JP7770944B2 - Photoelectric conversion elements, imaging elements, optical sensors, compounds - Google Patents

Description

The present invention relates to a photoelectric conversion element, an imaging element, an optical sensor, and a compound.

In recent years, progress has been made in the development of elements with photoelectric conversion films. For example, Patent Document 1 discloses a merocyanine dye as a material used in photoelectric conversion elements.

JP 2011-253861 A

In recent years, along with the demand for improved performance of image sensors, optical sensors, etc., further improvements in the properties required of photoelectric conversion elements used therein are being demanded. For example, the photoelectric conversion elements are being demanded to have a high ratio of the quantum efficiency (photoelectric conversion efficiency) after annealing to the quantum efficiency (photoelectric conversion efficiency) before annealing, and to have a high quantum efficiency (photoelectric conversion efficiency) after annealing.
The quantum efficiency after annealing refers to the quantum efficiency after heat treatment under specified conditions. Furthermore, a high ratio of the quantum efficiency (photoelectric conversion efficiency) after annealing to the quantum efficiency (photoelectric conversion efficiency) before annealing means that the quantum efficiency is less likely to decrease even after annealing. Hereinafter, the ratio of the quantum efficiency (photoelectric conversion efficiency) after annealing to the quantum efficiency (photoelectric conversion efficiency) before annealing is also referred to as the relative ratio before and after annealing.

The inventors investigated photoelectric conversion elements using the compounds disclosed in Patent Document 1 and other documents and found that it was difficult to achieve both a high relative ratio before and after annealing and a high quantum efficiency after annealing.

Therefore, an objective of the present invention is to provide a photoelectric conversion element that has a high relative ratio before and after annealing and a high quantum efficiency after annealing. Another objective of the present invention is to provide an imaging element, an optical sensor, and a compound.

After extensive research into the above-mentioned problems, the inventors discovered that the above-mentioned problems could be solved by using a compound with a specific structure in the photoelectric conversion film, leading to the completion of the present invention.

[1]
A photoelectric conversion element having a conductive film, a photoelectric conversion film, and a transparent conductive film in this order,
The photoelectric conversion element, wherein the photoelectric conversion film contains a compound represented by formula (1) described below.
[2]
The photoelectric conversion element according to [1], wherein the compound represented by the formula (1) is a compound represented by the formula (2) described below.
[3]
The photoelectric conversion element according to [2], wherein the compound represented by the formula (2) is a compound represented by the formula (3) described below.
[4]
The photoelectric conversion element according to [3], wherein ^R3 and ^R4 represent a hydrogen atom or a substituent other than a cyano group or a fluorine atom.
[5]
The photoelectric conversion element according to any one of [1] to [4], wherein R ^b2 represents a cyano group.
[6]
The photoelectric conversion element according to any one of [1] to [5], wherein R ^b1 represents an aromatic ring group which may have a substituent.
[7]
The photoelectric conversion element according to any one of [1] to [6], wherein R ¹ and R ² represent a hydrogen atom.
[8]
The photoelectric conversion element according to any one of [1] to [7], wherein X ¹ represents an oxygen atom.
[9]
[1] to [8], wherein one of R ^a1 and R ^a2 represents an aromatic ring group which may have a substituent, and the other represents an aliphatic hydrocarbon group which may have a substituent.
[10]
The photoelectric conversion element according to any one of [1] to [9], wherein the photoelectric conversion film further contains an n-type organic semiconductor.
[11]
The photoelectric conversion element according to [10], wherein the n-type organic semiconductor contains a fullerene selected from the group consisting of fullerenes and derivatives thereof.
[12]
The photoelectric conversion element according to any one of [1] to [11], wherein the photoelectric conversion film further contains a p-type organic semiconductor.
[13]
The photoelectric conversion element according to any one of [1] to [12], wherein the photoelectric conversion film further contains a dye.
[14]
The photoelectric conversion element according to any one of [1] to [13], further comprising one or more intermediate layers in addition to the photoelectric conversion film between the conductive film and the transparent conductive film.
[15]
An imaging device having the photoelectric conversion element according to any one of [1] to [14].
[16]
An optical sensor having the photoelectric conversion element according to any one of [1] to [14].
[17]
A compound represented by formula (1) described below.
[18]
The compound according to [17], wherein the compound represented by the formula (1) is a compound represented by the formula (2) described below.
[19]
The compound according to [18], wherein the compound represented by the formula (2) is a compound represented by the formula (3) described below.
[20]
The compound according to [19], wherein ^R3 and ^R4 represent a hydrogen atom or a substituent other than a cyano group or a fluorine atom.
[21]
The compound according to any one of [17] to [20], wherein R ^b2 represents a cyano group.
[22]
The compound according to any one of [17] to [21], wherein R ^b1 represents an aromatic ring group which may have a substituent.
[23]
The compound according to any one of [17] to [22], wherein R ¹ and R ² represent a hydrogen atom.
[24]
The compound according to any one of [17] to [23], wherein X ¹ represents an oxygen atom.
[25]
The compound according to any one of [17] to [24], wherein one of R ^a1 and R ^a2 represents an aromatic ring group which may have a substituent, and the other represents an aliphatic hydrocarbon group which may have a substituent.

The present invention can provide a photoelectric conversion element that has a high relative ratio before and after annealing and a high quantum efficiency after annealing. The present invention can also provide an imaging element, an optical sensor, and a compound.

FIG. 2 is a cross-sectional view showing a configuration example of a photoelectric conversion element. FIG. 2 is a cross-sectional view showing a configuration example of a photoelectric conversion element.

Hereinafter, embodiments of the photoelectric conversion element of the present invention will be described in detail.
In this specification, a numerical range expressed using "to" means a range that includes the numerical values written before and after "to" as the lower and upper limits.
In this specification, the hydrogen atom may be a protium atom (normal hydrogen atom) or a deuterium atom (for example, a deuterium atom, etc.).
In this specification, when there are a plurality of substituents, linking groups, etc. (hereinafter also referred to as "substituents, etc.") represented by specific symbols, or when a plurality of substituents, etc. are simultaneously specified, it means that the respective substituents, etc. may be the same or different from each other. This also applies to the specification of the number of substituents, etc.
In this specification, unless otherwise specified, examples of the "substituent" include the groups exemplified as the substituent W described below.

(Substituent W)
The substituent W in this specification will be described.
The substituent W may be, for example, a halogen atom (for example, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, etc.), an alkyl group (including a cycloalkyl group, a bicycloalkyl group, and a tricycloalkyl group), an alkenyl group (including a cycloalkenyl group and a bicycloalkenyl group), an alkynyl group, an aryl group, a heteroaryl group (a heterocyclic group), a cyano group, a nitro group, an alkoxy group, an aryloxy group, a silyloxy group, a heterocyclic oxy group, an acyloxy group, a carbamoyloxy group, an alkoxycarbonyloxy group, an aryloxycarbonyloxy group, a secondary or tricyclic aryloxy group, a cycloalkenyl group, a cycloalkenyl group, a bi ... Examples of the W substituent include primary amino groups (including anilino groups), alkylthio groups, arylthio groups, heterocyclic thio groups, alkyl or arylsulfinyl groups, alkyl or arylsulfonyl groups, acyl groups, aryloxycarbonyl groups, alkoxycarbonyl groups, aryl or heterocyclic azo groups, imido groups, phosphino groups, phosphinyl groups, phosphinyloxy groups, phosphinylamino groups, phosphono groups, silyl groups, carboxy groups, phosphate groups, sulfonic acid groups, hydroxy groups, thiol groups, acylamino groups, carbamoyl groups, ureido groups, boronic acid groups, and primary amino groups. Furthermore, each of the above groups may further have a substituent (e.g., one or more of the above groups), if possible. For example, an alkyl group that may have a substituent is also included as one form of the substituent W.
When the substituent W has a carbon atom, the number of carbon atoms contained in the substituent W is, for example, 1 to 20.
The number of atoms other than hydrogen atoms contained in the substituent W is, for example, 1 to 30.
It is also preferable that the specific compound described below does not have a carboxy group, a salt of a carboxy group, a salt of a phosphate group, a sulfonic acid group, a salt of a sulfonic acid group, a hydroxy group, a thiol group, an acylamino group, a carbamoyl group, a ureido group, a boronic acid group (-B(OH) ₂ ) and/or a primary amino group as a substituent.

In this specification, halogen atoms include, for example, fluorine atoms, chlorine atoms, bromine atoms, and iodine atoms.

In addition, in this specification, unless otherwise specified, the alkyl group preferably has 1 to 20 carbon atoms, more preferably 1 to 10 carbon atoms, and even more preferably 1 to 6 carbon atoms.
The alkyl group may be linear, branched, or cyclic.
Examples of the alkyl group include a methyl group, an ethyl group, an n-propyl group, an i-propyl group, an n-butyl group, a t-butyl group, an n-hexyl group, and a cyclopentyl group.
The alkyl group may be any of a cycloalkyl group, a bicycloalkyl group, and a tricycloalkyl group, and may have a cyclic structure of these as a partial structure.
In the alkyl group which may have a substituent, examples of the substituent which the alkyl group may have include the groups exemplified as the substituent W, and an aryl group (preferably having 6 to 18 carbon atoms, more preferably having 6 carbon atoms), a heteroaryl group (preferably having 5 to 18 carbon atoms, more preferably having 5 to 6 carbon atoms) or a halogen atom (preferably a fluorine atom or a chlorine atom) is preferred.

In this specification, unless otherwise specified, the alkyl group moiety in the alkoxy group is preferably the above-mentioned alkyl group, and the alkyl group moiety in the alkylthio group is preferably the above-mentioned alkyl group.
In the alkoxy group which may have a substituent, examples of the substituent that the alkoxy group may have include the same as the substituents in the alkyl group which may have a substituent. In the alkylthio group which may have a substituent, examples of the substituent that the alkylthio group may have include the same as the substituents in the alkyl group which may have a substituent.

In this specification, unless otherwise specified, the alkenyl group may be linear, branched, or cyclic. The number of carbon atoms in the alkenyl group is preferably 2 to 20. In the optionally substituted alkenyl group, examples of the substituent that the alkenyl group may have include the same as the substituents in the optionally substituted alkyl group.
In this specification, unless otherwise specified, the alkynyl group may be linear, branched, or cyclic. The number of carbon atoms in the alkynyl group is preferably 2 to 20. In the alkynyl group which may have a substituent, examples of the substituent which the alkynyl group may have are the same as those of the substituent in the alkyl group which may have a substituent.

