CN112209943A

CN112209943A - Material for photoelectric conversion element, organic thin film, photoelectric conversion element, imaging element, photosensor, and compound

Info

Publication number: CN112209943A
Application number: CN202010644340.3A
Authority: CN
Inventors: 泷宫和男; 大垣拓也; 前田健太郎; 岩田智史; 贞光雄一
Original assignee: NATIONAL RESEARCH AND DEVELOPMENT CORP; Nippon Kayaku Co Ltd
Current assignee: NATIONAL RESEARCH AND DEVELOPMENT CORP; Nippon Kayaku Co Ltd; RIKEN Institute of Physical and Chemical Research
Priority date: 2019-07-09
Filing date: 2020-07-07
Publication date: 2021-01-12
Also published as: JP2021015963A; KR20210006858A

Abstract

The present invention relates to a material for a photoelectric conversion element, an organic thin film, a photoelectric conversion element, an imaging element, a photosensor, and a compound. The invention provides a material for a photoelectric conversion element, which is a material of a barrier layer with excellent hole leakage prevention property, electron transport property, heat resistance to process temperature, visible light penetrability and the like; and a photoelectric conversion element including the sameA photoelectric conversion element made of a material is a typical example of various electronic devices. The solution of the present invention is a material for a photoelectric conversion element, which contains a compound represented by the following formula (1), wherein R in the formula (1)¹To R⁴Each independently represents a hydrogen atom, an aromatic group, a heterocyclic group, an aliphatic hydrocarbon group or a halogen atom; x represents an oxygen atom or a sulfur atom.

Description

Material for photoelectric conversion element, organic thin film, photoelectric conversion element, imaging element, photosensor, and compound

Technical Field

The present invention relates to a material for a photoelectric conversion element containing an organic compound having a specific structure, and a photoelectric conversion element containing the material for a photoelectric conversion element.

Background

In recent years, organic electronic devices have been attracting attention because of their characteristics such as flexibility, large area availability, and low-cost and high-speed production by a printing method. Typical organic electronic devices include organic EL elements, organic solar cell elements, organic photoelectric conversion elements, organic transistor elements, and the like, and among these, organic EL elements are expected to be applied to displays of mobile phones, TVs, and the like, which are main targets of the following world display applications, and development is continuously being performed with a view to higher functionality. Research and development of organic solar cell devices and the like as flexible and low-cost energy sources have been carried out, and research and development of organic transistor devices are being carried out with the aim of being applied to flexible displays or low-cost ICs.

In the field of organic electronic devices, it is very important to develop excellent materials constituting the devices, and thus many studies and developments are still actively conducted in the field of each material.

In recent years, organic photoelectric conversion devices that are expected to be used in solar cells and photodetectors of the next generation have been reported by several organizations. For example, patent document 1 discloses an example in which a Quinacridone (Quinacridone) derivative or a Quinazoline (Quinazoline) derivative is used for a photoelectric conversion element, and patent document 2 discloses an example in which a diketopyrrolopyrrole (diketto pyrolo pyrolole) derivative is used.

In an image pickup element, for the purpose of reducing a leak current from a photoelectric conversion element in the dark in order to obtain an S/N ratio, a method of inserting a hole blocking layer or an electron blocking layer between a photoelectric conversion portion and an electrode portion is generally employed.

A hole blocking layer and an electron blocking layer, which are generally widely used in the field of organic electronic devices, are disposed at an interface between an electrode or a conductive film and other films in a film constituting a device, and are used by controlling the reverse movement of each hole or electron to adjust the leakage of unnecessary holes or electrons, and are selected in consideration of heat resistance, a transmission wavelength, a film forming method, and the like according to the application of the device.

Patent document 3 discloses an example of using Fullerene (Fullerene) as a hole blocking layer, and patent document 4 discloses an example of using 1,4,5, 8-naphthalenetetracarboxylic dianhydride (NCTDA) as a hole blocking layer. However, the materials for photoelectric conversion devices are required to have extremely high performance, and the hole-blocking layer and the electron-blocking layer have not yet had sufficient performance in terms of current leakage prevention characteristics, heat resistance against process temperature, visible light transmittance, and the like, and thus have not yet been commercially available.

[ Prior art documents ]

[ patent document ]

[ patent document 1] Japanese patent No. 4972288

[ patent document 2] Japanese patent No. 5022573

[ patent document 3] Japanese patent application laid-open No. 2013-544440

[ patent document 4] Japanese patent application laid-open No. 2014-506736.

Disclosure of Invention

[ problems to be solved by the invention ]

The present invention has been made in view of the above circumstances, and an object thereof is to provide a material for a photoelectric conversion element, which is a material for a barrier layer, which is excellent in hole leakage prevention properties, electron transport properties, heat resistance against a device manufacturing process temperature, visible light transmittance, and the like, and various electronic devices including a photoelectric conversion element including the material for a photoelectric conversion element.

[ means for solving the problems ]

The present inventors have made extensive efforts to solve the above problems, and as a result, have found that the above problems can be solved by applying a material for a photoelectric conversion element containing a compound having a specific structure to a photoelectric conversion element, and have completed the present invention.

That is, the present invention is as follows.

[1] A material for a photoelectric conversion element, comprising a compound represented by the following formula (1),

in the formula (1), R¹To R⁴Each independently represents a hydrogen atom, an aromatic group, a heterocyclic group, an aliphatic hydrocarbon group or a halogen atom; x represents an oxygen atom or a sulfur atom.

[2] The material for photoelectric conversion elements according to the above item [1], wherein X is an oxygen atom.

[3]As in the above item [1]Or [2]]The material for a photoelectric conversion element, wherein R¹And R²Is a hydrogen atom, R³And R⁴One is a hydrogen atom, an aromatic group, a heterocyclic group, an aliphatic hydrocarbon group or a halogen atom, and the other is an aromatic group, a heterocyclic group, an aliphatic hydrocarbon group or a halogen atom.

[4] An organic thin film comprising the material for a photoelectric conversion element according to any one of the above items [1] to [3 ].

[5] A photoelectric conversion element comprising the organic thin film described in the aforementioned item [4 ].

[6] The photoelectric conversion element according to the above item [5], wherein the organic thin film is a hole blocking layer.

[7] The photoelectric conversion element according to the aforementioned item [5] or [6], which is a light-emitting element.

[8] An imaging element in which the photoelectric conversion element according to any one of the aforementioned items [5] to [7] is arranged in a Multiple array form (Multiple array).

[9] A photosensor comprising the photoelectric conversion element described in the aforementioned item [5] or the image pickup element described in the aforementioned item [8 ].

[10] A compound represented by the following formula (2),

in the formula (2), R⁵And R⁶One of them represents a hydrogen atom, an aromatic group, a heterocyclic group, an aliphatic hydrocarbon group or a halogen atom, and the other represents an aromatic group, a heterocyclic group, an aliphatic hydrocarbon group or a halogen atom; x represents an oxygen atom or a sulfur atom.

[11] The compound according to the above item [10], wherein X is an oxygen atom.

[ Effect of the invention ]

The material for a photoelectric conversion element of the present invention containing a compound having a specific structure is excellent in leak-preventing property or transport property of holes or electrons, and has heat resistance or visible light transmittance that can withstand a device manufacturing process, and thus can provide a photoelectric conversion element exhibiting excellent characteristics.

Drawings

Fig. 1 shows a cross-sectional view illustrating an embodiment of a photoelectric conversion element of the present invention.

Fig. 2 is a schematic cross-sectional view showing an example of the layer structure of the organic electroluminescent element.

Fig. 3 shows dark current-voltage graphs of the photoelectric conversion elements obtained in examples 3 to 5 and comparative examples 1 to 3.

Fig. 4 shows an absorption spectrum of a thin film of the compound of the synthesis example.

Description of the reference numerals

(FIG. 1)

1 insulating part

2 Upper electrode film

3 electron blocking layer

4 photoelectric conversion layer

5 hole blocking layer

6 lower electrode film

7 insulating substrate or other photoelectric conversion element.

(FIG. 2)

21 substrate

22 anode

23 hole injection layer

24 hole transport layer

25 light-emitting layer

26 electron transport layer

27 cathode.

Detailed Description

The present invention will be described in detail below. The following description of the constituent elements is a representative example or specific example according to the present invention, but the present invention is not limited to such example or specific example.

