Photoelectric conversion element, imaging element, method for manufacturing imaging element, optical sensor, and compound

Abstract

The present invention provides a photoelectric conversion element having excellent long-term stability of response speed regarding blue light. A photoelectric conversion element according to the present invention comprises a conductive film, a photoelectric conversion film, and a transparent conductive film in this order, wherein the photoelectric conversion film includes a compound represented by formula (1).

Description

Photoelectric conversion element, imaging element, imaging element manufacturing method, optical sensor, compound

[0001] The present invention relates to a photoelectric conversion element, an imaging element, a method for manufacturing an imaging element, an optical sensor, and a compound.

[0002] In recent years, development of elements having a photoelectric conversion film and organic electroluminescence (EL) elements has progressed as organic electronic devices. For example, Patent Document 1 discloses a photoelectric conversion element having a photoelectric conversion film with a narrow half-width of the absorption peak and excellent photoelectric conversion efficiency, the photoelectric conversion element containing a compound having a specific structure represented by formula (1).

[0003] International Publication No. 2019 / 189134

[0004] On the other hand, with the demand for improved performance of image sensors, optical sensors, and the like, there is a demand for photoelectric conversion elements that exhibit excellent characteristics. One of the characteristics required for a photoelectric conversion element is, for example, excellent stability over time of the response speed to blue light. In response to this demand, the present inventors fabricated and investigated a photoelectric conversion element using the compound disclosed in Patent Document 1, and found that the stability over time of the response speed to blue light needed to be improved. The blue light referred to above refers to light with a wavelength of 400 to 500 nm.

[0005] Therefore, an object of the present invention is to provide a photoelectric conversion element that has excellent stability over time in response speed to blue light. Another object of the present invention is to provide an imaging element, a manufacturing method for an imaging element, an optical sensor, and a compound related to the photoelectric conversion element.

[0006] As a result of extensive research into solving the above problems, the present inventors have found that the problems can be solved by the following configuration.

[0007] [1] A photoelectric conversion element having a conductive film, a photoelectric conversion film, and a transparent conductive film in this order, wherein the photoelectric conversion film contains a compound represented by formula (1) described later. [2] The photoelectric conversion element according to [1], wherein the compound represented by formula (1) is a compound represented by formula (2) described later. [3] Y １ But -C(R Ｙ１) (R Ｙ２ )-, R Ｙ１ and R Ｙ２ each independently represents an aliphatic hydrocarbon group which may have a substituent, an aromatic ring group which may have a substituent, or an aliphatic heterocyclic group which may have a substituent; R Ｙ１ and R Ｙ２ The photoelectric conversion element according to [1] or [2], wherein R may be bonded to each other to form a ring. Ｙ１ and R Ｙ２ each independently represents an aliphatic hydrocarbon group which may have a substituent, R Ｙ１ and R Ｙ２may be bonded to each other to form a ring. [5] The photoelectric conversion element according to any one of [1] to [4], wherein A represents a group represented by formula (A-1) above. [6] The photoelectric conversion element according to any one of [1] to [5], wherein A represents a group represented by formula (A-3) or formula (A-4) described later. [7] The photoelectric conversion element according to any one of [1] to [6], wherein A represents a group represented by formula (A-5) described later. [8] The photoelectric conversion element according to any one of [1] to [7], wherein the photoelectric conversion film further contains an n-type organic semiconductor, and the photoelectric conversion film has a bulk heterostructure formed by mixing a compound represented by formula (1) described later with the n-type organic semiconductor. [9] The photoelectric conversion element according to [8], wherein the n-type organic semiconductor contains a fullerene selected from the group consisting of fullerenes and derivatives thereof.

[10] The photoelectric conversion element according to any one of [1] to [9], wherein the photoelectric conversion film further contains a p-type organic semiconductor.

[11] The photoelectric conversion element according to any one of [1] to

[10] , wherein the photoelectric conversion film further contains a dye.