In this specification, unless otherwise specified, an aromatic ring or an aromatic ring constituting an aromatic ring group may be either a monocyclic ring or a polycyclic ring (e.g., 2 to 6 rings). A monocyclic aromatic ring is an aromatic ring having only one aromatic ring structure as a ring structure. A polycyclic (e.g., 2 to 6 rings) aromatic ring is an aromatic ring having a plurality of (e.g., 2 to 6 rings) aromatic ring structures condensed together as a ring structure.
The aromatic ring preferably has 5 to 15 ring atoms.
The aromatic ring may be an aromatic hydrocarbon ring or an aromatic heterocyclic ring.
When the aromatic ring is an aromatic heterocycle, the number of heteroatoms contained as ring member atoms is, for example, 1 to 10. Examples of the heteroatom include a nitrogen atom, a sulfur atom, an oxygen atom, a selenium atom, a tellurium atom, a phosphorus atom, a silicon atom, and a boron atom.
Examples of the aromatic hydrocarbon ring include a benzene ring, a naphthalene ring, an anthracene ring, and a phenanthrene ring.
Examples of the aromatic heterocycle include a pyridine ring, a pyrimidine ring, a pyridazine ring, a pyrazine ring, a triazine ring (for example, a 1,2,3-triazine ring, a 1,2,4-triazine ring, and a 1,3,5-triazine ring), a tetrazine ring (for example, a 1,2,4,5-tetrazine ring), a quinoxaline ring, a pyrrole ring, a furan ring, a thiophene ring, an imidazole ring, an oxazole ring, a thiazole ring, a benzopyrrole ring, a benzofuran ring, a benzothiophene ring, a benzimidazole ring, a benzoxazole ring, a benzothiazole ring, a naphthopyrrole ring, a naphthofuran ring, a naphthothiophene ring, a naphthoimidazole ring, a naphthoxazole ring, a 3H-pyrrolidine ring, a pyrroloimidazole ring (for example, a 5H-pyrrolo[1,2-a]imidazole ring), an imidazooxazole ring (for example, an imidazo[2,1-b]oxazo a thienothiazole ring (for example, a thieno[2,3-d]thiazole ring), a benzothiadiazole ring, a benzodithiophene ring (for example, a benzo[1,2-b:4,5-b']dithiophene ring), a thienothiophene ring (for example, a thieno[3,2-b]thiophene ring), a thiazolothiazole ring (for example, a thiazolo[5,4-d]thiazole ring), a naphthodithiophene ring (for example, a naphtho[ [2,3-b:6,7-b']dithiophene ring, naphtho[2,1-b:6,5-b']dithiophene ring, naphtho[1,2-b:5,6-b']dithiophene ring, 1,8-dithiadicyclopenta[b,g]naphthalene ring, etc.), benzothienobenzothiophene ring, dithieno[3,2-b:2',3'-d]thiophene ring, and 3,4,7,8-tetrathiadicyclopenta[a,e]pentalene ring.
In the aromatic ring which may have a substituent, the type of the substituent which the aromatic ring may have includes, for example, the groups exemplified as the substituent W. When the aromatic ring has a substituent, the number of the substituents may be 1 or more (for example, 1 to 4).
In this specification, the term "aromatic ring group" includes, for example, a group obtained by removing one or more (for example, 1 to 5) hydrogen atoms from the above-mentioned aromatic ring.
In this specification, the term "aryl group" includes, for example, a group obtained by removing one hydrogen atom from a ring that corresponds to an aromatic hydrocarbon ring among the above aromatic rings.
In this specification, the term "heteroaryl group" refers to, for example, a group obtained by removing one hydrogen atom from a ring corresponding to an aromatic heterocycle among the above aromatic rings.
In this specification, the term "arylene group" includes, for example, a group obtained by removing two hydrogen atoms from a ring corresponding to an aromatic hydrocarbon ring among the above aromatic rings.
In this specification, the term "heteroarylene group" refers to, for example, a group formed by removing two hydrogen atoms from a ring corresponding to an aromatic heterocycle among the above aromatic rings.
In the aromatic ring group which may have a substituent, the aryl group which may have a substituent, the heteroaryl group which may have a substituent, the arylene group which may have a substituent, and the heteroarylene group which may have a substituent, examples of the substituents which these groups may have include the substituent W. When these groups which may have a substituent have a substituent, the number of the substituents may be 1 or more (for example, 1 to 4).

In this specification, when a formula showing a chemical structure contains a plurality of identical symbols indicating the type or number of groups, the contents of the plurality of identical symbols are independent of each other, and the contents of the same symbols may be the same or different, unless otherwise specified.
In this specification, when a formula showing a chemical structure contains a plurality of groups of the same type (for example, alkyl groups, etc.), the specific details of the plurality of groups of the same type are independent of each other, and the specific details of the groups of the same type may be the same or different.

The bonding direction of divalent groups (e.g., -CO-O-) shown in this specification is not limited unless otherwise specified. For example, if Y in a compound represented by the formula "X-Y-Z" is -CO-O-, the compound may be either "X-O-CO-Z" or "X-CO-O-Z."

[Photoelectric conversion element]
The photoelectric conversion element of the present invention is a photoelectric conversion element having a conductive film, a photoelectric conversion film, and a transparent conductive film in this order, and the photoelectric conversion film contains a compound represented by formula (1) (hereinafter also referred to as a “specific compound”).
A feature of the present invention is, for example, that it contains a specific compound, and due to the characteristic chemical structure of the specific compound, it is presumed that the relative ratio before and after annealing of a photoelectric conversion element having a photoelectric conversion film containing the specific compound is high, and the quantum efficiency after annealing is high.
Hereinafter, the achievement of at least one of the effects of a higher relative ratio before and after annealing and a higher quantum efficiency after annealing will also be referred to as "the effect of the present invention being superior."

FIG. 1 is a schematic cross-sectional view of one embodiment of the photoelectric conversion element of the present invention.
The photoelectric conversion element 10a shown in Figure 1 has a configuration in which a conductive film (hereinafter also referred to as the "lower electrode") 11 functioning as a lower electrode, an electron blocking film 16A, a photoelectric conversion film 12 containing a specific compound, and a transparent conductive film (hereinafter also referred to as the "upper electrode") 15 functioning as an upper electrode are stacked in this order.
Fig. 2 shows an example of the configuration of another photoelectric conversion element. The photoelectric conversion element 10b shown in Fig. 2 has a configuration in which an electron blocking film 16A, a photoelectric conversion film 12, a hole blocking film 16B, and an upper electrode 15 are stacked in this order on a lower electrode 11. Note that the stacking order of the electron blocking film 16A, the photoelectric conversion film 12, and the hole blocking film 16B in Figs. 1 and 2 may be changed as appropriate depending on the application and characteristics.

In the photoelectric conversion element 10 a (or 10 b ), it is preferable that light be incident on the photoelectric conversion film 12 through the upper electrode 15 .
Furthermore, when the photoelectric conversion element 10a (or 10b) is used, a voltage can be applied. In this case, the lower electrode 11 and the upper electrode 15 form a pair of electrodes, and a voltage of 1×10 ⁻⁵ to 1×10 ⁷ V/cm is preferably applied between this pair of electrodes. From the viewpoints of performance and power consumption, the applied voltage is more preferably 1×10 ⁻⁴ to 1×10 ⁷ V/cm, and even more preferably 1×10 ⁻³ to 5×10 ⁶ V/cm.
1 and 2, the voltage is preferably applied so that the electron blocking film 16A side serves as the cathode and the photoelectric conversion film 12 side serves as the anode. When the photoelectric conversion element 10a (or 10b) is used as an optical sensor or incorporated into an imaging element, a voltage can be applied in a similar manner.
As will be described in detail later, the photoelectric conversion element 10a (or 10b) can be suitably used as an imaging element.
The configuration of each layer constituting the photoelectric conversion element of the present invention will be described in detail below.

[Photoelectric conversion film]
The photoelectric conversion element has a photoelectric conversion film.

<Specific compound>
The photoelectric conversion film contains a specific compound.

In the specific compound, with regard to geometric isomers that can be distinguished based on the C═C double bond formed by the carbon atom to which R ¹ , R ² or R ^b2 is bonded and the carbon atom adjacent thereto in formula (1), the specific compound includes all such geometric isomers. In other words, both cis isomers and trans isomers distinguished based on the C═C double bond are included in the specific compound.

In formula (1), R ^b1 represents an aliphatic hydrocarbon group which may have a substituent or an aromatic ring group which may have a substituent.
R ^b2 represents a cyano group or —C(═O)R ^C1 , where R ^C1 represents an aliphatic hydrocarbon group which may have a substituent or an aromatic ring group which may have a substituent.
When R ^b1 is an aliphatic hydrocarbon group which may have a substituent, R ^b2 is —C(═O)R ^C1 , and R ^C1 is an aliphatic hydrocarbon group which may have a substituent, the aliphatic hydrocarbon group represented by R ^b1 and the aliphatic hydrocarbon group represented by R ^C1 may be bonded directly or via a divalent aliphatic hydrocarbon group.
^X1 represents an oxygen atom, a sulfur atom, ═NR ^C2 , or ═CR ^C3 R ^C4 . R ^C2 represents a hydrogen atom or a substituent. ^{R C3} and R ^C4 each independently represent a cyano group, —C(═O)OR ^C5 , or —C(═O)R ^C6 . ^{R C5} and R ^C6 each independently represent an aliphatic hydrocarbon group which may have a substituent, or an aromatic ring group which may have a substituent.
R ¹ and R ² each independently represent a hydrogen atom, an aliphatic hydrocarbon group which may have a substituent, or an aromatic ring group which may have a substituent.
R ^a1 and R ^a2 each independently represent an optionally substituted aliphatic hydrocarbon group or an optionally substituted aromatic ring group, provided that at least one of R ^a1 and R ^a2 represents an optionally substituted aromatic ring group.
Ar ¹ represents an aromatic ring having two or more carbon atoms and which may have a substituent.

