WO2010109937A1

WO2010109937A1 - Method for forming thin film, method for forming multilayer thin film having the thin film therein, electronic device, and organic electroluminescence element

Info

Publication number: WO2010109937A1
Application number: PCT/JP2010/050885
Authority: WO
Inventors: 達夫田中; 弘志北
Original assignee: コニカミノルタホールディングス株式会社
Priority date: 2009-03-26
Filing date: 2010-01-25
Publication date: 2010-09-30
Also published as: JPWO2010109937A1; JP2014212328A; JP5831596B2; JP5594286B2

Abstract

Provided is a thin film forming method wherein the physicochemical properties of a thin film composed of an organic material are changed by forming the thin film and then by physicochemically processing the thin film, without changing the chemical structure of the organic material which forms the thin film. In the method, even in the cases of forming the organic thin film and an organic multilayer thin film by employing an application method which enables continuous manufacture, mixing of the lower layer material with the upper layer (contamination) and interface troubles are improved. An organic EL element having a high external extraction quantum efficiency and a long light emitting service life is provided using the method, and the electronic device and the organic EL element which include the organic thin film are also provided.

Description

Thin film forming method, laminated thin film forming method, electronic device and organic electroluminescence element

The present invention relates to a method for forming a thin film made of an organic material, a method for forming a thin film of thin films, and an electronic device and an organic electroluminescence element using them.

Conventionally, as a light-emitting electronic display device, there is an electroluminescence display (hereinafter also referred to as ELD). Examples of the constituent elements of ELD include inorganic electroluminescent elements and organic electroluminescent elements (hereinafter also referred to as organic EL elements). Inorganic electroluminescent elements have been used as planar light sources, but an alternating high voltage is required to drive the light emitting elements.

On the other hand, an organic EL element has a configuration in which a light emitting layer containing a compound that emits light is sandwiched between a cathode and an anode, and injects electrons and holes into the light emitting layer to recombine excitons. This is an element that emits light by utilizing the emission of light (fluorescence / phosphorescence) when the exciton (exciton) is deactivated, and can emit light at a voltage of several volts to several tens of volts. Since it is a self-luminous type, it has a wide viewing angle, high visibility, and since it is a thin-film type complete solid-state device, it has attracted attention from the viewpoints of space saving and portability.

For the development of organic EL elements for practical use in the future, organic EL elements that emit light efficiently and with high luminance with lower power consumption are desired.

For example, Japanese Patent No. 3093796 discloses a technique of doping a stilbene derivative, a distyrylarylene derivative or a tristyrylarylene derivative with a small amount of a phosphor to improve emission luminance and extend the lifetime of the device. Japanese Patent Application Laid-Open No. 63-264692 discloses an element having an organic light emitting layer in which 8-hydroxyquinoline aluminum complex is used as a host compound and a small amount of phosphor is doped therein. For example, an element having an organic light emitting layer in which an 8-hydroxyquinoline aluminum complex is used as a host compound and a quinacridone dye is doped is known.

In the technique disclosed in the above-mentioned patent document, when the emission from the excited singlet is used, the generation ratio of the singlet exciton and the triplet exciton is 1: 3, so the generation probability of the luminescent excited species is 25%. Since the light extraction efficiency is about 20%, the limit of the external extraction quantum efficiency (ηext) is set to 5%.

However, M.M. A. Baldo et al. , Nature, 395, 151-154 (1998), since Princeton University reported on an organic EL device using phosphorescence emission from an excited triplet. A. Baldo et al. , Nature, 403, 17, 750-753 (2000), US Pat. No. 6,097,147, research on materials that exhibit phosphorescence at room temperature has become active.

In addition, recently discovered organic EL devices that use phosphorescence can realize a luminous efficiency that is approximately four times that of previous devices that use fluorescence. Research and development of light-emitting element layer configurations and electrodes are performed all over the world.

For example, S. Lamansky et al. , J .; Am. Chem. Soc. , 123, 4304 (2001), a number of compounds are being studied for synthesis centering on heavy metal complexes such as iridium complexes.

In addition, the organic EL element is an all-solid element composed of an organic material film having a thickness of only about 0.1 μm between the electrodes, and can emit light at a relatively low voltage of about 2V to 20V. Therefore, it is a technology that is expected as a next-generation flat display and illumination.

In addition, the structure of the organic EL element is a simple one in which an organic layer is sandwiched between a transparent electrode and a counter electrode, and the number of parts is overwhelmingly smaller than that of a liquid crystal display, which is a typical flat display. Although the cost should be kept low, this is not always the case at present, and a large amount of water is drained from the liquid crystal display in terms of performance and cost. In particular, in terms of cost, poor productivity is considered as a factor.

Most of the organic EL currently commercialized are manufactured by a so-called vapor deposition method in which a low molecular material is vapor deposited. In this vapor deposition method, a low-molecular compound that can be easily purified can be used as an organic EL material (high-purity material is easy to obtain), and a laminated structure can be easily formed. Are better.

However, since vapor deposition is performed under a high vacuum condition of 10 ⁻⁴ Pa or less, restrictions are imposed on the film forming apparatus, and in practice it can be applied only to a substrate with a small area. It takes a long time and has a low throughput.

Especially, it becomes a problem when applied to lighting applications and large-area electronic displays, and organic EL is one of the causes not practically used for such applications.

On the other hand, coating methods that produce organic compound layers by processes such as spin coating, inkjet, printing, and spraying can produce thin films at normal pressure, and are suitable for producing uniform films over large areas. As one of means for enabling continuous production, a method using a solution containing an organic EL material has been proposed (for example, see Patent Document 1).

However, in order to achieve high luminous efficiency and long life at the same time, it is desirable to stack a plurality of functional layers. In order to laminate a plurality of layers using the coating method, it is a prerequisite that the lower layer does not dissolve in the upper layer coating solution, but it is slightly soluble for very thin films of the order of several tens of nm. Even if it is a solvent to show, a part of lower layer film | membrane melt | dissolves or the problem that an interface will be disturb | confused by a solvent arises.

Such contamination (mixing) on the upper layer material and disturbance of the interface cause a decrease in the light emission efficiency of the device and a deterioration in the device life, and therefore there is a need for improvement, and a solution to these problems is desired. .

JP 2004-292882 A

The present invention has been made in view of the above-mentioned problems, and the object of the present invention is to form an organic thin film or an organic laminated thin film by a coating method that enables continuous production. Providing a method for forming an organic thin film in which mixing (contamination) and interface disturbance are improved, and using the formation method, an organic EL device having high external extraction quantum efficiency and a long emission lifetime is provided. An electronic device including an organic thin film and an organic EL element are provided.

The above object of the present invention is achieved by the following configuration.

1. A thin film characterized by changing the physicochemical properties of the thin film without changing the chemical structure of the organic material forming the thin film by applying a physicochemical treatment after forming the thin film made of the organic material. Forming method.

2. 2. The method for forming a thin film as described in 1 above, wherein the organic substance is a compound having a partial structure represented by the following general formula (1).

(In the formula, Ar ¹ and Ar ² represent an aromatic ring, and R ¹ and R ² represent an atomic group necessary for bonding to each other to form a 5-membered or 6-membered aromatic ring, provided that (The aromatic ring represents an aromatic hydrocarbon ring or an aromatic heterocyclic ring.)
3. 3. The method for forming a thin film according to 1 or 2, wherein the change in physicochemical properties of the thin film is a change from amorphous to crystalline.

4. 4. The method for forming a thin film according to any one of 1 to 3, wherein the physicochemical treatment is thermal treatment.

5. 4. The method for forming a thin film according to any one of 1 to 3, wherein the physicochemical treatment is a chemical treatment.

6. 6. The method for forming a thin film according to any one of 1 to 5, wherein a coating process is used for forming the thin film.

7. A thin film adjacent to the thin film is formed on the thin film formed by the thin film forming method according to any one of 1 to 6, using the thin film forming method according to any one of 1 to 6. A method for forming a laminated thin film, wherein the laminated thin film is formed by a coating step that may be performed.

8. An electronic device comprising a thin film formed by the method for forming a thin film according to any one of 1 to 6 above.

9. 8. An electronic device comprising a laminated thin film formed by the method for forming a laminated thin film as described in 7 above.

10. 7. An organic electroluminescence device comprising a thin film formed by the method for forming a thin film according to any one of 1 to 6 above.

11. 8. An organic electroluminescence device comprising a laminated thin film formed by the method for forming a laminated thin film as described in 7 above.

More specifically, the above object of the present invention is achieved by the following configuration.

2. 2. The method for forming a thin film according to 1, wherein the organic substance is a compound having a partial structure represented by the following general formula (1).

(In the formula, Ar ¹ and Ar ² represent an aromatic ring, and R ¹ and R ² represent an atomic group necessary for bonding to each other to form a 5-membered or 6-membered aromatic ring, provided that (The aromatic ring represents an aromatic hydrocarbon ring or an aromatic heterocyclic ring.)
3. 3. The method for forming a thin film according to 1 or 2, wherein the organic substance has at least two partial structures of the general formula (1).

4). 4. The method for forming a thin film according to any one of 1 to 3, wherein Ar ^{1 in the} general formula (1) is a condensed ring formed from at least two aromatic rings.

5). 5. The method for forming a thin film according to any one of 1 to 4, wherein Ar ^{1 in the} general formula (1) is a condensed ring formed from at least three aromatic rings.

6). Ar ^{1 in the} general formula (1) is any one of an aryl ring, a carbazole ring, a carboline ring, or a 1,10-phenanthroline ring of a substituted or unsubstituted triarylamine. The method for forming a thin film according to any one of the above.

7). 7. The method for forming a thin film according to any one of 1 to 6, wherein Ar ^{2 in the} general formula (1) is a substituted or unsubstituted phenyl group.

8). 7. The method for forming a thin film according to any one of 1 to 6, wherein Ar ^{2 in the} general formula (1) is a substituted or unsubstituted nitrogen-containing 6-membered ring.

9. The compound having the partial structure of the general formula (1) is at least one of at least one selected from “triarylamine, carbazole ring, or carboline ring” as Ar ¹ of the partial structure of the general formula (1). One of triarylamines at one end or at one end of a structure in which two are linked via at least one selected from a single bond, a triarylamine, a dibenzofuran ring, or a benzene ring 9. The method for forming a thin film according to any one of 2 to 8, wherein the thin film is a compound sharing an aryl ring, a carbazole ring, or a carboline ring.

10. The compound having the partial structure of the general formula (1) is represented by Ar ¹ of at least two partial structures of the general formula (1), “a structure in which at least two triarylamines are linked via a single bond”. 10. The method for forming a thin film according to any one of 2 to 9, wherein the compound shares one of the aryl rings of the triarylamine at both terminal positions.

11. The compound having the partial structure of the general formula (1) is a biphenyl ring as Ar ¹ of at least two partial structures of the general formula (1) “at least two carbazole rings are in the N atom position (−9 position)”. , A dibenzofuran ring or a structure linked via at least one selected from a benzene ring ”, a compound sharing one or both of the carbazole rings at both terminal positions. The method for forming a thin film according to any one of 2 to 9.

