681) and triphenylbenzene. An aromatic triamine having a starburst structure as a derivative (US Pat.
3,774), N, N'-diphenyl-N,
N'-bis (3-methylphenyl) biphenyl-4,
Aromatic diamines such as 4'-diamine (U.S. Pat.
64,625), α, α, α ′, α′-tetramethyl-α, α′-bis (4-di-p-tolylaminophenyl) -p-xylene (JP-A-3-269084). ), A triphenylamine derivative which is sterically asymmetric as a whole molecule (JP-A-4-12971), a compound in which a plurality of aromatic diamino groups are substituted on a pyrenyl group (JP-A-4-175395), and an ethylene group. Aromatic diamines linked with tertiary aromatic amine units
264189), aromatic diamines having a styryl structure (JP-A-4-290851), those in which aromatic tertiary amine units are linked by a thiophene group (JP-A-4-304466), and starburst type aromatics. Triamine (JP-A-4-308688), benzylphenyl compound (JP-A-4-364153), and tertiary amine linked by a fluorene group (JP-A 5-2).
5473), triamine compounds (JP-A-5-23)
9455), bisdipyridylaminobiphenyl (JP-A-5-320634), N, N, N-triphenylamine derivative (JP-A-6-1972),
Aromatic diamine having phenoxazine structure
No. 138562), a diaminophenylphenanthridine derivative (JP-A-7-252474), a hydrazone compound (JP-A-2-311591), a silazane compound (US Pat. No. 4,950,950), Examples thereof include silanamine derivatives (JP-A-6-49079), phosphamine derivatives (JP-A-6-25659), and quinacridone compounds. These compounds may be used alone, or may be mixed and used as needed.

In addition to the above compounds, polyvinylcarbazole and polysilane (Ap) are used as materials for the hole transport layer 3a.
pl. Phys. Lett. 59, 2760, 1
991), polyphosphazene (JP-A-5-3109)
No. 49), polyamide (JP-A-5-310949), polyvinyl triphenylamine (JP-A-7-5).
3953), a polymer having a triphenylamine skeleton (Japanese Patent Application Laid-Open No. 4-1330065), and a polymer in which triphenylamine units are linked by a methylene group or the like (Synt.
hetic Metals, 55-57, 4163
P. 1993), polymethacrylates containing aromatic amines (J. Polym. Sci., Polym. C).
hem. Ed. , 21, 969, 1983).

The hole transport layer 3a is formed by laminating the above hole transport material on the anode 2 by a coating method or a vacuum deposition method. In the case of the coating method, one or more hole transporting materials and, if necessary, an additive such as a binder resin or a coatability improving agent that does not become a hole trap are added and dissolved to prepare a coating solution. Then, it is applied on the anode 2 by a method such as a spin coating method and dried to form the organic hole transport layer 3a. Examples of the binder resin include polycarbonate, polyarylate, and polyester. The addition amount of the binder resin decreases the hole mobility when it is added in a large amount.
The following is preferred.

In the case of the vacuum vapor deposition method, the hole transport material is put in a crucible installed in a vacuum container, the interior of the vacuum container is evacuated to about 10 ⁻⁴ Pa by an appropriate vacuum pump, and then the crucible is heated. Then, the hole transport material is evaporated to form the hole transport layer 3a on the anode 2 on the substrate 1 placed facing the crucible. When forming the hole transport layer 3a, a metal complex and / or a metal salt of an aromatic carboxylic acid is further used as an acceptor (JP-A-4-320484).
Benzophenone derivatives and thiobenzophenone derivatives (JP-A-5-295361), fullerenes (JP-A-5-331458), etc., in an amount of 10 ^-3 to 10% by weight.
, To generate holes as free carriers, thereby enabling low-voltage driving.

The thickness of the hole transport layer 3a is usually 10-3.
00 nm, preferably 30 to 100 nm. In order to uniformly form such a thin film, generally, a vacuum deposition method is often used. Further improve the efficiency of hole injection,
In addition, for the purpose of improving the adhesion of the entire organic layer to the anode, the hole injection layer 3a ′ is provided between the hole transport layer 3a and the anode 2.
Has also been inserted (Fig. 3). Hole injection layer 3
The material used for a'is preferably a material having a low ionization potential, a high conductivity, and a thermally stable thin film formed on the anode. A phthalocyanine compound or a porphyrin compound (JP-A-57-51781, JP-A-63-295695) is used. By inserting the hole injection layer 3a ', the driving voltage of the element at the initial stage is lowered, and at the same time, the voltage rise when the element is continuously driven with a constant current is suppressed. It is also possible to improve conductivity by doping the hole injection layer 3a ′ with an acceptor in the same manner as the hole transport layer 3a.