[ Compound of formula (1) ]

The material for a photoelectric conversion element of the present invention contains a compound represented by the following formula (1).

In the formula (1), R¹To R⁴Each independently represents a hydrogen atom, an aromatic group, a heterocyclic group, an aliphatic hydrocarbon group or a halogen atom.

R of formula (1)¹To R⁴The aromatic group means a residue obtained by excluding 1 hydrogen atom from the aromatic ring of the aromatic compound.

R of formula (1)¹To R⁴Examples of the aromatic group include: phenyl, biphenyl, terphenyl, tolyl, indenyl, naphthyl, anthryl, fluorenyl, pyrenyl, phenanthryl, trimethylphenyl and the like, with phenyl, biphenyl, terphenyl, naphthyl or anthryl being more preferred, and phenyl, biphenyl, terphenyl or naphthyl being particularly preferred.

R of formula (1)¹To R⁴The heterocyclic group represented means that 1 hydrogen atom is excluded from the heterocyclic ring of the heterocyclic compoundThe latter residue.

R of formula (1)¹To R⁴Examples of the heterocyclic group include: furyl, thienyl, thienothienyl, pyrrolyl, imidazolyl, N-methylimidazolyl, thiazolinyl, oxazolyl, pyridyl, pyrazinyl, pyrimidinyl, quinolinyl, indolyl, benzopyrazinyl, benzopyrimidinyl, benzothienyl, naphthylthienyl, benzofuranyl, benzothiazolinyl, pyridothiazolinyl, benzimidazolyl, pyridoimidazolyl, N-methylbenzimidazolyl, pyrido-N-methylimidazolyl, benzoxazolyl, pyridooxazolyl, benzothiadiazolyl, pyridothiadiazolyl, benzooxadiazolyl, pyridooxadiazolyl, carbazolyl, Phenoxazinyl (Phenoxazinyl) and Phenothiazinyl (Phenothiazinyl), etc., more preferably furyl, thienyl, thienothienyl, benzothienyl, benzofuranyl, pyridyl or pyrazinyl, particularly preferably furyl, thienyl, thienothienyl, benzothienyl, pyridyl or pyrazinyl, Thienyl, pyridyl or pyrazinyl.

R of formula (1)¹To R⁴The aliphatic hydrocarbon group represented herein means a residue excluding 1 hydrogen atom from the heterocyclic ring of the aliphatic hydrocarbon compound, and is not limited to any of a linear type, a branched type and a cyclic type, and may contain an unsaturated bond.

R of formula (1)¹To R⁴The aliphatic hydrocarbon group represented by the above general formula (i) is preferably an alkyl group having 1 to 20 carbon atoms such as a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a tert-butyl group, an n-pentyl group, an isopentyl group, a tertiary pentyl group, a secondary pentyl group, a cyclopentyl group, an n-hexyl group, an isohexyl group, a cyclohexyl group, an n-heptyl group, a secondary heptyl group, an n-octyl group, a Vinyl group (Vinyl), a Vinyl group (Ethenyl group), a propenyl group, a propargyl group, a butenyl group, a pentenyl group and a hexenyl group, more preferably an.

R of formula (1)¹To R⁴Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom and an iodine atom, and a fluorine atom, a chlorine atom or a bromine atom is more preferable.

R of formula (1)¹To R⁴The aromatic group, heterocyclic group and aliphatic hydrocarbon group may haveHas a substituent. R in the formula (1) is shown below¹To R⁴The substituents of the aromatic group, heterocyclic group and aliphatic hydrocarbon group are only described as "R of formula (1)¹To R⁴The substituent(s) mentioned above.

R of formula (1)¹To R⁴The substituent to be used may be any of an electron-withdrawing substituent and an electron-donating substituent, but an electron-withdrawing substituent is more preferable.

The electron-withdrawing substituent is preferably a halogen atom, perfluoroalkyl group, acyl group, benzoyl group, carboxyl group, alkoxycarbonyl group, nitro group, cyano group or isocyano group, more preferably a halogen atom, perfluoroalkyl group, acyl group, alkoxycarbonyl group or cyano group, and still more preferably a halogen atom, perfluoroalkyl group or cyano group.

The electron-donating substituent is preferably an alkyl group, an alkoxy group, a phenoxy group, an aromatic group, a hydroxyl group, a mercapto group, an alkyl-substituted amino group, an aryl-substituted amino group or an unsubstituted amino group (NH)₂Radical), particularly preferably alkyl, alkoxy, aromatic or aryl-substituted amino radicals, more preferably alkyl or alkoxy radicals.

R as formula (1)¹To R⁴Examples of the halogen atom of the substituent include R of the formula (1)¹To R⁴The halogen atoms represented by the above groups are the same, and the same may be preferably used.

R as formula (1)¹To R⁴The perfluoroalkyl group as the substituent means a substituent in which all hydrogen atoms of the alkyl group are substituted with fluorine atoms, and specific examples of the alkyl group which may be the perfluoroalkyl group include: an alkyl group having 1 to 20 carbon atoms such as a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a tert-butyl group, an n-pentyl group, an isopentyl group, a tertiary pentyl group, a secondary pentyl group, an n-hexyl group, an isohexyl group, an n-heptyl group, a secondary heptyl group, an n-octyl group, an n-nonyl group, a secondary nonyl group, an n-decyl group, an n-undecyl group, an n-dodecyl group, an n-tridecyl group, an n-tetradecyl group, an n-pentadecyl group, an n-hexadecyl.

R as formula (1)¹To R⁴The perfluoroalkyl group as the substituent is preferably a perfluoroalkyl group having 1 to 20 carbon atoms, more preferably a perfluoroalkyl group having 1 to 12 carbon atoms, still more preferably a perfluoroalkyl group having 1 to 6 carbon atoms, and particularly preferably a perfluoroalkyl group having 1 to 4 carbon atoms.

R as formula (1)¹To R⁴The acyl group as the substituent means a substituent in which a carbonyl group is bonded to an alkyl group, and specific examples of the alkyl group as the acyl group include: and R as formula (1)¹To R⁴The alkyl groups described in the item of the substituted perfluoroalkyl group are the same.

R as formula (1)¹To R⁴The acyl group as the substituent is preferably an acyl group having an alkyl group having 1 to 20 carbon atoms, more preferably an acyl group having an alkyl group having 1 to 12 carbon atoms, still more preferably an acyl group having an alkyl group having 1 to 6 carbon atoms, and particularly preferably an acyl group having an alkyl group having 1 to 4 carbon atoms.

R as formula (1)¹To R⁴The alkoxycarbonyl group as the substituent means a substituent in which a carbonyl group and an alkoxy group are bonded, and specific examples of the alkyl group in the alkoxy group of the alkoxycarbonyl group include: and R as formula (1)¹To R⁴The alkyl groups described in the item of the substituted perfluoroalkyl group are the same.

R as formula (1)¹To R⁴The alkoxycarbonyl group as the substituent is preferably an alkoxycarbonyl group having an alkoxy group having 1 to 20 carbon atoms, more preferably an alkoxycarbonyl group having an alkoxy group having 1 to 12 carbon atoms, still more preferably an alkoxycarbonyl group having an alkoxy group having 1 to 6 carbon atoms, and particularly preferably an alkoxycarbonyl group having an alkoxy group having 1 to 4 carbon atoms.

R as formula (1)¹To R⁴Examples of the alkyl group having a substituent include: and R as formula (1)¹To R⁴The alkyl groups described in the item of the substituted perfluoroalkyl group are the same.

R as formula (1)¹To R⁴The alkyl group as the substituent is preferably an alkyl group having 1 to 20 carbon atoms, more preferably an alkyl group having 1 to 12 carbon atoms, still more preferably an alkyl group having 1 to 6 carbon atoms, particularly preferablyIs selected from alkyl groups having 1 to 4 carbon atoms.

R as formula (1)¹To R⁴The alkoxy group as the substituent means a substituent in which an oxygen atom is bonded to an alkyl group, and specific examples of the alkyl group as the substituent include: and R as formula (1)¹To R⁴The alkyl groups described in the section of the perfluoroalkoxy group as the substituent are the same.

R as formula (1)¹To R⁴The alkoxy group as the substituent is preferably an alkoxy group having 1 to 20 carbon atoms, more preferably an alkoxy group having 1 to 12 carbon atoms, still more preferably an alkoxy group having 1 to 6 carbon atoms, and particularly preferably an alkoxy group having 1 to 4 carbon atoms.