12 The compound having the partial structure of the general formula (1) shares at least two “1,10-phenanthroline ring” structures as Ar ¹ of the partial structure of the general formula (1) at both terminal ring sites. 10. The method for forming a thin film according to any one of 2 to 9, wherein the thin film is a compound.

13. The compound having the partial structure of the general formula (1) is represented by “at least two carboline rings at the N atom position (−9 position) as Ar ¹ of the partial structure of the general formula (1), Any one of 2 to 9, wherein the carboline ring at both terminal positions of the structure connected through at least one selected from dibenzofuran ring or benzene ring is shared The method for forming a thin film according to claim 1.

14 The compound having the partial structure of the general formula (1) is a biphenyl ring as Ar ¹ of at least two partial structures of the general formula (1) “at least two carbazole rings are in the N atom position (−9 position)”. , A dibenzofuran ring, or a structure connected via at least one selected from a benzene ring, the carbazole ring at both terminal positions, and Ar ² is an aromatic heterocyclic ring. 10. The method for forming a thin film according to any one of 2 to 9, wherein

15. 15. The method for forming a thin film according to any one of 1 to 14, wherein the change in physicochemical properties of the thin film is a change from amorphous to crystalline.

16. 16. The method for forming a thin film according to any one of 1 to 15, wherein the physicochemical treatment is thermal treatment.

17. 16. The method for forming a thin film according to any one of 1 to 15, wherein the physicochemical treatment is a chemical treatment.

18. 18. The method for forming a thin film according to any one of 1 to 17, wherein a coating process is used for forming the thin film.

19. A thin film adjacent to the thin film is formed on the thin film formed by the thin film forming method according to any one of 19.1 to 18, using the thin film forming method according to any one of 1 to 18. A method for forming a laminated thin film, wherein the laminated thin film is formed by a coating step that may be performed.

An electronic device comprising a thin film formed by the method for forming a thin film according to any one of 20.1 to 18.

An electronic device comprising a laminated thin film formed by the method for forming a laminated thin film according to 21.19.

An organic electroluminescence element comprising a thin film formed by the method for forming a thin film according to any one of 22.1 to 18.

An organic electroluminescent device comprising a laminated thin film formed by the method for forming a laminated thin film described in 23.19.

For forming a conventionally known organic thin film, it is possible to use a relatively simple apparatus such as a high vacuum deposition method that requires high vacuum, spin coating, ink jet, coating coater, etc., although thin film formation is easy. A coating method is generally known.

When laminating thin films, it is possible to obtain a laminated film of any film thickness by the high vacuum vapor deposition method, but there are drawbacks such as high vacuum is necessary and continuous production is difficult, and large-scale equipment is required. is there.

On the other hand, in the coating method, when a thin film is to be laminated in the coating process, when the thin film adjacent to the first formed thin film is formed, the first formed thin film dissolves in the solvent. There were difficulties unique to the coating process, such as contamination and interface disturbance.

Accordingly, in the present invention and the like, dissolution of an organic compound means that a state in which organic compound molecules are solvated by a solvent stably exists. However, the solution depends on the structure of the organic compound, the type of the solvent, etc. It was noted that it was decided whether it could exist stably. Furthermore, paying attention to the existence of organic compounds that are easy to form solutions from the amorphous state and difficult to form solutions from the crystallized state, and applying these properties to thin film formation, It has been possible to easily achieve the lamination of thin films of organic compounds, which has been difficult until now. Furthermore, by making it possible to arbitrarily form a crystal film, it is possible to achieve expression of electrical characteristics peculiar to the crystal film and improvement of charge mobility. That is, changing the state of the thin film by subjecting the thin film to physicochemical treatment after forming the thin film can be applied in a wide range, and the object of the present invention can be achieved.

According to the present invention, even in the case of forming an organic thin film or an organic laminated thin film by a coating method that enables continuous production, the organic thin film with improved mixing (contamination) of the lower layer material and disturbance of the interface is improved. Providing an organic EL element having a high external extraction quantum efficiency and a long light emission lifetime, and providing an electronic device and an organic EL element including the organic thin film. Can do.

FIG. 3 is a diagram showing the measurement results of X-ray diffraction XRD (X-ray diffraction method apparatus, manufactured by Rigaku Corporation, model RINT-TTR2 apparatus) of Sample 1-1 in Example 1. FIG. 3 is a diagram showing the measurement results of X-ray diffraction XRD (X-ray diffraction apparatus, manufactured by Rigaku Corporation, model RINT-TTR2 apparatus) of Sample 1-2 in Example 1. It is the schematic of an illuminating device. It is sectional drawing of an illuminating device.

Hereinafter, the best mode for carrying out the present invention will be described, but the present invention is not limited thereto.

The thin film formation method of the present invention changes the physicochemical properties of the thin film without changing the chemical structure of the organic material forming the thin film by applying a physicochemical treatment after forming the thin film made of the organic material. It is characterized by that.
(Organic substance according to the present invention)
First, the organic substance according to the present invention will be described.

Preferred examples of the organic substance according to the present invention include compounds having the partial structure represented by the general formula (1).

The organic substance according to the present invention is preferably a so-called host compound that is conventionally used in an organic EL device, and is not particularly limited in terms of structure, but is typically a carbazole derivative, a triarylamine derivative, a carboline derivative, or a diazacarbazole derivative. (Here, the diazacarbazole derivative represents one in which at least one carbon atom of the hydrocarbon ring constituting the carboline ring of the carboline derivative is substituted with a nitrogen atom), 1,10-phenanthroline derivative, aromatic Examples of compounds having a basic skeleton such as a group borane derivative, a nitrogen-containing heterocyclic compound, a thiophene derivative, a furan derivative, and an oligoarylene compound include compounds having the partial structure of the general formula (1) of the present invention.

Among these, compounds having a partial structure of the general formula (1) of the present invention are preferable in carbazole derivatives, triarylamine derivatives, carboline derivatives, diazacarbazole derivatives, 1,10-phenanthroline derivatives, and the like. It is more preferable to have at least two partial structures of the general formula (1).

In the general formula (1) of the compound having the partial structure of the general formula (1) of the present invention, Ar ¹ and Ar ² represent an aromatic ring, and R ¹ and R ² are bonded to each other to form a 5-membered or Represents a group of atoms required to form a 6-membered aromatic ring. However, the aromatic ring represents an aromatic hydrocarbon ring or an aromatic heterocyclic ring.

Ar ^{1 in the} general formula (1) is preferably a condensed ring formed from at least two aromatic rings.

In addition, Ar ^{1 in the} general formula (1) is preferably a condensed ring formed from at least three aromatic rings.

In addition, Ar ^{1 in the} general formula (1) may be a part of a chemical structure of any ^one of a substituted or unsubstituted triarylamine structure, carbazole structure, carboline structure, or 1,10-phenanthroline structure. preferable.

Further, Ar ² in the general formula (1) is preferably a substituted or unsubstituted phenyl group.

In addition, Ar ^{2 in the} general formula (1) is preferably a substituted or unsubstituted nitrogen-containing 6-membered ring.

As the compound having the partial structure of the general formula (1), preferably, the compound having the partial structure of the general formula (1) is selected as “tria” as Ar ¹ of at least two partial structures of the general formula (1). A structure in which at least two members selected from a reelamine, a carbazole ring, or a carboline ring are linked via at least one selected from a single bond, a triarylamine, a dibenzofuran ring, or a benzene ring And a single terminal of the aryl ring, carbazole ring, or carboline ring of the triarylamine, respectively.

More preferably, the compound having the partial structure of the general formula (1) is a compound having the partial structure of the general formula (1) as Ar ¹ of at least two partial structures of the general formula (1). Examples include compounds in which at least two triarylamines each share one of the aryl rings of the triarylamine at both terminal positions of the structure in which the structure is linked via a single bond.

Specific examples of such compounds include exemplified compounds (1-1) to (1-5) described later.

The compound having the partial structure of the general formula (1) is more preferably a compound having the partial structure of the general formula (1) as Ar ¹ of at least two partial structures of the general formula (1). , “One or both ends of a structure in which at least two carbazole rings are linked via at least one selected from a biphenyl ring, a dibenzofuran ring, or a benzene ring at the N atom position (−9 position)” And a compound sharing each carbazole ring at the position.

Specific examples of such compounds include exemplified compounds (2-1) to (2-5) described later.

The compound having the partial structure of the general formula (1) is more preferably a compound having the partial structure of the general formula (1) as Ar ¹ of at least two partial structures of the general formula (1). And a compound having a “1,10-phenanthroline ring” structure at both terminal ring sites.

As a specific example compound of such a compound, for example, exemplified compound (3-1) described later can be mentioned.

The compound having the partial structure of the general formula (1) is more preferably a compound having the partial structure of the general formula (1) as Ar ¹ of at least two partial structures of the general formula (1). , “The carboline ring at both terminal positions of“ a structure in which at least two carboline rings are linked at the N atom position (−9 position) via at least one selected from a biphenyl ring, a dibenzofuran ring, and a benzene ring ” , And the like.

Specific examples of such compounds include exemplified compounds (3-2) and (3-3) described later.

The compound having the partial structure of the general formula (1) is more preferably a compound having the partial structure of the general formula (1) as Ar ¹ of at least two partial structures of the general formula (1). , “The carbazole ring at both terminal positions of“ a structure in which at least two carbazole rings are linked via at least one selected from a biphenyl ring, a dibenzofuran ring, or a benzene ring at the N atom position (−9 position) ” , And Ar ² is an aromatic heterocyclic ring.

Specific examples of such compounds include exemplified compounds (3-4) and (3-5) described later.

In the general formula (1), the aromatic hydrocarbon ring represented by Ar ¹ , Ar ² , R ¹ and R ² is also referred to as an aryl ring, for example, a benzene ring, a naphthalene ring, an anthracene ring, Examples thereof include an azulene ring, an acenaphthylene ring, a fluorene ring, a phenanthrene ring, an indene ring, a pyrene ring, and a biphenyl ring.

In the general formula (1), examples of the aromatic heterocycle represented by Ar ¹ , Ar ² , R ¹ and R ² include a furan ring, a thiophene ring, a pyridine ring, a pyridazine ring, a pyrimidin ring, and a pyrazine. Ring, triazine ring, imidazole ring, pyrazole ring, thiazole ring, quinazoline ring, carbazole ring, carboline ring, diazacarboline ring (in which one of the carbon atoms constituting the carboline ring of the carbolinyl group is replaced by a nitrogen atom) ), 1,10-phenanthroline ring, phthalazine ring, and the like.

In the general formula (1), the aromatic hydrocarbon ring represented by Ar ¹ is preferably a benzene ring, a naphthalene ring, or the like.

In the general formula (1), examples of the aromatic heterocycle represented by Ar ¹ include a carbazole ring, an azacarbazole (carboline (α-carboline, β-carboline, γ-carboline)) ring, and a 1,10-phenanthroline ring. , Etc. are preferred.

In the general formula (1), the aromatic hydrocarbon ring represented by Ar ² is preferably a benzene ring, a naphthalene ring, or the like.

In the general formula (1), the aromatic heterocyclic ring represented by Ar ² is preferably a pyridine ring.