[12] The photoelectric conversion element according to any one of [1] to

[11] , wherein one or more intermediate layers are provided between the conductive film and the transparent conductive film in addition to the photoelectric conversion film.

[13] An imaging element comprising the photoelectric conversion element according to any one of [1] to

[12] .

[14] An optical sensor comprising the photoelectric conversion element according to any one of [1] to

[12] .

[15] A method for manufacturing an imaging element, comprising a step of manufacturing the photoelectric conversion element according to any one of [1] to

[12] .

[16] A compound represented by formula (1) described later.

[17] The compound according to

[16] , wherein the compound represented by formula (1) is a compound represented by formula (2) described later.

[18] Y １ But -C(R Ｙ１ ) (R Ｙ２ )-, R Ｙ１ and R Ｙ２ each independently represents an aliphatic hydrocarbon group which may have a substituent, an aromatic ring group which may have a substituent, or an aliphatic heterocyclic group which may have a substituent; R Ｙ１ and R Ｙ２The compound according to

[16] or

[17] , wherein R may be bonded to each other to form a ring. Ｙ１ and R Ｙ２ each independently represents an aliphatic hydrocarbon group which may have a substituent, R Ｙ１ and R Ｙ２ may be bonded to each other to form a ring.

[20] The compound according to any one of

[16] to

[19] , wherein A represents a group represented by the above formula (A-1).

[21] The compound according to any one of

[16] to

[20] , wherein A represents a group represented by the below-mentioned formula (A-3) or the below-mentioned formula (A-4).

[22] The compound according to any one of

[16] to

[21] , wherein A represents a group represented by the below-mentioned formula (A-5).

[0008] According to the present invention, a photoelectric conversion element having excellent stability over time in response speed to blue light can be provided. Furthermore, according to the present invention, an imaging element, a manufacturing method of an imaging element, an optical sensor, and a compound related to the photoelectric conversion element can also be provided.

[0009] 1 is a schematic cross-sectional view showing an example of the configuration of a photoelectric conversion element.

[0010] The present invention will be described in detail below. The following description of the components may be based on representative embodiments of the present invention, but the present invention is not limited to such embodiments.

[0011] The meaning of each description in this specification is as follows. 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, a hydrogen atom may be a protist atom (a normal hydrogen atom) or a deuterium atom (for example, a deuterium atom, etc.).

[0012] In this specification, with respect to compounds that may have geometric isomers (cis-trans isomers), the general formula or structural formula representing the compound may be described in only one of the cis and trans forms for convenience. Even in such cases, unless otherwise specified, the form of the compound is not limited to either the cis or trans form, and the compound may be in either the cis or trans form.

[0013] Unless otherwise specified, the bonding direction of a divalent group (e.g., -CO-O-) represented in this specification is not limited. For example, when Y is -CO-O- in a compound represented by the formula "X-Y-Z," the compound may be either "X-O-CO-Z" or "X-CO-O-Z."

[0014] The symbol "*" shown in a chemical formula represents a bonding position unless otherwise specified. In this specification, when there are multiple substituents and linking groups, etc. (hereinafter also referred to as "substituents, etc.") represented by a specific symbol, or when multiple substituents, etc. are specified at the same time, 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, "substituents" include groups exemplified as the substituent W described below.

[0015] (Substituent W) The substituent W in this specification will be described. Examples of the substituent W include 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 heterocyclic group (a heteroaryl group, or an aliphatic heterocyclic group), a cyano group, a nitro group, an alkoxy group, an aryloxy group, a silyl group, a silyloxy group, a heterocyclic oxy group, an acyloxy group, a carbamoyloxy group, an alkoxycarbonyloxy group, an aryl ... Examples of the substituent W include an alkyloxy group, a primary, secondary, or tertiary amino group (including an anilino group), an alkylthio group, an arylthio group, a heterocyclic thio group, an alkyl or arylsulfinyl group, an alkyl or arylsulfonyl group, an acyl group, an aryloxycarbonyl group, an alkoxycarbonyl group, an aryl or heterocyclic azo group, an imido group, a phosphino group, a phosphinyl group, a phosphinyloxy group, a phosphinylamino group, a phosphono group, a carboxy group, a phosphate group, a sulfonic acid group, a hydroxy group, a thiol group, an acylamino group, a carbamoyl group, a ureido group, and a boronic acid group. Furthermore, each of the above groups may further have a substituent (e.g., one or more of the above groups, etc.) if possible. For example, an alkyl group which may have a substituent is also included as one form of the substituent W. Furthermore, 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. The specific compounds described below may have, as substituents, 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 has no primary amino groups.