R ^b1 represents an aliphatic hydrocarbon group which may have a substituent or an aromatic ring group which may have a substituent.
R ^b1 is preferably an aromatic ring group which may have a substituent.
The aliphatic hydrocarbon group may be any of linear, branched, and cyclic, and is preferably linear or branched.
Examples of the aliphatic hydrocarbon group include an alkyl group which may have a substituent, an alkenyl group which may have a substituent, and an alkynyl group which may have a substituent, and an alkyl group which may have a substituent is preferred.
The alkyl group preferably has 1 to 30 carbon atoms, more preferably 1 to 15 carbon atoms, and even more preferably 1 to 5 carbon atoms.
Examples of the alkyl group include linear or branched alkyl groups such as a methyl group, an ethyl group, a propyl group, and a butyl group, as well as cyclic alkyl groups such as a cyclopropane ring group, a cyclobutane ring group, a cyclopentane ring group, a cyclohexane ring group, a cycloheptane ring group, a bicyclopentane ring group, a norbornane ring group, a decalin ring group, and an adamantane ring group.
Examples of the substituent that the alkyl group may have include the groups exemplified as the substituent W, and an aryl group or a halogen atom is preferred, and a fluorine atom or a chlorine atom is more preferred.
The alkyl group preferably has no substituent.

The alkenyl group preferably has 2 to 30 carbon atoms, more preferably 2 to 15 carbon atoms, and even more preferably 2 to 5 carbon atoms.
Examples of the alkenyl group include groups in which —CH ₂ —CH ₂ — in the alkyl groups mentioned above is replaced with —CH═CH—.
Examples of the substituent that the alkenyl group may have include the groups exemplified as the substituent W, and an aryl group or a halogen atom is preferred.

The alkynyl group preferably has 2 to 30 carbon atoms, more preferably 2 to 15 carbon atoms, and even more preferably 2 to 5 carbon atoms.
Examples of the alkynyl group include groups in which —CH ₂ —CH ₂ — in the above alkyl groups is replaced with —C≡C—.
Examples of the substituent that the alkynyl group may have include the groups exemplified as the substituent W, and an aryl group or a halogen atom is preferred.

The aromatic ring group may be either monocyclic or polycyclic.
The aromatic ring group preferably has 6 to 30 carbon atoms, and more preferably has 6 to 15 carbon atoms.
The aromatic ring group may have a heteroatom as a ring member atom. The aromatic ring group may be either an aromatic hydrocarbon ring or an aromatic heterocyclic ring.
The number of the heteroatoms is preferably 1 to 10, and more preferably 1 to 3.
Examples of the heteroatom include a nitrogen atom, a sulfur atom, an oxygen atom, a selenium atom, a tellurium atom, a phosphorus atom, a silicon atom, and a boron atom, with a nitrogen atom, a sulfur atom, or an oxygen atom being preferred.
Examples of the substituent that the aromatic ring group may have include the groups exemplified as the substituent W, and a halogen atom is preferred, and a fluorine atom or a chlorine atom is more preferred.
When the aromatic ring group has a substituent, the number of the substituents is preferably 1 to 5, and more preferably 1 to 3.
Examples of the aromatic ring group include the above-mentioned aromatic hydrocarbon ring group and aromatic heterocyclic group, and a benzene ring group, a naphthalene ring group, a thiophene ring group, a benzothiazole ring group, or a thiazole ring group is preferred.

R ^b2 represents a cyano group or —C(═O)R ^C1 , where R ^C1 represents an aliphatic hydrocarbon group which may have a substituent or an aromatic ring group which may have a substituent.
Examples of the aliphatic hydrocarbon group and the aromatic ring group include the aliphatic hydrocarbon group which may have a substituent and the aromatic ring group which may have a substituent, represented by R ^b1 above.
R ^b2 is preferably a cyano group.

When R ^b1 is an aliphatic hydrocarbon group which may have a substituent, R ^b2 is —C(═O)R ^C1 , and R ^C1 is an aliphatic hydrocarbon group which may have a substituent, and the aliphatic hydrocarbon group represented by R ^b1 and the aliphatic hydrocarbon group represented by R ^C1 are bonded directly or via a divalent aliphatic hydrocarbon group, the compound represented by formula (1) is preferably a compound represented by formula (1-1).

In formula (1-1), L 1 ^S represents a divalent aliphatic hydrocarbon group, R ^{1 S} represents a substituent, and n ^S represents an integer of 0 to 3.
In formula (1-1), R ¹ , R ² , R ^a1 , R ^a2 and Ar ¹ have the same meanings as R ¹ , R ² , R ^a1 , R ^a2 and Ar ¹ in formula (1), respectively, and the preferred embodiments are also the same.

L 1 ^S represents a divalent aliphatic hydrocarbon group.
Examples of the divalent aliphatic hydrocarbon group include an alkylene group, an alkenylene group, and an alkynylene group.
The alkylene group may be either linear or branched, and is preferably linear.
The alkylene group preferably has 1 to 30 carbon atoms, more preferably 1 to 15 carbon atoms, even more preferably 1 to 5 carbon atoms, and particularly preferably 2 or 3 carbon atoms.
Examples of the alkylene group include a methylene group, an ethylene group, a propylene group, and a butylene group.
The alkenylene group preferably has 2 to 30 carbon atoms, more preferably 2 to 15 carbon atoms, even more preferably 2 to 5 carbon atoms, and particularly preferably 2 or 3 carbon atoms.
Examples of the alkenylene group include groups in which —CH ₂ —CH ₂ — in the alkyl groups mentioned above is replaced with —CH═CH—.
The alkynylene group preferably has 2 to 30 carbon atoms, more preferably 2 to 15 carbon atoms, even more preferably 2 to 5 carbon atoms, and particularly preferably 2 or 3 carbon atoms.
Examples of the alkynyl group include groups in which —CH ₂ —CH ₂ — in the above alkyl groups is replaced with —C≡C—.

R 1 ^S represents a substituent.
Examples of the substituent include the groups exemplified as the substituent W.
When a plurality of R 2 ^S's are present, the R 2 ^S's may be the same or different.

n ^S represents an integer of 0 to 3.
^nS is preferably an integer of 0 to 2, and more preferably 0.

^X1 represents an oxygen atom, a sulfur atom, ═NR ^C2 , or ═CR ^C3 R ^C4 . R ^C2 represents a hydrogen atom or a substituent. ^{R C3} and R ^C4 each independently represent a cyano group, —C(═O)OR ^C5 , or —C(═O)R ^C6 . ^{R C5} and R ^C6 each independently represent an aliphatic hydrocarbon group which may have a substituent, or an aromatic ring group which may have a substituent.
^X1 is preferably an oxygen atom or a sulfur atom, more preferably an oxygen atom.
Examples of the substituent represented by R ^C2 include the groups exemplified as the substituent W.
R ^C3 and R ^C4 are preferably a cyano group.
Examples of ^R and ^R include an aliphatic hydrocarbon group which may have a substituent, or an aromatic ring group which may have a substituent, represented by the above-mentioned R ^b1 , and are preferably an aliphatic hydrocarbon group which may have a substituent, and more preferably an alkyl group which may have a substituent.

R ¹ and R ² each independently represent a hydrogen atom, an aliphatic hydrocarbon group which may have a substituent, or an aromatic ring group which may have a substituent.
Examples of the optionally substituted aliphatic hydrocarbon group or optionally substituted aromatic ring group represented by ^R1 and ^R2 include the optionally substituted aliphatic hydrocarbon group or optionally substituted aromatic ring group represented by R ^b1 described above.
R ¹ and R ² are preferably hydrogen atoms.

R ^a1 and R ^a2 each independently represent an optionally substituted aliphatic hydrocarbon group or an optionally substituted aromatic ring group, provided that at least one of R ^a1 and R ^a2 represents an optionally substituted aromatic ring group.
Examples of the aliphatic hydrocarbon group include the aliphatic hydrocarbon groups represented by R ^b1 above which may have a substituent.
The aliphatic hydrocarbon group preferably has 1 to 30 carbon atoms, more preferably 1 to 15 carbon atoms, and even more preferably 1 to 6 carbon atoms.
The aliphatic hydrocarbon group preferably has no substituent.

The aromatic ring group may be either monocyclic or polycyclic.
The aromatic ring group preferably has 6 to 30 carbon atoms, and more preferably has 6 to 15 carbon atoms.
The aromatic ring group may have a heteroatom as a ring member atom. The aromatic ring group may be either an aromatic hydrocarbon ring or an aromatic heterocyclic ring, and is preferably an aromatic hydrocarbon ring.
Examples of the substituent that the aromatic ring group may have include the groups exemplified as the substituent W, and are preferably an alkyl group or a halogen atom, and more preferably an alkyl group, a fluorine atom, or a chlorine atom. Examples of the alkyl group include the alkyl groups represented by R ^b1 above.
The aromatic ring group is preferably an aromatic ring group which may have an alkyl group or a halogen atom, and more preferably an aromatic hydrocarbon ring which may have an alkyl group or a halogen atom.
The aromatic ring group is preferably a group represented by formula (W).

In formula (W), * represents a bonding position. ^{R W1} and R ^W2 each independently represent a hydrogen atom, an alkyl group, or a halogen atom. ^{T 1} to T ³ each independently represent -CH= or -CR ^W3 =. R ^W3 represents an alkyl group or a halogen atom.

R ^W1 and R ^W2 are preferably alkyl groups.
Examples of the alkyl group include the alkyl groups represented by R ^b1 described above.
It is preferred that at least one of T ¹ to T ³ represents -CR ^W3 = or all of T ¹ to T ³ represent -CH=, and it is more preferred that T ² represents -CR ^W3 = or T ¹ and T ³ represent -CH=.
The halogen atom is preferably a fluorine atom or a chlorine atom.

It is preferred that one of R ^a1 and R ^a2 represents an aromatic ring group which may have a substituent, and the other represents an aliphatic hydrocarbon group which may have a substituent (preferably an alkyl group which may have a substituent).

Ar ¹ represents an aromatic ring having two or more carbon atoms and which may have a substituent.
The aromatic ring may be either a monocyclic ring or a polycyclic ring, and is preferably a polycyclic ring.
The aromatic ring may be either an aromatic hydrocarbon ring or an aromatic heterocyclic ring.
Examples of the aromatic hydrocarbon ring include a benzene ring, a naphthalene ring, an anthracene ring, and a phenanthrene ring.
Examples of the aromatic heterocycle include a quinoxaline ring, a pyrazine ring, a pyrrole ring, a furan ring, a thiophene ring, an imidazole ring, and an oxazole ring.
The aromatic ring is preferably an aromatic heterocycle, more preferably a quinoxaline ring or a pyrazine ring.
Examples of the substituent that the aromatic ring may have include the groups exemplified as the substituent W, and an alkyl group is preferred. Examples of the alkyl group include the alkyl groups represented by R ^b1 above.
It is also preferable that the aromatic ring represented by Ar ¹ contains neither a cyano group nor a fluorine atom.

