JPH07147189A - Organic electroluminescent element - Google Patents

Abstract

PURPOSE:To significantly suppress the progress of deterioration by oxygen by providing a protecting layer on the outer surface of an organic electroluminescent (EL) element, and providing a sealing film in which a photosensitizer and an oxidizing compound are dispersed thereon. CONSTITUTION:A protecting layer 6 and a sealing layer 7 are formed, for example, on an organic EL element in which a transparent electrode 2, a positive hole transport layer 3, an EL layer 4 consisting of an organic material, and a counter electrode 5 are successively laminated on a glass base 1. The protecting layer 6 is formed of an electric insulating polymer compound film, and preferably provided on the whole outer surface of the laminated body structure, and its material is formed of a one film-formable by means of chemical phase evaporation, or a one soluble in a fluorine solvent. The sealing film 7 is formed of a light transmitting polymer preferably having a light transmittance of 80% or more, in which a photosensitizer and an oxidizable compound are dispersed. Since oxygen passing through the polymer is converted to singlet oxygen from the ground state by the photosensitizer in an excited state, the oxidizable compound is oxygenated, and oxygen is removed.

Description

Detailed Description of the Invention

[0001]

The present invention relates to a novel organic electroluminescence device (hereinafter abbreviated as organic EL device).
Regarding More specifically, the organic EL has a long life by significantly suppressing the progress of deterioration due to oxygen.
It is related to the element.

[0002]

2. Description of the Related Art For example, a plasma display panel (PDP) and an electroluminescence (EL) panel are known as those which emit light by themselves. The former plasma display panel was developed from the beginning for the purpose of a large-capacity flat display device and utilizes light emission generated by discharge in low-pressure gas. It is adopted as a device. On the other hand, the latter EL panel is expected as a completely solid, self-luminous thin flat display device. This is a semiconductor device similar to a light emitting diode (LED), but since it is a polycrystalline thin-layer device rather than a single crystal, it can have a large area and is advantageous in terms of cost.
The electrical characteristics and display performance are similar to those of the PDP, but the development history is short and the device is a promising device expected in the future.

When such EL light emitting devices are classified according to the material of the EL layer, those having an inorganic EL layer and those having an organic EL layer are used.
It is divided into those having an L layer. Regarding EL in organic compounds, research has started from the discovery of an EL emission phenomenon due to carrier injection in a single crystal such as anthracene having strong fluorescence, and has been developed into a thin film type element. In the above inorganic EL device, a transparent electrode, an insulating layer, a light emitting layer, an insulating layer, and a back electrode are sequentially formed on a glass substrate, and then sealed with an envelope to prevent invasion of moisture to further improve the moisture-proof effect. Therefore, the one in which silicon oil is enclosed in the envelope has been put into practical use. On the other hand, the organic EL element is extremely vulnerable to moisture or oxygen, for example, the interface between the metal electrode and the EL layer made of an organic material is peeled off due to the influence of moisture, the metal is oxidized to increase the resistance, or the organic material itself. Has a defect that it may be deteriorated by moisture and may not emit light. Therefore, in order to improve such a defect, it has been attempted to effectively prevent the harmful effects of water and oxygen by, for example, vacuum-sealing an organic EL element and then substituting it with helium gas.
36747). However, such a vacuuming structure requires a designing process of an airtight case, a sealing step after vacuuming, and the like, which causes a problem of inevitably increasing the manufacturing cost of the organic EL element.

[0004]

Under the circumstances, the present invention intends to effectively and significantly suppress the progress of deterioration due to oxygen by a simple method to extend the life of the organic EL. The purpose is to provide an element.

[0005]

Means for Solving the Problems The present inventors
As a result of intensive research on efficiently and significantly suppressing the deterioration of the element due to oxygen, a protective layer is provided on the outer surface of the element, and a photosensitizer and an oxidizable compound are dispersed on the protective layer. By providing the encapsulating film, the photosensitizer in the encapsulating film is excited by the light energy generated by the self-emission of the EL element, and the excited oxygen is activated by the excited photosensitizer. Furthermore, it was found that the activated oxygen oxidizes the oxidizable compound, and as a result, oxygen is efficiently removed, and the above-mentioned object can be achieved. The present invention has been completed based on such findings. That is, the present invention is an organic EL device including an anode and a cathode and one or more layers of organic material sandwiched between them.
An organic EL device, characterized in that a protective layer is provided on the outer surface of the device, and a sealing film in which a photosensitizer and an oxidizable compound are dispersed is further provided on the protective layer. Is. An organic EL element of the present invention will be described with reference to the accompanying drawings. FIG. 1 is a configuration diagram of an example of the organic EL element of the present invention, in which a transparent electrode 2 such as ITO and a hole transport layer 3 are formed on a glass substrate 1. , EL layer 4 made of organic material
1 and the counter electrode 5 are sequentially laminated, the protective layer 6 is provided on the outer surface of the laminated structure, and the sealing film 7 is further provided on the protective layer 6.