Examples of the 5-membered or 6-membered aromatic ring formed by combining R ¹ and R ² with each other include an aromatic hydrocarbon ring and an aromatic heterocyclic ring. Examples of the aromatic hydrocarbon ring include benzene A ring, a naphthalene ring, and the like, and a benzene ring is preferable. As an aromatic heterocyclic ring, a thiophen ring, a pyridine ring, etc. are mentioned, for example, A pyridine ring is preferable.

The compound of the present invention may further have a substituent, and examples of the substituent include an alkyl group (for example, methyl group, ethyl group, propyl group, isopropyl group, tert-butyl group, pentyl group, hexyl group). Group, octyl group, dodecyl group, tridecyl group, tetradecyl group, pentadecyl group etc.), cycloalkyl group (eg cyclopentyl group, cyclohexyl group etc.), alkenyl group (eg vinyl group, allyl group etc.), alkynyl group (eg , Ethynyl group, propargyl group etc.), aryl group (eg phenyl group, naphthyl group etc.), aromatic heterocyclic group (eg furyl group, thienyl group, pyridyl group, pyridazinyl group, pyrimidinyl group, pyrazinyl group, triazinyl group) , Imidazolyl group, pyrazolyl group, thiazolyl group, quinazolinyl group, carbazolyl group A carbolinyl group, a diazacarbazolyl group (in which one of carbon atoms constituting the carboline ring of the carbolinyl group is replaced by a nitrogen atom), a phthalazinyl group, etc.), a heterocyclic group (for example, a pyrrolidyl group, Imidazolidyl group, morpholyl group, oxazolidyl group, etc.), alkoxy group (for example, methoxy group, ethoxy group, propyloxy group, pentyloxy group, hexyloxy group, octyloxy group, dodecyloxy group, etc.), cycloalkoxy group (for example, Cyclopentyloxy group, cyclohexyloxy group, etc.), aryloxy group (eg, phenoxy group, naphthyloxy group, etc.), alkylthio group (eg, methylthio group, ethylthio group, propylthio group, pentylthio group, hexylthio group, octylthio group, dodecylthio group) Etc.), A cycloalkylthio group (eg, cyclopentylthio group, cyclohexylthio group, etc.), an arylthio group (eg, phenylthio group, naphthylthio group, etc.), an alkoxycarbonyl group (eg, methyloxycarbonyl group, ethyloxycarbonyl group, butyloxycarbonyl group, Octyloxycarbonyl group, dodecyloxycarbonyl group, etc.), aryloxycarbonyl group (eg, phenyloxycarbonyl group, naphthyloxycarbonyl group, etc.), sulfamoyl group (eg, aminosulfonyl group, methylaminosulfonyl group, dimethylaminosulfonyl group, Butylaminosulfonyl group, hexylaminosulfonyl group, cyclohexylaminosulfonyl group, octylaminosulfonyl group, dodecylaminosulfonyl group, phenylaminosulfonyl group Group, naphthylaminosulfonyl group, 2-pyridylaminosulfonyl group, etc.), acyl group (for example, acetyl group, ethylcarbonyl group, propylcarbonyl group, pentylcarbonyl group, cyclohexylcarbonyl group, octylcarbonyl group, 2-ethylhexylcarbonyl group, Dodecylcarbonyl group, phenylcarbonyl group, naphthylcarbonyl group, pyridylcarbonyl group, etc.), acyloxy group (for example, acetyloxy group, ethylcarbonyloxy group, butylcarbonyloxy group, octylcarbonyloxy group, dodecylcarbonyloxy group, phenylcarbonyloxy) Group), amide group (for example, methylcarbonylamino group, ethylcarbonylamino group, dimethylcarbonylamino group, propylcarbonylamino group, pentylcarbonyl group). Group, cyclohexylcarbonylamino group, 2-ethylhexylcarbonylamino group, octylcarbonylamino group, dodecylcarbonylamino group, phenylcarbonylamino group, naphthylcarbonylamino group, etc.), carbamoyl group (for example, aminocarbonyl group, methylaminocarbonyl group) Dimethylaminocarbonyl group, propylaminocarbonyl group, pentylaminocarbonyl group, cyclohexylaminocarbonyl group, octylaminocarbonyl group, 2-ethylhexylaminocarbonyl group, dodecylaminocarbonyl group, phenylaminocarbonyl group, naphthylaminocarbonyl group, 2- Pyridylaminocarbonyl group, etc.), ureido group (for example, methylureido group, ethylureido group, pentylureido group, cyclohexylurea) Group, octylureido group, dodecylureido group, phenylureido group, naphthylureido group, 2-pyridylaminoureido group, etc.), sulfinyl group (for example, methylsulfinyl group, ethylsulfinyl group, butylsulfinyl group, cyclohexylsulfinyl group, 2-ethylhexylsulfinyl group) Group, dodecylsulfinyl group, phenylsulfinyl group, naphthylsulfinyl group, 2-pyridylsulfinyl group, etc.), alkylsulfonyl group (for example, methylsulfonyl group, ethylsulfonyl group, butylsulfonyl group, cyclohexylsulfonyl group, 2-ethylhexylsulfonyl group, Dodecylsulfonyl group, etc.), arylsulfonyl group or heteroarylsulfonyl group (for example, phenylsulfonyl group, naphthylsulfonyl group, 2-pyridyl) Rusulfonyl group, etc.), amino group (eg, amino group, ethylamino group, dimethylamino group, butylamino group, cyclopentylamino group, 2-ethylhexylamino group, dodecylamino group, anilino group, naphthylamino group, 2-pyridylamino group) Group), halogen atom (eg fluorine atom, chlorine atom, bromine atom etc.), fluorinated hydrocarbon group (eg fluoromethyl group, trifluoromethyl group, pentafluoroethyl group, pentafluorophenyl group etc.), cyano Group, nitro group, hydroxy group, mercapto group, silyl group (for example, trimethylsilyl group, triisopropylsilyl group, triphenylsilyl group, phenyldiethylsilyl group, etc.). These substituents may be further substituted with the above substituents. In addition, a plurality of these substituents may be bonded to each other to form a ring.

Specific examples of the organic substance according to the present invention, preferably a compound having the partial structure represented by the general formula (1) (hereinafter also referred to as the compound of the present invention), are shown below. It is not limited.

The compound of the present invention can be synthesized by known synthesis methods such as Buchwald-Hartwig reaction and Suzuki reaction.

Of the above-described specific examples of the compound of the present invention, compounds 2-1 to 2-5 are preferably used in the light emitting layer as the host compound of the present invention.

Compounds 3-1 to 3-5 are preferably used as the electron transport material of the present invention, and compounds 1-1 to 1-5 are preferably used as the hole transport material of the present invention.
(Thin film formation)
In the method for forming a thin film of the present invention, the physicochemical properties of the thin film can be obtained without changing the chemical structure of the molecules forming the thin film by applying a physicochemical treatment after the formation of the organic thin film of the present invention. It is characterized by changing.

<Formation of organic thin films>
(Dissolving, coating, forming a thin film)
In the present invention, the formation of a thin film made of an organic material is not particularly limited, but it is preferable to use a coating process.

In the case of the amorphous type, the compound of the present invention can be easily dissolved in an organic solvent to prepare a coating solution, and a thin film can be easily formed by a coating method.

Examples of the organic solvent for the coating solution include aromatic hydrocarbons such as toluene, xylene, mesitylene, and cyclohexylbenzene, aliphatic hydrocarbons such as cyclohexane, decalin, and dodecane, halogenated hydrocarbons such as dichlorobenzene, methanol, Organic solvents such as alcohols such as ethanyl, propanol and butanol, ketones such as methyl ethyl ketone and cyclohexanone, and fatty acid esters such as ethyl acetate can be used.

Of these, toluene, o-dichlorobenzene, butanol, halogenated hydrocarbons and the like can be preferably used.

From the viewpoint of keeping the coating solution stable (low crystallization ability), it is preferable to use a solvent having a small polarity.

As the coating method, a coating method that is known as a wet process and that can use a relatively simple apparatus such as a spin coating method, a casting method, an ink jet method, a printing method, and a coating coater method is used. be able to. From the viewpoint that a homogeneous film can be easily obtained and pinholes are difficult to be generated, film formation by a coating method such as a spin coating method, an ink jet method, or a printing method is preferable.

In addition, when the compound of the present invention is not an amorphous type but a crystal type, it can be changed to an amorphous type by a treatment such as sublimation purification, reprecipitation using a good solvent and a poor solvent, By using this, dissolution, coating, and thin film can be suitably formed in the same manner as in the case of the amorphous type from the beginning.
(Thin film crystallization)
In the method for forming a thin film of the present invention, the physicochemical treatment of the thin film can be performed without changing the chemical structure of the organic material forming the thin film by applying a physicochemical treatment after forming the thin film made of the organic material. It is characterized by changing properties.

In the present invention, the change in the physicochemical properties of the thin film is preferably a change from amorphous to crystalline. The thin film formed by a coating method or the like in the state where the organic substance of the present invention is amorphous is subjected to heat treatment (physical Treatment), treatment with a specific solvent (chemical treatment), preferably, crystallization is performed by further applying physicochemical treatment such as heat treatment (physical treatment), and a thin film is formed. By changing the physicochemical properties of the thin film without changing the chemical structure of the molecule, the thin film can be made insoluble in the coating solution.
(Thin film crystallization by heat treatment)
The physicochemical treatment for crystallizing the thin film from amorphous is preferably a physical treatment, especially a thermal treatment, and the heat treatment is preferably in the range of 50 ° C to 250 ° C, and 70 ° C to 200 ° C. The range of is more preferable. Further, the heating time is preferably in the range of 5 seconds to 120 minutes, and from the viewpoint of increasing production efficiency, it is preferably in the range of 10 seconds to 60 minutes.

Examples of the heating method include blast heating, heating by radiant heat, microwave heating, infrared heating, and hot plate heating.
(Thin film crystallization by specific solvent treatment)
The physicochemical treatment for crystallizing the thin film from amorphous is preferably a chemical treatment, and among the chemical treatments, a solvent treatment is preferably used. As the solvent treatment, a solvent having a large crystallization ability is preferably used for the compound of the present invention, and can be appropriately selected and used depending on the type of the compound of the thin film. Examples include acetonitrile, methanol, ethanol, acetone, hexane, ethyl acetate, toluene, tetrahydrofuran, chloroform, and the like. Crystallization can be easily carried out by applying a solvent by a known treatment method such as dipping, spraying, spin coating and the like.

For the crystallization of the thin film, it is preferable to use physical treatment and chemical treatment as physicochemical treatments, and more preferably in combination.
(Formation of laminated thin film)
In the present invention, by applying the above-described coating solution of the compound of the present invention on the crystallized thin film produced as described above, the first formed thin film does not dissolve in the solvent, and the lower layer material The laminated thin film can be applied without the difficulties inherent in the coating process, such as mixing (contamination) with the upper layer and disorder of the interface. Thereafter, the thin film can be crystallized to form a crystallized laminated thin film.