The specific compound is preferably a compound represented by formula (2).

In formula (2), R ^b1 represents an aliphatic hydrocarbon group which may have a substituent or an aromatic ring group which may have a substituent.
R ^b2 represents a cyano group or —C(═O)R ^C1 , where R ^C1 represents an aliphatic hydrocarbon group which may have a substituent or an aromatic ring group which may have a substituent.
When R ^b1 is an aliphatic hydrocarbon group which may have a substituent, R ^b2 is —C(═O)R ^C1 , and R ^C1 is an aliphatic hydrocarbon group which may have a substituent, the aliphatic hydrocarbon group represented by R ^b1 and the aliphatic hydrocarbon group represented by R ^C1 may be bonded directly or via a divalent aliphatic hydrocarbon group.
^X1 represents an oxygen atom, a sulfur atom, ═NR ^C2 , or ═CR ^C3 R ^C4 . R ^C2 represents a hydrogen atom or a substituent. ^{R C3} and R ^C4 each independently represent a cyano group, —C(═O)OR ^C5 , or —C(═O)R ^C6 . ^{R C5} and R ^C6 each independently represent an aliphatic hydrocarbon group which may have a substituent, or an aromatic ring group which may have a substituent.
R ¹ and R ² each independently represent a hydrogen atom, an aliphatic hydrocarbon group which may have a substituent, or an aromatic ring group which may have a substituent.
R ^a1 and R ^a2 each independently represent an optionally substituted aliphatic hydrocarbon group or an optionally substituted aromatic ring group, provided that at least one of R ^a1 and R ^a2 represents an optionally substituted aromatic ring group.
Y ¹ to Y ⁴ each independently represent -N= or -CR ^C7 =. R ^C7 represents a hydrogen atom or a substituent. When there are multiple R ^C7s , the multiple R ^C7s may be bonded to each other to form a ring.

In formula (2), R ^b1 , R ^b2 , X ¹ , R ¹ , R ² , R ^a1 and R ^a2 have the same meanings as R ^b1 , R ^b2 , X ¹ , R ¹ , R ² , R ^a1 and R ^a2 in formula (1), respectively, and the preferred embodiments are also the same.

It is preferable that at least two of Y ¹ to Y ⁴ represent -N=, more preferable that at least Y ¹ and Y ⁴ represent -N=, and further preferable that Y ¹ and Y ⁴ represent -N= and Y ² and Y ³ represent -CR ^C7 =.
Examples of the substituent represented by R ^C7 include the groups exemplified as the substituent W.
The ring formed by bonding multiple R ^C7 to each other is preferably an aromatic ring, more preferably a benzene ring or a pyridine ring. The ring formed by bonding multiple R ^C7 to each other may further have a substituent. Examples of the substituent include the groups exemplified for the substituent W.
The substituent represented by R ^{3 C7} is preferably a substituent other than a cyano group or a fluorine atom, and more preferably a chlorine atom.

When R ^b1 is an aliphatic hydrocarbon group which may have a substituent, R ^b2 is —C(═O)R ^C1 , and R ^C1 is an aliphatic hydrocarbon group which may have a substituent, and the aliphatic hydrocarbon group represented by R ^b1 and the aliphatic hydrocarbon group represented by R ^C1 are bonded directly or via a divalent aliphatic hydrocarbon group, the compound represented by formula (2) is preferably a compound represented by formula (2-1).

In formula (2-1), R ¹ , R ² , R ^a1 , R ^a2 and Y ¹ to Y ⁴ have the same meanings as R ¹ , R ² , R ^a1 , R ^a2 and Y ¹ to Y ⁴ in formula (2), respectively, and the preferred embodiments are also the same.
In formula (2-1), L ^S , R ^S and n ^S have the same meanings as L ^S , R ^S and n ^S in formula (1-1), respectively, and the preferred embodiments are also the same.

The specific compound is more preferably a compound represented by formula (3).

In formula (3), R ^b1 represents an aliphatic hydrocarbon group which may have a substituent or an aromatic ring group which may have a substituent.
R ^b2 represents a cyano group or —C(═O)R ^C1 , where R ^C1 represents an aliphatic hydrocarbon group which may have a substituent or an aromatic ring group which may have a substituent.
When R ^b1 is an aliphatic hydrocarbon group which may have a substituent, R ^b2 is —C(═O)R ^C1 , and R ^C1 is an aliphatic hydrocarbon group which may have a substituent, the aliphatic hydrocarbon group represented by R ^b1 and the aliphatic hydrocarbon group represented by R ^C1 may be bonded directly or via a divalent aliphatic hydrocarbon group.
^X1 represents an oxygen atom, a sulfur atom, ═NR ^C2 , or ═CR ^C3 R ^C4 . R ^C2 represents a hydrogen atom or a substituent. ^{R C3} and R ^C4 each independently represent a cyano group, —C(═O)OR ^C5 , or —C(═O)R ^C6 . ^{R C5} and R ^C6 each independently represent an aliphatic hydrocarbon group which may have a substituent, or an aromatic ring group which may have a substituent.
R ¹ and R ² each independently represent a hydrogen atom, an aliphatic hydrocarbon group which may have a substituent, or an aromatic ring group which may have a substituent.
R ^a1 and R ^a2 each independently represent an optionally substituted aliphatic hydrocarbon group or an optionally substituted aromatic ring group, provided that at least one of R ^a1 and R ^a2 represents an optionally substituted aromatic ring group.
^Y5 and ^Y6 each independently represent a nitrogen atom or -CR ^C8 =, where ^{R C8} represents a hydrogen atom or a substituent.
^R3 and ^R4 each independently represent a hydrogen atom or a substituent.
When ^Y5 is -CR ^C8 ═, R ^C8 and R ³ , R ³ and R ⁴ , and when ^Y6 is -CR ^C8 ═, R ^C8 and R ⁴ may be bonded to each other to form a ring.

In formula (3), R ^b1 , R ^b2 , X ¹ , R ¹ , R ² , R ^a1 and R ^a2 have the same meanings as R ^b1 , R ^b2 , X ¹ , R ¹ , R ² , R ^a1 and R ^a2 in formula (1), respectively, and the preferred embodiments are also the same.

At least one of ^Y5 and ^Y6 preferably represents -CR ^C8 =, and more preferably ^Y5 and ^Y6 both represent -CR ^C8 =.
Examples of the substituent represented by R ^{3 C8} include the groups exemplified for the substituent W.
R ^C8 is preferably a hydrogen atom.

Examples of the substituent represented by ^R3 and ^R4 include the groups exemplified as the substituent W, and substituents other than a cyano group and a fluorine atom are preferred, with a chlorine atom being preferred.
The rings formed by bonding together R ^C8 and R ³ when Y ⁵ is -CR ^C8 =, R ³ and R ⁴ when Y 6 is -CR C8 =, and R ^C8 and R ⁴ when Y ⁶ is -CR ^C8 = may be either monocyclic or polycyclic, may be either aromatic or non-aromatic, and may further have a substituent. Examples of the substituent include the groups exemplified for the substituent W.
^R3 and ^R4 preferably represent a hydrogen atom or a substituent other than a cyano group or a fluorine atom, and more preferably represent a hydrogen atom or a chlorine atom.

When R ^b1 is an aliphatic hydrocarbon group which may have a substituent, R ^b2 is —C(═O)R ^C1 , and R ^C1 is an aliphatic hydrocarbon group which may have a substituent, and the aliphatic hydrocarbon group represented by R ^b1 and the aliphatic hydrocarbon group represented by R ^C1 are bonded directly or via a divalent aliphatic hydrocarbon group, the compound represented by formula (3) is preferably a compound represented by formula (3-1).

In formula (3-1), R ¹ , R ² , R ^a1 , R ^a2 , Y ⁵ , Y ⁶ , R ³ and R ⁴ have the same meanings as R ¹ , R ² , R ^a1 , R ^a2 , Y ⁵ , Y ⁶ , R ³ and R ⁴ in formula (3), respectively, and the preferred embodiments are also the same.
In formula (3-1), L ^S , R ^S and n ^S have the same meanings as L ^S , R ^S and n ^S in formula (1-1), respectively, and the preferred embodiments are also the same.

Examples of the specific compound include the following compounds.
As described above, the specific compounds exemplified below also include any geometric isomers that can be distinguished based on the C═C double bond. In other words, both cis and trans isomers distinguished based on the C═C double bond are included in the specific compounds.

The molecular weight of the specific compound is preferably 400 to 1,200, more preferably 400 to 1,000, and even more preferably 400 to 800.
When the molecular weight is within the above range, it is presumed that the sublimation temperature of the specific compound is low, and the photoelectric conversion efficiency is excellent even when the photoelectric conversion film is formed at high speed.

The specific compounds are particularly useful as materials for photoelectric conversion films used in imaging devices, photosensors, or photovoltaic cells. The specific compounds often function as dyes within the photoelectric conversion films. The specific compounds can also be used as coloring materials, liquid crystal materials, organic semiconductor materials, charge transport materials, pharmaceutical materials, and fluorescent diagnostic materials.

From the standpoint of stability when used as a p-type organic semiconductor and matching of the energy level with an n-type organic semiconductor, it is preferable that the ionization potential of the specific compound in the form of a single film be -5.0 to -6.0 eV.

The maximum absorption wavelength of the specific compound is preferably in the range of 400 to 600 nm, more preferably in the range of 450 to 580 nm.
The maximum absorption wavelength is a value measured in a solution state (solvent: chloroform) after adjusting the absorption spectrum of the specific compound to a concentration such that the absorbance is 0.5 to 1.0. However, if the specific compound is not soluble in chloroform, the specific compound is vapor-deposited into a film state, and the value measured using the specific compound is regarded as the maximum absorption wavelength of the specific compound.

The particular compound may be purified if necessary.
Examples of methods for purifying the specific compound include sublimation purification, purification using silica gel column chromatography, purification using gel permeation chromatography, reslurry washing, reprecipitation purification, purification using an adsorbent such as activated carbon, and recrystallization purification.

