JP2023107233A - Photoelectric transducers - Google Patents

Abstract

To provide photoelectric transducers excellent in quantum efficiency and dark current characteristics.SOLUTION: A photoelectric transducer has a layer consisting only of a compound represented by a formula (1) in the figure. (In the formula (1), R1 to R6 each independently represent a cyano group, a halogen atom, an alkyl halide group, an acyl group, a sulfonyl group, a phosphoryl group, an optionally substituted aryl group, or an optionally substituted heteroaryl group.)SELECTED DRAWING: Figure 1

Description

The present invention relates to photoelectric conversion elements.

A photoelectric conversion element is an element that has a function of converting received light into an electric signal or energy.

Demands from the market for photoelectric conversion devices have been increasing in recent years, and materials having excellent properties in all of charge transport properties, dark current, quantum efficiency, and the like are required. An organic photoelectric conversion element having a photoelectric conversion layer made of an organic material includes a hole transport layer that transports holes generated in the photoelectric conversion layer to a first electrode, and a hole transport layer that transports electrons generated in the photoelectric conversion layer to a second electrode. Laminate configurations having a charge transport layer, such as an electron transport layer that transports to the electron transport layer, are common (see, for example, US Pat. However, even with such a charge-transporting layer, the quantum efficiency and dark current characteristics are not sufficient, and a photoelectric conversion device with even better characteristics is desired.

WO2015/163349

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a photoelectric conversion device that is excellent in quantum efficiency and dark current characteristics.

The present inventors have found that the above problems can be solved by providing a photoelectric conversion element with a layer composed only of a specific radialene compound, and have completed the present invention.

（式（１）中、Ｒ^１～Ｒ^６は、それぞれ独立して、シアノ基、ハロゲン原子、ハロゲン化アルキル基、アシル基、スルホニル基、ホスホリル基、置換されていてもよいアリール基、又は置換されていてもよいヘテロアリール基を表す。） A photoelectric conversion device according to the present invention has a layer composed only of a compound represented by the following formula (1).

(In Formula (1), R ¹ to R ⁶ each independently represent a cyano group, a halogen atom, a halogenated alkyl group, an acyl group, a sulfonyl group, a phosphoryl group, an optionally substituted aryl group, or a substituted represents a heteroaryl group that may be

ADVANTAGE OF THE INVENTION According to this invention, the photoelectric conversion element which is excellent in a quantum efficiency and a dark current characteristic can be provided.

BRIEF DESCRIPTION OF THE DRAWINGS It is a schematic sectional drawing which shows an example of the photoelectric conversion element which concerns on one Embodiment of this invention.

<Photoelectric conversion element>
The photoelectric conversion element of this embodiment has a layer composed only of the compound represented by the following formula (1). In this specification, a bond with a wavy line indicates a cis-type, a trans-type, or a mixture of the cis-type and the trans-type at any ratio.

（式（１）中、Ｒ^１～Ｒ^６は、それぞれ独立して、シアノ基、ハロゲン原子、ハロゲン化アルキル基、アシル基、スルホニル基、ホスホリル基、置換されていてもよいアリール基、又は置換されていてもよいヘテロアリール基を表す。）

(In Formula (1), R ¹ to R ⁶ each independently represent a cyano group, a halogen atom, a halogenated alkyl group, an acyl group, a sulfonyl group, a phosphoryl group, an optionally substituted aryl group, or a substituted represents a heteroaryl group that may be

When the photoelectric conversion element has a layer composed only of the compound represented by the above formula (1), the quantum efficiency and dark current characteristics of the photoelectric conversion element can be improved.

Hereinafter, the compound represented by formula (1) will be described first.

[Compound represented by formula (1)]
Preferred embodiments of the compound represented by formula (1) are as follows, since they can improve the quantum efficiency and dark current characteristics of the photoelectric conversion device.

A fluorine atom is preferable as the halogen atom represented by R ¹ to R ⁶ .
As the halogenated alkyl group represented by R ¹ to R ⁶ , a halogenated alkyl group having 1 to 5 carbon atoms is preferable, and a halogenated alkyl group having 1 to 3 carbon atoms is more preferable. As the halogenated alkyl group, a fluorinated alkyl group is preferable, and a perfluoroalkyl group is more preferable. The fluorinated alkyl group is preferably a perfluorobutyl group, a perfluoropropyl group, a perfluoroethyl group, or a trifluoromethyl group, more preferably a trifluoromethyl group.
Acyl groups represented by R ¹ to R ⁶ include alkylacyl groups and arylacyl groups, and alkylacyl groups having 2 to 5 carbon atoms and arylacyl groups having 7 to 15 carbon atoms are preferred. The alkylacyl group includes, for example, an acetyl group, a propionyl group, a trifluoroacetyl group and the like. The arylacyl group includes, for example, a benzoyl group, a cyanobenzoyl group, a fluorobenzoyl group, a trifluoromethylbenzoyl group and the like.
Sulfonyl groups represented by R ¹ to R ⁶ include alkylsulfonyl groups and arylsulfonyl groups, and alkylsulfonyl groups having 1 to 5 carbon atoms and arylsulfonyl groups having 6 to 15 carbon atoms are preferred. The alkylsulfonyl group includes, for example, methylsulfonyl group, ethylsulfonyl group, n-propylsulfonyl group, isopropylsulfonyl group and the like. The arylsulfonyl group includes, for example, a phenylsulfonyl group, a cyanophenylsulfonyl group, a fluorophenylsulfonyl group and the like.
Phosphoryl groups represented by R ¹ to R ⁶ include dialkylphosphoryl groups, diarylphosphoryl groups and the like, and dialkylphosphoryl groups having 2 to 10 carbon atoms and diarylphosphonyl groups having 12 to 30 carbon atoms are preferred. The dialkylphosphoryl group includes, for example, a dimethylphosphoryl group, a diethylphosphoryl group, a dipropylphosphoryl group and the like. The diarylphosphoryl group includes, for example, a diphenylphosphoryl group, a di(fluorophenyl)phosphoryl group, and the like.