The film thickness of the hole injection layer 3a 'is usually 2-1.
00 nm, preferably 5 to 50 nm. In order to uniformly form such a thin film, generally, a vacuum deposition method is often used. An electron transport layer 3b is formed on the hole transport layer 3a.
Is provided. The electron-transporting layer 3b efficiently transfers electrons from the cathode between the electrodes to which an electric field is applied.
Formed of a compound that can be transported in the direction of.

The electron-transporting compound used in the electron-transporting layer 3b needs to be a compound having a high electron injection efficiency from the cathode 4 and capable of efficiently transporting the injected electrons. For this purpose, it is required that the compound has a high electron affinity, a high electron mobility, a high stability, and an impurity which becomes a trap and hardly occurs during production or use.

As a material satisfying such a condition, an aromatic compound such as tetraphenyl butadiene (Japanese Patent Application Laid-Open No. Sho 5 (1999) -58138)
7-51781), a metal complex such as an aluminum complex of 8-hydroxyquinoline (JP-A-59-1943).
No. 93), cyclopentadiene derivatives (Japanese Unexamined Patent Publication No.
289675), perinone derivatives (JP-A-2-2)
No. 89676), oxadiazole derivatives (Japanese Patent Application Laid-Open No. 2-216991), and bisstyrylbenzene derivatives (Japanese Patent Application Laid-Open Nos. 1-245087 and 2-222448).
4), perylene derivative (JP-A-2-189890).
JP-A No. 3-791), coumarin compounds (JP-A-2-191694, JP-A-3-792), rare earth complexes (JP-A-1-256584), and distyrylpyrazine derivatives (JP-A-2-252793). Gazette), p-phenylene compound (JP-A-3-33183), thiadiazolopyridine derivative (JP-A-3-37292), pyrrolopyridine derivative (JP-A-3-37293), naphthyridine derivative (special Kaihei 3-203982
Publication).

Electron transport layer 3b using these compounds
Can generally play a role of transporting electrons and a role of producing light emission upon recombination of holes and electrons at the same time. When the hole transport layer 3a has a light emitting function, the electron transport layer 3b may serve only to transport electrons. For the purpose of improving the luminous efficiency of the device and changing the luminescent color, for example, by doping an aluminum complex of 8-hydroxyquinoline as a host material with a fluorescent dye for laser such as coumarin (J. Appl. Phys.,
65, 3610, 1989).
Also in the present invention, the emission characteristics of the device can be further improved by doping the above-mentioned organic electron transport material as a host material with various fluorescent dyes at 10 ⁻³ to 10 mol%. The thickness of the electron transport layer 3b is usually 10 to 200.
nm, preferably 30-100 nm.

The electron transport layer can also be formed in the same manner as the hole transport layer, but a vacuum deposition method is usually used. As a method of further improving the luminous efficiency of the organic electroluminescent device, another electron transport layer 3c can be further stacked on the electron transport layer 3b. The compound used for the electron transport layer 3c is required to be capable of easily injecting electrons from the cathode and have a higher electron transport capability. As such an electron transport material, an oxadiazole derivative (A
ppl. Phys. Lett. , 55, 1489 pages,
1989 and others) and polymethylmethacrylate (P
Systems dispersed in resin such as MMA (Appl. Phys.
Lett. , 61, 2793, 1992), phenanthroline derivative (JP-A-5-331459), n-type hydrogenated amorphous silicon carbide, n-type zinc sulfide, n-type zinc selenide and the like. The thickness of the electron transport layer 3c is usually 5 to 200 nm, preferably 10
-100 nm.

Single-layer organic light-emitting layer 3 without function separation
As the above-mentioned poly (p-phenylene vinylene)
(Nature, 347, 539, 1990 et al.), Poly [2-methoxy-5- (2-ethylhexyloxy) -1,4-phenylenevinylene] (Appl.
Phys. Lett. , 58, 1982, 1991.
Etc.), poly (3-alkylthiophene) (Jpn.
J. Appl. Phys, Volume 30, L1938, 19
1991, etc.), a system in which a light emitting material and an electron transfer material are mixed with a polymer such as polyvinylcarbazole (Applied Physics, 61, 1044, 1992).