R as formula (1)¹To R⁴The phenoxy group as the substituent means a substituent in which an oxygen atom is bonded to an aromatic group, and specific examples of the aromatic group as the phenoxy group include R in the formula (1)¹To R⁴The aromatic groups represented by the above groups are the same, and the same groups are preferably used.

R as formula (1)¹To R⁴Specific examples of the aromatic group having a substituent include R of the formula (1)¹To R⁴The aromatic groups represented by the above groups are the same, and the same groups are preferably used.

R as formula (1)¹To R⁴The alkyl-substituted amino group having a substituent is not limited to any of the monoalkyl-substituted amino group and the dialkyl-substituted amino group, and examples of the alkyl group in these alkyl-substituted amino groups include: and R as formula (1)¹To R⁴The alkyl groups described in the item of the substituted perfluoroalkyl group are the same.

R as formula (1)¹To R⁴The alkyl-substituted amino group as the substituent is preferably an amino group substituted with a mono-or dialkyl group having 1 to 6 carbon atoms in each alkyl group, and more preferably an amino group substituted with a mono-or dialkyl group having 1 to 4 carbon atoms in each alkyl group.

R as formula (1)¹To R⁴The substituted amino group having an aryl group as a substituent is not limitedIn the substituted amino group with monoaryl and the substituted amino group with diaryl, the aryl group in these substituted amino groups can be listed as: and R of formula (1)¹To R⁴The aromatic group is the same as R in the formula (1)¹To R⁴The heteroaromatic groups described in the item of the heterocyclic group are the same, and the same may be preferably used.

X in the formula (1) represents an oxygen atom or a sulfur atom, and preferably an oxygen atom.

The compound represented by the formula (1) is more preferably R¹And R²Is a hydrogen atom, R³And R⁴A compound in which one is a hydrogen atom, an aromatic group, a heterocyclic group, an aliphatic hydrocarbon group or a halogen atom, and the other is an aromatic group, a heterocyclic group, an aliphatic hydrocarbon group or a halogen atom, that is, a compound represented by the following formula (2).

In the formula (2), R⁵And R⁶One of them represents a hydrogen atom, an aromatic group, a heterocyclic group, an aliphatic hydrocarbon group or a halogen atom, and the other represents an aromatic group, a heterocyclic group, an aliphatic hydrocarbon group or a halogen atom. X represents an oxygen atom or a sulfur atom.

R of formula (2)⁵And R⁶Specific examples of the aromatic group, heterocyclic group, aliphatic hydrocarbon group and halogen atom include R in the formula (1)¹To R⁴The aromatic group, heterocyclic group, aliphatic hydrocarbon group and halogen atom represented by the above are the same, and the same may be preferably used.

The compound represented by the formula (2) can be synthesized by, for example, a method shown in the following scheme using the compound represented by the formula (1-1) as a starting material. Specifically, the tetraesters represented by the formula (M-1) can be synthesized by subjecting the compounds represented by the formula (1-1) to a halogenation reaction accompanied by ring opening of a dicarboxylic anhydride and an alkylation reaction followed by the halogenation reaction. The intermediate represented by the formula (M-2) is obtained by introducing a substituent by subjecting the compound represented by the formula (M-1) to a cross-coupling reaction. Then, a cyclization reaction is performed to obtain the desired compound represented by formula (2).

In the formula (M-1), X represents a halogen atom, and Me represents a methyl group.

In the above formula (M-2), R⁵And R⁶R in the formula (2)⁵And R⁶In the same sense, Me represents a methyl group.

The method for purifying the compound represented by formula (1) is not particularly limited, and a generally known method such as recrystallization, column chromatography, and vacuum sublimation purification can be used. In addition, these methods may be combined as desired.

Specific examples of the compound represented by formula (1) are shown below, but the compound represented by formula (1) contained in the material for a photoelectric conversion element of the present invention is not limited to these specific examples.

In the present specification, "Hx" in the structural formula means n-hexyl, "Ph" means phenyl and "Me" means methyl.

[ CHEM 6]

[ CHEM 7]

[ CHEM 8]

[ CHEM 9]

[ CHEM 10]

[ CHEM 11]

[ CHEM 12 ]

[ CHEM 13 ]

[ CHEM 14 ]

[ CHEM 15 ]

[ CHEM 16 ]

[ CHEM 17 ]

[ CHEM 18 ]

[ CHEM 19 ]

[ CHEM 20 ]

[ CHEM 21 ]

The content of the compound represented by formula (1) in the material for a photoelectric conversion element of the present invention is not particularly limited as long as the material can exhibit the required performance in the use of the material for a photoelectric conversion element, and is usually 50% by mass or more, preferably 80% by mass or more, more preferably 90% by mass or more, and still more preferably 95% by mass or more.

The material for a photoelectric conversion element of the present invention may be used in combination with a compound other than the compound represented by formula (1) (for example, a material for a photoelectric conversion element other than the compound represented by formula (1)), an additive, or the like. The compound, additive, and the like that can be used in combination are not particularly limited as long as they can exhibit the necessary performance in the use of the material for a photoelectric conversion element.

[ organic thin film ]

The organic thin film of the present invention contains the material for a photoelectric conversion element of the present invention.

The organic thin film of the present invention can be produced by a general dry film formation method or a general wet film formation method. Specific examples thereof include: the resistance heating evaporation, electron beam evaporation, sputtering and molecular lamination methods belonging to vacuum process; belongs to the coating methods of casting, spin coating, dip coating, blade coating, wire rod coating, spray coating and the like in the solution process; printing methods such as inkjet printing, screen printing, lithographic printing, and relief printing; and soft lithography techniques such as microcontact printing.

In general, from the viewpoint of ease of processing, the material for a photoelectric conversion element is preferably used in a process of applying a compound in a solution state, but when an organic electronic device such as an organic layer is laminated, the application solution is not suitable because the application solution is likely to intrude into the lower organic film.

In order to realize such a multilayer laminated structure, a material that can be used in a dry film formation method, for example, a vapor deposition process such as resistance heating vapor deposition, is suitably used. Therefore, a material for a vapor-depositable photoelectric conversion element is more preferable.

The film formation of each layer can be carried out by a method combining a plurality of the above methods. The thickness of each layer is not limited because it depends on the resistance value/charge mobility of each substance, but is usually in the range of 0.5 to 5,000nm, more preferably 1 to 1,000nm, and particularly preferably 5 to 500 nm.

[ organic electronic device ]

The photoelectric conversion element of the present invention comprises the organic thin film of the present invention. The photoelectric conversion element is an element in which a photoelectric conversion portion (film) is disposed between a pair of opposing electrode films, and light is made incident on the photoelectric conversion portion from above the electrode films. And an element in which the photoelectric conversion film portion generates electrons and holes in response to the incident light, and a signal corresponding to the charges is read by the semiconductor, thereby displaying the amount of incident light corresponding to the absorption wavelength of the photoelectric conversion film portion. A transistor for reading may be connected to the electrode film on the side where light is not incident. When a plurality of photoelectric conversion elements are arranged in an array, incident position information is displayed in addition to the amount of incident light, and therefore, an imaging element is obtained. In addition, in the case where the photoelectric conversion element disposed closer to the light source does not shield (penetrate) the absorption wavelength of the photoelectric conversion element disposed behind the light source when viewed from the light source side, a plurality of photoelectric conversion elements may be used in a stacked manner.

The photoelectric conversion element of the present invention uses a material for a photoelectric conversion element containing the compound represented by the formula (1) as a constituent material of the photoelectric conversion portion.

The photoelectric conversion part is composed of: and an organic thin film layer other than the photoelectric conversion layer, the organic thin film layer being selected from one or more of the group consisting of an electron transport layer, a hole transport layer, an electron blocking layer, a hole blocking layer, an anti-crystallization layer, and an interlayer contact improvement layer. In the following, in particular, the electron transport layer, the hole transport layer, the electron blocking layer and the hole blocking layer are also denoted as carrier blocking layers. The material for a photoelectric conversion element of the present invention may be used in addition to the carrier blocking layer, but it is more preferable to use an organic thin film layer as the carrier blocking layer. The carrier blocking layer may be composed of only the compound represented by the above formula (1), or may contain a generally known blocking material or other materials in addition to the compound represented by the above formula (1).