Here, as the constitution of the laminated structure,
For example, (1) electrode (cathode) / light emitting layer / hole injection layer / electrode (anode), (2) electrode (anode) / light emitting layer / electron injection layer / electrode (cathode), (3) electrode (anode) / Hole injecting layer / light emitting layer / electron injecting layer / electrode (cathode), (4) electrode (anode or cathode) / light emitting layer / electrode (cathode or anode), etc. Organic E with structure
It can also be applied to L elements. The shape, size, material, manufacturing method, etc. of this laminated structure are the same as those of the organic EL.
It is appropriately selected depending on the use of the element, etc., but these are not particularly limited in the present invention. However, in order to obtain a long-life organic EL device, it is desirable to suppress the characteristic deterioration of the light emitting layer in the process of forming the laminated structure as much as possible. For that purpose, from the formation of the light emitting layer to the formation of the counter electrode. It is particularly preferable to carry out under a series of vacuum environments.
In the present invention, first, a protective layer (6 in FIG. 1) made of an electrically insulating polymer compound film is provided on the outer surface of the laminated structure. The protective layer may be provided at least on the main surface of the counter electrode, but it is particularly preferable that it be provided on the entire outer surface of the laminated structure. In the organic EL element in which the counter electrode is structurally provided on a part of the main surface of any one of the light emitting layer, the hole injection layer, and the electron injection layer, at least the layer serving as the base of the counter electrode. It is preferable to provide a protective layer on the main surface of the counter electrode and on a portion of the main surface where the counter electrode is not provided. The electrically insulating polymer compound as a material for the protective layer can be formed into a film by a physical vapor deposition method (hereinafter sometimes referred to as PVD method), a chemical vapor deposition method (hereinafter sometimes referred to as CVD method). .), Or a substance soluble in a fluorine-based solvent such as perfluoroalcohol, perfluoroether, or perfluoroamine.
There is no particular limitation, but a material having a low water vapor permeability is preferable.
Specific examples of such an electrically insulating polymer compound include:
The following are listed.

(1) Electrically insulating polymer compound which can be formed into a film by the PVD method: polyethylene, polypropylene, polystyrene, polymethylmethacrylate, polyimide [2
A type of monomer deposited on a substrate and polymerized,
"Technical Journal" Volume 30, Page 22 (1
1988)], polyurea [two kinds of monomers deposited on a substrate and polymerized, "Technical Journal", Vol. 30, page 22 (1988)], JP-A-63-18964. Fluorine-based polymer compounds disclosed, JP-A-63-22206, fluorine-based polymer compounds, JP-A-63-2381
Fluorine polymer compounds disclosed in JP-A-15, polytetrafluoroethylene, polychlorotrifluoroethylene, polydichlorodifluoroethylene, copolymers of chlorotrifluoroethylene and dichlorodifluoroethylene, and fluorine-containing compounds having a cyclic structure Copolymer (Japanese Patent Application No. 3)
129852)) and the like.

(2) Electrically insulating polymer compound which can be formed by the CVD method (plasma polymerization method (plasma CVD method)): polyethylene, polytetrafluoroethylene, polyvinyltrimethylsilane, polymethyltrimethoxysilane, polysiloxane, etc. . (3) perfluroalcohol, perfluoroether,
Electrically Insulating Polymer Compound Soluble in Fluorine Solvents such as Perfluoroamine: Fluorine Polymer Compounds Disclosed in JP-A-63-18964, JP-A-63-22
No. 206, a fluorine-containing polymer compound,
Fluorine-based polymer compounds disclosed in JP-A-63-238115, polychlorotrifluoroethylene,
Polydichlorodifluoroethylene, a copolymer of chlorotrifluoroethylene and dichlorodifluoroethylene,
Fluorine-containing copolymer having cyclic structure (Japanese Patent Application No. 3-12
Fluorine-based polymer compounds such as 9852).

The protective layer may be formed by the PVD method (polymer compound of the above (1)), CV depending on the type of polymer compound used.
It can be provided by the method D (polymer compound of (2) above), the cast method or the spin coating method (polymer compound of (3) above.) The thickness of the protective layer depends on the material used and the forming method. Usually, the thickness is selected in the range of 10 nm to 100 μm, and when the side provided with the protective layer is used as a light emitting surface, a material is provided so that a protective layer excellent in translucency to EL light from the organic EL element can be obtained. It is desirable to select the forming method and the forming method.
No. 75 publication. In the present invention, a sealing film (7 in FIG. 1) is further provided on the protective layer thus provided. The sealing film is preferably a light-transmitting polymer, particularly a polymer having a light transmittance of 80% or more, such as ethyl cellulose, polystyrene, cellulose acetate, polyvinyl alcohol, polycarbonate, polyethylene, polypropylene, acrylic resin, polymethylmethacrylate (PMMA). ) And others, formed from a polymer of diethylene glycol bisallyl carbonate, etc., and having a photosensitizer and an oxidizable compound dispersed therein.

It is impossible to prevent permeating oxygen by simply fixing the above light-transmitting polymer on the protective layer of the laminated structure. According to the literature, oxygen permeability (STP volume of oxygen per unit area per unit time when there is a unit pressure difference in a unit thickness membrane, unit: m ³ s
^-1 P _a ^-1 ) is ethyl cellulose 1.99 × 10 ^-15 , polystyrene 1.97 × 10 ^-16 , cellulose acetate 5.85 × 1.
0 ^-17 , polyvinyl alcohol 6.68 × 10 ^-19 (J. Brandrup and EH Immergut ed. Polymer Handbook
2nd ed., J.Wiley 1975), it is necessary to efficiently remove the permeating oxygen.
It is already known that the oxygenation reaction by singlet oxygen is a known fact. In the sealing film, as shown in the following formulas [1] to [3], the reaction is such that the sensitizer in the excited state ( ¹ D ^* or ³ D ^* ) is oxygen ³ O _{2 in the} ground state. Energy is transferred to generate singlet oxygen ¹ O ₂ , which is a reaction for oxygenating the oxidizable compound (R). ¹ D ^* + ³ O ₂ → ³ D ^* + ¹ O ₂ [1] ³ D ^* + ³ O ₂ → ¹ D + ¹ O ₂ [2] ¹ O ₂ + R → RO ₂ [3] Here, as the photosensitizer (D), for example, benzaldehyde, acetophenone, benzophenone, fluorene,
Examples thereof include quinoline, naphthalene, fluorescein, eosin, erythrosine, rose bengal, thiocin, styrene blue, chlorophyll, tetraphenylporphyrin, rubrene, etc. These may be used alone or in combination of two or more. The excited state of the photosensitizer (D) is brought about by the light emission of the organic EL device under the protective film (equations [4] and [5]).

[0011]

[Chemical 1]

The following five types are known as reaction examples of the above-mentioned formula [3] ["sensitizer" Tokumaru Katsumi, Okawara Shin, published by Kodansha]. (A) 1,4 addition to cis-type 1,3-dienes: [π
4S + π2S] to produce endoperoxides.