Examples of aryl groups represented by R ¹ to R ⁶ include phenyl group, biphenylyl group, terphenylyl group, naphthyl group, phenanthryl group, anthryl group, fluorenyl group, dimethylfluorenyl group, spirofluorenyl group, pyrenyl group, fluoranthenyl group, triphenylenyl group, tetracenyl group, chrysenyl group and the like. Among these, a phenyl group, a biphenylyl group and a naphthyl group are preferred.

Heteroaryl groups represented by R ¹ to R ⁶ include, for example, pyridyl group, bipyridyl group, terpyridyl group, phenylpyridyl group, diphenylpyridyl group, pyridylphenyl group, pyrazyl group, phenylpyrazyl group, pyrazylphenyl group, pyrimidyl group, phenylpyrimidyl group, diphenylpyrimidyl group, pyrimidylphenyl group, triazyl group, phenyltriazyl group, diphenyltriazyl group, triazylphenyl group, diphenyltriazylphenyl group, quinolyl group, phenylquinolyl group, quinolylphenyl group, isoquinolyl group, phenylisoquinolyl group, quinolylphenyl group, quinazolyl group, azaanthryl group, diazaanthryl group, triazaanthryl group, tetraazaanthryl group, azaphenanthryl group, diaza phenanthryl group, triazaphenanthryl group, tetraazaphenanthryl group, azapyrenyl group, diazapyrenyl group, triazapyrenyl group, tetraazapyrenyl group, azafluoranthenyl group, diazafluoranthenyl group, triazaflu olanthenyl group, tetraazafluoranthenyl group, azatriphenylenyl group, diazatriphenylenyl group, triazatriphenylenyl group, tetraazatriphenylenyl group, pentaazatriphenylenyl group, hexaazatriphenylenyl group group, thienyl group, thiazolyl group, furanyl group, oxazolyl group, pyrrolyl group, imidazolyl group, triazolyl group, thiadiazolyl group, oxadiazolyl group, benzothienyl group, benzofuranyl group, benzothiazolyl group, benzoxazolyl group, benzothiadiazolyl group , benzoxadiazolyl group, dibenzothienyl group, dibenzofuranyl group, phenylthianyl group, pyridylthienyl group, phenylfuranyl group, pyridylfuranyl group, phenylimidazolyl group, imidazolylphenyl group, furopyrimidyl group, furopyrazyl group, thienopyrimidyl group, thienopyrazyl group, pyrrolopyrimidyl group, pyrrolopyrazyl group, oxazolopyrimidyl group, oxazolopyrazyl group, benzofuropyrazyl group, benzothienopyrazyl group and the like. The heteroaryl group includes a group in which the above-mentioned aryl group and a heteroaryl group are combined (e.g., phenylpyridyl group, pyridylphenyl group, etc.), a group in which the above-described heteroaryl groups are combined (e.g., pyridylpyrimidyl groups, pyrimidylpyridyl groups, etc.) are also included. Among these, a pyridyl group, a triazyl group, a thienyl group, a furanyl group and a triazolyl group are preferred.

Substituents possessed by the aryl group and heteroaryl group include, for example, a deuterium atom, a cyano group, a halogen atom (fluorine atom, chlorine atom, bromine atom, iodine atom, etc.), and a halogenated alkyl group (fluorinated alkyl group, etc.). , an acyl group (such as a formyl group), a nitro group, a sulfonyl group, a phosphoryl group, an alkyl group having 1 to 20 carbon atoms, an alkenyl group and a cycloalkyl group, an alkoxy group having 1 to 10 carbon atoms, -P (=O a group represented by )(Ar′) ₂ , a group represented by —OSO ₂ Ar′, a group represented by —S(=O)Ar′, a group represented by —B(Ar′) ₂ , Examples thereof include a group represented by -B(OAr') ₂ and a group represented by -Si(Ar') ₃ (Ar' represents an aryl group). Among these, a cyano group, a halogen atom, a halogenated alkyl group, an acyl group, a sulfonyl group, and a phosphoryl group are preferred, and a cyano group, a halogen atom, and a halogenated alkyl group are more preferred, and a cyano group, a fluorine atom, and a fluorinated alkyl group. groups are more preferred, and cyano groups, fluorine atoms, and trifluoromethyl groups are particularly preferred. Halogenated alkyl groups, acyl groups, sulfonyl groups and phosphoryl groups are the same as those described for these groups represented by R ¹ to R ⁶ .