When a photoelectric conversion layer included in a photoelectric conversion portion described later has a hole-transporting property, or when an organic thin film layer other than the photoelectric conversion layer is a hole-transporting layer having a hole-transporting property, an electrode film used in the photoelectric conversion element of the present invention functions to extract holes from the photoelectric conversion layer or other organic thin film layer and trap the holes; alternatively, when the photoelectric conversion layer included in the photoelectric conversion portion has an electron transporting property, or when the organic thin film layer is an electron transporting layer having an electron transporting property, the electrode film used in the photoelectric conversion element of the present invention functions to extract electrons from the photoelectric conversion layer or other organic thin film layers and to send out the electrons. Therefore, the material that can be used as the electrode film is not particularly limited as long as it has a certain conductivity, and is preferably selected in consideration of adhesion to the adjacent photoelectric conversion layer or other organic thin film layer, electron affinity, ionization potential, stability, and the like. Materials that can be used as the electrode film include, for example: conductive metal oxides such as tin oxide (NESA), indium oxide, Indium Tin Oxide (ITO), and Indium Zinc Oxide (IZO); metals such as gold, silver, platinum, chromium, aluminum, iron, cobalt, nickel, and tungsten; inorganic conductive materials such as copper iodide and copper sulfide; conductive polymers such as polythiophene, polypyrrole, polyaniline, and the like; carbon, and the like. These materials may be mixed and used as a mixture of a plurality of materials as required, or may be laminated in 2 layers or more. The conductivity of the material used in the electrode film is not particularly limited as long as it is not so high as necessary as to prevent the light reception of the photoelectric conversion element, and is preferably as high as possible from the viewpoint of the signal intensity and power consumption of the photoelectric conversion element. For example, an ITO film having a sheet resistance of 300 Ω/□ or less is preferably used because it can sufficiently function as an electrode film and a commercially available substrate having an ITO film having a sheet resistance of about several Ω/□ is available. The thickness of the ITO film (electrode film) may be arbitrarily selected in consideration of conductivity, but is usually 5 to 500nm, more preferably about 10 to 300 nm. Examples of the method for forming a film such as ITO include conventionally generally known vapor deposition, electron beam, sputtering, chemical reaction, and coating methods. The ITO film provided on the substrate may be subjected to UV-ozone treatment, plasma treatment, or the like as required.

Among the electrode films, the material of the transparent electrode film used on at least one of the light incident sides includes: ITO, IZO, SnO₂ATO (antimony doped tin oxide), ZnO, AZO (Al doped zinc oxide), GZO (gallium doped zinc oxide), TiO₂And FTO (fluorine doped tin oxide), and the like. The transmittance of light incident through the transparent electrode film at the absorption peak wavelength of the photoelectric conversion layer is preferably 60% or more, more preferably 80% or more, and particularly preferably 95% or more.

In addition, when a plurality of photoelectric conversion layers having different detection wavelengths are stacked, the electrode film used between the photoelectric conversion layers (electrode film other than the pair of electrode films) must transmit light having a wavelength other than light detected by the photoelectric conversion layers, and the electrode film is preferably made of a material that transmits 90% or more of incident light, and more preferably 95% or more of light.

The electrode film is preferably formed without plasma treatment. By forming these electrode films by the plasma-free treatment, the influence of plasma on the substrate provided with the electrode films can be reduced, and the photoelectric conversion characteristics of the photoelectric conversion element can be improved. The plasma-free treatment means that plasma is not generated at the time of forming the electrode film, or plasma reaching the substrate is reduced by setting the distance from the plasma generation source to the substrate to 2cm or more, preferably 10cm or more, and more preferably 20cm or more.

Examples of the device that does not generate plasma when forming the electrode film include an electron beam vapor deposition device (EB vapor deposition device) and a pulse laser vapor deposition device. A method of forming a transparent electrode film using an EB vapor deposition apparatus is referred to as an EB vapor deposition method, and a method of forming a transparent electrode film using a pulse laser vapor deposition apparatus is referred to as a pulse laser vapor deposition method.

Examples of the apparatus capable of achieving a state in which plasma during film formation can be reduced include a facing target type sputtering apparatus, an arc plasma evaporation apparatus, and the like.

When the transparent conductive film is formed as an electrode film (e.g., a first conductive film), a DC short circuit or an increase in leakage current may occur. One of the reasons for this is considered to be that fine cracks generated in the photoelectric conversion layer are covered with a dense film such as TCO (Transparent Conductive Oxide), and the conduction between the electrode film on the opposite side of the Transparent Conductive film is increased. Therefore, when a material having relatively poor film quality such as Al is used as an electrode, an increase in leakage current is less likely to occur. By controlling the film thickness of the electrode film in accordance with the film thickness (crack depth) of the photoelectric conversion layer, an increase in leakage current can be suppressed.

Generally, when the conductive film is thinned to a thickness smaller than a predetermined value, a sharp increase in resistance value is caused. The sheet resistance of the conductive film in the photoelectric conversion element for a photosensor of the present embodiment is generally 100 to 10,000 Ω/□, and the degree of freedom of the film thickness is large. In addition, as the thickness of the transparent conductive film becomes thinner, the amount of light absorbed is reduced, and the light transmittance is generally increased. When the light transmittance is increased, the light absorbed by the photoelectric conversion layer is increased, and the photoelectric conversion performance is improved, which is highly preferable.

The photoelectric conversion element of the present invention has a photoelectric conversion portion including: a photoelectric conversion layer, a carrier blocking layer, and an organic thin film layer other than these. The photoelectric conversion layer constituting the photoelectric conversion portion generally uses an organic semiconductor film, which may be one layer or a plurality of layers, and in the case of one layer, a P-type organic semiconductor film, an N-type organic semiconductor film, or a mixed film (mixed layer heterostructure) of these is used. On the other hand, in the case of a multilayer, about 2 to 10 layers, a structure of any one of a P-type organic semiconductor film, an N-type organic semiconductor film, or a mixed film (mixed layer heterostructure) of these is laminated, and a buffer layer may be interposed between the layers.

The organic semiconductor film of the photoelectric conversion layer may use the following compounds in accordance with the absorbed wavelength band: triarylamine compounds, benzidine compounds, pyrazoline compounds, styrylamine compounds, hydrazone compounds, triphenylmethane compounds, carbazole compounds, polysilane compounds, thiophene compounds, phthalocyanine compounds, naphthalocyanine compounds, anthocyanin compounds, merocyanine compounds, oxacyanine (Oxonol) compounds, polyamine compounds, indole compounds, pyrrole compounds, pyrazole compounds, polyarylene compounds, carbazole derivatives, naphthalene derivatives, anthracene derivatives, aromatic compounds, aromatic,

A derivative, a phenanthrene derivative, a pentacene derivative, a phenylbutadiene derivative, a styryl derivative, a quinoline derivative, a tetracene derivative, a pyrene derivative, a perylene derivative, a fluoranthene derivative, a quinacridone derivative, a coumarin derivative, a porphyrin derivative, a boron dipyrromethene derivative, a fullerene derivative, a complex (an Ir complex, a Pt complex, an Eu complex, or the like), or the like.

The electron transport layer of the present invention exhibits: a function of transporting electrons generated by the photoelectric conversion layer to the electrode film, and a function of blocking holes from moving from the electrode film at the electron transport destination to the photoelectric conversion layer. The hole transport layer functions as: a function of transporting the generated holes from the photoelectric conversion layer to the electrode film, and a function of blocking electrons from moving from the electrode film at the hole transport destination to the photoelectric conversion layer. The electron blocking layer functions as: the function of preventing the electrons from moving from the electrode film to the photoelectric conversion layer and preventing the recombination of the photoelectric conversion layer to reduce the dark current. The hole blocking layer has: the function of preventing the movement of holes from the electrode film to the photoelectric conversion layer and preventing the recombination of holes in the photoelectric conversion layer to reduce dark current.

The hole-blocking layer is formed by forming a film by mixing two or more hole-blocking substances alone or in combination, or by laminating two or more hole-blocking substances. The hole blocking substance is not particularly limited as long as it is a compound that can prevent holes from flowing out of the electrode to the outside of the device. The compounds that can be used in the hole-blocking layer include, in addition to the compounds represented by the above formula (1): phenanthroline derivatives such as bathophenanthrine (bathophenanthrine) and Bathocuproine (Bathocuproine), silacyclopentadiene (Silole) derivatives, quinolol (Quinolinol) derivative metal complexes, oxadiazole derivatives, oxazole derivatives, quinoline derivatives and the like. One or more of these may be used.