The specific compounds may be used alone or in combination of two or more.
The content of the specific compound in the photoelectric conversion film (=film thickness of the specific compound in terms of a single layer/film thickness of the photoelectric conversion film × 100) is preferably 15 to 75 vol%, more preferably 20 to 60 vol%, and still more preferably 25 to 50 vol%.

<n-type organic semiconductor>
The photoelectric conversion film preferably contains an n-type organic semiconductor in addition to the specific compound.
The n-type organic semiconductor is a compound different from the above-mentioned specific compound.
An n-type organic semiconductor is an acceptor organic semiconductor material (compound) that has the property of readily accepting electrons. In other words, an n-type organic semiconductor is the organic compound that has the greater electron affinity when two organic compounds are used in contact with each other. In other words, any organic compound that has electron-accepting properties can be used as an acceptor organic semiconductor.
Examples of n-type organic semiconductors include fullerenes selected from the group consisting of fullerenes and derivatives thereof; condensed aromatic carbon ring compounds (e.g., naphthalene derivatives, anthracene derivatives, phenanthrene derivatives, tetracene derivatives, pyrene derivatives, perylene derivatives, and fluoranthene derivatives); 5- to 7-membered heterocyclic compounds having at least one selected from the group consisting of a nitrogen atom, an oxygen atom, and a sulfur atom (e.g., pyridine, pyrazine, pyrimidine, pyridazine, triazine, quinoline, quinoxaline, quinazoline, phthalazine, cinnoline, isoquinoline, pteridine, acridine, phenazine, phenanthroline, tetrazole, pyridine ... 1,4,5,8-naphthalenetetracarboxylic anhydride; 1,4,5,8-naphthalenetetracarboxylic anhydride imide derivatives and oxadiazole derivatives; anthraquinodimethane derivatives; diphenylquinone derivatives; bathocuproine, bathophenanthroline and derivatives thereof; triazole compounds; distyrylarylene derivatives; metal complexes having a nitrogen-containing heterocyclic compound as a ligand; silole compounds; and the compounds described in paragraphs [0056] to [0057] of JP-A No. 2006-100767.

As the n-type organic semiconductor (compound), fullerenes selected from the group consisting of fullerenes and derivatives thereof are preferred.
Examples of fullerenes include fullerene C60, fullerene C70, fullerene C76, fullerene C78, fullerene C80, fullerene C82, fullerene C84, fullerene C90, fullerene C96, fullerene C240, fullerene C540, and mixed fullerenes.
Examples of fullerene derivatives include compounds in which a substituent is added to the above-mentioned fullerene. The substituent is preferably an alkyl group, an aryl group, or a heterocyclic group. Preferred fullerene derivatives are the compounds described in JP-A-2007-123707.

The molecular weight of the n-type organic semiconductor is preferably 200 to 1,200, and more preferably 200 to 900.

The maximum absorption wavelength of the n-type organic semiconductor is preferably 400 nm or less or in the range of 500 to 600 nm.

The photoelectric conversion film preferably has a bulk heterostructure formed by mixing a specific compound with an n-type organic semiconductor. A bulk heterostructure is a layer in the photoelectric conversion film in which a specific compound and an n-type organic semiconductor are mixed and dispersed. A photoelectric conversion film having a bulk heterostructure can be formed by either a wet method or a dry method. Bulk heterostructures are described in detail in paragraphs [0013] and [0014] of JP 2005-303266 A.

It is preferable that the difference in electron affinity between the specific compound and the n-type organic semiconductor be 0.1 eV or more.

The n-type organic semiconductor may be used alone or in combination of two or more.
When the photoelectric conversion film contains an n-type organic semiconductor, the content of the n-type organic semiconductor in the photoelectric conversion film (film thickness of the n-type organic semiconductor in terms of a single layer/film thickness of the photoelectric conversion film × 100) is preferably 15 to 75 vol%, more preferably 20 to 60 vol%, and still more preferably 25 to 50 vol%.

When the n-type organic semiconductor material contains fullerenes, the content of fullerenes relative to the total content of n-type organic semiconductor materials (film thickness of fullerenes converted into a single layer / total film thickness of each n-type organic semiconductor material converted into a single layer × 100) is preferably 50 to 100% by volume, more preferably 80 to 100% by volume. Fullerenes may be used singly or in combination of two or more types.

From the viewpoint of the response speed of the photoelectric conversion element, the content of the specific compound relative to the total content of the specific compound and the n-type organic semiconductor (film thickness of the specific compound in terms of a single layer/(film thickness of the specific compound in terms of a single layer+film thickness of the n-type organic semiconductor in terms of a single layer)×100) is preferably 20 to 80 vol %, more preferably 40 to 80 vol %.
When the photoelectric conversion film contains an n-type organic semiconductor and a p-type organic semiconductor, the content of the specific compound (film thickness of the specific compound in terms of a single layer/(film thickness of the specific compound in terms of a single layer+film thickness of the n-type organic semiconductor in terms of a single layer+film thickness of the p-type organic semiconductor in terms of a single layer)×100) is preferably 15 to 75 vol%, more preferably 30 to 75 vol%.
It is preferable that the photoelectric conversion film is substantially composed of the specific compound, the n-type organic semiconductor, and optionally a p-type organic semiconductor. By "substantially," we mean that the total content of the specific compound, the n-type organic semiconductor, and the p-type organic semiconductor is 90 to 100% by volume, preferably 95 to 100% by volume, and more preferably 99 to 100% by volume, based on the total mass of the photoelectric conversion film.

<p-type organic semiconductor>
The photoelectric conversion film preferably contains a p-type organic semiconductor in addition to the specific compound.
The p-type organic semiconductor is a compound different from the above-mentioned specific compound.
A p-type organic semiconductor is a donor organic semiconductor material (compound) that has the property of readily donating electrons. In other words, a p-type organic semiconductor is the organic compound that has the smaller ionization potential when two organic compounds are used in contact with each other.
The p-type organic semiconductor may be used alone or in combination of two or more.

Examples of p-type organic semiconductors include triarylamine compounds (e.g., N,N'-bis(3-methylphenyl)-(1,1'-biphenyl)-4,4'-diamine (TPD), 4,4'-bis[N-(naphthyl)-N-phenyl-amino]biphenyl (α-NPD), the compounds described in paragraphs [0128] to [0148] of JP-A No. 2011-228614, the compounds described in paragraphs [0052] to [0063] of JP-A No. 2011-225544, compounds described in paragraphs [0119] to [0158], compounds described in paragraphs [0044] to [0051] of JP-A-2015-153910, and compounds described in paragraphs [0086] to [0090] of JP-A-2012-94660, etc.), pyrazoline compounds, styrylamine compounds, hydrazone compounds, polysilane compounds, thiophene compounds (for example, thienothiophene derivatives, dibenzothiophene derivatives, benzodithiophene derivatives, dithienothiophene derivatives, [1]benzothieno[3,2 -b]thiophene (BTBT) derivatives, thieno[3,2-f:4,5-f']bis[1]benzothiophene (TBBT) derivatives, compounds described in paragraphs [0031] to [0036] of JP-A-2018-014474, compounds described in paragraphs [0043] to [0045] of WO2016-194630, compounds described in paragraphs [0025] to [0037] and [0099] to [0109] of WO2017-159684, and paragraphs [0029] to [0034] of JP-A-2017-076766 the compounds described in paragraphs [0015] to [0025] of WO2018-207722, the compounds described in paragraphs [0045] to [0053] of JP2019-054228, the compounds described in paragraphs [0045] to [0055] of WO2019-058995, the compounds described in paragraphs [0063] to [0089] of WO2019-081416, the compounds described in paragraphs [0033] to [0036] of JP2019-80052, the compounds described in paragraphs [0044] to [00 54], the compounds described in paragraphs [0041] to [0046] of WO2019-093188, etc.), the compounds of paragraphs [0034] to [0037] of JP2019-050398A, the compounds of paragraphs [0033] to [0036] of JP2018-206878A, the compounds of paragraphs [0038] of JP2018-190755A, the compounds of paragraphs [0019] to [0021] of JP2018-026559A, the compounds of paragraphs [0031] to [ JP-A-2018-078270, paragraphs [0036] to [0041], JP-A-2018-166200, paragraphs [0055] to [0082], JP-A-2018-113425, paragraphs [0041] to [0050], JP-A-2018-85430, paragraphs [0044] to [0048], JP-A-2018-056546, paragraphs [0041] to [0045], JP-A-2018-046267, paragraph [0042] ] to [0049], the compounds described in paragraphs [0031] to [0036] of JP 2018-014474 A, the compounds described in paragraphs [0036] to [0046] of WO 2018-016465 A, the compounds described in paragraphs [0045] to [0048] of JP 2020-010024 A, etc.), cyanine compounds, oxonol compounds, polyamine compounds, indole compounds, pyrrole compounds, pyrazole compounds, polyarylene compounds, fused aromatic carbocyclic compounds (for example, naphthalene derivatives, Examples of the metal complexes having a nitrogen-containing heterocyclic compound as a ligand include anthracene derivatives, phenanthrene derivatives, tetracene derivatives, pentacene derivatives, pyrene derivatives, perylene derivatives, and fluoranthene derivatives), porphyrin compounds, phthalocyanine compounds, triazole compounds, oxadiazole compounds, imidazole compounds, polyarylalkane compounds, pyrazolone compounds, amino-substituted chalcone compounds, oxazole compounds, fluorenone compounds, silazane compounds, and metal complexes having a nitrogen-containing heterocyclic compound as a ligand.
Examples of p-type organic semiconductors include compounds that have a smaller ionization potential than n-type organic semiconductors, and if this condition is met, the organic dyes exemplified as n-type organic semiconductors can be used.
Examples of compounds that can be used as p-type organic semiconductor compounds are shown below.

The difference in ionization potential between the specific compound and the p-type organic semiconductor is preferably 0.1 eV or more.

The p-type semiconductor material may be used alone or in combination of two or more kinds.
When the photoelectric conversion film contains a p-type organic semiconductor, the content of the p-type organic semiconductor in the photoelectric conversion film (film thickness of the p-type organic semiconductor in terms of a single layer/film thickness of the photoelectric conversion film × 100) is preferably 15 to 75 vol%, more preferably 20 to 60 vol%, and still more preferably 25 to 50 vol%.