[0013]

[Chemical 2]

(B) Attaching 1, 2 to electron-rich olefin
Addition: With vinyl ether and enamine¹O ₂By reaction with
Produces dioxetane. However, this is unstable and
Normal decomposition gives two carbonyl compounds.

[0015]

[Chemical 3]

(C) ene reaction to olefin: An olefin having an allyl hydrogen reacts with ¹ O ₂ in a concerted manner to give an allyl hydroperoxide.

[0017]

[Chemical 4]

(D) Oxidation of sulfides: ¹ O ₂ oxidizes 2 moles of sulfides to give sulfoxides.

[0019]

[Chemical 5]

(E) Electron transfer reaction: A substrate having a low oxidation potential (Eo <0.5 V, SCE) produces O ₂ ⁻ by electron transfer with ¹ O ₂ in a polar solvent. R + ¹ O ₂ → R ^{+ +} O ₂ ^- Accordingly, as the oxidizable compound (R), for example, cis 1,3-diene compounds, olefins, and the like sulfides. Other reactions that can be performed in the solid phase are already dual spectrum methods (3M
Company) is known. This is one in which 4-methoxy-α-naphthol is used as an oxidizable compound (R) to carry out an oxidation reaction, whereby the generated singlet oxygen is efficiently used for oxidation (formula [6]). .

[0021]

[Chemical 6]

Specific examples of the oxidizable compound include the following compounds in addition to 4-methoxy-α-naphthol.

[0023]

[Chemical 7]

These compounds may be used alone or in combination of two or more. The dispersion amount of the photosensitizer and the oxidizable compound in the sealing film is not particularly limited, but the light transmittance is 50% or less compared to the case where the photosensitizer and the oxidizable compound are not used. It is desirable to select a dispersion amount within the range that does not occur. The organic solvent used for dispersion may be appropriately selected according to the solubility of the polymer used. The sealing film in which the photosensitizer and the oxidizable compound are dispersed can be provided by, for example, a casting method or a spin coating method. When the sealing film is formed by the casting method, first, the light-transmitting polymer is dissolved in a suitable organic solvent, and then a photosensitizer and an oxidizable compound are added,
Next, this solution is spread on the protective layer of the laminated structure provided with the protective layer, and then air-dried for about 8 to 16 hours to form a sealing film. The drying time may generally be 8 hours or more and is not particularly limited, but it is not suitable even if drying is performed for more than 16 hours because there is no great difference in the degree of drying. A suitable drying time is usually about 12 hours. The solution concentration is appropriately selected according to the desired thickness of the sealing film.

On the other hand, when the sealing film is formed by the spin coating method, the solution obtained in the same manner as in the casting method is about 100 to 20,000 rpm, preferably 200.
An appropriate amount is dropped on the protective layer of the laminated structure provided with the protective layer rotating at ˜8,000 rpm, and the laminated structure is left as it is for about 5 to 60 seconds, preferably 10 minutes.
After rotating for about 30 seconds, the sealing film is formed by drying in the same manner as in the casting method. The dropping amount of the solution at this time varies depending on the size of the laminated structure, but the size of a normal slide glass (25 × 75 × 1.
1 mm) of the laminated structure is about 0.1 to 5 ml, preferably 0.5 to 3 ml. The solution concentration is appropriately selected according to the desired thickness of the sealing film, as in the case of the cast method, but the range is narrower than that of the case of the cast method, and the film thickness control and film uniformity are important points. From 1 to 40g
/ 100 ml, preferably 4 to 20 g / 100
It is preferably in the milliliter range. Although the thickness of the sealing film thus formed depends on the material used and the forming method, it is usually preferable that the thickness is in the range of 10 nm to 100 μm.

There are various organic materials for the organic EL element used in the present invention. For example, the organic compound that can be used as the light emitting material is not particularly limited, but a brightening agent such as benzothiazole-based, benzimidazole-based, benzoxazole-based, a metal chelated oxinoid compound, a styrylbenzene-based compound, or the like can be used. Can be mentioned. Specific examples of the compound name include those described in JP-A-59-194393.
A typical example thereof is 2,5-bis (5,7-di-t-
Pentyl-2-benzoxazolyl) -1,3,4-thiadiazole; 4,4'-bis (5,7-t-pentyl-2-benzoxazolyl) stilbene; 4,4'-bis [5 , 7-Di- (2-methyl-2-butyl) -2-benzoxazolyl] stilbene; 2,5-bis (5,7
-Di-t-pentyl-2-benzoxazolyl) thiophene; 2,5-bis [5-α, α-dimethylbenzyl]
2-benzoxazolyl) thiophene; 2,5-bis [5,7-di- (2-methyl-2-butyl) -2-benzoxazolyl] -3,4-diphenylthiophene;
2,5-bis (5-methyl-2-benzoxazolyl)
Thiophene; 4,4'-bis (2-benzoxazolyl) biphenyl; 5-methyl-2- [2- [4- (5-
Methyl-2-benzoxazolyl) phenyl] vinyl] benzoxazolyl; 2- [2- (4-chlorophenyl) vinyl] naphtho [1,2-d] oxazole and other benzoxazoles, 2,2′- Benzothiazoles such as (p-phenylenedivinylene) -bisbenzothiazole, 2- [2- [4- (2-benzimidazolyl) phenyl] vinyl] benzimidazole; 2- [2
Examples include fluorescent whitening agents such as benzimidazole-based compounds such as-(4-carboxyphenyl) vinyl] benzimidazole. Still other useful compounds are chemistry
Of Synthetic Soybean 1971, 628-63
They are listed on pages 7 and 640. Examples of the metal chelated oxinoid compound include, for example, JP-A-63-2
Those described in Japanese Patent No. 95695 can be used. Typical examples are tris (8-quinolinol) aluminum; bis (8-quinolinol) magnesium; bis (benzo [f] -8-quinolinol) zinc; bis (2-
Methyl-8-quinolinolato) aluminum oxide;
Tris (8-quinolinol) indium; Tris (5-
Methyl-8-quinolinol) aluminum; 8-quinolinol lithium; tris (5-chloro-8-quinolinol) gallium; bis (5-chloro-8-quinolinol)
Calcium; 8-hydroxyquinoline-based metal complexes such as poly [zinc (II) -bis (8-hydroxy-5-quinolinonyl) methane] and dilithium epindridione.