Fig. 1 shows a typical element structure of the photoelectric conversion element of the present invention, but the present invention is not limited to this structure. In the example of fig. 1,1 denotes an insulating portion, 2 denotes one electrode film (upper electrode film), 3 denotes an electron blocking layer, 4 denotes a photoelectric conversion layer, 5 denotes a hole blocking layer, 6 denotes another electrode film (lower electrode film), and 7 denotes an insulating base material or another photoelectric conversion element. Although the transistor for reading is not shown in the figure, it is only required to be connected to the electrode film of 2 or 6, and the photoelectric conversion layer 4 may be formed outside the electrode film on the side opposite to the side on which light is incident, as long as it is transparent. As long as the components other than the photoelectric conversion layer 4 do not extremely inhibit the incidence of the light of the wavelength mainly absorbed by the photoelectric conversion layer, the incidence of the light to the photoelectric conversion element may be from either the upper portion or the lower portion.

[ organic EL element ]

An organic electroluminescent device (organic EL device) as an example of a light-emitting device using an organic thin film containing the material for photoelectric conversion devices of the present invention will be described.

Organic EL devices have been attracting attention and have been extensively developed because they can be used for self-luminous large-area color displays, illumination, and the like. The constitution thereof is known: a 2-layer structure having a light-emitting layer and a charge transport layer between opposing electrodes composed of a cathode and an anode; a 3-layer structure having an electron transport layer, a light-emitting layer, and a hole transport layer laminated between opposing electrodes; and a layer having 3 or more layers, and the like, and a light-emitting layer having a single layer is also known.

Fig. 2 shows a representative device structure of an organic electroluminescent device according to an embodiment of the present invention, but the present invention is not limited to this structure. In the example of fig. 2, 1 denotes a substrate, 2 denotes an anode, 3 denotes a hole injection layer, 4 denotes a hole transport layer, 5 denotes a light emitting layer, 6 denotes an electron transport layer, and 7 denotes a cathode.

Here, the hole transport layer has: a function of injecting holes from the anode and transporting the holes to the light-emitting layer to easily inject the holes into the light-emitting layer, and a function of blocking electrons. In addition, the electron transport layer has: a function of injecting electrons from the cathode and transporting the electrons to the light-emitting layer to easily inject the electrons into the light-emitting layer, and a function of blocking holes. In addition, the electrons and holes injected separately recombine in the light-emitting layer to generate an excitation photon, and the energy emitted by the excitation photon is detected as light emission in the process of radiation deactivation.

The anode used in the organic EL element is an electrode having a function of injecting holes into the hole injection layer, the hole transport layer, and the light-emitting layer. In general, a metal oxide, a metal, an alloy, a conductive material, or the like having a work function of 4.5eV or more is preferable. Materials suitable for the anode of the organic EL element are not particularly limited, and examples thereof include: conductive metal oxides such as tin oxide (NESA), indium oxide, Indium Tin Oxide (ITO), and Indium Zinc Oxide (IZO); metals such as gold, silver, platinum, chromium, aluminum, iron, cobalt, nickel, and tungsten; inorganic conductive materials such as copper iodide and copper sulfide; conductive polymers such as polythiophene, polypyrrole, and polyaniline, and carbon. Among these, ITO or NESA is more preferably used.

The anode may be formed of a variety of materials as needed, or may be formed of 2 or more layers of different materials. The resistance of the anode is not particularly limited as long as it is light emission that can supply a sufficient current to the element, and is preferably low in terms of power consumption of the element. For example, an ITO film having a sheet resistance of 300. omega./□ or less can function as an element electrode, and a substrate having a sheet resistance of several Ω/□ or so can be obtained, so that a low-resistance product is preferably used. The thickness of ITO can be arbitrarily selected depending on the resistance value, but it is usually used at 5 to 500nm, preferably at 10 to 300 nm. Examples of the method for forming the film of ITO and the like include vapor deposition, electron beam, sputtering, chemical reaction, coating and the like.

The cathode used in the organic EL element is an electrode having a function of injecting electrons into the electron injection layer, the electron transport layer, and the light-emitting layer. In general, a metal or alloy having a small work function (about 4eV or less) is suitable. Specific examples thereof include: platinum, gold, silver, copper, iron, tin, zinc, aluminum, indium, chromium, lithium, sodium, potassium, calcium, magnesium, and the like, and lithium, sodium, potassium, calcium, or magnesium is more preferable in order to improve the electron injection efficiency and improve the device characteristics. As the alloy, an alloy of a metal such as aluminum or silver containing the metal having a low work function, an electrode having a structure in which these are stacked, or the like can be used. An inorganic salt such as lithium fluoride may be used for the electrode having a laminated structure. In the case where light emission is extracted not to the anode side but to the cathode side, the cathode may be a transparent electrode which can be formed at a low temperature. Examples of the method for forming the cathode film include, but are not particularly limited to, vapor deposition, electron beam, sputtering, chemical reaction, and coating. The resistance of the cathode is not particularly limited as long as it is light emission that can supply a sufficient current to the element, and is preferably low in terms of power consumption of the element, and is more preferably about 100 Ω/□ to several Ω/□. The film thickness of the cathode is usually in the range of 5 to 500nm, more preferably 10 to 300 nm.

The cathode can be made of oxide or nitride such as titanium oxide, silicon nitride, silicon oxide, silicon oxynitride, germanium oxide, etc., or mixture of these; polyvinyl alcohol, vinyl chloride, hydrocarbon polymers, fluorine polymers, etc., or can be sealed with a dehydrating agent such as barium oxide, phosphorus pentoxide, calcium oxide, etc.

In order to extract light emission, it is generally preferable to form an electrode on a substrate having sufficient transparency in the light emission wavelength region of the device. Examples of the substrate having transparency include a glass substrate and a polymer substrate. Soda-lime glass, alkali-free glass, quartz, or the like is used as the glass substrate. The thickness of the glass substrate is preferably 0.5mm or more as long as the mechanical and thermal strength can be sufficiently maintained. The glass is preferably made of a material having a small amount of ion eluted from the glass, and for example, alkali-free glass may be used, but commercially available SiO may be used₂Soda-lime glass after barrier coating. Examples of the substrate made of a polymer other than glass include: polycarbonate, polypropylene, polyethersulfone, polyethylene terephthalate, acrylic substrates, and the like.

The organic thin film of the organic EL device may be formed in 1 or more layers between the anode and the cathode. When the organic thin film contains the compound represented by the formula (1), an element which emits light by electric energy can be obtained.

The "layer" formed by the organic thin film means a single layer having functions of these layers as shown in a hole transporting layer, an electron transporting layer, a hole transporting light-emitting layer, an electron transporting light-emitting layer, a hole blocking layer, an electron blocking layer, a hole injecting layer, an electron injecting layer, a light-emitting layer, or the following configuration example 9). The structure of the layer forming the organic thin film in the present invention may be any one of the structures exemplified in the following structural examples 1) to 9).

Example of construction

1) Hole-transporting layer/electron-transporting light-emitting layer.

2) Hole transport layer/light emitting layer/electron transport layer.

3) Hole-transporting light-emitting layer/electron-transporting layer.

4) Hole transport layer/light emitting layer/hole blocking layer.

5) Hole transport layer/light emitting layer/hole blocking layer/electron transport layer.

6) Hole-transporting light-emitting layer/hole-blocking layer/electron-transporting layer.

7) In each of the combinations of 1) to 6), a structure of a hole injection layer is further provided before the hole transport layer or the hole transporting light-emitting layer.

8) In each of the combinations of 1) to 3), 5) to 7), an electron injection layer is further provided before the electron transport layer or the electron transporting light-emitting layer.

9) The materials used in the combinations of 1) to 8) described above are mixed, respectively, and have only a constitution of one layer containing the mixed material.

The foregoing 9) is generally a single layer formed of a material called a bipolar light emitting material; or only one layer containing a light-emitting material and a hole-transporting material or an electron-transporting material is provided. Generally, by constituting a multilayer structure, it is possible to efficiently transport charges (that is, holes and/or electrons) and recombine the charges. Further, by suppressing quenching of charges or the like, the stability of the element can be prevented from being lowered, and the light emission efficiency can be improved.