[0016] In this specification, the aliphatic hydrocarbon group may be linear, branched, or cyclic. Furthermore, the phrase "the aliphatic hydrocarbon group may have an etheric oxygen atom" means that the aliphatic hydrocarbon group may have a divalent linking group represented by -O- in the middle or at the end. Examples of the aliphatic hydrocarbon group include alkyl groups, alkenyl groups, and alkynyl groups. Furthermore, unless otherwise specified in this specification, the number of carbon atoms in the alkyl group is preferably 1 to 20, more preferably 1 to 10, and even more preferably 1 to 6. 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 isopropyl group, an n-butyl group, a t-butyl group, an n-hexyl group, and a cyclopentyl group. Furthermore, the alkyl group may be a cycloalkyl group, a bicycloalkyl group, or a tricycloalkyl group, and may have these ring structures as partial structures. In the alkyl group that may have a substituent, examples of the substituent that the alkyl group may have include the groups exemplified for the substituent W. Of these, 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.

[0017] In this specification, unless otherwise specified, the alkyl group moiety in the alkoxy group is preferably the above-mentioned alkyl group. 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 substituent 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 substituent in the alkyl group which may have a substituent.

[0018] 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 alkenyl group which may have a substituent, examples of the substituent that the alkenyl 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 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 that the alkynyl group may have include the same as the substituents in the alkyl group which may have a substituent.

[0019] In this specification, unless otherwise specified, the aromatic ring or the aromatic ring constituting the aromatic ring group may be either a monocyclic ring or a polycyclic ring (for example, 2 to 6 rings). １The aromatic ring represented by the formula (I) is a monocyclic aromatic ring. 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) condensed aromatic ring structures as a ring structure. The number of ring members in the aromatic ring is preferably 5 to 15. The aromatic ring may be an aromatic hydrocarbon ring or an aromatic heterocycle. 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, a pyrene ring, a phenanthrene ring, and a fluorene ring.Examples of the aromatic heterocycle include a pyridine ring, a pyrimidine ring, a pyridazine ring, a pyrazine ring, a triazine ring (e.g., a 1,2,3-triazine ring, a 1,2,4-triazine ring, and a 1,3,5-triazine ring), a tetrazine ring (e.g., 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 pyrroloimidazole ring (e.g., a 5H-pyrrolo[1,2-a]imidazole ring), an imidazooxazole ring (e.g., an imidazo[2,1-b]oxazole ring). , thienothiazole rings (for example, thieno[2,3-d]thiazole rings, etc.), benzothiadiazole rings, benzodithiophene rings (for example, benzo[1,2-b:4,5-b']dithiophene rings, etc.), thienothiophene rings (for example, thieno[3,2-b]thiophene rings, etc.), thiazolothiazole rings (for example, thiazolo[5,4-d]thiazole rings, etc.), naphthodithiophene rings (for example, naphtho[2,3 [2,1-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.