Photoelectric conversion films containing specific compounds are non-luminescent films and have characteristics that differ from organic electroluminescent devices (OLEDs: organic light-emitting diodes). A non-luminescent film refers to a film with a luminescent quantum efficiency of 1% or less, preferably 0.5% or less, and more preferably 0.1% or less. The lower limit is often 0% or more.

<Pigment>
The photoelectric conversion film preferably contains a dye in addition to the specific compound.
The dye is a compound different from the above-mentioned specific compound.
The dye is preferably an organic dye.
Examples of organic dyes include cyanine dyes, styryl dyes, hemicyanine dyes, merocyanine dyes (including zeromethine merocyanine (simple merocyanine)), rhodacyanine dyes, allopolar dyes, oxonol dyes, hemioxonol dyes, squarium dyes, croconium dyes, azamethine dyes, coumarin dyes, arylidene dyes, anthraquinone dyes, triphenylmethane dyes, azo dyes, azomethine dyes, metallocene dyes, fluorenone dyes, fulgide dyes, perylene dyes, phenazine dyes, phenothiazine dyes, quinone dyes, diphenylmethane dyes, polyene dyes, acridine dyes, acridinone dyes, diphenylamine dyes, quinophthalone dyes, phenoxazine dyes, phthaloperylene dyes, dioxane dyes, porphyrin dyes, chlorophyll dyes, phthalocyanine dyes, subphthalocyanine dyes, and metal complex dyes.

The dye's maximum absorption wavelength is preferably in the visible light region, more preferably 400 to 650 nm, and even more preferably 450 to 650 nm.

The dyes may be used alone or in combination of two or more.
The content of the dye relative to the total content of the specific compound and the dye in the photoelectric conversion film (=(film thickness of the dye in terms of a single layer/(film thickness of the specific compound in terms of a single layer+film thickness of the dye in terms of a single layer)×100) is preferably 15 to 75 vol%, more preferably 20 to 60 vol%, and still more preferably 25 to 50 vol%.

<Film formation method>
The photoelectric conversion film may be formed by, for example, a dry film formation method.
Examples of dry film formation methods include physical vapor deposition methods such as vapor deposition (particularly vacuum deposition), sputtering, ion plating, and MBE (Molecular Beam Epitaxy), as well as CVD (Chemical Vapor Deposition) methods such as plasma polymerization, with vacuum deposition being preferred. When forming the photoelectric conversion film by vacuum deposition, the manufacturing conditions, such as the degree of vacuum and deposition temperature, can be set according to conventional methods.

The thickness of the photoelectric conversion film is preferably 10 to 1,000 nm, more preferably 50 to 800 nm, and even more preferably 50 to 500 nm.

[electrode]
The photoelectric conversion element preferably has an electrode.
The electrodes (upper electrode (transparent conductive film) 15 and lower electrode (conductive film) 11) are made of a conductive material. Examples of the conductive material include metals, alloys, metal oxides, electrically conductive compounds, and mixtures thereof.
Since light is incident from the upper electrode 15, the upper electrode 15 is preferably transparent to the light to be detected. Examples of materials constituting the upper electrode 15 include conductive metal oxides such as antimony- or fluorine-doped tin oxide (ATO: Antimony Tin Oxide, FTO: Fluorine-doped Tin Oxide), tin oxide, zinc oxide, indium oxide, indium tin oxide (ITO: Indium Tin Oxide), and indium zinc oxide (IZO); metal thin films such as gold, silver, chromium, and nickel; mixtures or laminates of these metals and conductive metal oxides; organic conductive materials such as polyaniline, polythiophene, and polypyrrole; and nanocarbon materials such as carbon nanotubes and graphene. From the viewpoint of high conductivity and transparency, conductive metal oxides are preferred.

Generally, when a conductive film is made thinner than a certain range, the resistance value often increases sharply. In a solid-state imaging device incorporating a photoelectric conversion element according to this embodiment, the sheet resistance may be 100 to 10,000 Ω/□, and there is a large degree of freedom in the range of the film thickness that can be reduced.
Furthermore, the thinner the upper electrode (transparent conductive film) 15, the less light it absorbs, and generally the higher the light transmittance. An increase in light transmittance is preferable because it increases light absorption in the photoelectric conversion film and enhances photoelectric conversion performance. Considering the suppression of leakage current, the increase in the resistance value of the thin film, and the increase in transmittance that accompany a thinner film, the thickness of the upper electrode 15 is preferably 5 to 100 nm, and more preferably 5 to 20 nm.

Depending on the application, the bottom electrode 11 may be transparent or non-transparent and reflective. Examples of materials that can be used to form the bottom electrode 11 include conductive metal oxides such as antimony- or fluorine-doped tin oxide (ATO, FTO), tin oxide, zinc oxide, indium oxide, indium tin oxide (ITO), and indium zinc oxide (IZO); metals such as gold, silver, chromium, nickel, titanium, tungsten, and aluminum; conductive compounds such as oxides or nitrides of these metals (e.g., titanium nitride (TiN)); mixtures or laminates of these metals and conductive metal oxides; and organic conductive materials such as polyaniline, polythiophene, and polypyrrole.

The method for forming the electrodes can be appropriately selected depending on the electrode material, and specific examples include wet methods such as printing and coating, physical methods such as vacuum deposition, sputtering, and ion plating, and chemical methods such as CVD and plasma CVD.
When the electrode material is ITO, methods such as an electron beam method, a sputtering method, a resistance heating vapor deposition method, a chemical reaction method (such as a sol-gel method), and coating of a dispersion of indium tin oxide can be used.

[Charge-blocking film: electron-blocking film, hole-blocking film]
The photoelectric conversion element preferably has one or more intermediate layers in addition to the photoelectric conversion film between the conductive film and the transparent conductive film.
The intermediate layer may be, for example, a charge-blocking film. If the photoelectric conversion element has this film, the resulting photoelectric conversion element will have better properties (such as photoelectric conversion efficiency and response speed). Examples of the charge-blocking film include an electron-blocking film and a hole-blocking film.

<Electron blocking film>
The electron blocking film is a donor organic semiconductor material (compound), and the above-mentioned p-type organic semiconductor can be used.
Furthermore, polymeric materials can also be used as the electron blocking film.
Examples of polymeric materials include polymers of phenylene vinylene, fluorene, carbazole, indole, pyrene, pyrrole, picoline, thiophene, acetylene, and diacetylene, as well as derivatives thereof.

The electron blocking film may be made up of multiple films.
The electron blocking film may be composed of an inorganic material. Generally, inorganic materials have a higher dielectric constant than organic materials, so when an inorganic material is used for the electron blocking film, a higher voltage is applied to the photoelectric conversion film, resulting in higher photoelectric conversion efficiency. Examples of inorganic materials that can be used for the electron blocking film include calcium oxide, chromium oxide, chromium copper oxide, manganese oxide, cobalt oxide, nickel oxide, copper oxide, gallium copper oxide, strontium copper oxide, niobium oxide, molybdenum oxide, indium copper oxide, indium silver oxide, and iridium oxide.

<Hole-blocking film>
The hole-blocking film is an acceptor organic semiconductor material (compound), and the above-mentioned n-type y organic semiconductor can be used.
The hole blocking film may be made up of multiple films.

Methods for manufacturing charge blocking films include, for example, dry film formation and wet film formation. Dry film formation methods include, for example, vapor deposition and sputtering. Vapor deposition methods may be either physical vapor deposition (PVD) or chemical vapor deposition (CVD), with physical vapor deposition methods such as vacuum deposition being preferred. Wet film formation methods include, for example, inkjet printing, spraying, nozzle printing, spin coating, dip coating, casting, die coating, roll coating, bar coating, and gravure coating, with inkjet printing being preferred from the perspective of high-precision patterning.

The thickness of each of the charge blocking films (electron blocking film and hole blocking film) is preferably 3 to 200 nm, more preferably 5 to 100 nm, and even more preferably 5 to 30 nm.

<Substrate>
The photoelectric conversion element may further include a substrate.
Examples of the substrate include a semiconductor substrate, a glass substrate, and a plastic substrate.
The substrate is usually positioned such that a conductive film, a photoelectric conversion film, and a transparent conductive film are laminated in this order on the substrate.

<Sealing layer>
The photoelectric conversion element may further include a sealing layer.
The performance of photoelectric conversion materials can be significantly degraded in the presence of degrading factors such as water molecules, etc. Therefore, the degradation can be prevented by covering and sealing the entire photoelectric conversion film with a sealing layer made of ceramics such as dense metal oxide, metal nitride, or metal nitride oxide, or diamond-like carbon (DLC), which does not allow water molecules to penetrate.
The sealing layer is described, for example, in paragraphs [0210] to [0215] of JP-A-2011-082508, the contents of which are incorporated herein by reference.

[Image sensor]
Photoelectric conversion elements are used, for example, in imaging devices.
An imaging element is an element that converts the optical information of an image into an electrical signal, and typically has multiple photoelectric conversion elements arranged in a matrix on the same plane, with each photoelectric conversion element (pixel) converting the optical signal into an electrical signal and outputting the electrical signal pixel by pixel from the imaging element. To this end, each pixel is composed of one or more photoelectric conversion elements and one or more transistors.

[Optical sensor]
Other uses of the photoelectric conversion element include, for example, a photocell and an optical sensor, and the photoelectric conversion element of the present invention is preferably used as an optical sensor. As an optical sensor, the photoelectric conversion element may be used alone, or may be used as a line sensor in which the photoelectric conversion elements are arranged linearly or as a two-dimensional sensor in which the photoelectric conversion elements are arranged on a plane.

[Compound]
The present invention also includes inventions of compounds. The compounds of the present invention are the above-mentioned specific compounds.

The present invention will be described in further detail below based on the following examples. The materials, amounts used, ratios, processing details, processing procedures, etc. shown in the following examples can be modified as appropriate without departing from the spirit of the present invention. Therefore, the scope of the present invention should not be interpreted as being limited by the following examples.

[Compounds used in photoelectric conversion films]
[Synthesis of compound (2-4)]
Compound (2-4) was synthesized according to the following scheme.