The substituents possessed by the aryl group and the heteroaryl group may be one or more, and if there are more than one, they may be the same or different. In the aryl group and heteroaryl group, it is preferable that half or more of the substitutable positions in the ring to which the substituent is bonded are substituted, and it is more preferable that all substitutable positions are substituted.

From the viewpoint of ease of synthesis, among R ¹ to R ⁶ , R ¹ , R ³ and R ⁵ are preferably the same substituents, and R ² , R ⁴ and R ⁶ are the same substituents. preferable.

Among R ¹ to R ⁶ , R ¹ , R ³ and R ⁵ are preferably a cyano group, a fluorinated alkyl group or a fluorine atom, more preferably a cyano group.
Further, among R ¹ to R ⁶ , R ² , R ⁴ and R ⁶ are each independently selected from the group consisting of a cyano group, a halogen atom, a halogenated alkyl group, an acyl group, a sulfonyl group and a phosphoryl group. or an aryl group substituted with at least one selected from the group consisting of a cyano group, a halogen atom, a halogenated alkyl group, an acyl group, a sulfonyl group, and a phosphoryl group. A heteroaryl group is preferred.

In another aspect, R ¹ to R ⁶ are each independently at least one selected from the group consisting of a cyano group, a halogen atom, a halogenated alkyl group, an acyl group, a sulfonyl group, and a phosphoryl group. A substituted aryl group, or a heteroaryl group substituted with at least one selected from the group consisting of a cyano group, a halogen atom, a halogenated alkyl group, an acyl group, a sulfonyl group, and a phosphoryl group is preferred.

Specific examples of the compound represented by formula (1) include compounds (A-001) to (A-306) shown below.

（式（２）中、環Ａは、それぞれ独立して、環構成原子数が６の単環式芳香環、又は、該芳香環を部分構造として含み、環構成原子数が９～１５の多環式芳香環である。環Ａの環構成原子は、それぞれ独立して、炭素原子又は窒素原子である。Ｒ^７～Ｒ^９は、それぞれ独立して、シアノ基、ハロゲン原子、ハロゲン化アルキル基、アシル基、スルホニル基、ホスホリル基、置換されていてもよいアリール基、又は置換されていてもよいヘテロアリール基を表す。ｎは、それぞれ独立して、０以上［環Ａにおいて置換可能な環構成原子の数］以下の整数である。） A compound represented by the following formula (2) is preferable as the compound represented by the formula (1).

(In formula (2), each ring A is independently a monocyclic aromatic ring having 6 ring-constituting atoms, or a polycyclic ring containing the aromatic ring as a partial structure and having 9-15 ring-constituting atoms. It is a cyclic aromatic ring.The ring-constituting atoms of ring A are each independently a carbon atom or a nitrogen atom.R ⁷ to R ⁹ are each independently a cyano group, a halogen atom, or a halogenated alkyl group. , an acyl group, a sulfonyl group, a phosphoryl group, an optionally substituted aryl group, or an optionally substituted heteroaryl group, n is each independently 0 or more [a ring that can be substituted in ring A Number of constituent atoms] is an integer below.)

The ring A is preferably a monocyclic aromatic ring having 6 ring atoms or a polycyclic aromatic ring having 10 to 12 ring atoms, and a monocyclic aromatic ring having 6 ring atoms. more preferred.

The number of ring-constituting nitrogen atoms in ring A is preferably an integer of 0-3, more preferably an integer of 0-2. Moreover, it is preferable that the nitrogen atoms are not adjacent to each other.

The monocyclic aromatic ring having 6 ring-constituting atoms includes a benzene ring, pyridine ring, pyrazine ring, pyrimidine ring, pyridazine ring, triazine ring and the like. Among them, a benzene ring, a pyrimidine ring and a triazine ring are preferred, and a benzene ring is more preferred.
Polycyclic aromatic rings having 9 to 15 ring atoms include indene ring, indole ring, isoindole ring, indolizine ring, benzimidazole ring, purine ring, indazole ring, azaindole ring, azaindazole ring, pyra zolopyrimidine ring, pyrrolopyrimidine ring, naphthalene ring, quinoline ring, isoquinoline ring, quinoxaline ring, quinazoline ring, cinnoline ring, phthalazine ring, quinolidine ring, tetraazaanthracene ring, tetraazaphenanthrene ring, diazaanthracene ring, diazaphenanthrene ring and the like. Among them, a naphthalene ring, a quinazoline ring, and a quinoxaline ring are preferable.

Halogen atoms, halogenated alkyl groups, acyl groups ^{, sulfonyl groups, phosphoryl groups, optionally substituted aryl groups, and optionally substituted heteroaryl groups represented by R 7 to} R ⁹ are is the same as described in . R ⁷ to R ⁹ are preferably a cyano group, a halogen atom, a halogenated alkyl group, an acyl group, a sulfonyl group and a phosphoryl group, more preferably a cyano group, a halogen atom and a halogenated alkyl group, a cyano group, a fluorine atom, A fluorinated alkyl group is more preferred, and a cyano group, a fluorine atom, and a trifluoromethyl group are particularly preferred.