The cathode 4 plays a role of injecting electrons into the organic light emitting layer 3. The material used for the cathode 4 may be the material used for the anode 2, but a metal having a low work function is preferable for efficient electron injection, and tin, magnesium, indium, calcium, Suitable metals such as aluminum and silver or alloys thereof are used. The thickness of the cathode 4 is usually the same as that of the anode 2. In order to protect the cathode made of low work function metal,
Furthermore, laminating a metal layer having a high work function and being stable to the atmosphere increases the stability of the device. For this purpose, metals such as aluminum, silver, nickel, chromium, gold, platinum and the like are used.

Besides the structure shown in FIGS. 1 to 3, an organic electroluminescent device having the following layer structure is used in the present invention.

[0028]

[Table 1] Anode / hole transport layer / electron transport layer / interface layer / cathode, anode / hole transport layer / electron transport layer / other electron transport layer /
Cathode, anode / hole transport layer / electron transport layer / other electron transport layer / interface layer / cathode, anode / hole injection layer / hole transport layer / electron transport layer / interface layer / cathode, anode / hole injection Layer / hole transport layer / electron transport layer / other electron transport layer / cathode.

In the above layer structure, the interface layer is for improving the contact between the cathode and the organic layer, and is an aromatic diamine compound (JP-A-6-267658) or a quinacridone compound (JP-A-6-330031). ), A naphthacene derivative (JP-A-6-330032), an organic silicon compound (JP-A-6-325871), an organic phosphorus compound (JP-A-6-325872), a compound having an N-phenylcarbazole skeleton (special Wishhei 6-19
9562), N-vinylcarbazole polymer (Japanese Patent Application No. 6-200942) and the like.
The thickness of the interface layer is usually 2 to 100 nm, preferably 5
３０30 nm. Instead of providing the interface layer, a region containing 50% by weight or more of the material for the interface layer may be provided near the cathode interface between the organic light emitting layer and the electron transport layer.

It is also possible to have a structure opposite to that shown in FIG. 1, that is, a cathode 4, an organic light emitting layer 3 and an anode 2 may be laminated in this order on the substrate, and as described above, at least one of them has high transparency. It is also possible to provide the organic electroluminescent element of the present invention between two substrates. Similarly, it is also possible to stack in a structure opposite to that shown in FIGS. As described above, the organic thin film formed by the vacuum vapor deposition method or the coating method causes local crystallization due to Joule heat generation when the device is driven, and partially aggregates from the uniform amorphous state after formation. The state changes, and the flatness of the thin film shape is lost. As a result, the adhesion at the interface between the organic light emitting layer and the anode and at the interface between the organic light emitting layer and the cathode is reduced, leading to a decrease in brightness and the generation of non-light emitting portions called dark spots. This deterioration phenomenon is a problem common to each laminated structure shown in FIGS.
Even if the above-mentioned shape deterioration occurs in which layer and which interface, the light emission characteristics are deteriorated.

In the present invention, it was found that the shape of the thin film is remarkably stabilized by forming the organic thin film by the vacuum vapor deposition method or the coating method and then irradiating with light in a non-oxidizing atmosphere. In the device structure shown in FIG. 1, the organic thin film is irradiated with light before the cathode 4 is formed. 2 and 3 in which the organic light emitting layer has a laminated structure, a sufficient effect can be obtained even after the formation of all the organic layers and the formation of the hole transport layer 3a.

The light source wavelength range for light irradiation is preferably 300 to 750 nm, and chemical bonds are broken on the shorter wavelength side than 300 nm, causing a chemical change in the organic thin film and deteriorating the light emission characteristics. On the wavelength side longer than 750 nm, the energy of light is insufficient, so that migration of molecules cannot be sufficiently caused, and the effect of stabilizing the thin film shape cannot be obtained.

If an oxidizing gas such as oxygen is present in the atmosphere during light irradiation, the organic thin film is photooxidized and deteriorated. Therefore,
The atmosphere during light irradiation must be non-oxidizing,
It is desirable that oxygen, water, carbon dioxide, nitrogen oxides, and sulfur oxides are not present in the atmosphere. Therefore, light irradiation is performed in an atmosphere of an inert gas such as nitrogen or argon or in a vacuum. The irradiation intensity of light is preferably in the range of 0.1 to 100 mW / cm 2, and the treatment time is selected in the range of 1 second to 30 minutes.