Compound (2-4-1) (5 mmol), compound (2-4-2) (6.5 mmol), tetrahydrofuran (25 mL), and piperidine (2.5 mL) were placed in a glass reaction vessel and reacted at 70°C for 3 hours under a nitrogen atmosphere. Methanol was added to the resulting reaction solution, and the solid was collected by filtration. The resulting solid was purified by silica gel column chromatography and then by sublimation to obtain compound (2-4) (3.2 mmol).
^1H -NMR (DMSO- _d6 , 400MHz) δ = 2.12 (6H, s), 2.19 (6H, s), 5.20 (1H, d), 6.92 (1H, d), 7.14 ( 3H, s), 7.29 (2H, d), 7.41-7.48 (4H, m), 7.54-7.60 (2H, m), 8.23 (2H, d).

The compounds used in the photoelectric conversion film other than the compound (2-4) were synthesized with reference to the synthesis method of the compound (2-4) above.
The compounds are shown below. Compounds (1-1) to (1-16) and compounds (2-1) to (2-35) are specific compounds, and compounds (C-1) to (C-7) are comparative compounds.

[n-type organic semiconductor]
C60: Fullerene ( _C60 )

[p-type organic semiconductor]

[Pigment]

〔evaluation〕
[Test X]
<Fabrication of photoelectric conversion element>
The obtained compound was used to fabricate a photoelectric conversion element having the configuration shown in Fig. 2. The photoelectric conversion element comprises a lower electrode 11, an electron blocking film 16A, a photoelectric conversion film 12, a hole blocking film 16B, and an upper electrode 15.
Specifically, amorphous ITO was deposited on a glass substrate by sputtering to form a lower electrode 11 (thickness: 30 nm). Compound (EB-1) was then deposited on the lower electrode 11 by vacuum thermal evaporation to form an electron blocking film 16A (thickness: 30 nm). Materials were then deposited on the electron blocking film 16A in predetermined ratios as shown in Tables 1 and 2 to form a photoelectric conversion film 12 having a bulk heterostructure. Compound (EB-2) was then deposited on the photoelectric conversion film 12 to form a hole blocking film 16B (thickness: 10 nm). Amorphous ITO was then deposited on the hole blocking film 16B by sputtering to form an upper electrode 15 (transparent conductive film) (thickness: 10 nm). An SiO film was formed as a sealing layer on the upper electrode 15 by vacuum deposition, and then an aluminum oxide (Al ₂ O ₃ ) layer was formed thereon by atomic layer chemical vapor deposition (ALCVD), thereby producing a photoelectric conversion element.

<Dark current>
The dark current of each of the obtained photoelectric conversion elements was measured by the following method.
A voltage was applied to the lower and upper electrodes of each photoelectric conversion element to achieve an electric field strength of 2.5 × 10 ⁵ V/cm, and the current value (dark current) in a dark place was measured. As a result, it was confirmed that the dark current in all photoelectric conversion elements was 50 nA/cm ² or less, indicating a sufficiently low dark current.

<Quantum efficiency>
The quantum efficiency of each of the obtained photoelectric conversion elements was measured by the following method.
First, a voltage was applied to each photoelectric conversion element so that the electric field strength was 2.0 × 10 ⁵ V/cm, and light was irradiated from the upper electrode (transparent conductive film) side to evaluate the photoelectric conversion efficiency at a wavelength of 460 nm, which was taken as the quantum efficiency before annealing. Next, the photoelectric conversion element was heated at 150 ° C. for 30 minutes in a glove box, and then the photoelectric conversion efficiency at a wavelength of 460 nm was evaluated again in the same manner as above, and the quantum efficiency after annealing was calculated according to formula (S1). In addition, the relative ratio before and after annealing was evaluated according to formula (S2).

(Quantum efficiency after annealing)
Equation (S1): quantum efficiency after annealing (relative ratio) = (quantum efficiency at a wavelength of 460 nm after annealing of each Example or Comparative Example) / (quantum efficiency at a wavelength of 460 nm after annealing of Example 1-1)
A: Quantum efficiency after annealing is 1.6 or more B: Quantum efficiency after annealing is 1.2 or more and less than 1.6 C: Quantum efficiency after annealing is 0.8 or more and less than 1.2 D: Quantum efficiency after annealing is 0.4 or more and less than 0.8 E: Quantum efficiency after annealing is less than 0.4

(Relative ratio before and after annealing)
Equation (S2): Relative ratio before and after annealing (relative ratio of quantum efficiency) = (quantum efficiency at a wavelength of 460 nm after annealing for each Example or Comparative Example) / (quantum efficiency at a wavelength of 460 nm before annealing for each Example or Comparative Example)
A: The relative ratio before and after annealing is 1.1 or more. B: The relative ratio before and after annealing is 1.0 or more and less than 1.1. C: The relative ratio before and after annealing is 0.9 or more and less than 1.0. D: The relative ratio before and after annealing is 0.6 or more and less than 0.9. E: The relative ratio before and after annealing is less than 0.6. Note that in formula (S2), the photoelectric conversion elements in the numerator and denominator are the same.

<Response speed>
The response speed of each of the obtained photoelectric conversion elements was evaluated by the following method.
A voltage was applied to the photoelectric conversion element to an intensity of 2.0 × 10 ⁵ V / cm. Thereafter, the LED (light emitting diode) was momentarily turned on and light was irradiated from the upper electrode (transparent conductive film) side, and the photocurrent at a wavelength of 460 nm at that time was measured with an oscilloscope to measure the rise time from 0% signal intensity to 97% signal intensity. Next, under the same conditions, the rise time at a wavelength of 460 nm of the photoelectric conversion element when using compound (1-1) was normalized to 1, and the relative response speed of the rise time at a wavelength of 460 nm of each photoelectric conversion element relative to the rise time at a wavelength of 460 nm of the photoelectric conversion element when using compound (1-1) (rise time at a wavelength of 460 nm of each photoelectric conversion element / rise time at a wavelength of 460 nm of the photoelectric conversion element when using compound (1-1)) was determined and evaluated according to the following criteria.
A: Relative response speed is less than 0.5 B: Relative response speed is 0.5 or more and less than 1.0 C: Relative response speed is 1.0 or more and less than 1.5 D: Relative response speed is 1.5 or more and less than 2.0 E: Relative response speed is 2.0 or more

<Response speed dependence on electric field strength>
The electric field strength dependency of the response speed of each of the obtained photoelectric conversion elements was evaluated by the following method.
In the evaluation of the response speed of Test X, the response speed at 7.5×10 ⁴ V/cm was measured in the same manner as above, except that the voltage applied to each photoelectric conversion element was changed to 7.5×10 ⁴ V/cm.
The electric field strength dependency of the response speed was calculated according to formula (S3) and evaluated.
Equation (S3): Dependence of response speed on electric field strength=(rise time at 7.5×10 ⁴ V/cm at a wavelength of 460 nm in each Example or Comparative Example)/(rise time at 2.0×10 ⁵ V/cm at a wavelength of 460 nm in each Example or Comparative Example).
In addition, in the formula (S3), the photoelectric conversion elements in the numerator and denominator are the same.
A: The electric field strength dependency of the response speed is less than 2.0. B: The electric field strength dependency of the response speed is 2.0 or more and less than 3.0. C: The electric field strength dependency of the response speed is 3.0 or more and less than 4.0. D: The electric field strength dependency of the response speed is 4.0 or more and less than 5.0. E: The electric field strength dependency of the response speed is 5.0 or more.

Tables 1 and 2 show the evaluation results of Test X.
The symbols in Tables 1 and 2 indicate the following:
In the "R ^a1 R ^a2 " column, when one of R ^a1 and R ^a2 in a specific compound represents an aromatic ring group which may have a substituent, and the other represents an aliphatic hydrocarbon group which may have a substituent, it is marked as "A", and when the other case is not the above, it is marked as "B".
In the column "R ^b2 =CN group", when R ^b2 represents a cyano group, it is marked as "A", and when it is other than the above, it is marked as "B".
In the "R ³ R ⁴ " column, when R ³ and R ⁴ represent a hydrogen atom or a substituent other than a cyano group or a fluorine atom, the case is marked as "A", and when they represent other than the above, the case is marked as "B".
The "Ratio" column indicates the content ratio of the compound: the p-type organic semiconductor: the n-type organic semiconductor.

From the results shown in the above table, it was confirmed that the photoelectric conversion element of the present invention can obtain the desired effects.
It was confirmed that the effects and response speed of the present invention were better when one of R ^a1 and R ^a2 represented an aromatic ring group which may have a substituent, and the other represented an aliphatic hydrocarbon group which may have a substituent (Examples 1-1 to 1-12 and Examples 1-13 to 1-17, etc.).
It was confirmed that when R ^b2 represents a cyano group, the effects of the present invention are more excellent (Examples 1-1 to 1-12 and Examples 1-18 to 1-21, etc.).
It was confirmed that when ^R3 and ^R4 represent a hydrogen atom or a substituent other than a cyano group or a fluorine atom, the effects of the present invention are more excellent (Examples 1-18 to 1-23, etc.).

[Test Y]
<Fabrication of light source conversion element>
In the same manner as in Test X, photoelectric conversion films were formed using the materials in the prescribed ratios shown in Tables 3 and 4 to prepare photoelectric conversion elements for each of the Examples and Comparative Examples.

<Dark current>
In the same manner as in Test X, the dark current was measured.
As a result, it was confirmed that the dark current was 50 nA/cm ² or less in all the photoelectric conversion elements, and that the dark current was sufficiently low.

<Quantum efficiency>
The quantum efficiency of each of the obtained photoelectric conversion elements was measured by the following method.
First, a voltage was applied to each photoelectric conversion element to achieve an electric field strength of 2.0 × 10 ⁵ V/cm, and light was irradiated from the upper electrode (transparent conductive film) side to evaluate the photoelectric conversion efficiency at a wavelength of 460 nm or 600 nm, which was taken as the quantum efficiency before annealing. Next, the photoelectric conversion element was heated at 150 ° C. for 30 minutes in a glove box, and then the photoelectric conversion efficiency at the wavelength selected above was evaluated again in the same manner as above, and the quantum efficiency after annealing was calculated according to formula (S4). In addition, the relative ratio before and after annealing was evaluated according to formula (S5).