Each n is independently preferably 1 or more, more preferably 3 or more, and still more preferably [the number of substitutable ring-constituting atoms in ring A].
When at least one n is an integer of 2 or more, at least one of R ⁷ to R ⁹ may be a cyano group, a halogen atom, a halogenated alkyl group, an acyl group, a sulfonyl group, or a phosphoryl group. preferable.

The compound represented by formula (1) and the compound represented by formula (2) can be synthesized by a known method.

[Structure of photoelectric conversion element]
The configuration of the photoelectric conversion element is not particularly limited, but includes, for example, the following configurations (i) and (ii).

(i): first electrode/hole transport promoting layer/hole transport layer (electron blocking layer)/photoelectric conversion layer (light receiving layer)/second electrode (ii): first electrode/hole transport promoting layer layer / hole-transporting layer (electron-blocking layer) / photoelectric conversion layer (light-receiving layer) / electron-transporting layer (hole-blocking layer) / second electrode , which have different names but mean the same layer. The electron transport layer and the hole blocking layer have different names, but mean the same layer. Furthermore, the photoelectric conversion layer and the light-receiving layer have different names, but mean the same layer.
Similarly, hole-transporting material and electron-blocking material, electron-transporting material and hole-blocking material refer to the same material, although they have different names.

The photoelectric conversion element according to the present embodiment preferably has a layer composed only of the compound represented by formula (1) between the electrode and the photoelectric conversion layer, and only the compound represented by formula (1) is preferably the layer adjacent to the electrode. In particular, it is more preferable that the layer composed only of the compound represented by Formula (1) is the hole transport promoting layer. Moreover, it is preferable to have an organic layer between the layer consisting only of the compound represented by formula (1) and the photoelectric conversion layer.

Hereinafter, the photoelectric conversion device of the present embodiment will be described with reference to FIG. 1, with reference to FIG. will be described in more detail. FIG. 1 is a schematic cross-sectional view showing an example of the laminated structure of the photoelectric conversion element of this embodiment.

The photoelectric conversion element 100 includes a first electrode 1, a hole transport promoting layer 2, a hole transport layer 3, a photoelectric conversion layer 4, an electron transport layer 5, and a second electrode 6 in this order. However, some of these layers may be omitted, or conversely, other layers may be added. Among the layers described above, the hole transport promoting layer 2, the hole transport layer 3, the photoelectric conversion layer 4, and the electron transport layer 5 constitute the organic layer 10. FIG.

In the photoelectric conversion element 100 shown in FIG. 1, light is incident from below the transparent first electrode 1 and received by the photoelectric conversion layer 4 . The incident direction of the light is not particularly limited, and the second electrode 6 may be made transparent and the light may be incident from the second electrode 6 side.
In the photoelectric conversion element 100, charges (holes) generated by photoelectric conversion in the photoelectric conversion layer 4 are caused by an internal electric field due to a difference in carrier concentration and a difference in work function between the first electrode 1 and the second electrode 6. and electrons), electrons move to the second electrode 6 and holes move to the first electrode 1 . In addition, electric charges can be transferred by applying a voltage between the second electrode 6 and the first electrode 1 . Thus, the second electrode 6 is used as an electron collecting electrode, and the first electrode 1 is used as a hole collecting electrode.
1, the substrate provided on the lower surface of the first electrode 1 is omitted. The substrate here is not particularly limited, and examples thereof include a glass plate, a quartz plate, a plastic plate and the like. In addition, in the case of a configuration in which light is incident from the substrate side, the substrate is transparent to the wavelength of light. The substrate may be provided on the second electrode 6 side. Each of the above layers will be described below.

(First electrode 1)
A first electrode 1 is provided on the substrate.
In the case of a photoelectric conversion element configured such that light passes through the first electrode 1 and is incident on the photoelectric conversion layer 4, the first electrode is made of a transparent material that transmits or substantially transmits the light. In addition, in the case of a configuration in which light passes through the second electrode 6, the second electrode is made of a transparent material. Thus, either the first electrode or the second electrode should be made of a transparent material.

The transparent material used for the first electrode 1 is not particularly limited, but examples include indium-tin oxide (ITO; Indium Tin Oxide), indium-zinc oxide (IZO; Indium Zinc Oxide), tin oxide, aluminum-doped tin oxide, magnesium-indium oxide, nickel-tungsten oxide, other metal oxides, metal nitrides such as gallium nitride, metal selenides such as zinc selenide, and zinc sulfide A metal sulfide etc. are mentioned.

In the case of an organic photoelectric conversion element configured such that light enters the photoelectric conversion layer 4 only from the second electrode 6 side, the transmission characteristics of the first electrode 1 are not important. Accordingly, examples of materials used for the first electrode in this case include gold, iridium, molybdenum, palladium, platinum, and the like.

(Hole transport promotion layer 2)
A hole transport promoting layer 2 is provided between the first electrode 1 and a hole transport layer 3 to be described later. The hole transport promoting layer 2 is provided to promote hole transport from the hole transport layer 3 to the first electrode 1 . Acceleration of hole transport is brought about by the interaction of the hole transport facilitating material with surrounding materials to change the internal electric field.
The hole transport promoting layer 2 consists of only the compound represented by the above formula (1).