The above-mentioned light irradiation dramatically improves the shape stability of the organic thin film, and particularly the heat resistance is remarkably improved.
In order to improve the reliability of the organic electroluminescent device, the present invention provides
Has a great effect. FIG. 4 shows an example of an apparatus for performing light irradiation processing. A xenon lamp is used as the light source 11,
After passing through the infrared cut filter 12, a wavelength is selected by a bandpass filter 13 having a predetermined wavelength, and after being introduced into the container 18 through a quartz irradiation window 14, the organic thin film sample 16 is irradiated by a mirror 15. Light irradiation processing container 18
The atmosphere inside uses purge valves 19 and 20,
For example, it is replaced with nitrogen gas.

The present invention can be applied to any one of the organic electroluminescence device, a single device, a device having an arrayed structure, and a structure in which an anode and a cathode are arranged in an XY matrix. You can

[0036]

EXAMPLES Next, the present invention will be described more specifically with reference to examples, but the present invention is not limited to the description of the following examples unless it exceeds the gist. Example 1 An organic thin film was prepared by the following method using a vacuum deposition method by resistance heating.

As the organic hole transport layer material, N, N'-diphenyl-N, N'-bis (3-methylphenyl) -1,1'-biphenyl-4,4'-diamine (H1) shown below is used.

[0038]

Embedded image

Tungsten in a normal vacuum evaporation system
It is placed in a boat and a transparent conductive film of indium tin oxide (ITO) is deposited to a thickness of 120 nm on a glass substrate (HO
Ultrasonic cleaning of YA company; sputtered film product) with acetone,
After washing with pure water, ultrasonic washing with isopropyl alcohol, and drying with dry nitrogen, it was placed facing the boat in the vacuum deposition apparatus at a distance of 30 cm. The degree of vacuum in the equipment is 3 × 1
It was evacuated using an oil diffusion pump equipped with a liquid nitrogen trap until it became 0 ^-5 Torr (about 4 × 10 ^-3 Pa) or less.

The tungsten boat was heated to evaporate the sample for vapor deposition. Vapor deposition rate is 0.2-0.3
A vapor deposition film sample A having a film thickness of 50 nm was obtained at nm / sec. After forming the hole transport layer (film thickness 50 nm) made of the compound (H1) under the same production conditions as the vapor deposition film sample A, aluminum 8 shown in the following structural formula was used as a material for the light emitting electron transport layer.
-Hydroxyquinoline complex, Al (C ₉ H ₆ NO) ₃ (E
1)

[0041]

Embedded image

Vapor deposition was performed in the same manner as in Sample A except that Deposition rate is 0.2-0.3 nm / sec and film thickness is 5
A 0 nm light emitting layer was laminated on the hole transport layer to prepare a vapor deposition film sample B. After taking out the samples A and B thus obtained from the vacuum vapor deposition apparatus, light irradiation treatment was performed using the apparatus shown in FIG. The light irradiation conditions are as follows: ・ Light source: Xenon lamp ・ Wavelength: 390 nm (using infrared cut filter and bandpass filter) ・ Light intensity: 7.5 mW / cm ²・ Time: 20 minutes The atmosphere was purged with nitrogen to prevent photooxidation of the sample.

Next, the samples A and B which had been subjected to the above light irradiation treatment were stored at a temperature of 60 ° C. for 24 hours and then observed under a microscope. In each of Samples A and B, the uniform thin film shape after vapor deposition was maintained, and crystallization was not observed.

Comparative Example 1 ITO was prepared in the same manner as in Example 1 except that the light irradiation treatment was not performed.
The following samples were prepared on a glass substrate. Sample C: Compound (H1) 50 nm Sample D: Compound (H1) 50 nm / Compound (E1) 50
nm Samples C and D were stored at a temperature of 60 ° C. for 24 hours in the same manner as in Example 1 and then observed under a microscope. It was observed that in the sample C, crystals having an average diameter of about 0.4 mm were uniformly generated on the entire surface of the sample. It was observed that a large number of dendrite-like crystallization patterns were generated in Sample D as well.

Example 2 An organic electroluminescent device having the structure shown in FIG. 2 was produced by the following method. Indium tin oxide (ITO) transparent conductive film deposited to 120 nm on a glass substrate (HO
A sputtering film-forming product manufactured by YA Co., Ltd.) was patterned into a stripe having a width of 5 mm using an ordinary photolithography technique and hydrochloric acid etching to form an anode. The patterned ITO substrate was washed in the order of ultrasonic cleaning with acetone, water cleaning with pure water, and ultrasonic cleaning with isopropyl alcohol, followed by drying with nitrogen blow and installation in a vacuum deposition apparatus. After the equipment was roughly evacuated by an oil rotary pump, the degree of vacuum in the equipment was 2 × 10 ⁻⁶ Torr (about 2.7 × 10 ^−4).
It was evacuated using an oil diffusion pump equipped with a liquid nitrogen trap until the pressure became below Pa).