As the styrylbenzene compound, for example, European Patent No. 0319881 and European Patent No. 0.
The thing described in 373582 can be used. As typical examples thereof, 1,4-bis (2-methylstyryl) benzene; 1,4- (3-methylstyryl) benzene; 1,4-bis- (4-methylstyryl) benzene;
Distyrylbenzene; 1,4-bis (2-ethylstyryl) benzene; 1,4-bis (3-ethylstyryl) benzene; 1,4-bis (2-methylstyryl) 2-methylbenzene; 1,4- Bis (2-methylstyryl) -2
-Ethylbenzene and the like. Furthermore, the compound represented by the following formula can also be mentioned.

[0028]

[Chemical 8]

[0029]

[Chemical 9]

[0030]

[Chemical 10]

[0031]

[Chemical 11]

[0032]

[Chemical 12]

[0033]

[Chemical 13]

[0034]

[Chemical 14]

[0035]

[Chemical 15]

[0036]

[Chemical 16]

[0037]

[Chemical 17]

[0038]

[Chemical 18]

[0039]

[Chemical 19]

[0040]

[Chemical 20]

[0041]

[Chemical 21]

[0042]

[Chemical formula 22]

[0043]

[Chemical formula 23]

[0044]

[Chemical formula 24]

[0045]

[Chemical 25]

[0046]

[Chemical formula 26]

[0047]

[Chemical 27]

[0048]

[Chemical 28]

[0049]

[Chemical 29]

[0050]

[Chemical 30]

[0051]

[Chemical 31]

Further, the distyrylpyrazine derivative described in JP-A-2-252793 can be used as a light emitting material. A typical example is 2,5-bis (4
-Methylstyryl) pyrazine; 2,5-bis (4-ethylstyryl) pyrazine; 2,5-bis [2- (1-naphthyl) vinyl] pyrazine; 2,5-bis (4-methoxystyryl) pyrazine; 2 , 5-bis [2- (4-biphenyl) vinyl] pyrazine; 2,5-bis [2- (1-pyrenyl) vinyl] pyrazine and the like. As other substances, for example, the polyphenyl compounds described in European Patent No. 0387715 can also be used as the light emitting material. Specific examples thereof include compounds of the following formula.

[0053]

[Chemical 32]

In addition to the above compounds, for example, 12-
Phthaloperinone ["Journal of Applied Physics", Vol. 27, L713 (1988)
Year)]; 1,4-diphenyl-1,3-butadiene;
1,1,4,4-Tetraphenyl-1,3-butadiene ["Appl. Phys.
Lett.) Vol. 56, 799 (1990)], naphthalimide derivative (JP-A-2-305886), perylene derivative (JP-A-2-189890), oxadiazole derivative (JP-A-2-216791). Gazette), aldazine derivative (JP-A-2-220393), pyrazirine derivative (JP-A-2-220394), cyclopentadiene derivative (JP-A-2-289675), pyrrolopyrrole derivative (JP-A-2-296891).
), Styrylamine derivatives (Appl. Phys. Lett., Vol. 56, 799 (1990)), or coumarin compounds (Japanese Patent Laid-Open No. 2-19194). . As a typical example,

[0055]

[Chemical 33]

[0056]

[Chemical 34]

[0057]

[Chemical 35]

Compounds such as In addition to these, aromatic dimethylidyne compounds (European Patent No. 0388768)
No.) specification can be used, and a typical example thereof is

[0059]

[Chemical 36]

[0060]

[Chemical 37]

[0061]

[Chemical 38]

[0062]

[Chemical Formula 39]

[0063]

[Chemical 40]

[0064]

[Chemical 41]

[0065]

[Chemical 42]

[0066]

[Chemical 43]

[0067]

[Chemical 44]

[0068]

[Chemical formula 45]

[0069]

[Chemical formula 46]

[0070]

[Chemical 47]

[0071]

[Chemical 48]

[0072]

[Chemical 49]

And the like. Further, as a light emitting material, Japanese Patent Application No. 2-2448749 and Japanese Patent Application No. 2-27.
No. 9304, the following general formula (I)

[0074]

[Chemical 50]

[X and Y represent a fluorescent compound having an electroluminescence device function and may be the same or different. Q represents a divalent group that cuts the conjugated system. ] The compound represented by these is mentioned. General formula (I)
The light-emitting material represented by X and Y in the above means a visible light region (400 to 70) when excited with various energies.
It is an organic compound that emits 0 nm fluorescence. Among the light-emitting materials used in the present invention, near ultraviolet (330-380 n
m) light is absorbed, and the short wavelength region (400 to 45) of the visible region is absorbed.
A fluorescent whitening agent which emits a purple or blue fluorescent light at 0 nm) may also be included. The above Q is a divalent group that cuts the conjugated system, and the conjugation here is due to the non-existence of π electrons, and includes conjugated double bonds or unpaired electrons or lone electron pairs. Specifically, a divalent group obtained by removing one H atom from a linear alkane, for example,

[0076]

[Chemical 51]

[0077]

[Chemical 52]