(Hole transport layer 3)
A hole transport layer 3 is provided between the hole transport promoting layer 2 and the photoelectric conversion layer 4 .
The hole transport layer 3 serves to transport holes generated in the photoelectric conversion layer 4 from the photoelectric conversion layer 4 to the first electrode 1, and electrons generated in the photoelectric conversion layer 4 move to the first electrode 1 side. It has the role of blocking Depending on the application, it may also have a role of blocking electron injection from the first electrode 1 .

The hole transport layer 3 may have a single layer structure composed of one or more materials, or may have a laminated structure composed of a plurality of layers having the same composition or different compositions.

The hole transport layer 3 preferably contains a known hole transport material. Known hole transport materials include aromatic tertiary amine compounds, naphthalene compounds, anthracene compounds, tetracene compounds, pentacene compounds, phenanthrene compounds, pyrene compounds, perylene compounds, fluorene compounds, carbazole compounds, indole compounds, pyrrole compounds, picene compounds, thiophene compounds, benzotrifuran compounds, benzotrithiophene compounds, naphthodithiophene compounds, naphthothienothiophene compounds, benzodifuran compounds, benzodithiophene compounds, benzothiophene compounds, naphthobisbenzothiophene compounds, chrysenodithiophene compounds, benzothienobenzothiophene compounds, indolocarbazole compounds, and the like.
Among these, preferred are fluorene compounds, naphthodithiophene compounds, naphthothienothiophene compounds, benzodifuran compounds, benzothiophene compounds, naphthobisbenzothiophene compounds, chrysenodithiophene compounds, benzothienobenzothiophene compounds, indolocarbazole compounds, and the like. Fluorene compounds, chrysenodithiophene compounds, benzothienobenzothiophene compounds, and indolocarbazole compounds are particularly preferred.

Specific examples of known hole transport materials include N,N'-bis(1-naphthyl)-1,1-biphenyl-4,4'-diamine (NPD), 9,9'-(9,9' -spirobi[9H-fluorene]-2,7'-diyl)bis[9H-carbazole], 2,7-diphenyl[1]benzothieno[3,2-b][1]benzothiophene (DiPh-BTBT), benzo [1,2-b:3,4-b′:5,6-b″]trifuran compound, benzo[1,2-b:3,4-b′:5,6-b″]trithiophene compounds, naphtho[1,2-b:5,6-b′]dithiophene, naphtho[2,3-b]naphtho[2′,3′:4,5]thieno[2,3-d]thiophene, benzo [1,2-b:4,5-b′]difuran, benzo[1,2-b:4,5-b′]dithiophene, benzo[1,2-b:4,5-b′]bis[ 1]benzothiophene, naphtho[1,2-b:5,6-b']bis[1]benzothiophene, chryseno[1,2-b:8,7-b']dithiophene, [1]benzothieno[3 ,2-b][1]benzothiophene, compounds (ic-1), (ic-2) and (ic-3) shown below, and the like.

(Photoelectric conversion layer 4)
A photoelectric conversion layer 4 is provided between the hole transport layer 3 and an electron transport layer 5 to be described later.
Examples of materials for the photoelectric conversion layer 4 include materials having a photoelectric conversion function.

The photoelectric conversion layer 4 may have a single-layer structure composed of one or more materials, or may have a laminated structure composed of multiple layers having the same composition or different compositions.
Examples of the material used for the photoelectric conversion layer 4 having a single-layer structure made of one material include (1) coumarin and its derivatives, quinacridone and its derivatives, phthalocyanine and its derivatives, and the like.
Examples of materials used for the photoelectric conversion layer 4, which has a single-layer structure composed of two materials, include (i) coumarin and its derivatives, quinacridone and its derivatives, phthalocyanine and its derivatives, and (ii) fullerene and Combinations with derivatives thereof are also included. The photoelectric conversion layer 4 made of these materials may be formed by vapor deposition in a state in which powders are mixed in advance, or may be formed by co-evaporation in an arbitrary ratio.
Materials used for the photoelectric conversion layer 4, which has a single-layer structure composed of three kinds of materials, include (i) coumarin and its derivatives, quinacridone and its derivatives, phthalocyanine and its derivatives, (ii) fullerene and its derivatives, and (iii) combinations with hole-transporting materials; The photoelectric conversion layer 4 made of these materials may be formed by vapor deposition in a state in which powders are mixed in advance, or may be formed by co-evaporation in an arbitrary ratio.

(i) Specific examples of coumarin derivatives include coumarin 6 and coumarin 30. Specific examples of quinacridone derivatives include N,N-dimethylquinacridone. Specific examples of phthalocyanine derivatives include boron-subphthalocyanine chloride and boron-subnaphthalocyanine chloride (SubNC).
(ii) Specific examples of fullerene and derivatives thereof include [60]fullerene, [70]fullerene, and [6,6]-phenyl-C61-methylbutyrate ([60]PCBM).
(iii) Preferred compounds and specific examples of the hole-transporting material are the same as those described for the hole-transporting layer 3 above.