In the same manner as in Example 1, the hole transport layer (H
After forming 50 nm of 1), a luminescent electron transport layer (E
1) was laminated in a thickness of 50 nm. Here, the element on which the electron transport layer 3b was vapor-deposited was once taken out from the vacuum vapor deposition apparatus into the atmosphere and subjected to light irradiation treatment using the apparatus of FIG. 4 under the same conditions as in Example 1.

After the light irradiation treatment, a striped shadow mask having a width of 5 mm was used as a mask for depositing the cathode, and
Adhere to the element so that it is orthogonal to the TO stripe,
It is installed in another vacuum deposition apparatus and the degree of vacuum in the apparatus is 2 × 10 ^-6 Torr (about 2.7 × 10 ^-4 P
a) Evacuated to below. Then, as the cathode 4,
Aluminum was vapor-deposited by a vacuum vapor deposition method so as to have a film thickness of 100 nm. The evaporation is done using a molybdenum boat.
Degree of vacuum 1 × 10 ⁻⁵ Torr (about 1.3 × 10 ⁻³ Pa),
The deposition rate was 1 nm / sec.

A forward voltage, IT, was applied to each electrode of the organic electroluminescence device having a size of 5 mm × 5 mm obtained as described above.
A positive voltage was applied to the O anode and a negative voltage was applied to the aluminum cathode, and the light emission characteristics were measured. As a result, a light emission efficiency of 0.34 lumen / W was obtained. A non-luminous part called a dark spot was not observed. Subsequently, the device was stored in a nitrogen atmosphere at 60 ° C. for 24 hours, and the luminous efficiency was measured in the same manner. As a result, it was 0.32 lumen / W, which was not a practical problem. No dark spots were observed.

Comparative Example 2 An element was manufactured in the same manner as in Example 2 except that the light irradiation treatment was not performed. The luminous efficiency of the device was 0.36 lumen / W, and no dark spot was observed. This device was used in Example 2.
When the luminous efficiency was measured after storing it in a nitrogen atmosphere at 60 ° C. for 24 hours in the same manner as above, 0.10 lumen / W was not significantly decreased. The dark spot has an area of 5
Reached 0%.

[0050]

EFFECTS OF THE INVENTION According to the method for manufacturing an organic electroluminescent device of the present invention, by performing light irradiation treatment in a non-oxidizing atmosphere after forming an organic light emitting layer, a thin film shape that is stable for a long period of time, particularly heat resistance is obtained. It is possible to obtain an excellent element. Therefore, the organic electroluminescent device according to the present invention is a flat panel
A light source (for example, for an OA computer or a wall-mounted TV) or a surface light-emitting body (for example,
It can be applied to light sources of copiers, backlight sources of liquid crystal displays and instruments), display boards, and marker lights, and its technical value is great.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view showing an example of an organic electroluminescence device.

FIG. 2 is a schematic sectional view showing another example of the organic electroluminescent device.

FIG. 3 is a schematic cross-sectional view showing still another example of the organic electroluminescent element.

FIG. 4 is a schematic diagram showing an example of a light irradiation device for manufacturing an organic electroluminescent element.

[Explanation of symbols]

 1 substrate 2 anode 3 organic light emitting layer 4 cathode 3a hole transport layer 3b electron transport layer 3a 'hole injection layer 11 irradiation light source 12 infrared cut filter 13 bandpass filter 14 irradiation window 15 mirror 16 sample 17 sample stage 18 container 19 Purge gas introduction valve 20 Purge outlet valve

Claims (3)

[Claims] 1. When manufacturing an organic electroluminescent device in which an anode, at least an organic light emitting layer, and a cathode are sequentially laminated on a substrate, after the organic light emitting layer is formed, light irradiation is performed in a non-oxidizing atmosphere. And a method for manufacturing an organic electroluminescent device. 2. The light source wavelength of light irradiation is 300 to 750 nm.
The method for manufacturing an organic electroluminescent device according to claim 1, wherein 3. The light intensity of light irradiation is 0.1 to 100 mW /
The method for manufacturing an organic electroluminescent element according to claim 1, wherein the organic electroluminescent element has a size of cm ² .