The hole injection layer and the hole transport layer are formed by stacking a hole transport material alone or a mixture of two or more of the materials. The hole transport material can be used more preferably: triphenylamines such as N, N ' -diphenyl-N, N ' -bis (3-methylphenyl) -4,4 ″ -diphenyl-1, 1' -diamine and N, N ' -dinaphthyl-N, N ' -diphenyl-4, 4' -diphenyl-1, 1' -diamine; bis (N-allylcarbazole) or bis (N-alkylcarbazole) type; heterocyclic compounds represented by pyrazoline derivatives, stilbene compounds, hydrazone compounds, triazole derivatives, oxadiazole derivatives, or porphyrin derivatives; the polymer is not particularly limited as long as it is a substance having a side chain containing the above-mentioned monomer, such as a polycarbonate, a styrene derivative, polyvinylcarbazole, or polysilane, and is capable of forming an organic thin film necessary for device fabrication, injecting holes from an electrode, and transporting holes. Examples of the hole injection layer provided between the hole transport layer and the anode for improving the hole injection property include: prepared from a starburst amine such as a phthalocyanine derivative and m-MTDATA (4,4' -tris [ phenyl (m-tolyl) amino ] triphenylamine), and a polythiophene such as PEDOT (poly (3, 4-ethylenedioxythiophene)) and a polyvinylcarbazole derivative in a polymer system.

The electron transport layer is formed by forming a film of an electron transport material alone or a film of a mixture of two or more of the materials. The electron transport material functions to transport electrons from the negative electrode between the electrodes for applying an electric field, and it is preferable that the electron injection efficiency is high and the injected electrons can be efficiently transported. Therefore, the electron transport material is required to have a high electron affinity, a high electron mobility, and excellent stability, and to be less likely to generate impurities that become traps during production and use. Examples of substances satisfying this condition include: quinolyl derivative metal complexes represented by tris (8-hydroxyquinoline) aluminum complexes, Tropolone (Tropolone) metal complexes, perylene derivatives, peryleneone (Perinone) derivatives, naphthalimide derivatives, naphthalenedicarboxylic acid derivatives, oxazole derivatives, oxadiazole derivatives, thiazole derivatives, thiadiazole derivatives, triazole derivatives, bisstyryl derivatives, pyrazine derivatives, phenanthroline derivatives, benzoxazole derivatives, Quinoxaline (Quinoxaline) derivatives, and the like, but are not limited thereto. These electron transport materials may be used alone, or different electron transport materials may be used in a stacked or mixed manner. The electron injection layer provided between the electron transport layer and the cathode for improving the electron injection property includes metals such as cesium, lithium, and strontium, and lithium fluoride.

The hole blocking layer is formed by stacking a hole blocking substance alone or by mixing two or more kinds of the substance. The hole-blocking substance is preferably a phenanthroline derivative such as bathophenoline or bathocuproine, a silacyclopentadiene derivative, a quinolol derivative metal complex, an oxadiazole derivative, an oxazole derivative, or the like. The hole-blocking substance is not particularly limited as long as it is a compound that can prevent holes from flowing out of the cathode side to the outside of the device and prevent a decrease in light emission efficiency.

The light-emitting layer means an organic thin film which emits light, and may be, for example, a hole transport layer, an electron transport layer, or a bipolar transport layer having strong light-emitting properties. The light-emitting layer may be formed of a light-emitting material (a host material, a dopant material, or the like), and may be a mixture of a host material and a dopant material, a single host material, or both. The host material and the dopant material may be one or a combination of materials.

The dopant material may be contained in whole or in part in the host material, or both. The doping material may be layered or dispersed, both. Examples of the material used for the light-emitting layer include: carbazole derivatives, anthracene derivatives, naphthalene derivatives, phenanthrene derivatives, phenyl butadiene derivatives, styryl derivatives, pyrene derivatives, perylene derivatives, quinoline derivatives, tetracene derivatives, perylene derivatives, quinacridone derivatives, coumarin derivatives, porphyrin derivatives, phosphorescent metal complexes (Ir complexes, Pt complexes, Eu complexes, etc.), and the like.

As a method for forming an organic thin film of an organic EL device, generally: the method belongs to the vacuum process of resistance heating evaporation, electron beam evaporation, sputtering and molecular lamination; belongs to the coating methods of casting, spin coating, dip coating, blade coating, wire rod coating, spray coating and the like in the solution process; or printing methods such as inkjet printing, screen printing, offset printing and relief printing; a method of soft lithography such as a microcontact printing method, and a method of combining a plurality of these methods can also be used. The thickness of each layer is not particularly limited depending on the resistance value and the charge mobility of each substance, but is usually selected from the range of 0.5 to 5,000nm, more preferably 1 to 1,000nm, and particularly preferably 5 to 500 nm.

In the organic thin film constituting the organic EL element, 1 or more layers of thin films such as a light-emitting layer, a hole transport layer, and an electron transport layer, which are present between an anode and a cathode, contain the compound represented by the above formula (1), and thus an element which can emit light efficiently even with low electric energy can be obtained.

The compound represented by the above formula (1) can be used more preferably as a hole-blocking layer, a light-emitting layer, or an electron-transporting layer, but is more preferably used as a hole-blocking layer. For example, the compound may be used in combination with or in admixture with the aforementioned electron-transporting material, hole-transporting material, light-emitting material, and the like.

Represented by the above formula (1)When a compound is used as a host material in combination with a dopant material, specific examples of the dopant material include: perylene derivatives such as bis (diisopropylphenyl) perylene tetracarboxylic acid imide, perinone derivatives, metal phthalocyanine derivatives such as 4- (dicyanomethylene) -2-methyl-6- (p-dimethylaminostyryl) -4H-piperazine (DCM) or analogues thereof, magnesium phthalocyanine and aluminum phthalocyanine chloride, rose bengal (Rhodamine) compounds, Deazaflavin (Deazaflavin) derivatives, coumarin derivatives, oxazine compounds, squaraine (Squarylium) compounds, Violanthrone (Vinthrone) compounds, nilosol red, 5-cyanopyrrolylidene-BF₄Pyrromethene derivatives such as complexes, Eu complexes using acetylacetone or benzoylacetone and phenanthroline as a ligand, or porphyrins such as Ir complexes, Ru complexes, Pt complexes, and Os complexes, and metallated metal complexes, which are phosphorescent materials, may be used, but the present invention is not particularly limited thereto. In addition, when 2 kinds of dopant materials are mixed, an auxiliary dopant such as Rubrene (Rubrene) may be used to efficiently transfer energy from the host dye to obtain light emission with improved color purity. In any case, in order to obtain high luminance characteristics, it is preferable that the doped fluorescence quantum yield is high.

Since the concentration quenching phenomenon occurs when the dopant is used in excess, the amount used is usually 30% by mass or less, more preferably 20% by mass or less, and particularly preferably 10% by mass or less, based on the host material. The method of doping the host material with the dopant material in the light-emitting layer may be a co-evaporation method with the host material, but may be a method of mixing the host material with the dopant material in advance and then simultaneously evaporating the mixture. Alternatively, the sheet may be sandwiched between the main materials. In this case, two or more doped layers may be stacked with the host material.

These doping layers may be formed as individual layers or as a mixture of these. Further, the dopant material may be used as a polymer binder dissolved or dispersed in a solvent-soluble resin such as polyvinyl chloride, polycarbonate, polystyrene sulfonic acid, poly (N-vinylcarbazole), poly (meth) acrylate, polybutylmethacrylate, polyester, polysulfone, polyphenylene oxide, polybutadiene, hydrocarbon resin, ketone resin, phenoxy resin, polysulfone, polyamide, ethyl cellulose, vinyl acetate, ABS resin (acrylonitrile-butadiene-styrene copolymer resin), polyurethane resin, or a curable resin such as phenol resin, xylene resin, petroleum resin, urea resin, melamine resin, unsaturated polyester resin, alkyd resin, epoxy resin, or silicone resin.

The organic EL element can be preferably used as a flat display. In addition, the flat backlight may be used, and in this case, either one of colored light emission and white light emission may be used. The backlight is mainly used for the purpose of improving the visibility of a display device which does not emit light, and is used in a liquid crystal display device, a clock, an audio device, an automobile instrument panel, a display panel, a sign, and the like. In particular, although conventional backlights for personal computers, which are used in liquid crystal display devices and have a problem of being thin, are difficult to be thin because they are composed of fluorescent lamps or light guide plates, the backlights using the light emitting element of the present invention are thin and lightweight, and thus the above-described problem can be solved. Likewise, it may be useful for illumination.