[0020] As used herein, the term "aromatic ring group" includes, for example, a group obtained by removing one or more hydrogen atoms (e.g., 1 to 5) from the above-mentioned aromatic ring. As used herein, the term "aryl group" includes, for example, a group obtained by removing one hydrogen atom from a ring corresponding to an aromatic hydrocarbon ring among the above-mentioned aromatic rings. As used herein, the term "heteroaryl group" includes, for example, a group obtained by removing one hydrogen atom from a ring corresponding to an aromatic heterocycle among the above-mentioned aromatic rings. As used herein, 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-mentioned aromatic rings. As used herein, the term "heteroarylene group" includes, for example, a group obtained by removing two hydrogen atoms from a ring corresponding to an aromatic heterocycle among the above-mentioned aromatic rings. In the optionally substituted aromatic ring, optionally substituted aromatic ring group, optionally substituted aryl group, optionally substituted heteroaryl group, optionally substituted arylene group, and optionally substituted heteroarylene group, the types of substituents that these may have include, for example, the groups exemplified for the substituent W. When these groups which may have a substituent have a substituent, the number of the substituents may be one or more (for example, 1 to 4, etc.).

[0021] As used herein, the term "non-aromatic ring" refers to a ring structure that is not aromatic, and examples thereof include an aliphatic hydrocarbon ring and an aliphatic heterocycle. Examples of the aliphatic hydrocarbon ring include cycloalkanes, cycloalkenes, and cycloalkynes. As used herein, the term "aliphatic heterocyclic group" refers to, for example, a group obtained by removing one hydrogen atom from the aliphatic heterocycle. As used herein, the number of ring members in the aliphatic heterocyclic group is preferably 5 to 20, more preferably 5 to 12, and even more preferably 6 to 8. Examples of heteroatoms contained in the aliphatic heterocyclic group include a sulfur atom, an oxygen atom, a nitrogen atom, a selenium atom, a tellurium atom, a phosphorus atom, a silicon atom, and a boron atom, with a sulfur atom, an oxygen atom, or a nitrogen atom being preferred. Examples of the aliphatic heterocycle constituting the aliphatic heterocyclic group include a pyrrolidine ring, an oxolane ring (tetrahydrofuran ring), a thiolane ring, a piperidine ring, a tetrahydropyran ring, a thiane ring (pentamethylene sulfide ring), a piperazine ring, a morpholine ring, a quinuclidine ring, an azetidine ring, an oxetane ring, an aziridine ring, a dioxane ring, and a γ-butyrolactone ring.

[0022] [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").

[0023] Although the reason why the photoelectric conversion element having the above configuration can solve the problem of the present invention is not entirely clear, the inventors speculate as follows. Note that the following speculation does not limit the mechanism by which the effect is obtained. In other words, even if the effect is obtained by a mechanism other than the one described below, it is still within the scope of the present invention. The specific compound is a so-called DA-type dye compound having a donor moiety (D) and an acceptor moiety (A). The photoelectric conversion element of the present invention achieves the problem of the present invention, namely, the stability over time of the response speed when receiving blue light, by virtue of the specific compound having a structure represented by formula (1). Although the detailed mechanism for solving the above problem is unknown, the inventors have discovered that it is important that molecules are less likely to move in the photoelectric conversion film, i.e., that the molecular weight of the specific compound is appropriately large and has appropriate intermolecular interactions. This led to adjusting the molecular weight of the donor moiety of the specific compound so that the number of fused ring structures is appropriate, as shown in formula (1). Hereinafter, better stability over time of the response speed to blue light will also be referred to as "better effect of the present invention."

[0024] FIG. 1 shows a cross-sectional schematic diagram of one embodiment of the photoelectric conversion element of the present invention. The photoelectric conversion element 10a shown in FIG. 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.

[0025] In the photoelectric conversion element 10a (or 10b), it is preferable that light is incident on the photoelectric conversion film 12 through the upper electrode 15. 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 is applied between the pair of electrodes.－５ ~1 x 10 ７ In terms of performance and power consumption, it is preferable to apply a voltage of 1×10 V / cm. －４ ~1 x 10 ７ V / cm is more preferable, and 1×10 －３ ~5 x 10 ６ V / cm is more preferable. Regarding the voltage application method, it is preferable to apply the voltage so that the electron blocking film 16A side serves as the cathode and the photoelectric conversion film 12 side serves as the anode in FIGS. 1 and 2. When the photoelectric conversion element 10a (or 10b) is used as a photosensor 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.