(Quantum efficiency after annealing)
Equation (S4): quantum efficiency after annealing (relative ratio) = (quantum efficiency at a wavelength of 460 nm or 600 nm after annealing of each Example or Comparative Example) / (quantum efficiency at a wavelength of 460 nm or 600 nm after annealing of Example 2-1)
A: Quantum efficiency after annealing is 1.6 or more B: Quantum efficiency after annealing is 1.2 or more and less than 1.6 C: Quantum efficiency after annealing is 0.8 or more and less than 1.2 D: Quantum efficiency after annealing is 0.4 or more and less than 0.8 E: Quantum efficiency after annealing is less than 0.4

(Relative ratio before and after annealing)
Equation (S5): Relative ratio before and after annealing (relative ratio of quantum efficiency) = (quantum efficiency at a wavelength of 460 nm or 600 nm after annealing for each Example or Comparative Example) / (quantum efficiency at a wavelength of 460 nm or 600 nm before annealing for each Example or Comparative Example)
A: The relative ratio before and after annealing is 1.1 or more. B: The relative ratio before and after annealing is 1.0 or more and less than 1.1. C: The relative ratio before and after annealing is 0.9 or more and less than 1.0. D: The relative ratio before and after annealing is 0.6 or more and less than 0.9. E: The relative ratio before and after annealing is less than 0.6. Note that in formula (S5), the photoelectric conversion elements and wavelengths in the numerator and denominator are the same.

<Response speed>
The response speed of each of the obtained photoelectric conversion elements was evaluated by the following method.
A voltage was applied to the photoelectric conversion element so that the intensity was 2.0 × 10 ⁵ V/cm. Thereafter, the LED was momentarily turned on to irradiate light from the upper electrode (transparent conductive film) side, and the photocurrent at a wavelength of 460 nm or 600 nm at that time was measured with an oscilloscope to measure the rise time from 0% signal intensity to 97% signal intensity. Next, the rise time at each wavelength of the photoelectric conversion element when compound (1-1) was used under the same conditions was normalized to 1, and the relative response speed of the rise time at each wavelength of each photoelectric conversion element relative to the rise time at each wavelength of the photoelectric conversion element when compound (1-1) was used (rise time at each wavelength of each photoelectric conversion element/rise time at each wavelength of the photoelectric conversion element when compound (1-1) was used) was determined and evaluated according to the following criteria. Note that when determining the relative response speed, the numerator and denominator are the rise times at the same wavelength.
A: Relative response speed is less than 0.5 B: Relative response speed is 0.5 or more and less than 1.0 C: Relative response speed is 1.0 or more and less than 1.5 D: Relative response speed is 1.5 or more and less than 2.0 E: Relative response speed is 2.0 or more

<Response speed dependence on electric field strength>
The electric field strength dependency of the response speed of each of the obtained photoelectric conversion elements was evaluated by the following method.
In the evaluation of the response speed of Test Y, the response speed at 7.5×10 ⁴ V/cm was measured in the same manner as above, except that the voltage applied to each photoelectric conversion element was changed to 7.5×10 ⁴ V/cm.
The electric field strength dependency of the response speed was calculated according to formula (S6) and evaluated.
Equation (S6): Dependence of response speed on electric field strength=(rise time at 7.5×10 ⁴ V/cm at each wavelength in each Example or Comparative Example)/(rise time at 2.0×10 ⁵ V/cm at each wavelength in each Example or Comparative Example).
In addition, in the formula (S3), the photoelectric conversion elements in the numerator and denominator are the same.
A: The electric field strength dependency of the response speed is less than 2.0. B: The electric field strength dependency of the response speed is 2.0 or more and less than 3.0. C: The electric field strength dependency of the response speed is 3.0 or more and less than 4.0. D: The electric field strength dependency of the response speed is 4.0 or more and less than 5.0. E: The electric field strength dependency of the response speed is 5.0 or more.

Tables 3 and 4 show the evaluation results of Test Y.
The notations in Tables 3 and 4 indicate the following:
In the "R ^a1 R ^a2 " column, when one of R ^a1 and R ^a2 in a specific compound represents an aromatic ring group which may have a substituent, and the other represents an aliphatic hydrocarbon group which may have a substituent, it is marked as "A", and when the other case is not the above, it is marked as "B".
In the column "R ^b2 =CN group", when R ^b2 represents a cyano group, it is marked as "A", and when it is other than the above, it is marked as "B".
In the "R ³ R ⁴ " column, when R ³ and R ⁴ represent a hydrogen atom or a substituent other than a cyano group or a fluorine atom, the case is marked as "A", and when they represent other than the above, the case is marked as "B".
The "Ratio" column indicates the content ratio of the compound:dye:p-type organic semiconductor:n-type organic semiconductor.

From the results shown in the above table, it was confirmed that the photoelectric conversion element of the present invention can obtain the desired effects.
It was confirmed that the effects of the present invention are more excellent when one of R ^a1 and R ^a2 represents an aromatic ring group which may have a substituent, and the other represents an aliphatic hydrocarbon group which may have a substituent (Examples 2-8 to 2-18 and Examples 2-19 to 2-23, etc.).
It was confirmed that when R ^b2 represents a cyano group, the effects of the present invention are more excellent (Examples 2-8 to 2-18 and Examples 2-24 to 2-27, etc.).
It was confirmed that when ^R3 and ^R4 represent a hydrogen atom or a substituent other than a cyano group or a fluorine atom, the effects of the present invention are more excellent (Examples 2-24 to 2-29, etc.).

10a, 10b Photoelectric conversion element 11 Conductive film (lower electrode)
12 Photoelectric conversion film 15 Transparent conductive film (upper electrode)
16A: Electron blocking film 16B: Hole blocking film

Claims (17)

A photoelectric conversion element having a conductive film, a photoelectric conversion film, and a transparent conductive film in this order,
The photoelectric conversion element, wherein the photoelectric conversion film contains a compound represented by formula ( 3 ):
In formula (3), R ^b1 represents an aliphatic hydrocarbon group which may have a substituent or an aromatic ring group which may have a substituent.
R ^b2 represents a cyano group or —C(═O)R ^C1 , where R ^C1 represents an aliphatic hydrocarbon group which may have a substituent or an aromatic ring group which may have a substituent.
When R ^b1 is an aliphatic hydrocarbon group which may have a substituent, R ^b2 is —C(═O)R ^C1 , and R ^C1 is an aliphatic hydrocarbon group which may have a substituent, the aliphatic hydrocarbon group represented by R ^b1 and the aliphatic hydrocarbon group represented by R ^C1 may be bonded directly or via a divalent aliphatic hydrocarbon group.
X1 represents an oxygen atom ^.
R1 ^and R2 represent a hydrogen atom ^.
R ^a1 and R ^a2 each independently represent an optionally substituted aliphatic hydrocarbon group or an optionally substituted benzene ring group, provided that at least one of R ^a1 and R ^a2 represents an optionally substituted benzene ring group.
Y5 and Y6 ^each independently represent -CR ^C8 =, where ^{R C8} represents a hydrogen atom or a substituent.
R3 ^and R4 each independently represent a hydrogen atom or a substituent ^.
R ^C8 and R ³ , R ³ and R ⁴ in —CR ^C8 = represented by Y ⁵ , and R ^C8 and R ⁴ in —CR ^C8 = represented by Y ⁶ may be bonded to each other to form a ring. The photoelectric conversion element according to claim 1 , wherein R ³ and R ⁴ each represent a hydrogen atom or a substituent other than a cyano group or a fluorine atom. The photoelectric conversion element according to claim 1 or 2 , wherein R ^b2 represents a cyano group. 4. The photoelectric conversion element according to claim 1 , wherein R ^b1 represents an aromatic ring group which may have a substituent. The photoelectric conversion element according to any one of claims 1 to 4 , wherein one of R ^a1 and R ^a2 represents a benzene ring group which may have a substituent, and the other represents an aliphatic hydrocarbon group which may have a substituent. The photoelectric conversion element according to any one of claims 1 to 5 , wherein the photoelectric conversion film further contains an n-type organic semiconductor. The photoelectric conversion element according to claim 6 , wherein the n-type organic semiconductor comprises a fullerene selected from the group consisting of fullerenes and derivatives thereof. The photoelectric conversion element according to any one of claims 1 to 7 , wherein the photoelectric conversion film further contains a p-type organic semiconductor. The photoelectric conversion element according to any one of claims 1 to 8 , wherein the photoelectric conversion film further contains a dye. The photoelectric conversion element according to any one of claims 1 to 9 , further comprising one or more intermediate layers in addition to the photoelectric conversion film between the conductive film and the transparent conductive film. An imaging device comprising the photoelectric conversion element according to any one of claims 1 to 10 . An optical sensor comprising the photoelectric conversion element according to any one of claims 1 to 10 . A compound represented by formula (3):
In formula (3), R ^b1 represents an aliphatic hydrocarbon group which may have a substituent or an aromatic ring group which may have a substituent.
R ^b2 is a cyano group or —C(═O)R ^C1 Represents R ^C1 represents an aliphatic hydrocarbon group which may have a substituent or an aromatic ring group which may have a substituent.
R ^b1 is an aliphatic hydrocarbon group which may have a substituent, and R ^b2 is -C(=O)R ^C1 and R ^C1 is an aliphatic hydrocarbon group which may have a substituent, R ^b1 The aliphatic hydrocarbon group represented by R ^C1 The aliphatic hydrocarbon group represented by the formula (I) may be bonded directly or via a divalent aliphatic hydrocarbon group.
X ¹ represents an oxygen atom.
R ¹ and R ² represents a hydrogen atom.
R ^a1 and R ^a2 each independently represents an aliphatic hydrocarbon group which may have a substituent or a benzene ring group which may have a substituent. ^a1 and R ^a2 At least one of the groups represents a benzene ring group which may have a substituent.
Y ⁵ and Y ⁶ are each independently -CR ^C8 = represents. R ^C8 represents a hydrogen atom or a substituent.
R ³ and R ⁴ each independently represents a hydrogen atom or a substituent.
Y ⁵ Represents -CR ^C8 =R in ^C8 and R ³ , R ³ and R ⁴ , and Y ⁶ Represents -CR ^C8 =R in ^C8 and R ⁴ may be bonded to each other to form a ring. The compound according to claim 13 , wherein ^R3 and ^R4 represent a hydrogen atom or a substituent other than a cyano group and a fluorine atom. 15. The compound according to claim 13 or 14 , wherein R ^b2 represents a cyano group. The compound according to any one of claims 13 to 15 , wherein R ^b1 represents an aromatic ring group which may have a substituent. The compound according to any one of claims 13 to 16 , wherein one of R ^a1 and R ^a2 represents an optionally substituted benzene ring group, and the other represents an optionally substituted aliphatic hydrocarbon group.