When the compound represented by the above formula (1) of the present invention is used, an organic EL display device having high luminous efficiency and a long lifetime can be obtained. In addition, an organic EL display device in which the switching phenomenon of the applied voltage is electrically controlled with high accuracy can be provided at low cost by combining with a thin film transistor element.

[ examples ] A method for producing a compound

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples. The microwave synthesis reaction in the examples was carried out using Initiator + (Biotage Co.). The structure of the compound described in the synthesis examples can be determined by Mass Spectrometry (MS) or Nuclear Magnetic Resonance (NMR) as required. The mass spectrometry spectra in the examples were measured by GCMS-QP2020 (Shimadzu corporation),¹the H NMR spectrum was measured by ECS400(JEOL Ltd.), and the absorption spectrum was measured by ultraviolet visible light spectrophotometer UV-1700 (Shimadzu corporation)Company). The melting point is a value measured by an M-565 melting point measuring apparatus (Buchi Co., Ltd.).

Example 1 (Synthesis of Compound represented by the following formula (E1))

(step 1) Synthesis of intermediate Compound represented by the following formula (M-3)

Commercially available 2,3,6, 7-naphthalenetetracarboxylic dianhydride represented by the following formula (1-1) (690mg, 2.50mmol) and concentrated sulfuric acid (25ml) were charged into a flask and dissolved by stirring. N-bromosuccinimide (4.45g, 25mmol) was charged thereto, and reacted at room temperature for 72 hours. Methanol (30ml) was added to the reaction solution, followed by addition of water (50 ml). The resulting mixed solution was extracted by ethyl acetate, and the aqueous layer was further extracted twice by ethyl acetate. The obtained organic layer was concentrated under reduced pressure to obtain a solid. Methylene chloride (10ml) and water (5ml) were added to the obtained solid and stirred to dissolve it. Dimethyl sulfuric acid (1.89g, 15mmol) and a 40% tetrabutylammonium hydroxide aqueous solution (9.73g, 15mmol) were charged and reacted at room temperature for 5 hours. The reaction solution was extracted 3 times with ethyl acetate, and the resulting organic layer was concentrated under reduced pressure to give a solid. The obtained solid was purified by silica gel column chromatography to obtain 700mg (0.74mmol, yield 30%) of an intermediate compound represented by the following formula (M-3).

The results of mass spectrometry and NMR spectroscopy of the intermediate compound represented by the formula (M-3) are shown below.

EI-MS(m/z)：516([M]⁺,50％)、518([M]⁺,100％)、520([M]⁺,50％)

¹H NMR(400MHz,CDCl₃)：δ8.80(s,2H)、4.01(s,6H)、3.99(s,6H)

(step 2) Synthesis of intermediate Compound represented by the following formula (M-4)

The intermediate compound represented by the formula (M-3) synthesized in step 1 (259mg, 0.50mmol), 3, 5-bis (trifluoromethyl) phenylboronic acid (516mg, 2.0mmol), [1,1' -bis (diphenylphosphino) iron shen ] -dichloropalladium (II) dichloromethane adduct (7.32mg, 0.01mmol), potassium phosphate (637mg, 3.0mmol), and 9 of degassed toluene and water: 1 Mixed solvent (5ml) was charged in a flask, and the reaction was carried out at 170 ℃ for 1 hour using a microwave apparatus. To the resulting mixture was added water (10ml) and extracted 3 times with ethyl acetate (10 ml). The obtained organic layer was concentrated under reduced pressure to obtain a solid. The obtained solid was purified by silica gel column chromatography to obtain 349mg (0.445mmol, yield 89%) of an intermediate compound represented by the following formula (M-4).

The results of mass spectrometry and NMR spectroscopy of the intermediate compound represented by the formula (M-4) are shown below.

EI-MS(m/z)：784[M]⁺

¹H NMR(400MHz,CDCl₃)：δ8.08(s,2H)、7.90(s,2H)、7.87(s,4H)、3.89(s,6H)、3.58(s,6H)

(step 3) Synthesis of Compound represented by the following formula (E1)

The intermediate compound represented by the formula (M-4) synthesized in step 2 (319mg, 0.41mmol) and acetic acid (5ml) were charged in a flask and stirred. To this was added methanesulfonic acid (1mL, 15.4mmol) and the reaction was allowed to proceed for 3 hours while the temperature was raised to 130 ℃. Volatile components were distilled off from the reaction mixture by concentration under reduced pressure, and the obtained residual solid was purified by vacuum sublimation purification, whereby 164mg (0.238mmol, 58% yield) of the compound represented by the formula (E1) was obtained as a colorless solid.

The results of mass spectrometry, NMR spectrum and melting point measurement of the compound represented by formula (E1) are shown below.

EI-MS(m/z)：692[M]⁺

¹H NMR (400MHz, acetone-d 6): Δ 8.72(s,2H), 8.41(s,2H), 8.33(s,4H)

Melting point: 357 to 358 deg.C

Example 2 (Synthesis of Compound represented by the following formula (E2))

(step 4) Synthesis of intermediate Compound represented by the following formula (M-5)

The intermediate compound represented by the formula (M-3) synthesized in step 1 of example 1 (259mg, 0.50mmol), 3, 5-bis (trifluoromethyl) phenylboronic acid (516mg, 2.0mmol), [1,1' -bis (diphenylphosphino) iron shen ] -dichloropalladium (II) dichloromethane adduct (7.32mg, 0.01mmol), potassium phosphate (637mg, 3.0mmol), and 9 of degassed toluene and water: 1 Mixed solvent (5ml) was charged in a flask, and the reaction was carried out at 170 ℃ for 1 hour using a microwave apparatus. To the resulting mixture was added water (10ml) and extracted 3 times with ethyl acetate (10 ml). The obtained organic layer was concentrated under reduced pressure to obtain a solid. The obtained solid was purified by silica gel column chromatography to obtain 349mg (0.445mmol, yield 89%) of an intermediate compound represented by the following formula (M-5).

The results of mass spectrometry and NMR spectroscopy of the intermediate compound represented by the formula (M-5) are shown below.

EI-MS(m/z)：784[M]⁺

(step 5) Synthesis of Compound represented by the following formula (E2)

The intermediate compound represented by the formula (M-5) synthesized in step 4 (319mg, 0.41mmol) and acetic acid (5ml) were charged in a flask and stirred. To this was added methanesulfonic acid (1mL, 15.4mmol) and the reaction was allowed to proceed for 3 hours while the temperature was raised to 130 ℃. Volatile components were distilled off from the reaction mixture by concentration under reduced pressure, and the obtained residual solid was purified by vacuum sublimation purification, whereby 164mg (0.238mmol, 58% yield) of the compound represented by the formula (E2) was obtained as a colorless solid.

The results of mass spectrometry, NMR spectrum and melting point measurement of the compound represented by formula (E2) are shown below.

EI-MS(m/z)：692[M]⁺

¹H NMR (400MHz, acetone-d 6): Δ 8.72(s,2H), 8.41(s,2H), 8.33(s,4H)

Melting point: 357 to 358 deg.C

In the following examples and comparative examples of the photoelectric conversion element, the photoelectric conversion element was produced by an evaporation apparatus, and the current and voltage were applied and measured in the atmosphere. The photoelectric conversion element thus produced was placed in a closed bottle-shaped measuring chamber (ALS Technology) in a glove box in a nitrogen atmosphere, and current and voltage were applied and measured. The current and voltage application was measured using a semiconductor parameter analyzer 4200-SCS (Keithley Instruments). The irradiation with the incident light was carried out using PVL-3300 (Asahi-Mitsuka Co., Ltd.) at an irradiation light wavelength of 550nm and an irradiation light half width of 20 nm. The light-dark ratio in the embodiment indicates a value obtained by dividing a current value at the time of light irradiation by a current value in a dark place.

Example 3 (production of photoelectric conversion element and evaluation thereof)

Tin phthalocyanine as a photoelectric conversion layer was formed on an ITO transparent conductive glass (ITO film thickness 150nm, manufactured by geomantec corporation) in a vacuum of 100nm, and a compound represented by the above formula (1) as a hole blocking layer was formed thereon in a vacuum deposition by resistance heating in the presence of 50 nm. Finally, aluminum as an electrode was formed in a vacuum of 100nm on the hole blocking layer to produce the photoelectric conversion element of the present invention.