Etc. are represented. The reason for using a divalent group that cuts the conjugated system in this way is that the EL emission color obtained when the above-described light emitting material X or Y having EL element ability is used alone as the organic EL element of the present invention. When,
This is because the EL emission color obtained when the compound represented by the general formula (I) is used as the organic EL device of the present invention does not change. In other words, this is to prevent the wavelength from becoming shorter or longer. Also,
When connecting with a divalent group that cuts the conjugated system, the glass transition temperature (T
It was confirmed that g) increased, and that it was possible to obtain uniform pinhole-free microcrystalline or amorphous thin films. Furthermore, by binding with a divalent group that cuts the conjugated system, EL emission does not have a long wavelength,
It also has the advantage that it can be easily synthesized or purified. It is to be noted that having EL element ability means that a compound is made into a thin film by a known method such as a vapor deposition method, a spin coating method, a casting method, and an LB method, and when this is used as a light emitting layer, it is an anode or a positive electrode when an electric field is applied. An injection function capable of injecting holes from the hole injecting and transporting layer and electrons from the cathode or the electron injecting and transporting layer, and a transporting function of moving the injected charges (electrons and holes) by the force of the electric field. , Provides a field for recombination of electrons and holes, and has a light emitting function to connect this to light emission. Specific examples of the fluorescent compound having an EL device function represented by X and Y include organic compounds that can be used as the above-described various light emitting materials.
Specific examples of the compound represented by the general formula (I) include those shown below.

[0079]

[Chemical 53]

[0080]

[Chemical 54]

[0081]

[Chemical 55]

[0082]

[Chemical 56]

[0083]

[Chemical 57]

[0084]

[Chemical 58]

[0085]

[Chemical 59]

[0086]

[Chemical 60]

[0087]

[Chemical formula 61]

[0088]

[Chemical formula 62]

[0089]

[Chemical formula 63]

The light emitting layer can be formed by thinning it by a known method such as a vapor deposition method, a spin coating method, a casting method, and an LB method, but a molecular deposition film is particularly preferable. Is more preferable. Here, the molecular deposition film is a thin film formed by depositing the compound from the gas phase state, or a film formed by solidifying from the solution state or liquid phase state of the compound, and usually this molecular deposition film. Can be distinguished from the thin film (molecular cumulative film) formed by the LB method by the difference in the aggregation structure, the higher order structure, and the functional difference caused by the difference. Further, the light emitting layer is prepared by dissolving a binder such as a resin and the compound in a solvent to form a solution, as disclosed in JP-A-57-51781, and then spin coating the solution. Can be formed into a thin film. The thickness of the light emitting layer thus formed is not particularly limited and may be appropriately selected depending on the circumstances, but is usually preferably in the range of 5 nm to 5 μm. The light emitting layer in the EL device used in the present invention has an injection function capable of injecting holes from an anode or a hole injecting and transporting layer and electrons from a cathode or an electron injecting and transporting layer when an electric field is applied, It has a transport function of moving the injected charges (electrons and holes) by the force of the electric field, a field of recombination of electrons and holes, and a light emitting function of connecting this to light emission. Note that there may be a difference between the ease of injecting holes and the ease of injecting electrons. The transport function represented by the mobilities of holes and electrons may have different sizes, but it is preferable to move one of them.

Next, the hole injecting / transporting material of the organic EL device of the present invention is not particularly limited as long as it has the above-mentioned preferable properties, and conventionally, in the light-transmitting material, the hole charge injecting / transporting material is used. Commonly used as EL
Any known material used for the hole injecting and transporting layer of the device can be selected and used. Examples of the charge transport material include triazole derivatives (US Pat.
112,197, etc.), oxadiazole derivatives (see US Pat. No. 3,189,447, etc.), imidazole derivatives (see JP-B-37-16096, etc.), polyarylalkane derivatives (US Pat. No. 3,615,402). , 3,820,989, 3,542,544,
JP-B-45-555, JP-A-51-10983, JP-A-51-93224 and JP-A-55-1710.
5 gazette, the same 56-4148 gazette, the same 55-1086.
67 gazette, the same 55-156953 gazette, the same 56-3.
6656), pyrazoline derivatives and pyrazolone derivatives (US Pat. Nos. 3,180,729 and 4,278,
746, JP-A-55-88064, 55
No. 88065, No. 49-105537, No. 55-51086, No. 56-80051,
56-88141, 57-45545, 54-112637, 55-74546.
), Phenylenediamine derivatives (U.S. Pat. No. 3,615,404, JP-B-51-10105, JP-A-46-3712, JP-A-47-25336, JP-A-54-53435, and JP-A-54-53435, 54-1105
No. 36, No. 54-119925, etc.), arylamine derivatives (US Pat. No. 3,567,450,
No. 3,180,703, No. 3,240,597, No. 3,65
8,520, 4,232,103, 4,175,961
No. 4,012,376, Japanese Patent Publication No. 49-357
02, 39-27577, JP-A-55-
144250, 56-119132, 56-22437, West German Patent 1,110,518, etc.), amino-substituted chalcone derivatives (US Pat. No. 3,
526,501), oxazole derivatives (described in US Pat. No. 3,257,203, etc.), styrylanthracene derivatives (see JP-A-56-46234), fluorenone derivatives (JP-A-54-1108).
37, etc.), hydrazone derivatives (US Pat. No. 3,
717,462, JP-A-54-59143, JP-A-55-52063, JP-A-55-52064,
55-46760, 55-85495, 57-11350 and 57-148749.
JP-A No. 2-311591, etc.), and stilbene derivatives (JP-A-61-210363, JP-A-6-210363).
1-228451, 61-14642,
61-72255, 62-47646, 62-36674, 62-10652, 62-30255, 60-93445.
No. 60-94462, No. 60-1747.
No. 49, No. 60-175052, etc.) and the like. Further, as a hole injecting and transporting material, a silazane derivative (US Pat. No. 4,950,950), a polysilane type (JP-A-2-204996), an aniline type copolymer (JP-A-2-28263), and Examples thereof include conductive polymer oligomers described in Japanese Patent Application No. 1-211399, particularly thiophene oligomers.