[0026] [Photoelectric Conversion Film] The photoelectric conversion element has a photoelectric conversion film.

[0027] <Specific Compound> The photoelectric conversion film contains a compound (specific compound) represented by formula (1).

[0028]

[0029] In formula (1), R １ and R ２ R each independently represents a hydrogen atom or a substituent. ３ represents a hydrogen atom, an aliphatic hydrocarbon group which may have a substituent other than an acid group and a salt thereof, an aromatic ring group which may have a substituent other than an acid group and a salt thereof, or an aliphatic heterocyclic group which may have a substituent other than an acid group and a salt thereof. １ and X ２ Each independently represents a nitrogen atom or -C(Rx)=, where Rx represents a hydrogen atom or a substituent. Y １ is -C(R Ｙ１ ) (R Ｙ２ )-, an oxygen atom, a sulfur atom, or a selenium atom. Ｙ１ and R Ｙ２each independently represents an aliphatic hydrocarbon group which may have a substituent, an aromatic ring group which may have a substituent, or an aliphatic heterocyclic group which may have a substituent. Ｙ１ and R Ｙ２ may be bonded to each other to form a ring. １ represents a monocyclic aromatic ring which may have a substituent, provided that X １ and X ２ When both of them represent -C(Rx)=, A １ represents a nitrogen-containing 6-membered aromatic ring which may have a substituent, and A represents a group represented by formula (A-1) or (A-2) described later.

[0030] In formula (1), R １ and R ２ Each independently represents a hydrogen atom or a substituent. Examples of the substituent include the substituents exemplified for the substituent W. In terms of the effects of the present invention, R １ and R ２ is preferably a hydrogen atom.

[0031] In formula (1), R ３ represents a hydrogen atom, an aliphatic hydrocarbon group which may have a substituent other than an acid group and a salt thereof, an aromatic ring group which may have a substituent other than an acid group and a salt thereof, or an aliphatic heterocyclic group which may have a substituent other than an acid group and a salt thereof. ３ Each group represented by the formula (I) does not have an acid group or a salt thereof. Furthermore, it is preferable that the specific compound does not have an acid group or a salt thereof in its structure. Examples of the acid group include a carboxy group, a phosphate group, and a sulfonic acid group. Examples of substituents other than acid groups and salts thereof include those groups exemplified as the substituent W that do not fall under the category of an acid group. Among these, alkyl groups are preferred as substituents other than acid groups and salts thereof. The alkyl group may be linear, branched, or cyclic. The alkyl group preferably has 1 to 10 carbon atoms, more preferably 1 to 6, and even more preferably 1 to 3.

[0032] R ３As the aliphatic hydrocarbon group, an aliphatic hydrocarbon group optionally having a substituent other than an acid group and a salt thereof, or an aromatic ring group optionally having a substituent other than an acid group and a salt thereof, is preferred. Examples of the aliphatic hydrocarbon group in the aliphatic hydrocarbon group optionally having a substituent other than an acid group and a salt thereof include a linear aliphatic hydrocarbon group, a branched aliphatic hydrocarbon group, and a cyclic aliphatic hydrocarbon group. The aliphatic hydrocarbon group preferably has 1 to 20 carbon atoms. The linear aliphatic hydrocarbon group preferably has 1 to 10 carbon atoms, more preferably 1 to 6, and even more preferably 1 to 3. The branched aliphatic hydrocarbon group preferably has 3 to 20 carbon atoms, more preferably 3 to 7, and even more preferably 3 to 5. The cyclic aliphatic hydrocarbon group may be either monocyclic or polycyclic. The cyclic aliphatic hydrocarbon group preferably has 3 to 20 carbon atoms, more preferably 3 to 8, and even more preferably 3 to 6.