Moreover, the material having a photoelectric conversion function is not limited to being contained only in the photoelectric conversion layer. For example, the material having a photoelectric conversion function may be contained in a layer adjacent to the photoelectric conversion layer 4 (the hole transport layer 3 or the electron transport layer 5).

(Electron transport layer 5)
An electron transport layer 5 is provided between the photoelectric conversion layer 4 and a second electrode 6 which will be described later.
The electron transport layer 5 has a role of transporting electrons generated in the photoelectric conversion layer 4 to the second electrode 6 and blocking the movement of holes from the second electrode 6 to the photoelectric conversion layer 4 to which the electrons are transported. have a role. Moreover, depending on the application, it may have a role of blocking hole injection from the second electrode 6 .

Further, the electron transport layer 5 can contain a known electron transport material. Examples of known electron transport materials include fullerenes, fullerene derivatives, bis(8-hydroxyquinolinato)manganese, tris(8-hydroxyquinolinato)aluminum, and tris(2-methyl-8-hydroxyquinolinato). Aluminum, BCP (2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline), Bphen (4,7-diphenyl-1,10-phenanthroline), BAlq (bis(2-methyl-8-quinolinolate) -4-(phenylphenolato)aluminum), 4,6-bis(3,5-di(pyridin-4-yl)phenyl)-2-methylpyrimidine, N,N'-diphenyl-1,4,5, 8-naphthalenetetracarboxylic acid diimide, N,N'-di(4-pyridyl)-1,4,5,8-naphthalenetetracarboxylic acid diimide, and the like.

The electron transport layer 5 may have a single layer structure made of one or more materials, or may have a laminated structure made up of a plurality of layers having the same composition or different compositions.

(Second electrode 6)
A second electrode 6 is provided on the electron transport layer 5 .
Materials for the second electrode 6 include, for example, indium-tin oxide (ITO; Indium Tin Oxide), indium-zinc oxide (IZO; Indium Zinc Oxide), sodium, sodium-potassium alloy, magnesium, lithium, magnesium /copper mixtures, magnesium/silver mixtures, magnesium/aluminum mixtures, magnesium/indium mixtures, aluminum/aluminum oxide ( _Al2O3 ) mixtures, indium _, lithium/aluminum mixtures, gold, platinum, rare earth metals, molybdenum oxide, etc. be done. The first electrode 1 and the second electrode 6 may be the same or different.

[Method of Forming Each Layer]
Each layer except for the first electrode 1 and the second electrode 6 described above is formed by applying the material of each layer (with a material such as a binder resin and a solvent as necessary), for example, by vacuum deposition, spin coating, It can be formed by thinning by a known method such as a casting method, LB (Langmuir-Blodgett method) method, or the like.
The thickness of each layer thus formed is not particularly limited and can be appropriately selected depending on the situation, but is usually in the range of 5 nm or more and 5 μm or less.

The first electrode 1 and the second electrode 6 can be formed by thinning an electrode material by a method such as vapor deposition or sputtering. A pattern may be formed through a mask of a desired shape during vapor deposition or sputtering, or a pattern of a desired shape may be formed by photolithography after forming a thin film by vapor deposition, sputtering, or the like.

The film thickness of the first electrode 1 and the second electrode 6 is preferably 1 μm or less, more preferably 10 nm or more and 200 nm or less.

The materials constituting the first electrode 1 and the second electrode 6 may be exchanged as necessary (also called an inverted structure). In the case of such a structure, the organic photoelectric conversion element is configured such that light passes through the second electrode 6 and is incident on the photoelectric conversion layer 4 .

The organic photoelectric conversion device of the present embodiment is suitably used as an image pickup device, and can be applied to, for example, image pickup devices of digital cameras and digital video cameras, and image pickup devices built into mobile phones and the like.

EXAMPLES The present invention will be described in more detail below based on examples, but the present invention should not be construed as being limited by these examples.

[Synthesis Example 1: A-254]
1.00 g (2.86 mmol, 2.83 equiv.) of bis(perfluorophenyl)methane and 48 ml of THF were placed in a flask, cooled to −70° C., and 1.86 ml of n-BuLi (1.6 M hexane solution) was added dropwise. , and stirred for 30 minutes. Then, 2.1 ml of a THF solution containing 0.18 g (1.01 mmol, 1.00 equiv.) of tetrachlorocyclopropene was added dropwise, and the mixture was heated to room temperature and stirred overnight. After the reaction solution was concentrated to dryness, the resulting solid was dissolved in chloroform, air was bubbled for 2 minutes, and the mixture was stirred overnight at room temperature. The reaction solution was filtered, and the filtrate was concentrated to dryness to obtain 0.97 g of crude product. The crude product was purified by silica gel column chromatography using heptane as a solvent to obtain 0.63 g of A-245 (yield 58%). MS (MALDI-TOF): m / z 1074 [M]-