In the present invention, these compounds can be used as a hole injecting / transporting material, and the following porphyrin compounds (described in JP-A No. 63-295965) and aromatic tertiary compounds. Amine compounds and styrylamine compounds (U.S. Pat. No. 4,127,412, JP-A-53-27033, JP-A-54-5844)
5 gazette, the same 54-149634 gazette, the same 54-64.
299, 55-79450, 55-1
No. 44250, No. 56-119132, No. 6
No. 1-295558, No. 61-98353,
63-295695, etc.), and it is particularly preferable to use the aromatic tertiary amine compound.

Typical examples of the porphyrin compound include:
Porphine, 1,10,15,20-tetraphenyl-
21H, 23H-porphine copper (II), 1,10,1
5,20-tetraphenyl 21H, 23H-porphine zinc (II), 5,10,15,20-tetrakis (pentafluorophenyl) -21H, 23H-porphine,
Silicon phthalocyanine oxide, aluminum phthalocyanine chloride, phthalocyanine (metal free), dilithium phthalocyanine, copper tetramethylphthalocyanine,
Copper phthalocyanine, chromium phthalocyanine, zinc phthalocyanine, lead phthalocyanine, titanium phthalocyanine oxide, magnesium phthalocyanine, copper octamethyl phthalocyanine and the like can be mentioned. Further, as typical examples of the aromatic tertiary amine compound and the styrylamine compound, N, N, N ′, N′-tetraphenyl-4,
4'-diaminophenyl, N, N'-diphenyl-N,
N'-di (3-methylphenyl) -4,4'-diaminobiphenyl (TPDA), 2,2-bis (4-di-p-
Trilylaminophenyl) propane, 1,1-bis (4-
Di-p-tolylaminophenyl) cyclohexane, N,
N, N ', N'-tetra-p-tolyl-4,4'-diaminobiphenyl, 1,1-bis (4-di-p-tolylaminophenyl) -4-phenylcyclohexane, bis (4-dimethylamino) 2-Methylphenyl) phenylmethane, bis (4-di-p-tolylaminophenyl) phenylmethane, N, N'-diphenyl-N, N'-di (4-methoxyphenyl) -4,4'-diamino Biphenyl, N, N, N ', N'-tetraphenyl-4,4'
-Diaminodiphenyl ether, 4,4'-bis (diphenylamino) quadriphenyl, N, N, N-tri (p-tolyl) amine, 4- (di-p-tolylamino)
-4 '-[4 (di-p-tolylamino) styryl] stilbene, 4-N, N-diphenylamino- (2-diphenylvinyl) benzene, 3-methoxy-4'-N, N-
Examples thereof include diphenylaminostilbenzene, N-phenylcarbazole and the like. Further, the aromatic dimethylidyne compounds shown as the hole injecting / transporting material or the light emitting material can also be used.

The hole injecting and transporting layer used in the present invention can be formed by forming the above compound into a film by a known thinning method such as a vacuum vapor deposition method, a spin coating method, a casting method and an LB method. The thickness of the hole injecting and transporting layer is not particularly limited, but is usually 5 nm to 5 μm. The hole injecting and transporting layer may be composed of a single layer composed of one or more of these hole injecting and transporting materials, or a hole injecting and transporting layer composed of a compound different from the hole injecting and transporting layer. It may be a stack of layers. The electron injecting and transporting layer of the organic EL element of the present invention is made of an electron injecting material and has a function of transmitting the electrons injected from the cathode to the light emitting layer. There is no particular limitation on such an electron injection material, and an arbitrary material can be selected and used from conventionally known compounds. As a preferable example of the electron injection material,

[0095]

[Chemical 64]

And the like, nitro-substituted fluorenone derivatives, anthraquinodimethane derivatives described in JP-A Nos. 57-149259, 58-55450, 63-104061 and the like, "Polymer Preprints, Japan (Polymer Preprints, Japan) "Volume 37, Volume 3
Issue, page 681 (1988), etc.

[0097]

[Chemical 65]

A diphenylquinone derivative such as

[0099]

[Chemical formula 66]

Thiopyran dioxide derivatives such as

[0101]

[Chemical formula 67]

Examples thereof include heterocyclic tetracarboxylic acid anhydrides such as naphthalene perylene and carbodiimide. Furthermore, it is described in "Journal of Applied Physics," Vol. 27, page 269 (1988).

[0103]

[Chemical 68]

A compound represented by: JP-A-60-6965
No. 7, No. 61-143764, No. 61-148159.
Fluorenylidene methane derivatives described in JP-A Nos. 61-225151 and 61-2337.
Anthraquinodimethane derivatives and anthrone derivatives described in Japanese Patent Publication No. 50, etc., "Appl. Phys. Lett.", Vol. 55, 15
(1989) oxadiazole derivatives

[0105]

[Chemical 69]

And the like. Further, a series of electron-transporting compounds described in JP-A-59-194393 are disclosed as materials for forming a light-emitting layer in the publication, but as a result of studies by the present inventors, electron injection was performed. It has been found that it can be used as a material for forming a transport layer. In particular

[0107]

[Chemical 70]

Compounds represented by are preferred. further,
A metal complex of an 8-quinolinol derivative, specifically, tris (8-quinolinol) aluminum, tris (5,7-
Dichloro-8-quinolinol) aluminum, tris (5,7-dibromo-8-quinolinol) aluminum, tris (2-methyl-8-quinolinol) aluminum, and the corresponding magnesium, copper, gallium, tin, lead, etc. Complexes, or metal-free or metal phthalocyanines, or their ends are alkyl groups,
Those substituted with sulphone groups, eg

[0109]

[Chemical 71]