[0033] The aromatic ring group in the aromatic ring group that may have a substituent other than the acid group and its salt may be either an aromatic hydrocarbon group or an aromatic heterocyclic group, with an aromatic hydrocarbon group being preferred. The aromatic ring group may be either a monocyclic or polycyclic ring. The number of ring members in the aromatic ring group is preferably 5 to 15, more preferably 5 to 10, and even more preferably 5 to 6. The number of carbon atoms in the aromatic ring group that may have a substituent (the number of carbon atoms including the carbon atoms in the substituent) is preferably 1 to 30, more preferably 3 to 20, and even more preferably 4 to 10. Examples of heteroatoms contained in the aromatic heterocyclic group include sulfur atoms, oxygen atoms, nitrogen atoms, selenium atoms, tellurium atoms, phosphorus atoms, silicon atoms, and boron atoms, with sulfur atoms, oxygen atoms, or nitrogen atoms being preferred. Among these, a phenyl group is preferred as the aromatic ring group. The number of substituents other than the acid group and its salt that the aromatic ring group may have is preferably 1 to 5, more preferably 1 to 3, and even more preferably 1 or 2. Furthermore, as the aromatic ring group which may have a substituent other than an acid group or a salt thereof, a phenyl group which may have an alkyl group having 1 to 3 carbon atoms is preferred.

[0034] In formula (1), X １ and X ２Each independently represents a nitrogen atom or -C(Rx)=. Rx represents a hydrogen atom or a substituent. In terms of the effects of the present invention, X １ preferably represents a nitrogen atom, and X ２ preferably represents each -C(Rx)=. Rx is preferably a hydrogen atom. Examples of the substituent represented by Rx include the groups exemplified above for the substituent W, and among these, an alkyl group or a halogen atom is preferred.

[0035] In formula (1), Y １ is -C(R Ｙ１ ) (R Ｙ２ )-, an oxygen atom, a sulfur atom, or a selenium atom. Ｙ１ and R Ｙ２ each independently represents an aliphatic hydrocarbon group which may have a substituent, an aromatic ring group which may have a substituent, or an aliphatic heterocyclic group which may have a substituent. Ｙ１ and R Ｙ２ may be bonded to each other to form a ring. １ As -C(R Ｙ１ ) (R Ｙ２ )- is preferably represented by R Ｙ１ and R Ｙ２ Preferably, each independently represents an aliphatic hydrocarbon group which may have a substituent, or an aromatic ring group which may have a substituent, and more preferably represents an aliphatic hydrocarbon group which may have a substituent.

[0036] Examples of the aliphatic hydrocarbon group in the aliphatic hydrocarbon group which may have a substituent include a straight-chain aliphatic hydrocarbon group, a branched-chain aliphatic hydrocarbon group, and a cyclic aliphatic hydrocarbon group. The aliphatic hydrocarbon group preferably has 1 to 20 carbon atoms. The straight-chain aliphatic hydrocarbon group preferably has 1 to 10 carbon atoms, more preferably 1 to 6, and even more preferably 1 to 3. The branched-chain aliphatic hydrocarbon group preferably has 3 to 20 carbon atoms, more preferably 3 to 7, and even more preferably 3 to 5. The cyclic aliphatic hydrocarbon group may be either monocyclic or polycyclic. The cyclic aliphatic hydrocarbon group preferably has 3 to 20 carbon atoms, more preferably 3 to 8, and even more preferably 3 to 6.

[0037] The aromatic ring group in the aromatic ring group which may have a substituent may be either an aromatic hydrocarbon group or an aromatic heterocyclic group, with an aromatic hydrocarbon group being preferred. The aromatic ring group may be either a monocyclic or polycyclic ring. The number of ring members in the aromatic ring group is preferably 5 to 15, more preferably 5 to 10, and even more preferably 5 to 6. The number of carbon atoms in the aromatic ring group which may have a substituent (the number of carbon atoms including the carbon atoms in the substituent) is preferably 1 to 30, more preferably 3 to 20, and even more preferably 4 to 10. Examples of heteroatoms contained in the aromatic heterocyclic group include sulfur atoms, oxygen atoms, nitrogen atoms, selenium atoms, tellurium atoms, phosphorus atoms, silicon atoms, and boron atoms, with sulfur atoms, oxygen atoms, or nitrogen atoms being preferred. Among these, a phenyl group is preferred as the aromatic ring group. When the aromatic ring group has a substituent, the number of substituents is not particularly limited, but is preferably 1 to 6, and more preferably 1 to 3.