It is possible to easily form a stack of organic compound thin films, which has been difficult in the coating process, and to make it possible to arbitrarily form a crystalline film. Expression and charge mobility can be improved.
(Confirmation of amorphous structure or crystal structure)
Confirmation and measurement of the compound of the present invention and the thin film having an amorphous structure or a crystal structure can be carried out using X-ray diffraction (XRD) (X-ray diffractometer, for example, manufactured by Rigaku Denki Co., Ltd. RINT-TTR2 apparatus) can be easily performed.

Furthermore, as a method for quantitatively measuring the degree of crystallization, for example, a thin layer sample is treated with a solvent that dissolves in the case of an amorphous structure and has no action of crystallization, such as toluene. The degree of crystallization can be measured from the degree of mass reduction.

The organic thin film of the present invention thus obtained can be suitably used for the organic EL element of the present invention, the electronic device of the present invention and the like.

《Electronic device》
The electronic device of the present invention will be described.

The electronic device of the present invention can be formed into various electronic devices using the organic thin film of the present invention. Among them, an element involving light is preferably used.

Examples of elements that involve light include liquid crystal display elements, electrophotography using organic photoreceptor thin films, organic photovoltaic cells, photochemical hole burning (PHB) recording elements, organic electroluminescence elements (organic EL elements), Langmuir / Blodgets. Various optical functional elements using the (LB) film can be mentioned, and an organic EL element is particularly preferable.

Hereinafter, the organic EL element, which is a preferred embodiment among the electronic devices of the present invention, will be described in more detail.

<< Organic EL element >>
The organic EL element of the present invention having an organic thin film obtained by the method for forming an organic thin film of the present invention will be described.

By the organic thin film formation method of the present invention, the first thin film is not dissolved in the solvent, and there is no mixing (contamination) of the lower layer material to the upper layer or disturbance of the interface. The organic EL device manufactured by this method can improve the light emission efficiency of the organic EL device, improve the device lifetime, and the like.

<< Constituent layers of organic EL elements >>
The constituent layers of the organic EL element of the present invention will be described. In this invention, although the preferable specific example of the layer structure of an organic EL element is shown below, this invention is not limited to these.

(I) Anode / light emitting layer / electron transport layer / cathode (ii) Anode / hole transport layer / light emitting layer / electron transport layer / cathode (iii) Anode / hole transport layer / light emitting layer / hole blocking layer / electron Transport layer / cathode (iv) Anode / hole transport layer / light emitting layer / hole blocking layer / electron transport layer / cathode buffer layer / cathode (v) Anode / anode buffer layer / hole transport layer / light emitting layer / hole Blocking layer / electron transport layer / cathode buffer layer / cathode In the organic EL device of the present invention, the blue light emitting layer preferably has an emission maximum wavelength of 430 nm to 480 nm, and the green light emitting layer has an emission maximum wavelength of 510 nm to 550 nm, The red light emitting layer is preferably a monochromatic light emitting layer having a light emission maximum wavelength in the range of 600 nm to 640 nm, and is preferably a display device using these. Alternatively, a white light emitting layer may be formed by laminating at least three light emitting layers. Further, a non-light emitting intermediate layer may be provided between the light emitting layers. The organic EL element of the present invention is preferably a white light emitting layer, and is preferably a lighting device using these.

Each layer constituting the organic EL element of the present invention will be described.

<Light emitting layer>
The light emitting layer according to the present invention is a layer that emits light by recombination of electrons and holes injected from the electrode, the electron transport layer, or the hole transport layer, and the light emitting portion is in the layer of the light emitting layer. May be the interface between the light emitting layer and the adjacent layer.

The total film thickness of the light emitting layer is not particularly limited, but from the viewpoint of improving the uniformity of the film, preventing unnecessary application of high voltage during light emission, and improving the stability of the emission color with respect to the drive current. It is preferable to adjust in the range of 2 nm to 5 μm, more preferably in the range of 2 nm to 200 nm, and particularly preferably in the range of 10 nm to 20 nm.

For the production of the light-emitting layer according to the present invention, a light-emitting dopant or a host compound (also referred to as a light-emitting host compound) to be described later is used, for example, spin coating method, casting method, LB method, inkjet method, vacuum deposition method, etc. The film can be formed by the thinning method.

The light emitting layer of the organic EL device of the present invention preferably contains a light emitting host compound and at least one kind of light emitting dopant (such as a phosphorescent dopant (also referred to as a phosphorescent dopant) or a fluorescent dopant).

(Host compound)
The host compound used in the present invention will be described.

Here, the host compound in the present invention is a phosphorescent quantum yield of phosphorescence emission at a room temperature (25 ° C.) having a mass ratio of 20% or more in the compound contained in the light emitting layer. Is defined as a compound of less than 0.1. The phosphorescence quantum yield is preferably less than 0.01. Moreover, it is preferable that the mass ratio in the layer is 20% or more among the compounds contained in a light emitting layer.

As the host compound, the compounds of the present invention, for example, exemplified compounds 2-1 to 2-5 can be preferably used.

The host compound may be used alone or in combination of two or more. By using a plurality of types of host compounds, it is possible to adjust the movement of charges, and the organic EL element can be made highly efficient. Moreover, it becomes possible to mix different light emission by using multiple types of light emission dopants mentioned later, and, thereby, arbitrary luminescent colors can be obtained.

As a known host compound that may be used in combination as long as the effect of the present invention is not impaired, it has a hole transporting ability and an electron transporting ability, and prevents a long wavelength emission, and has a high Tg (glass transition). Compound) is preferred.

Specific examples of known host compounds include compounds described in the following documents.

JP-A-2001-257076, 2002-308855, 2001-313179, 2002-319491, 2001-357777, 2002-334786, 2002-8860, 2002-334787, 2002-15871, 2002-334788, 2002-43056, 2002-334789, 2002-75645, 2002-338579, 2002-105445, 2002-343568, 2002-141173, 2002-352957, 2002-203683, 2002-363227, 2002-231453, 2003-3165, 2002-234888, 2003-27048, 2002-255934, 2002-260861, 2002-280183, 2002-299060, 2002 -302516, 2002-305083, 2002-305084, 2002-308837, and the like.

(Luminescent dopant)
As a light-emitting dopant that can be used in the present invention, a fluorescent dopant (also referred to as a fluorescent compound) or a phosphorescent dopant (also referred to as a phosphorescent emitter, a phosphorescent compound, or a phosphorescent compound) can be used. However, from the viewpoint of obtaining an organic EL device with higher luminous efficiency, the above-mentioned host is used as a light-emitting dopant (sometimes referred to simply as a light-emitting material) used in the light-emitting layer or light-emitting unit of the organic EL device of the present invention. It is preferable to contain a phosphorescent dopant simultaneously with the compound.

(Phosphorescent dopant)
The phosphorescent dopant that can be used in the present invention is a compound in which light emission from an excited triplet is observed, specifically, a compound that emits phosphorescence at room temperature (25 ° C.), and a phosphorescence quantum yield. Is defined as a compound of 0.01 or more at 25 ° C., but a preferable phosphorescence quantum yield is 0.1 or more.

The phosphorescent quantum yield can be measured by the method described in Spectroscopic II, page 398 (1992 edition, Maruzen) of the Fourth Edition Experimental Chemistry Course 7. Although the phosphorescence quantum yield in a solution can be measured using various solvents, the phosphorescence dopant according to the present invention achieves the phosphorescence quantum yield (0.01 or more) in any solvent. That's fine.

There are two types of light emission of phosphorescent dopants in principle. One is the recombination of carriers on the host compound to which carriers are transported to generate an excited state of the host compound, and this energy is transferred to the phosphorescent dopant. The energy transfer type that obtains light emission from the phosphorescent dopant, and the other is that the phosphorescent dopant becomes a carrier trap, carrier recombination occurs on the phosphorescent dopant, and light emission from the phosphorescent dopant is obtained. Although it is a trap type, in any case, the excited state energy of the phosphorescent dopant is required to be lower than the excited state energy of the host compound.

The phosphorescent dopant can be appropriately selected from known materials used for the light emitting layer of the organic EL element.

The phosphorescent dopant that can be used in the present invention is preferably a complex compound containing a group 8-10 metal in the periodic table of elements, more preferably an iridium compound, an osmium compound, or a platinum compound (platinum complex). System compounds), rare earth complexes, and most preferred are iridium compounds.

Specific examples of compounds used as phosphorescent dopants are shown below, but the present invention is not limited to these. These compounds are described, for example, in Inorg. Chem. 40, 1704 to 1711, and the like.

(Fluorescent dopant)
As fluorescent dopants (also referred to as fluorescent compounds), coumarin dyes, pyran dyes, cyanine dyes, croconium dyes, squalium dyes, oxobenzanthracene dyes, fluorescein dyes, rhodamine dyes, pyrylium dyes, Examples include perylene dyes, stilbene dyes, polythiophene dyes, and rare earth complex phosphors.

Next, an injection layer, a blocking layer, an electron transport layer, and the like used as a constituent layer of the organic EL element of the present invention will be described.

<< Injection layer: electron injection layer, hole injection layer >>
The injection layer is provided as necessary, and there are an electron injection layer and a hole injection layer, and as described above, it exists between the anode and the light emitting layer or the hole transport layer and between the cathode and the light emitting layer or the electron transport layer. May be.

An injection layer is a layer provided between an electrode and an organic layer in order to reduce drive voltage and improve light emission luminance. “Organic EL element and its forefront of industrialization (issued by NTT Corporation on November 30, 1998) 2), Chapter 2, “Electrode Materials” (pages 123 to 166) in detail, and includes a hole injection layer (anode buffer layer) and an electron injection layer (cathode buffer layer).

The details of the anode buffer layer (hole injection layer) are described in JP-A-9-45479, JP-A-9-260062, JP-A-8-288069 and the like. As a specific example, copper phthalocyanine is used. Examples thereof include a phthalocyanine buffer layer represented by an oxide, an oxide buffer layer represented by vanadium oxide, an amorphous carbon buffer layer, and a polymer buffer layer using a conductive polymer such as polyaniline (emeraldine) or polythiophene.

The details of the cathode buffer layer (electron injection layer) are described in JP-A-6-325871, JP-A-9-17574, JP-A-10-74586, and the like. Specifically, strontium, aluminum, etc. Metal buffer layer typified by lithium, alkali metal compound buffer layer typified by lithium fluoride, alkaline earth metal compound buffer layer typified by magnesium fluoride, oxide buffer layer typified by aluminum oxide, etc. . The buffer layer (injection layer) is preferably a very thin film, and the film thickness is preferably in the range of 0.1 nm to 5 μm, although it depends on the material.

<Blocking layer: hole blocking layer, electron blocking layer>
The blocking layer is provided as necessary in addition to the basic constituent layer of the organic compound thin film as described above. For example, it is described in JP-A Nos. 11-204258 and 11-204359, and “Organic EL elements and the forefront of industrialization (published by NTT Corporation on November 30, 1998)” on page 237. There is a hole blocking (hole blocking) layer.

The hole blocking layer has a function of an electron transport layer in a broad sense, and is made of a hole blocking material that has a function of transporting electrons and has a remarkably small ability to transport holes. The probability of recombination of electrons and holes can be improved by blocking. Moreover, the structure of the electron carrying layer mentioned later can be used as a hole-blocking layer concerning this invention as needed.