The compound represented by and the like can also be used as the electron injecting and transporting material. Further, the distyrylpyrazine derivative shown as the light emitting material can also be mentioned as the electron injecting and transporting material. The electron injecting and transporting layer in the organic EL device of the present invention can be formed by forming the above compound into a film by a known thinning method such as a vacuum vapor deposition method, a spin coating method, a casting method and an LB method. The thickness of the electron injecting and transporting layer is not particularly limited, but is usually 5 nm to 5 μm. This electron injecting and transporting layer may be composed of one layer made of one or more of these electron injecting and transporting materials, or is a layer in which an electron injecting and transporting layer made of a compound different from the above layer is laminated. May be. Furthermore, a hole injecting / transporting material made of an inorganic material such as p-type-Si or p-type-SiC and an electron injecting / transporting material made of n-type α-Si or n-type α-SiC can be used as the electron injecting / transporting material. For example, the inorganic semiconductor disclosed in International Patent Publication WO90 / 05998 and the like can be mentioned. As the positive electrode in this EL element, a material having an electrode substance of a metal, an alloy, an electrically conductive compound having a large work function (4 eV or more) and a mixture thereof is preferably used. Specific examples of such an electrode material include metals such as Au, CuI, and IT.
Dielectric transparent materials such as O, SnO ₂ and ZnO are mentioned. The positive electrode can be produced by forming a thin film of these electrode substances by a method such as vapor deposition or sputtering. When the emitted light is taken out from this electrode, it is desirable that the transmittance is higher than 10%, and the sheet resistance as an electrode is preferably several hundred Ω / □ or less. Further, the film thickness depends on the material, but is usually 10 nm to 1 μm.
m, preferably 10 to 200 nm.

On the other hand, as the cathode, those having an electrode substance of a metal, an alloy, an electrically conductive compound having a small work function (4 eV or less) and a mixture thereof are used. Specific examples of such an electrode material include sodium, sodium-potassium alloy, magnesium, lithium, magnesium / copper mixture, Al / Al ₂ O ₃ , indium and the like. The cathode can be produced by forming a thin film of these electrode substances by a method such as vapor deposition or sputtering. The sheet resistance as an electrode is preferably several hundred Ω / □ or less, and the film thickness is usually 10
It is selected in the range of 500 nm, preferably 50 to 200 nm. In this EL element, it is convenient that either the anode or the cathode is transparent or semi-transparent to allow the emitted light to pass therethrough, so that the emission efficiency of the emitted light is good.

Next, a preferred example for producing the laminated structure in the organic EL device of the present invention will be described. Explaining the method for producing the above-mentioned laminated structure consisting of the anode / hole injecting / transporting layer / light emitting layer / cathode, first, a thin film of a desired electrode substance, for example, a substance for anode, of 1 μm or less is formed on a suitable substrate. Preferably, the anode is formed by a method such as vapor deposition or sputtering so that the thickness is in the range of 10 to 200 nm. Next, a thin film made of a hole injecting and transporting material is formed on this to provide a hole injecting and transporting layer. As a method for thinning the hole injecting and transporting material, there are spin coating method, casting method, vapor deposition method and the like as described above, but it is easy to obtain a homogeneous film and it is difficult to form pinholes. Therefore, the vacuum deposition method is preferable. When this vapor deposition method is used for thinning the hole injection material, the vapor deposition conditions vary depending on the type of compound used, the desired crystal structure of the molecular deposited film, the association structure, etc. 50 to 450 ° C., vacuum degree 10 ⁻⁵ to 10 ⁻³ Pa, vapor deposition rate 0.01 to 50 nm / sec, substrate temperature −50 to 30
It is desirable to appropriately select the temperature in the range of 0 ° C. and the film thickness of 5 nm to 5 μm. Next, after forming this light emitting layer, a thin film made of a substance for the cathode is formed thereon to have a thickness of 10 to 500 nm, preferably 50 to 2 nm.
A desired laminated structure can be obtained by forming a film having a film thickness in the range of 00 nm by a method such as vapor deposition or sputtering and providing a cathode. In the production of this laminated structure, it is also possible to reverse the production order to produce the cathode, the light emitting layer, the hole injecting and transporting layer and the anode in this order.

The organic EL element of the present invention can be obtained by providing the protective layer on the outer surface of the laminated structure thus obtained, as described above, and further providing the sealing film thereon. This organic EL element has an extremely long life because the progress of deterioration due to oxygen is significantly suppressed. When a direct current voltage is applied to the organic EL device of the present invention, light emission can be observed by applying a voltage of about 5 to 40 V with the positive electrode having a positive polarity and the negative electrode having a negative polarity. Moreover, even if a voltage is applied with the opposite polarity, no current flows and no light emission occurs. further,
When an AC voltage is applied, light is emitted only when the positive electrode is in the + state and the negative electrode is in the − state. The waveform of the alternating current applied may be arbitrary.

[0114]

The present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples. The life of the obtained organic EL device was determined as follows. That is, the organic EL element is placed in the atmosphere 7
After leaving for a day, the device has an initial luminance of 100 cd / m.
^A direct current is applied so that the brightness becomes 2. After that, the brightness is measured in the atmosphere at a constant current (a direct current value at which the initial brightness has become 100 cd / m ² ) at regular intervals, and the brightness is 1% of the initial brightness. /
The time required to reach 2 was measured. In addition, the current continues to flow even after the brightness becomes half the initial brightness, and the brightness becomes 0
The time required to reach cd / m ² was measured, and this time was taken as the breakdown time of the device. The luminance was measured by using the ITO film as an anode and the counter electrode provided on the ITO film via the hole injection layer and the light emitting layer as a cathode, and continuously supplying a current from a DC power source to the organic EL device. E from organic EL element
The brightness was calculated from the value of the output voltage obtained by photoelectrically converting the L light with a photodiode.