[Synthesis Example 2: A-306]
0.57 g (14.2 mmol, 5.94 equiv.) of NaH and 33 ml of DME are placed in a flask, cooled to 0° C., 1.00 g (7.00 mmol, 2.93 equiv.) of 4-(cyanomethyl)benzonitrile are added dropwise, Stirred for 30 minutes. After that, 5.0 ml of a DME solution containing 0.43 g (2.40 mmol, 1.00 equiv.) of tetrachlorocyclopropene was added dropwise, and after the temperature was raised to room temperature, the mixture was stirred overnight. The reaction solution was added to a saturated aqueous solution of ammonium chloride, and the precipitate was collected by filtration. The obtained solid was dissolved in chloroform, 5.0 ml of 1N potassium carbonate aqueous solution and 0.13 mL of bromine were added, and the mixture was stirred overnight at room temperature. The reaction liquid was liquid-separated and the organic layer was purified by column chromatography to obtain 0.17 g of A-306 (yield 15%). MS (MALDI-TOF): m/z 456 [M]-
[Example 1]
A photoelectric conversion element 100 having a laminated structure consisting of substrate/second electrode 6/electron transport layer 5/photoelectric conversion layer 4/hole transport layer 3/hole transport promoting layer 2/first electrode 1 is produced, Dark current and external quantum efficiency of the photoelectric conversion device were evaluated.

(Preparation of substrate and second electrode 6)
As a substrate having a second electrode on its surface, a glass substrate with an ITO transparent electrode, in which an indium-tin oxide (ITO) film (thickness: 110 nm) with a width of 2 mm was patterned in stripes, was prepared. Then, after washing the substrate with isopropyl alcohol, the surface was treated by ozone ultraviolet washing.

(Preparation for vacuum deposition)
Each layer was vacuum-deposited on the surface-treated substrate after cleaning by a vacuum deposition method to laminate each layer.
First, the glass substrate was introduced into a vacuum deposition tank, and the pressure was reduced to 7.0×10 ⁻⁵ Pa. Then, each layer was produced in the following order according to the film forming conditions of each layer.

(Preparation of electron transport layer 5)
An electron-transporting layer 5 was produced by forming a film of 10 nm from the sublimation-purified compound 4,6-bis(3,5-di(pyridin-4-yl)phenyl)-2-methylpyrimidine at a rate of 0.03 nm/sec. .

(Preparation of photoelectric conversion layer 4)
A photoelectric conversion layer 4 was produced by depositing N,N-dimethylquinacridone and C60 at a ratio of 4:1 (mass ratio) to a thickness of 125 nm. The deposition rate was 0.13 nm/sec.

(Preparation of hole transport layer 3)
A 10 nm film of N,N'-di-1-naphthyl-N,N'-diphenylbenzidine (α-NPD) was formed at a rate of 0.10 nm/sec to prepare a hole transport layer 3 .

(Production of hole transport promoting layer 2)
Compound (A-122) (2,2′,2″-(cyclopropane-1,2,3-triylidene)tris(2-(4-cyano-2,3,5,6-tetrafluorophenyl)acetonitrile )) was deposited to a thickness of 10 nm at a rate of 0.20 nm/sec to prepare the hole transport promoting layer 2 .

(Preparation of first electrode 1)
Finally, a metal mask was placed so as to be perpendicular to the ITO stripes on the substrate, and the first electrode 1 was deposited. The first electrode was formed by depositing silver to a thickness of 80 nm. The deposition rate of silver was 0.1 nm/sec.

As described above, a photoelectric conversion element 100 having an area of 4 mm ² as shown in FIG. 1 was produced. Each film thickness was measured with a stylus film thickness meter (DEKTAK, manufactured by Bruker).

Further, this device was sealed in a nitrogen atmosphere glove box with an oxygen and water concentration of 1 ppm or less. Sealing was performed by using a bisphenol F type epoxy resin (manufactured by Nagase ChemteX Corporation) between the glass sealing cap and the film formation substrate (element).

When a voltage of 2.5 V as an absolute value is applied to the photoelectric conversion element produced as described above so that electrons are transported to the second electrode 6 side and holes are transported to the first electrode 1 side. were evaluated for current in the dark (dark current) and external quantum efficiency. Dark current measurements were evaluated using a Keithley Source Measure Unit 2636B. A solar cell spectral sensitivity measuring device (manufactured by Soma Kogaku Co., Ltd.) was used to measure the external quantum efficiency. The wavelength of the irradiation light was 560 nm, and the measurement was performed at an intensity of 50 μW/cm ² . Table 1 shows the results. The dark current and the external quantum efficiency are relative values with the results in Comparative Example 1 as reference values (1.0) and (100), respectively. A lower value for dark current indicates better performance, and a higher value for external quantum efficiency indicates better performance.

[Example 2]
In the preparation of the hole transport promoting layer 2 of Example 1, in the same manner as in Example 1, except that the compound (A-254) was used instead of the compound (A-122). A photoelectric conversion device was produced, and dark current and external quantum efficiency were measured in the same manner as in Example 1. Table 1 shows the results.

[Example 3]
In the preparation of the hole transport promoting layer 2 of Example 1, the compound (A-306) was used instead of the compound (A-122). A photoelectric conversion device was produced, and dark current and external quantum efficiency were measured in the same manner as in Example 1. Table 1 shows the results.

[Comparative Example 1]
A photoelectric conversion element of Comparative Example 1 was produced in the same manner as in Example 1 except that the hole transport promoting layer 2 was not provided in Example 1, and dark current and external Quantum efficiency was measured. Table 1 shows the results.