The hole blocking layer of the organic EL device of the present invention is preferably provided adjacent to the light emitting layer.

The hole blocking layer preferably contains the azacarbazole derivative mentioned as the host compound described above.

In the present invention, when a plurality of light emitting layers having different light emission colors are provided, the light emitting layer having the shortest wavelength of light emission is preferably closest to the anode among all the light emitting layers. In this case, it is preferable to additionally provide a hole blocking layer between the shortest wave layer and the light emitting layer next to the anode next to the anode. Furthermore, it is preferable that 50% by mass or more of the compound contained in the hole blocking layer provided at the position has an ionization potential of 0.3 eV or more larger than the host compound of the shortest wave emitting layer.

The ionization potential is defined by the energy required to emit electrons at the HOMO (highest occupied molecular orbital) level of the compound to the vacuum level, and can be obtained by the following method, for example.

(1) Using Gaussian 98 (Gaussian 98, Revision A.11.4, MJ Frisch, et al, Gaussian, Inc., Pittsburgh PA, 2002.), a molecular orbital calculation software manufactured by Gaussian, USA The ionization potential can be obtained as a value obtained by rounding off the second decimal place of the value (eV unit converted value) calculated by performing structural optimization using B3LYP / 6-31G *. The reason why this calculated value is effective is that there is a high correlation between the calculated value obtained by this method and the experimental value.

(2) The ionization potential can also be obtained by a method of directly measuring by photoelectron spectroscopy. For example, a low energy electron spectrometer “Model AC-1” manufactured by Riken Keiki Co., Ltd. or a method known as ultraviolet photoelectron spectroscopy can be suitably used.

On the other hand, the electron blocking layer has a function of a hole transport layer in a broad sense, and is made of a material that has a function of transporting holes and has an extremely small ability to transport electrons, and transports electrons while transporting holes. By blocking, the recombination probability of electrons and holes can be improved. Moreover, the structure of the positive hole transport layer mentioned later can be used as an electron blocking layer as needed. The film thickness of the hole blocking layer and the electron transport layer according to the present invention is preferably 3 nm to 100 nm, and more preferably 5 nm to 30 nm.

《Hole transport layer》
The hole transport layer is made of a hole transport material having a function of transporting holes, and in a broad sense, a hole injection layer and an electron blocking layer are also included in the hole transport layer. The hole transport layer can be provided as a single layer or a plurality of layers.

As the hole transport material, the compound of the present invention can be used. For example, exemplary compounds 1-1 to 1-5 can be preferably used. It can be suitably formed by a coating method.

A well-known hole transport material can be used in combination as long as the effects of the present invention are not significantly impaired.

The known hole transport material has either hole injection or transport or electron barrier property, and may be either organic or inorganic. For example, triazole derivatives, oxadiazole derivatives, imidazole derivatives, polyarylalkane derivatives, pyrazoline derivatives and pyrazolone derivatives, phenylenediamine derivatives, arylamine derivatives, amino-substituted chalcone derivatives, oxazole derivatives, styrylanthracene derivatives, fluorenone derivatives, hydrazone derivatives, Examples thereof include stilbene derivatives, silazane derivatives, aniline copolymers, and conductive polymer oligomers, particularly thiophene oligomers.

As the known hole transport material, the above-mentioned materials can be used, but it is preferable to use a porphyrin compound, an aromatic tertiary amine compound and a styrylamine compound, particularly an aromatic tertiary amine compound.

Representative examples of aromatic tertiary amine compounds and styrylamine compounds include N, N, N ′, N′-tetraphenyl-4,4′-diaminophenyl; N, N′-diphenyl-N, N′— Bis (3-methylphenyl)-[1,1′-biphenyl] -4,4′-diamine (TPD); 2,2-bis (4-di-p-tolylaminophenyl) 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-tolyl) Aminophenyl) -4-phenylcyclohexane; bis (4-dimethylamino-2-methylphenyl) phenylmethane; bis (4-di-p-tolylaminophenyl) phenylmethane; N, N'-diphenyl-N, N ' Di (4-methoxyphenyl) -4,4'-diaminobiphenyl; 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-diphenylaminostilbenzene; N-phenylcarbazole, and also two described in US Pat. No. 5,061,569 Having a condensed aromatic ring of, for example, 4,4'-bis [N- (1-naphthyl) -N-phenylamino] biphenyl (NPD), JP-A-4-308 4,4 ′, 4 ″ -tris [N- (3-methylphenyl) -N-phenylamino] triphenylamine in which three triphenylamine units described in Japanese Patent No. 88 are linked in a starburst type ( MTDATA) and the like.

Further, a polymer material in which these materials are introduced into a polymer chain or these materials are used as a polymer main chain can also be used. In addition, inorganic compounds such as p-type-Si and p-type-SiC can also be used as the hole injection material and the hole transport material.

Also, JP-A-11-251067, J. Org. Huang et. al. A so-called p-type hole transport material described in a book (Applied Physics Letters 80 (2002), p. 139) can also be used. In the present invention, these materials are preferably used because a light-emitting element with higher efficiency can be obtained.

The hole transport layer can be formed by thinning the hole transport material by a known method such as a vacuum deposition method, a spin coating method, a casting method, a printing method including an ink jet method, or an LB method. it can. The thickness of the hole transport layer is not particularly limited, but is usually about 5 nm to 5 μm, preferably 5 nm to 200 nm. The hole transport layer may have a single layer structure composed of one or more of the above materials.

It is also possible to use a hole transport layer having a high p property doped with impurities. Examples thereof include JP-A-4-297076, JP-A-2000-196140, JP-A-2001-102175, J. Pat. Appl. Phys. 95, 5773 (2004), and the like.

In the present invention, it is preferable to use a hole transport layer having such a high p property because a device with lower power consumption can be produced.

《Electron transport layer》
The electron transport layer is made of a material having a function of transporting electrons, and in a broad sense, an electron injection layer and a hole blocking layer are also included in the electron transport layer. The electron transport layer can be provided as a single layer or a plurality of layers.

Conventionally, in the case of a single electron transport layer and a plurality of layers, an electron transport material (also serving as a hole blocking material) used for an electron transport layer adjacent to the light emitting layer on the cathode side is injected from the cathode. The compound of the present invention can be used as the material as long as it has a function of transferring electrons to the light emitting layer. For example, exemplary compounds 3-1 to 3-5 can be preferably used. It can be suitably formed by a coating method.

Conventionally known compounds include, for example, nitro-substituted fluorene derivatives, diphenylquinone derivatives, thiopyran dioxide oxide derivatives, carbodiimides, fluorenylidenemethane derivatives, anthraquinodimethane and anthrone derivatives, oxadiazole derivatives, and the like. Furthermore, in the above oxadiazole derivative, a thiadiazole derivative in which the oxygen atom of the oxadiazole ring is substituted with a sulfur atom, and a quinoxaline derivative having a quinoxaline ring known as an electron withdrawing group can also be used as an electron transport material. Furthermore, a polymer material in which these materials are introduced into a polymer chain or these materials are used as a polymer main chain can also be used.

Also, metal complexes of 8-quinolinol derivatives such as tris (8-quinolinol) aluminum (Alq), tris (5,7-dichloro-8-quinolinol) aluminum, tris (5,7-dibromo-8-quinolinol) aluminum, Tris (2-methyl-8-quinolinol) aluminum, tris (5-methyl-8-quinolinol) aluminum, bis (8-quinolinol) zinc (Znq), etc., and the central metals of these metal complexes are In, Mg, Cu , Ca, Sn, Ga, or Pb can also be used as an electron transport material.

In addition, metal-free or metal phthalocyanine, or those having terminal ends substituted with an alkyl group or a sulfonic acid group can be preferably used as the electron transporting material. In addition, the distyrylpyrazine derivative exemplified as the material for the light emitting layer can also be used as an electron transport material, and an inorganic semiconductor such as n-type-Si, n-type-SiC, etc. as in the case of the hole injection layer and the hole transport layer. Can also be used as an electron transporting material.

The electron transport layer can be formed by thinning the electron transport material by a known method such as a vacuum deposition method, a spin coating method, a casting method, a printing method including an ink jet method, or an LB method. The thickness of the electron transport layer is not particularly limited, but is usually about 5 nm to 5 μm, preferably 5 nm to 200 nm. The electron transport layer may have a single layer structure composed of one or more of the above materials.

It is also possible to use an electron transport layer having a high n property doped with impurities. Examples thereof include JP-A-4-297076, JP-A-10-270172, JP-A-2000-196140, 2001-102175, J.A. Appl. Phys. 95, 5773 (2004), and the like.

In the present invention, it is preferable to use an electron transport layer having such a high n property because an element with lower power consumption can be produced.

"anode"
As the anode in the organic EL element, an electrode material made of a metal, an alloy, an electrically conductive compound, or a mixture thereof having a high work function (4 eV or more) is preferably used. Specific examples of such electrode materials include metals such as Au, and conductive transparent materials such as CuI, indium tin oxide (ITO), SnO ₂ , and ZnO. Alternatively, an amorphous material such as IDIXO (In ₂ O ₃ —ZnO) capable of forming a transparent conductive film may be used.

For the anode, these electrode materials may be formed into a thin film by a method such as vapor deposition or sputtering, and a pattern having a desired shape may be formed by a photolithography method, or when pattern accuracy is not so high (about 100 μm or more) A pattern may be formed through a mask having a desired shape at the time of vapor deposition or sputtering of the electrode material.

Alternatively, when a material that can be applied such as an organic conductive compound is used, a wet film forming method such as a printing method or a coating method can be used. When light emission is extracted from the anode, it is desirable that the transmittance be greater than 10%, and the sheet resistance as the anode is preferably several hundred Ω / □ or less. Further, although the film thickness depends on the material, it is usually selected in the range of 10 nm to 1000 nm, preferably 10 nm to 200 nm.

"cathode"
On the other hand, as the cathode, a material having a low work function (4 eV or less) metal (referred to as an electron injecting metal), an alloy, an electrically conductive compound, and a mixture thereof as an electrode material is used. Specific examples of such electrode materials include sodium, sodium-potassium alloy, magnesium, lithium, magnesium / copper mixture, magnesium / silver mixture, magnesium / aluminum mixture, magnesium / indium mixture, aluminum / aluminum oxide (Al ₂ O ₃ ) Mixtures, indium, lithium / aluminum mixtures, rare earth metals and the like. Among these, from the point of durability against electron injection and oxidation, etc., a mixture of an electron injecting metal and a second metal which is a stable metal having a larger work function than this, for example, a magnesium / silver mixture, Magnesium / aluminum mixtures, magnesium / indium mixtures, aluminum / aluminum oxide (Al ₂ O ₃ ) mixtures, lithium / aluminum mixtures, aluminum and the like are preferred.

The cathode can be produced by forming a thin film of these electrode materials by a method such as vapor deposition or sputtering.

The sheet resistance as a cathode is preferably several hundred Ω / □ or less, and the film thickness is usually selected in the range of 10 nm to 5 μm, preferably 50 nm to 200 nm. In order to transmit the emitted light, if either one of the anode or the cathode of the organic EL element is transparent or translucent, the light emission luminance is improved, which is convenient.