Example 1 A glass plate having a size of 25 × 75 × 1.1 mm [HOYA
White plate glass manufactured by Co., Ltd.] was used as a substrate, and an ITO film was formed on this substrate to a thickness of 100 nm to form a transparent electrode (hereinafter, the substrate on which the ITO film was formed is referred to as a transparent support substrate). ) This transparent support substrate was ultrasonically cleaned with isopropyl alcohol for 30 minutes, then with pure water for 5 minutes, rinsed with isopropyl alcohol, and then dried by blowing dry nitrogen gas. And finally, UV
Ozone cleaning device [Samco International Co., Ltd.]
Washed for 10 minutes. The transparent supporting substrate after cleaning was fixed to a substrate holder of a commercially available vacuum deposition apparatus [manufactured by Nippon Vacuum Technology Co., Ltd.], and N, N'-diphenyl-N, N'-bis- (3 -Methylphenyl)-
[1,1'-Biphenyl] -4,4'-diamine (hereinafter referred to as TPD) (200 mg) was put into another molybdenum resistance heating boat and purified by sublimation of tris (8-quinolinol) aluminum (hereinafter referred to as Alq). .) 2
00 mg was added and the pressure in the vacuum chamber was reduced to 1 × 10 ⁻⁴ Pa.

Next, the resistance heating boat containing TPD is heated to 215 to 220 ° C. to vapor-deposit TPD at a rate of 0.2.
1-0.3 nm / s is deposited on the ITO film, and the film thickness is 60
A hole injection layer having a thickness of nm was formed. The substrate temperature at this time was room temperature. Then, while keeping the transparent support substrate on which the hole injection layer is formed fixed on the substrate holder, the Alq-containing molybdenum resistance heating boat is heated to 275 ° C.
q was deposited on the hole injection layer at a vapor deposition rate of 0.1 to 0.2 nm / s to form a light emitting layer having a film thickness of 60 nm. The substrate temperature at this time was also room temperature. Next, a resistance heating boat made of molybdenum containing 1 g of magnesium and silver 500
Each is heated with a resistance heating boat made of molybdenum containing mg in advance, and magnesium is vapor-deposited at a vapor deposition rate of about 1.5 nm / s, and silver is vapor-deposited at a vapor deposition rate of about 0.1 nm / s at the same time. An electrode (counter electrode) made of a mixed metal of magnesium and silver and having a film thickness of 150 nm was provided on the light emitting layer. Thus, a laminated structure was obtained in which the ITO film (electrode), the hole injection layer, the light emitting layer, and the counter electrode were sequentially provided on the glass substrate.

Next, on the outer surface of this laminated structure, using the same apparatus as the vacuum vapor deposition apparatus used for forming the laminated structure, under a series of vacuum environments from the formation of the hole injection layer and the light emitting layer. Then, the protective layer was provided in the following manner. First, an alumina crucible containing 1.5 g of an amorphous copolymer powder of tetrafluoroethylene and perfluoro-2,2-dimethyl-1,3-dioxole [trade name: Teflon AF, manufactured by DuPont] as a vapor deposition source. 12 μm above the tungsten basket (on the alumina crucible) in which the
It was covered with φ stainless steel mesh. Then, after decompressing the inside of the vacuum chamber to 1 × 10 ⁻⁴ Pa, the tungsten basket is electrically heated to heat the vapor deposition source to 455 ° C., and the vapor deposition rate is 0.5 nm / s on the outer surface of the laminated structure.
Then, a protective layer made of a Teflon AF thin film having a thickness of 0.8 μm (800 nm) was provided. In addition, the film thickness and vapor deposition rate of each layer except the ITO electrode are controlled while monitoring the film thickness of the vapor deposited film by a crystal vibration type film thickness meter (manufactured by Nippon Vacuum Technology Co., Ltd.) arranged in the vacuum chamber. did. The film thickness of each layer thus obtained was measured with a stylus type film thickness meter, and it was confirmed that the film thickness was in agreement with the reading of the crystal vibration type film thickness meter.

Further, the laminated structure provided with the protective layer in this manner was taken out from the vacuum chamber, and a sealing film was provided outside the protective layer in the following manner. First, 2 parts by weight of polyvinyl alcohol (PVA) powder, 0.1 parts by weight of rose bengal (RB), 0.05 parts by weight of 4-methoxy-α-naphthol (4MN) and 7.85 parts by weight of methylene chloride were mixed together. 1 ml of the obtained liquid was dropped on the protective layer of the laminated structure provided with the protective layer, and the spin coater [manufactured by Mikasa Co., Ltd.] was operated at 500 rpm at 3 rpm.
After spin coating for 0 seconds, air dry for 8 hours,
Furthermore, put it in a vacuum dryer (made by Yamato Scientific Co., Ltd.),
It dried at 60 degreeC for 10 hours, and formed the sealing film. The film thickness at this time was 300 nm. The lifetime of the organic EL device thus obtained was measured, and the time required for the brightness to become 1/2 of the initial brightness and the breakdown time of the device were determined. The results are shown in Table 1.

Comparative Example 1 An organic EL device was prepared in the same manner as in Example 1 except that the protective layer and the sealing film were not provided, and the life was measured. The results are shown in Table 1.

Comparative Example 2 Except that the sealing film was not provided in Example 1,
An organic EL device was produced in the same manner as in Example 1, and the life was measured. The results are shown in Table 1.

[0121]

[Table 1]

As is clear from Table 1, the organic EL device of the present invention (Example 1) has a much longer life than those of Comparative Examples 1 and 2.

[0123]

The organic EL device of the present invention comprises a protective layer provided on the outer surface of the device, and further a specific sealing film provided thereon, which significantly suppresses the progress of deterioration due to oxygen. And has an extremely long life.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an example of an organic EL element of the present invention.

[Explanation of symbols]

 1: Glass Substrate 2: Transparent Electrode 3: Hole Transport Layer 4: EL Layer Made of Organic Material 5: Counter Electrode 6: Protective Layer 7: Sealing Film

Claims (2)

[Claims] 1. An organic electroluminescence device comprising an anode and a cathode, and a layer composed of one or a plurality of layers of an organic material sandwiched between the anode and the cathode, wherein a protective layer is provided on the outer surface of the device, and An organic electroluminescence device comprising a sealing film having a photosensitizer and an oxidizable compound dispersed thereon. 2. The organic electroluminescence device according to claim 1, wherein the oxidizable compound is oxidized by singlet oxygen.