In the photoelectric conversion element obtained above, when a voltage of 3V was applied using ITO and aluminum as electrodes, the contrast ratio was calculated from the measurement results of the current value in the dark and the current value when irradiated with light, and the results are shown in table 1.

Example 4 (production of photoelectric conversion element and evaluation thereof)

A photoelectric conversion element was produced according to example 3, except that the compound represented by the formula (E1) obtained in example 1 was used instead of the compound represented by the formula (1-1). When a voltage of 3V was applied using ITO and aluminum as electrodes, the contrast ratio was calculated from the measurement results of the current value in the dark and the current value when light was irradiated, and the results are shown in table 1.

Example 5 (production of photoelectric conversion element and evaluation thereof)

A photoelectric conversion element was produced according to example 3, except that the compound represented by the formula (E2) obtained in example 2 was used instead of the compound represented by the formula (1-1). When a voltage of 3V was applied using ITO and aluminum as electrodes, the contrast ratio was calculated from the measurement results of the current value in the dark and the current value when light was irradiated, and the results are shown in table 1.

Comparative example 1 (production of photoelectric conversion element for comparison and evaluation thereof)

A comparative photoelectric conversion element was produced in accordance with example 3, except that 1,4,5, 8-naphthalene tetracarboxylic dianhydride (NTCDA) was used instead of the compound represented by formula (1-1), and the contrast ratio was calculated. The results are shown in table 1.

Comparative example 2 (production of photoelectric conversion element for comparison and evaluation thereof)

A photoelectric conversion element for comparison was produced and the contrast ratio was calculated in accordance with example 3, except that 3,4,9, 10-perylenetetracarboxylic dianhydride (PTCDA) was used in place of the compound represented by formula (1-1). The results are shown in table 1.

Comparative example 3 (production of photoelectric conversion element for comparison and evaluation thereof)

A comparative photoelectric conversion element was produced and the contrast ratio was calculated in accordance with example 3, except that fullerene (C60) was used instead of the compound represented by formula (1-1). The results are shown in table 1.

[ Table 1] evaluation results of photoelectric conversion elements

As is clear from the results in table 1, the photoelectric conversion element of the present invention using the compounds represented by the formula (1-1) or the formula (E1) and the formula (E2) as the hole blocking layer exhibits a higher contrast ratio and a lower dark current value of one digit or more than that of a photoelectric conversion element for comparison using a generally known compound as the hole blocking layer, and therefore has preferable leak-preventing properties (in the dark) and is suitable as a hole-blocking material for an organic photoelectric conversion element.

Example 6 (Synthesis of Compound represented by the following formula (E3))

(step 6) Synthesis of intermediate Compound represented by the following formula (M-6)

The intermediate compound represented by the formula (M-3) synthesized in step 1 (259mg, 0.50mmol), phenylboronic acid (244mg, 2.0mmol), [1,1' -bis (diphenylphosphino) iron shen ] -dichloropalladium (II) dichloromethane adduct (12mg, 0.015mmol), potassium phosphate (637mg, 3.0mmol), and degassed toluene and water 9: 1 Mixed solvent (20ml) was charged in a flask, and the reaction was carried out at 170 ℃ for 1 hour using a microwave apparatus. To the resulting mixture was added water (10ml), the mixture was filtered, and then extracted 3 times with ethyl acetate (10ml), and the organic layer was washed 3 times with saturated brine (10 ml). The obtained organic layer was dried over anhydrous magnesium sulfate and then concentrated under reduced pressure to obtain a solid. The obtained solid was purified by silica gel column chromatography to obtain 195mg (0.380mmol, yield 76%) of an intermediate compound represented by the following formula (M-6).

The results of mass spectrometry and NMR spectroscopy of the intermediate compound represented by the formula (M-6) are shown below.

EI-MS(m/z)：512[M]⁺

¹H NMR(400MHz,CDCl₃)：δ8.07(s,2H)、7.55-7.47(m,6H)、7.38(m,4H)、3.85(s,6H)、3.52(s,6H)

(step 7) Synthesis of Compound represented by the following formula (E3)

The intermediate compound represented by the formula (M-6) synthesized in step 6 (160mg, 0.31mmol) and acetic acid (1.5ml) were charged in a flask and stirred. To this was added methanesulfonic acid (0.5mL, 7.7mmol) and the reaction was allowed to proceed for 10 hours while the temperature was raised to 130 ℃. Volatile components were distilled off from the reaction solution by concentration under reduced pressure, and the precipitated solid was filtered and washed with a small amount of acetic acid. The obtained solid was purified by vacuum sublimation purification, whereby 90.7mg (0.216mmol, yield 70%) of the compound represented by the formula (E3) was obtained as a pale yellow solid.

The results of mass spectrometry, NMR spectrum and melting point measurement of the compound represented by formula (E3) are shown below.

EI-MS(m/z)：420[M]⁺

¹H NMR (400MHz, acetone-d 6): Δ 8.49(s,2H), 7.71-7.68(m,6H), 7.62(m,4H)

Melting point: above 400 DEG C

Example 7 (Compound represented by the formula (E4)

(step 8) Synthesis of Compound represented by the following formula (E4)

The intermediate compound represented by the formula (M-3) synthesized in step 1 (273.4mg, 0.528mmol) and acetic acid (1.5ml) were charged in a flask and stirred. To this was added methanesulfonic acid (0.5mL, 7.7mmol) and the reaction was allowed to proceed for 15.5 hours while the temperature was raised to 130 ℃. Volatile components were distilled off from the reaction solution by concentration under reduced pressure, and the precipitated solid was filtered and washed with a small amount of acetic acid. The obtained solid was purified by vacuum sublimation purification, whereby 165mg (0.387mmol, yield 73%) of the compound represented by the formula (E4) was obtained as a yellow solid.

The results of mass spectrometry, NMR spectrum and melting point measurement of the compound represented by formula (E4) are shown below.

EI-MS(m/z)：424[M]⁺、55％、426[M]⁺、100％、428[M]⁺、51％

¹H NMR (400MHz, acetone-d 6): delta 9.34(s,2H)

Melting point: 322 to 325 ℃ or higher

FIG. 4 shows the results of light absorption spectra when each compound of the formula (1-1), the formula (E1), the formula (E2), the formula (E3) and the formula (E4) was in a thin film state. From the results of the light absorption spectrum, it was found that each of the compounds of the formulae (E1), (E2), (E3) and (E4) has a main absorption band in the visible light region (400 to 800nm) in a thin film state. Therefore, by using such a compound for the blocking layer, an appropriate blocking layer can be obtained without causing interference of the photoelectric conversion layer with external irradiation light.

[ Industrial applicability ]

By using the material for a photoelectric conversion element of the present invention containing a compound having a specific structure, a photoelectric conversion element having excellent hole or electron leakage resistance and excellent electron transport properties, and further having excellent required characteristics such as heat resistance and visible light transmittance can be provided.

Claims

1. A material for a photoelectric conversion element, comprising a compound represented by the following formula (1),

2. The material for photoelectric conversion elements according to claim 1, wherein X is an oxygen atom.

3. The material for photoelectric conversion elements according to claim 1 or 2, wherein R¹And R²Is a hydrogen atom, R³And R⁴One is a hydrogen atom, an aromatic group, a heterocyclic group, an aliphatic hydrocarbon group or a halogen atom, and the other is an aromatic group, a heterocyclic group, an aliphatic hydrocarbon group or a halogen atom.

4. An organic thin film comprising the material for a photoelectric conversion element according to any one of claims 1 to 3.

5. A photoelectric conversion element comprising the organic thin film according to claim 4.

6. The photoelectric conversion element according to claim 5, wherein the organic thin film is a hole blocking layer.

7. The photoelectric conversion element according to claim 5 or 6, which is a light-emitting element.

8. An imaging element in which the photoelectric conversion elements according to any one of claims 5 to 7 are arranged in a multiple array.

9. A photosensor comprising the photoelectric conversion element according to claim 5 or the image pickup element according to claim 8.

10. A compound represented by the following formula (2),

11. The compound of claim 10, wherein X is an oxygen atom.