In addition, a transparent or semi-transparent cathode can be produced by producing the conductive transparent material mentioned in the description of the anode on the cathode after producing the metal with a film thickness of 1 nm to 20 nm. By applying this, an element in which both the anode and the cathode are transmissive can be manufactured.

《Support substrate》
As a support substrate (hereinafter also referred to as a substrate, substrate, substrate, support, etc.) that can be used in the organic EL device of the present invention, there is no particular limitation on the type of glass, plastic, etc., and it is transparent. May be opaque. When extracting light from the support substrate side, the support substrate is preferably transparent. Examples of the transparent support substrate preferably used include glass, quartz, and a transparent resin film. A particularly preferable support substrate is a resin film capable of giving flexibility to the organic EL element.

Examples of the resin film include polyesters such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN), polyethylene, polypropylene, cellophane, cellulose diacetate, cellulose triacetate, cellulose acetate butyrate, cellulose acetate propionate (CAP), Cellulose esters such as cellulose acetate phthalate (TAC) and cellulose nitrate or derivatives thereof, polyvinylidene chloride, polyvinyl alcohol, polyethylene vinyl alcohol, syndiotactic polystyrene, polycarbonate, norbornene resin, polymethylpentene, polyether ketone, polyimide , Polyethersulfone (PES), polyphenylene sulfide, polysulfone , Polyetherimide, polyetherketoneimide, polyamide, fluororesin, nylon, polymethylmethacrylate, acrylic or polyarylates, cyclone resins such as Arton (trade name, manufactured by JSR) or Appel (trade name, manufactured by Mitsui Chemicals) Etc.

On the surface of the resin film, an inorganic film, an organic film or a hybrid film of both may be formed. The water vapor permeability (25 ± 0.5 ° C.) measured by a method according to JIS K 7129-1992. , Relative humidity (90 ± 2)% RH) is preferably 0.01 g / (m ² · 24 h) or less, and further, oxygen measured by a method according to JIS K 7126-1987. A high barrier film having a permeability of 10 ⁻³ ml / (m ² · 24 h · MPa) or less and a water vapor permeability of 10 ⁻⁵ g / (m ² · 24 h) or less is preferable.

The material for forming the barrier film may be any material that has a function of suppressing the intrusion of elements that cause deterioration of elements such as moisture and oxygen. For example, silicon oxide, silicon dioxide, silicon nitride, or the like can be used. Further, in order to improve the brittleness of the film, it is more preferable to have a laminated structure of these inorganic layers and organic material layers. Although there is no restriction | limiting in particular about the lamination | stacking order of an inorganic layer and an organic layer, It is preferable to laminate | stack both alternately several times.

The method for forming the barrier film is not particularly limited. For example, vacuum deposition, sputtering, reactive sputtering, molecular beam epitaxy, cluster ion beam, ion plating, plasma polymerization, atmospheric pressure plasma polymerization A plasma CVD method, a laser CVD method, a thermal CVD method, a coating method, or the like can be used, but an atmospheric pressure plasma polymerization method as described in JP-A-2004-68143 is particularly preferable.

Examples of the opaque support substrate include metal plates such as aluminum and stainless steel, films, opaque resin substrates, ceramic substrates, and the like.

The external extraction efficiency at room temperature of light emission of the organic EL element of the present invention is preferably 1% or more, more preferably 5% or more.

Here, the external extraction quantum efficiency (%) = the number of photons emitted to the outside of the organic EL element / the number of electrons sent to the organic EL element × 100.

Also, a hue improvement filter such as a color filter may be used in combination, or a color conversion filter that converts the emission color from the organic EL element into multiple colors using a phosphor may be used in combination. In the case of using a color conversion filter, the λmax of light emission of the organic EL element is preferably 480 nm or less.

<Sealing>
As a sealing means used for this invention, the method of adhere | attaching a sealing member, an electrode, and a support substrate with an adhesive agent can be mentioned, for example.

The sealing member may be disposed so as to cover the display area of the organic EL element, and may be a concave plate shape or a flat plate shape. Further, transparency and electrical insulation are not particularly limited.

Specific examples include a glass plate, a polymer plate / film, and a metal plate / film. Examples of the glass plate include soda-lime glass, barium / strontium-containing glass, lead glass, aluminosilicate glass, borosilicate glass, barium borosilicate glass, and quartz. Examples of the polymer plate include polycarbonate, acrylic, polyethylene terephthalate, polyether sulfide, and polysulfone. Examples of the metal plate include those made of one or more metals or alloys selected from the group consisting of stainless steel, iron, copper, aluminum, magnesium, nickel, zinc, chromium, titanium, molybdenum, silicon, germanium, and tantalum.

In the present invention, a polymer film and a metal film can be preferably used because the element can be thinned. Furthermore, the polymer film has an oxygen permeability measured by a method according to JIS K 7126-1987 of 1 × 10 ⁻³ ml / (m ² · 24 h · MPa) or less, and a method according to JIS K 7129-1992. It is preferable that the water vapor permeability (25 ± 0.5 ° C., relative humidity (90 ± 2)% RH) measured in (1) is 1 × 10 ⁻³ g / (m ² · 24 h) or less.

For processing the sealing member into a concave shape, sandblasting, chemical etching, or the like is used.

Specific examples of the adhesive include photocuring and thermosetting adhesives having reactive vinyl groups of acrylic acid oligomers and methacrylic acid oligomers, and moisture curing adhesives such as 2-cyanoacrylates. be able to. Moreover, heat | fever and chemical curing types (two-component mixing), such as an epoxy type, can be mentioned. Moreover, hot-melt type polyamide, polyester, and polyolefin can be mentioned. Moreover, a cationic curing type ultraviolet curing epoxy resin adhesive can be mentioned.

In addition, since an organic EL element may deteriorate by heat processing, what can be adhesively cured from room temperature to 80 ° C. is preferable. A desiccant may be dispersed in the adhesive. Application | coating of the adhesive agent to a sealing part may use commercially available dispenser, and may print like screen printing.

In addition, it is also preferable that the electrode and the organic layer are coated on the outside of the electrode facing the support substrate with the organic layer interposed therebetween, and an inorganic or organic layer is formed in contact with the support substrate to form a sealing film. . In this case, the material for forming the film may be any material that has a function of suppressing intrusion of elements that cause deterioration of elements such as moisture and oxygen. For example, silicon oxide, silicon dioxide, silicon nitride, or the like may be used. it can. Further, in order to improve the brittleness of the film, it is preferable to have a laminated structure of these inorganic layers and layers made of organic materials. The method for forming these films is not particularly limited. For example, vacuum deposition, sputtering, reactive sputtering, molecular beam epitaxy, cluster ion beam, ion plating, plasma polymerization, atmospheric pressure plasma A combination method, a plasma CVD method, a laser CVD method, a thermal CVD method, a coating method, or the like can be used.

In the gap between the sealing member and the display area of the organic EL element, an inert gas such as nitrogen or argon, or an inert liquid such as fluorinated hydrocarbon or silicon oil can be injected in the gas phase and liquid phase. preferable. A vacuum is also possible. Moreover, a hygroscopic compound can also be enclosed inside.

Examples of the hygroscopic compound include metal oxides (eg, sodium oxide, potassium oxide, calcium oxide, barium oxide, magnesium oxide, aluminum oxide), sulfates (eg, sodium sulfate, calcium sulfate, magnesium sulfate, cobalt sulfate). Etc.), metal halides (eg calcium chloride, magnesium chloride, cesium fluoride, tantalum fluoride, cerium bromide, magnesium bromide, barium iodide, magnesium iodide etc.), perchloric acids (eg perchloric acid) Barium, magnesium perchlorate, and the like), and anhydrous salts are preferably used in sulfates, metal halides, and perchloric acids.

《Protective film, protective plate》
In order to increase the mechanical strength of the element, a protective film or a protective plate may be provided on the outer side of the sealing film on the side facing the support substrate with the organic layer interposed therebetween or on the sealing film. In particular, when the sealing is performed by the sealing film, the mechanical strength is not necessarily high, and thus it is preferable to provide such a protective film and a protective plate. As a material that can be used for this, the same glass plate, polymer plate / film, metal plate / film, and the like used for the sealing can be used, but the polymer film is light and thin. Is preferably used.

《Light extraction》
The organic EL element emits light inside a layer having a refractive index higher than that of air (refractive index is about 1.7 to 2.1) and can extract only about 15% to 20% of the light generated in the light emitting layer. It is generally said. This is because the light incident on the interface (interface between the transparent substrate and air) at an angle θ greater than the critical angle causes total reflection and cannot be taken out of the element, or between the transparent electrode or the light emitting layer and the transparent substrate. This is because the light is totally reflected between the light and the light is guided through the transparent electrode or the light emitting layer, and as a result, the light escapes in the direction of the element side surface.

As a method of improving the light extraction efficiency, for example, a method of forming irregularities on the surface of the transparent substrate and preventing total reflection at the transparent substrate and the air interface (US Pat. No. 4,774,435), A method for improving efficiency by giving light condensing property to a substrate (Japanese Patent Laid-Open No. 63-314795), a method of forming a reflective surface on the side surface of an element (Japanese Patent Laid-Open No. 1-220394), and light emission from the substrate A method of forming an antireflection film by introducing a flat layer having an intermediate refractive index between the bodies (Japanese Patent Laid-Open No. 62-172691), a flat having a lower refractive index between the substrate and the light emitter than the substrate A method of introducing a layer (Japanese Patent Laid-Open No. 2001-202827), a method of forming a diffraction grating between any one of a substrate, a transparent electrode layer and a light emitting layer (including between the substrate and the outside) (Japanese Patent Laid-Open No. 11-283951) Gazette).

In the present invention, these methods can be used in combination with the organic EL device of the present invention. However, a method of introducing a flat layer having a lower refractive index than the substrate between the substrate and the light emitter, or a substrate, transparent A method of forming a diffraction grating between any layers of the electrode layer and the light emitting layer (including between the substrate and the outside) can be suitably used.

In the present invention, by combining these means, it is possible to obtain an element having higher brightness or durability.

When a medium having a low refractive index is formed between the transparent electrode and the transparent substrate with a thickness longer than the wavelength of light, the efficiency of taking out the light from the transparent electrode to the outside increases as the refractive index of the medium decreases.

Examples of the low refractive index layer include aerogel, porous silica, magnesium fluoride, and a fluorine-based polymer. Since the refractive index of the transparent substrate is generally about 1.5 to 1.7, the low refractive index layer preferably has a refractive index of about 1.5 or less. Further, it is preferably 1.35 or less.

Also, the thickness of the low refractive index medium is preferably at least twice the wavelength in the medium. This is because the effect of the low refractive index layer is diminished when the thickness of the low refractive index medium is about the wavelength of light and the electromagnetic wave that has exuded by evanescent enters the substrate.

The method of introducing a diffraction grating into an interface or any medium that causes total reflection is characterized by a high effect of improving light extraction efficiency. This method uses the property that the diffraction grating can change the direction of light to a specific direction different from refraction by so-called Bragg diffraction such as first-order diffraction and second-order diffraction. Light that cannot be emitted due to total internal reflection between layers is diffracted by introducing a diffraction grating in any layer or medium (in a transparent substrate or transparent electrode), and the light is removed. I want to take it out.