[Comparative Example 2]
In the preparation of the hole transport promoting layer 2 of Example 1, 2,3,6,7,10,11-hexacyano-1,4,5,8,9,12- A photoelectric conversion device of Comparative Example 2 was produced in the same manner as in Example 1 except that hexaazatriphenylene (HATCN) was used, and dark current and external quantum efficiency were measured in the same manner as in Example 1. Table 1 shows the results. HATCN is a typical hole injection material for organic EL.

[Comparative Example 3]
The photoelectric conversion of Comparative Example 3 was performed in the same manner as in Example 1, except that molybdenum oxide (MoOx) was used instead of the compound (A-122) in the preparation of the hole transport promoting layer 2 of Example 1. A conversion element was produced, and dark current and external quantum efficiency were measured in the same manner as in Example 1. Table 1 shows the results. Note that MoOx is a typical hole-transporting material for photoelectric conversion elements.

From the results in Table 1, the photoelectric conversion element having a layer consisting only of the compound represented by formula (1) has better quantum efficiency and dark current characteristics than the photoelectric conversion element having a layer consisting only of the comparative example compound. I found it to be excellent.

REFERENCE SIGNS LIST 1 first electrode 2 hole transport promoting layer 3 hole transport layer 4 photoelectric conversion layer 5 electron transport layer 6 second electrode 10 organic layer 100 photoelectric conversion element

Claims (15)

A photoelectric conversion device having a layer composed only of a compound represented by the following formula (1).

(In Formula (1), R ¹ to R ⁶ each independently represent a cyano group, a halogen atom, a halogenated alkyl group, an acyl group, a sulfonyl group, a phosphoryl group, an optionally substituted aryl group, or a substituted represents a heteroaryl group that may be the aryl group is substituted with at least one selected from the group consisting of a cyano group, a halogen atom, a halogenated alkyl group, an acyl group, a sulfonyl group, and a phosphoryl group;
The photoelectric conversion according to claim 1, wherein the heteroaryl group is substituted with at least one selected from the group consisting of a cyano group, a halogen atom, a halogenated alkyl group, an acyl group, a sulfonyl group, and a phosphoryl group. element. The photoelectric conversion device according to claim 1, wherein ^R1 , ^R3 , and ^R5 are cyano groups. R ² , R ⁴ , and R ⁶ are each independently substituted with at least one selected from the group consisting of a cyano group, a halogen atom, a halogenated alkyl group, an acyl group, a sulfonyl group, and a phosphoryl group; or an aryl group substituted with at least one selected from the group consisting of a cyano group, a halogen atom, a halogenated alkyl group, an acyl group, a sulfonyl group, and a phosphoryl group. The photoelectric conversion element according to . an aryl group in which R ¹ to R ⁶ are each independently substituted with at least one selected from the group consisting of a cyano group, a halogen atom, a halogenated alkyl group, an acyl group, a sulfonyl group, and a phosphoryl group; or a heteroaryl group substituted with at least one selected from the group consisting of a cyano group, a halogen atom, a halogenated alkyl group, an acyl group, a sulfonyl group, and a phosphoryl group. conversion element. 2. The photoelectric conversion device according to claim 1, wherein the compound represented by formula (1) is a compound represented by formula (2) below.

(In formula (2), each ring A is independently a monocyclic aromatic ring having 6 ring-constituting atoms, or a polycyclic ring containing the aromatic ring as a partial structure and having 9-15 ring-constituting atoms. It is a cyclic aromatic ring.The ring-constituting atoms of ring A are each independently a carbon atom or a nitrogen atom.R ⁷ to R ⁹ are each independently a cyano group, a halogen atom, or a halogenated alkyl group. , an acyl group, a sulfonyl group, a phosphoryl group, an optionally substituted aryl group, or an optionally substituted heteroaryl group, n is each independently 0 or more [a ring that can be substituted in ring A Number of constituent atoms] is an integer below.) Ring A is a benzene ring,
When at least one n is an integer of 2 or more, at least one of R ⁷ to R ⁹ is a cyano group, a halogen atom, a halogenated alkyl group, an acyl group, a sulfonyl group, or a phosphoryl group. Item 7. The photoelectric conversion device according to item 6. 7. The photoelectric conversion device according to claim 6, wherein each n is independently an integer of 1 or more and no more than [the number of substitutable ring-constituting atoms in ring A]. 7. The photoelectric conversion device according to claim 6, wherein each n is independently an integer of 3 or more and no more than [the number of substitutable ring-constituting atoms in ring A]. 7. The photoelectric conversion device according to claim 6, wherein n is [the number of substitutable ring-constituting atoms in ring A]. 7. The photoelectric conversion device according to claim 6, wherein R ⁷ to R ⁹ are each independently a cyano group, a halogen atom, or a halogenated alkyl group. The photoelectric conversion element according to any one of claims 1 to 11, comprising the layer between the electrode and the photoelectric conversion layer. The photoelectric conversion element according to any one of claims 1 to 11, wherein said layer is a layer adjacent to an electrode. The photoelectric conversion element according to any one of claims 1 to 11, comprising an organic layer between the layer and the photoelectric conversion layer. The photoelectric conversion device according to any one of claims 1 to 11, which is used for an imaging device.

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