It is desirable that the diffraction grating to be introduced has a two-dimensional periodic refractive index. This is because light emitted from the light-emitting layer is randomly generated in all directions, so in a general one-dimensional diffraction grating having a periodic refractive index distribution only in a certain direction, only light traveling in a specific direction is diffracted. Therefore, the light extraction efficiency does not increase so much. However, by making the refractive index distribution a two-dimensional distribution, light traveling in all directions is diffracted, and light extraction efficiency is increased.

As described above, the position where the diffraction grating is introduced may be in any of the layers or in the medium (in the transparent substrate or the transparent electrode), but is preferably in the vicinity of the organic light emitting layer where light is generated.

At this time, the period of the diffraction grating is preferably about 1/2 to 3 times the wavelength of light in the medium.

The arrangement of the diffraction grating is preferably two-dimensionally repeated such as a square lattice, a triangular lattice, or a honeycomb lattice.

<Condenser sheet>
The organic EL device of the present invention is processed on the light extraction side of the substrate so as to provide, for example, a microlens array structure, or combined with a so-called condensing sheet, for example, with respect to a specific direction, for example, the light emitting surface By condensing in the front direction, the luminance in a specific direction can be increased.

As an example of a microlens array, quadrangular pyramids having a side of 30 μm and an apex angle of 90 degrees are arranged two-dimensionally on the light extraction side of the substrate. One side is preferably 10 μm to 100 μm. If it becomes smaller than this, the effect of diffraction will generate | occur | produce and color, and if too large, thickness will become thick and is not preferable.

As the condensing sheet, it is possible to use, for example, a sheet that has been put to practical use in an LED backlight of a liquid crystal display device. As such a sheet, for example, a brightness enhancement film (BEF) manufactured by Sumitomo 3M Limited can be used. As the shape of the prism sheet, for example, the base material may be formed by forming a △ -shaped stripe having a vertex angle of 90 degrees and a pitch of 50 μm, or the vertex angle is rounded and the pitch is changed randomly. Other shapes may be used.

Further, in order to control the light emission angle from the light emitting element, a light diffusion plate / film may be used in combination with the light collecting sheet. For example, a diffusion film (light-up) manufactured by Kimoto Co., Ltd. can be used.

<< Method for producing organic EL element >>
As an example of the method for producing the organic EL device of the present invention, a method for producing an organic EL device comprising an anode / hole injection layer / hole transport layer / light emitting layer / electron transport layer / electron injection layer / cathode will be described.

First, a desired electrode material, for example, a thin film made of an anode material is formed on a suitable substrate by a method such as vapor deposition or sputtering so as to have a film thickness of 1 μm or less, preferably 10 nm to 200 nm.

Next, an organic compound thin film of a hole injection layer, a hole transport layer, a light emitting layer, an electron transport layer, an electron injection layer, and a hole blocking layer, which are organic EL element materials, is formed thereon.

As a method for forming each of these layers, there are a vapor deposition method, a wet process (spin coating method, casting method, ink jet method, printing method) and the like as described above, but it is easy to obtain a homogeneous film and it is difficult to generate pinholes. In view of the above, film formation by a coating method such as a spin coating method, an ink jet method, or a printing method is preferable in the present invention.

Examples of the liquid medium for dissolving or dispersing the organic EL material according to the present invention include ketones such as methyl ethyl ketone and cyclohexanone, fatty acid esters such as ethyl acetate, halogenated hydrocarbons such as dichlorobenzene, toluene, xylene, and mesitylene. Aromatic hydrocarbons such as cyclohexylbenzene, aliphatic hydrocarbons such as cyclohexane, decalin, and dodecane, and organic solvents such as DMF and DMSO can be used. Moreover, as a dispersion method, it can disperse | distribute by dispersion methods, such as an ultrasonic wave, high shear force dispersion | distribution, and media dispersion | distribution.

After forming these layers, a thin film made of a cathode material is formed thereon by a method such as vapor deposition or sputtering so as to have a film thickness of 1 μm or less, preferably in the range of 50 nm to 200 nm. By providing, a desired organic EL element can be obtained.

It is also possible to reverse the production order to produce a cathode, an electron injection layer, an electron transport layer, a light emitting layer, a hole transport layer, a hole injection layer, and an anode in this order. When a DC voltage is applied to the multicolor display device thus obtained, light emission can be observed by applying a voltage of about 2 to 40 V with the positive polarity of the anode and the negative polarity of the cathode. An alternating voltage may be applied. The alternating current waveform to be applied may be arbitrary.

<Application>
The organic EL element of the present invention can be used as a display device, a display, and various light emission sources. For example, lighting devices (home lighting, interior lighting), clock and liquid crystal backlights, billboard advertisements, traffic lights, light sources of optical storage media, light sources of electrophotographic copying machines, light sources of optical communication processors, light Although the light source of a sensor etc. are mentioned, It is not limited to this, Especially, it can use effectively for the use as a backlight of a liquid crystal display device, and a light source for illumination.

In the organic EL device of the present invention, patterning may be performed by a metal mask, an ink jet printing method, or the like during film formation, if necessary. In the case of patterning, only the electrode may be patterned, the electrode and the light emitting layer may be patterned, or the entire layer of the element may be patterned. In the fabrication of the element, a conventionally known method is used. Can do.

The light emission color of the organic EL device of the present invention and the compound according to the present invention is shown in FIG. 4.16 on page 108 of “New Color Science Handbook” (edited by the Japan Color Society, University of Tokyo Press, 1985). It is determined by the color when the result measured with a total CS-1000 (manufactured by Konica Minolta Sensing) is applied to the CIE chromaticity coordinates.

When the organic EL element of the present invention is a white element, white means that the chromaticity in the CIE1931 color system at 1000 cd / m ² is X when the 2 ° viewing angle front luminance is measured by the above method. = 0.33 ± 0.07 and Y = 0.33 ± 0.1.

Hereinafter, although an example explains the present invention, the present invention is not limited to these. In addition, although the display of "%" is used in an Example, unless otherwise indicated, "mass%" is represented.

Example 1
<< Preparation of X-ray diffraction measurement sample >>
Compound 3-3 (10 g) was dissolved in 50 ml of o-dichlorobenzene, and this solution was added little by little to 500 ml of acetonitrile while stirring. After the addition was completed, stirring was continued for 3 hours at room temperature. The sample was blown and dried at 70 ° C. for 6 hours to obtain Sample 1-1.

In the same procedure, Sample 1-2 was obtained using n-hexane instead of acetonitrile.

<< Measurement of X-ray diffraction (XRD) >>
The measurement results of X-ray diffraction XRD (X-ray diffraction apparatus, manufactured by Rigaku Corporation, model RINT-TTR2 apparatus) of Sample 1-1 and Sample 1-2 are shown in FIGS.

From this data, it can be confirmed that the compound having a specific structure of the present invention can stably extract the amorphous state (sample 1-2) and the crystalline state (sample 1-1) by properly using any treatment method. did it.

X-ray diffraction measurement conditions Equipment: RINT-TTR2 manufactured by Rigaku Corporation
X-ray: Cu (1.54mm)
X-ray operating conditions: 15 kV, 300 mA
Optical system: Bragg-Brentano optical system Form of measurement materials: After grinding in a mortar and filling in a non-reflective sample plate Slit conditions DS, SS: 1/2 °
RS: 0.3mm
Scanning conditions: 2θ = 2 to 45 ° (in increments of 0.04 °), scanning speed: 1 ° / min.
<Formation of laminated thin film>
A substrate with a 150 nm ITO film formed on glass (NH Techno Glass: NA-45) was ultrasonically cleaned with iso-propyl alcohol, dried with dry nitrogen gas, UV ozone cleaned for 5 minutes, and a transparent support substrate Got.

The substrate was transferred to a nitrogen atmosphere, and a film obtained by dissolving compound 2-2 (60 mg) in 6 ml of toluene was formed into a film by spin coating at 1000 rpm for 30 seconds, and heated in vacuum at 150 ° C. for 3 hours. And Sample 2-1 was obtained. Subsequently, the sample 2-1 was set on a spin coater, and 6 ml of acetonitrile was used to obtain a sample 2-2 treated with acetonitrile by a spin coating method under conditions of 1000 rpm and 300 seconds. Next, Sample 2-2 was heated in vacuum at 150 ° C. for 3 hours to obtain Sample 2-3.

In the preparation of Sample 2-3, Compound 2-2 was replaced with Compound 1-1, Compound 1-2, Compound 1-4, Compound 3-1, Compound 3-3, and Compound 3-5. Similar operations were performed to obtain Samples 2-4, 2-5, 2-6, 2-7, 2-8, and 2-9, respectively.

In the preparation of Sample 2-1, Sample 2-2, and Sample 2-3, the same operation was performed except that Compound 2-2 was replaced with CBP, and Samples 2-10, 2-11, 2-12 Respectively.

In the preparation of Sample 2-1, Sample 2-2, and Sample 2-3, the same operation was carried out except that Compound 2-2 was replaced with α-NPD, and Samples 2-13, 2-14, 2 -15 were obtained respectively.

In the preparation of Sample 2-1, Sample 2-2, and Sample 2-3, the same procedure was performed except that Compound 2-2 was replaced with Compound A (Compound (23) described in JP-A No. 2004-292882). And Samples 2-16, 2-17, and 2-18 were obtained.

<< Durability test of thin film >>
The prepared samples (Samples 2-1 to 2-18) are placed on a spin coater, 6 ml of toluene is used, and a toluene rinsing process is performed by spin coating under conditions of 1000 rpm and 30 seconds. Absorbance was measured with a spectrophotometer (Hitachi UV-3300). The residual rate of the thin film after toluene rinsing of each sample was obtained by the following formula and used as an index indicating the durability (solvent resistance) of the thin film. The results are shown in Table 1.

Residual rate = (absorbance after rinsing) / (absorbance before rinsing) × 100

Compound A: Compound (23) described in JP-A No. 2004-292784
From Table 1, by applying a physicochemical treatment after forming a thin film using the compound of the present invention, the solvent solubility is changed, and it is possible to form a thin film having excellent thin film durability (solvent resistance). I understood it. When the UV spectral absorption spectrum was measured, the waveform did not change, and the chemical structure of the molecules forming the thin film did not change.

Example 3
<< Preparation of organic EL element 3-1 >>
This ITO transparent electrode was provided after patterning was performed on a substrate (NA-45 manufactured by NH Techno Glass Co., Ltd.) formed by depositing 100 nm of ITO (indium tin oxide) on a 100 mm × 100 mm × 1.1 mm glass substrate as an anode. The transparent support substrate was ultrasonically cleaned with isopropyl alcohol, dried with dry nitrogen gas, and subjected to UV ozone cleaning for 5 minutes.

On this transparent support substrate, a solution obtained by diluting poly (3,4-ethylenedioxythiophene) -polystyrene sulfonate (PEDOT / PSS, Bayer, Baytron P Al 4083) to 70% with pure water at 3000 rpm for 30 seconds. After forming the film by spin coating, the film was dried at 200 ° C. for 1 hour to provide a hole transport layer having a thickness of 30 nm.

The substrate was transferred to a nitrogen atmosphere, and a solution of CBP (60 mg), compound Ir-9 (3.0 mg), and Ir-12 (3.0 mg) dissolved in 6 ml of toluene was used on the hole transport layer at 1000 rpm. For 30 seconds under the condition of spin coating. Heating was performed in vacuum at 150 ° C. for 1 hour to obtain a light emitting layer having a thickness of 30 nm.

Next, this transparent support substrate was fixed to a substrate holder of a commercially available vacuum deposition apparatus, while BCP and Alq ₃ were placed in five tantalum resistance heating boats, respectively, and attached to the vacuum deposition apparatus (first vacuum chamber). . Further, lithium fluoride was placed in a resistance heating boat made of tantalum, and aluminum was placed in a resistance heating boat made of tungsten, and attached to the second vacuum tank of the vacuum evaporation apparatus.

The first vacuum chamber was depressurized to 4 × 10 ⁻⁴ Pa, and then heated by energizing the heating boat containing BCP, and the first vacuum chamber having a thickness of 10 nm at a deposition rate of 0.1 to 0.2 nm / sec. An electron transport layer was provided. Further, the heating boat containing Alq ₃ was heated by energization to provide a second electron transport layer having a film thickness of 20 nm at a deposition rate of 0.1 to 0.2 nm / second.

Next, after the element formed up to the second electron transport layer is transferred to the second vacuum chamber while being vacuumed, a stainless steel rectangular perforated mask is arranged on the electron transport layer from the outside of the apparatus. Installed with remote control.

After depressurizing the second vacuum tank to 2 × 10 ⁻⁴ Pa, a current was passed through a boat containing lithium fluoride to provide a cathode buffer layer having a thickness of 0.5 nm at a deposition rate of 0.01 to 0.02 nm / second, Next, a boat containing aluminum was energized, and a cathode having a film thickness of 150 nm was attached at a deposition rate of 1 to 2 nm / second to produce an organic EL element 3-1.

<< Preparation of organic EL element 3-2 >>
This ITO transparent electrode was provided after patterning was performed on a substrate (NA-45 manufactured by NH Techno Glass Co., Ltd.) formed by depositing 100 nm of ITO (indium tin oxide) on a 100 mm × 100 mm × 1.1 mm glass substrate as an anode. The transparent support substrate was ultrasonically cleaned with isopropyl alcohol, dried with dry nitrogen gas, and subjected to UV ozone cleaning for 5 minutes.

This substrate was transferred to a nitrogen atmosphere, and a film obtained by dissolving α-NPD (60 mg) in 6 ml of toluene on a transparent support substrate was formed by spin coating at 1000 rpm for 30 seconds. After heating in vacuum at 150 ° C for 1 hour, the substrate was set on a spin coater, spin-coated using 6 ml of acetonitol at 1000 rpm for 300 seconds, and further heated in vacuum at 150 ° C for 1 hour. A hole transport layer having a thickness of 30 nm was provided.

This substrate was transferred to a nitrogen atmosphere, and a spin coating method was performed on the hole transport layer using a solution of CBP (60 mg) and Ir-12 (6.0 mg) dissolved in 6 ml of toluene at 1000 rpm for 30 seconds. To form a film. Heating was performed in vacuum at 150 ° C. for 1 hour to obtain a light emitting layer having a thickness of 30 nm.

After depressurizing the second vacuum tank to 2 × 10 ⁻⁴ Pa, a current was passed through a boat containing lithium fluoride to provide a cathode buffer layer having a thickness of 0.5 nm at a deposition rate of 0.01 to 0.02 nm / second, Next, a boat containing aluminum was energized, a cathode having a film thickness of 150 nm was attached at a deposition rate of 1 to 2 nm / second, and an organic EL element 3-2 was produced.

<< Preparation of organic EL elements 3-3 to 3-5 >>
In the production of the organic EL device 3-2, the organic EL device 3-3 was prepared in the same manner except that α-NPD (hole transport material) was changed to the compounds shown in Table 2 when the hole transport layer was provided. ~ 3-5 were produced.

<< Evaluation of organic EL elements >>
When evaluating the obtained organic EL elements 3-1 to 3-5, the non-light emitting surface of each organic EL element after production was covered with a glass case, and a glass substrate having a thickness of 300 μm was used as a sealing substrate. An epoxy-based photo-curing adhesive (Lux Track LC0629B manufactured by Toagosei Co., Ltd.) is applied as a sealing material in the periphery, and this is placed on the cathode to be in close contact with the transparent support substrate and irradiated with UV light from the glass substrate side. Then, it was cured and sealed, and an illumination device as shown in FIGS. 3 and 4 was formed and evaluated.

FIG. 3 is a schematic diagram of the lighting device, and the organic EL element 101 is covered with a glass cover 102 (in addition, the sealing operation with the glass cover is performed in a nitrogen atmosphere without bringing the organic EL element 101 into contact with the atmosphere. (In a high purity nitrogen gas atmosphere with a purity of 99.999% or more).

FIG. 4 shows a cross-sectional view of the lighting device. In FIG. 4, 105 denotes a cathode, 106 denotes an organic EL layer, and 107 denotes a glass substrate with a transparent electrode. The glass cover 102 is filled with nitrogen gas 108 and a water catching agent 109 is provided.

(External quantum efficiency)
By lighting the organic EL element under a constant current condition of room temperature (about 23 to 25 ° C.) and 2.5 mA / cm ² , and measuring the emission luminance (L) [cd / m ² ] immediately after the start of lighting, External extraction quantum efficiency (ηext) was calculated. Here, CS-1000 (manufactured by Konica Minolta Sensing) was used for measurement of light emission luminance. The external extraction quantum efficiency was expressed as a relative value where the organic EL element 3-1 was 100.

(Luminescent life)
The organic EL element was continuously lit at a constant current of ^2.5 mA / cm ² at room temperature, and the time (τ _1/2 ) required to reach half the initial luminance was measured. The light emission lifetime is expressed as a relative value where the organic EL element 3-1 is set to 100.

Table 2 shows the results obtained.

In Table 2, the comparative organic EL device 3-2 did not function as a light emitting device, and performance evaluation could not be performed. In addition, it is clear that the organic EL element of the present invention can achieve a longer emission lifetime than the comparative organic EL element 3-1, and the manufacturing method of the present invention is used as a manufacturing method of the organic EL element. I found it suitable.

Example 4
<< Preparation of organic EL element 4-1 >>
This ITO transparent electrode was provided after patterning was performed on a substrate (NA-45 manufactured by NH Techno Glass Co., Ltd.) formed by depositing 100 nm of ITO (indium tin oxide) on a 100 mm × 100 mm × 1.1 mm glass substrate as an anode. The transparent support substrate was ultrasonically cleaned with isopropyl alcohol, dried with dry nitrogen gas, and subjected to UV ozone cleaning for 5 minutes.

This substrate was transferred to a nitrogen atmosphere, and a film obtained by dissolving compound 1-4 (60 mg) in 6 ml of toluene on a transparent support substrate was formed by spin coating at 1000 rpm for 30 seconds. After heating in vacuum at 150 ° C for 1 hour, the substrate was set on a spin coater, spin-coated using 6 ml of acetonitol at 1000 rpm for 300 seconds, and further heated in vacuum at 150 ° C for 1 hour. A hole transport layer having a thickness of 30 nm was provided.

The substrate was transferred to a nitrogen atmosphere, and a solution of compound 2-1 (60 mg), compound Ir-9 (3.0 mg), and Ir-12 (3.0 mg) dissolved in 6 ml of toluene was placed on the hole transport layer. The film was formed by spin coating under conditions of 1000 rpm and 30 seconds. After heating in vacuum at 150 ° C for 1 hour, the substrate was set on a spin coater, spin-coated using 6 ml of acetonitol at 1000 rpm for 300 seconds, and further heated in vacuum at 150 ° C for 1 hour. A light emitting layer having a thickness of 30 nm was provided.

Further, a film obtained by dissolving Exemplified Compound 3-2 (60 mg) in 6 ml of butanol was formed into a film by spin coating under conditions of 1000 rpm and 30 seconds. After heating in vacuum at 150 ° C for 1 hour, the substrate was set on a spin coater, spin-coated using 6 ml of acetonitol at 1000 rpm for 300 seconds, and further heated in vacuum at 150 ° C for 1 hour. A first electron transport layer having a thickness of 30 nm was provided.

Subsequently, this substrate was fixed to a substrate holder of a vacuum vapor deposition apparatus, and 200 mg of Alq ₃ was put into a molybdenum resistance heating boat and attached to the vacuum vapor deposition apparatus. The vacuum chamber was depressurized to 4 × 10 ⁻⁴ Pa, and then heated by energizing the heating boat containing Alq ₃ and deposited on the first electron transport layer at a deposition rate of 0.1 nm / second, Further, a second electron transport layer having a thickness of 40 nm was provided.

In addition, the substrate temperature at the time of vapor deposition was room temperature.

Subsequently, lithium fluoride 0.5 nm and aluminum 110 nm were vapor-deposited to form a cathode, and a white light-emitting organic EL element 4-1 was produced.

When this organic EL element 4-1 was energized, almost white light was obtained, and it was found that it could be used as a lighting device.

DESCRIPTION OF SYMBOLS 101 Organic EL element 102 Glass cover 105 Cathode 106 Organic EL layer 107 Glass substrate with a transparent electrode 108 Nitrogen gas 109 Water catching agent

Claims

A thin film characterized by changing the physicochemical properties of the thin film without changing the chemical structure of the organic material forming the thin film by applying a physicochemical treatment after forming the thin film made of the organic material. Forming method.
The method for forming a thin film according to claim 1, wherein the organic substance is a compound having a partial structure represented by the following general formula (1).

(In the formula, Ar 1 and Ar 2 represent an aromatic ring, and R 1 and R 2 represent an atomic group necessary for bonding to each other to form a 5-membered or 6-membered aromatic ring, provided that (The aromatic ring represents an aromatic hydrocarbon ring or an aromatic heterocyclic ring.)
The method for forming a thin film according to claim 1 or 2, wherein the change in the physicochemical properties of the thin film is a change from amorphous to crystalline.
The method for forming a thin film according to any one of claims 1 to 3, wherein the physicochemical treatment is thermal treatment.
4. The method for forming a thin film according to claim 1, wherein the physicochemical treatment is a chemical treatment.
The method for forming a thin film according to any one of claims 1 to 5, wherein a coating step is used in forming the thin film.
The thin film forming method according to any one of claims 1 to 6, wherein a thin film adjacent to the thin film is formed on the thin film formed by the thin film forming method according to any one of claims 1 to 6. A method for forming a laminated thin film, characterized in that the laminated thin film is formed by a coating process that may be used.
An electronic device comprising a thin film formed by the method for forming a thin film according to any one of claims 1 to 6.
An electronic device comprising a laminated thin film formed by the method for forming a laminated thin film according to claim 7.
An organic electroluminescence device comprising a thin film formed by the method for forming a thin film according to any one of claims 1 to 6.
An organic electroluminescence device comprising a laminated thin film formed by the method for forming a laminated thin film according to claim 7.