[0038] The aliphatic heterocyclic group in the optionally substituted aliphatic heterocyclic group may be either monocyclic or polycyclic. The number of ring members in the aliphatic heterocyclic group is preferably 3 to 20, more preferably 3 to 10, and even more preferably 3 to 6. The number of carbon atoms in the optionally substituted aliphatic heterocyclic group (the number of carbon atoms including the carbon atoms in the substituent) is preferably 1 to 30, more preferably 3 to 20, and even more preferably 4 to 10. Examples of heteroatoms contained in the aliphatic heterocyclic group include sulfur atoms, oxygen atoms, nitrogen atoms, selenium atoms, tellurium atoms, phosphorus atoms, silicon atoms, and boron atoms, with sulfur atoms, oxygen atoms, or nitrogen atoms being preferred. Specific examples of the aliphatic heterocyclic group are as described above, with thiolane ring groups, piperidine ring groups, tetrahydrofuran ring groups, and tetrahydropyran ring groups being preferred. When the aliphatic heterocyclic group has a substituent, the number of substituents is not particularly limited, but is preferably 1 to 4, and more preferably 1 to 3.

[0039] Examples of the substituent that the aliphatic hydrocarbon group, aromatic ring group, and aliphatic heterocyclic group may have include the groups exemplified above as the substituent W, and among these, an alkyl group is preferred. The alkyl group may be linear, branched, or cyclic. The alkyl group preferably has 1 to 10 carbon atoms, more preferably 1 to 6, and even more preferably 1 to 3 carbon atoms.

[0040] R Ｙ１ and R Ｙ２ The ring formed by bonding together may be either an aromatic ring or an alicyclic structure, but an alicyclic structure is preferred. Ｙ１ and R Ｙ２ Examples of the ring formed by bonding together include a cyclopentane ring, a cyclohexane ring, and a fluorene ring.

[0041] In formula (1), A １ represents a monocyclic aromatic ring which may have a substituent, provided that X １ and X ２ When both of them represent -C(Rx)=, A １ represents a nitrogen-containing 6-membered aromatic ring which may have a substituent. １The monocyclic aromatic ring in the monocyclic aromatic ring which may have a substituent represented by the following formula (I) may be either an aromatic hydrocarbon ring or an aromatic heterocycle, but is preferably an aromatic hydrocarbon ring. １ The number of ring members of the monocyclic aromatic ring represented by the formula (I) is not particularly limited, but is preferably 5 to 15, and more preferably 5 to 10.

[0042] Examples of the aromatic hydrocarbon ring include a benzene ring. The number of heteroatoms contained as ring member atoms in the aromatic heterocycle is preferably 1 to 5, and more preferably 1 or 2. Examples of the heteroatoms 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 heterocycle include a pyridine ring, a pyrimidine ring, a pyridazine ring, a pyrazine ring, a triazine ring (e.g., a 1,2,3-triazine ring, a 1,2,4-triazine ring, and a 1,3,5-triazine ring), a tetrazine ring (e.g., a 1,2,4,5-tetrazine ring), a pyrrole ring, a furan ring, a thiophene ring, an imidazole ring, an oxazole ring, and a thiazole ring. The nitrogen-containing 6-membered aromatic ring means a 6-membered aromatic ring containing a nitrogen atom. Examples of the nitrogen-containing 6-membered aromatic ring include, among the above-mentioned aromatic heterocycles, a pyridine ring, a pyrimidine ring, and a pyrazine ring. A １ Among these, a benzene ring, a pyridine ring, a pyrazine ring, a pyrimidine ring, and a thiophene ring are preferred as the monocyclic aromatic ring represented by the formula:

[0043] A １Examples of the substituent that the monocyclic aromatic ring represented by the formula (I) may have include the substituents exemplified for the substituent W described above, and among these, a halogen atom, an alkyl group, an alkoxy group, or a monocyclic aromatic ring group that may further have a substituent is preferred. The halogen atom is preferably a chlorine atom. The alkyl group may be linear, branched, or cyclic. The number of carbon atoms in the alkyl group is preferably 1 to 10, more preferably 1 to 6, and even more preferably 1 to 3. The alkoxy group is preferably an alkoxy group in which the alkyl group moiety is the above-mentioned alkyl group. The monocyclic aromatic ring group that may further have a substituent is preferably a phenyl group that may have an alkyl group having 1 to 3 carbon atoms.

[0044] In formula (1), A represents a group represented by formula (A-1) or formula (A-2). Formula (A-1) and formula (A-2) will be described in detail later.

[0045] In terms of achieving better effects of the present invention, the compound represented by the formula (1) is preferably a compound represented by the formula (2).

[0046]

[0047] In formula (2), R １ , R ２ , R ３ , Y １ and A is R in formula (1). １ , R ２ , R ３ , Y １ and A. ４ and R ５ Each of X independently represents a hydrogen atom or a substituent. １ represents a nitrogen atom. ２ ~X ４ each independently represents a nitrogen atom or —C(Rx)═, where Rx represents a hydrogen atom or a substituent.

[0048] R specified in formula (2) １ , R ２ , R ３ , Y １ and A is R in formula (1). １ , R ２ , R３ , Y １ and A, and the preferred embodiments thereof are also the same.

[0049] In formula (2), R ４ and R ５ R each independently represents a hydrogen atom or a substituent. ４ and R ５ As the substituent, a hydrogen atom is preferred. １ Among these, a halogen atom, an alkyl group, an alkoxy group, or a monocyclic aromatic ring group which may further have a substituent is preferred. Preferred embodiments of the halogen atom, the alkyl group, the alkoxy group, and the monocyclic aromatic ring group which may further have a substituent are as described above.

[0050] In formula (2), X １ represents a nitrogen atom, and X ２ ~X ４ Each of X independently represents a nitrogen atom or -C(Rx)=. Rx represents a hydrogen atom or a substituent. Rx is preferably a hydrogen atom. ２ In the preferred embodiment, X in formula (1) ２ The preferred embodiments are the same as those of X. ３ is preferably -C(Rx)=, and X ４ It is preferable that Rx represents -C(Rx)=. Specific and preferred embodiments of the substituent represented by Rx are the same as the specific and preferred embodiments of the substituent represented by Rx in formula (1).

[0051] In formula (1) and formula (2), A represents a group represented by formula (A-1) or formula (A-2). In terms of achieving better effects of the present invention, A preferably represents a group represented by formula (A-1). The group represented by formula (A-1) or formula (A-2) will be described in detail below.

[0052]

[0053] In formula (A-1), B １ represents a ring containing two or more carbon atoms and which may have a substituent.１ represents an oxygen atom, a sulfur atom, and ═NR Ｚ１ or = C(R Ｚ２ ) (R Ｚ３ ) represents. Ｚ１ represents a hydrogen atom or a substituent. Ｚ２ and R Ｚ３ each independently represents a cyano group, —SO ２ R Ｚ４ , -COOR Ｚ５ , or -COR Ｚ６ Represents R Ｚ４ ~R Ｚ６ each independently represents an aliphatic hydrocarbon group which may have a substituent, an aromatic ring group which may have a substituent, or an aliphatic heterocyclic group which may have a substituent.

[0054] In formula (A-1), B １ represents a ring containing two or more carbon atoms and which may have a substituent. １ The two carbon atoms contained in are the two carbon atoms specified in formula (A-1). The number of carbon atoms in the ring is preferably 3 to 30, more preferably 3 to 20, and even more preferably 3 to 10. The number of carbon atoms in the ring is the number including the two carbon atoms specified in the formula. The ring may be either an aromatic ring or a non-aromatic ring. The ring may be either a monocyclic or polycyclic ring, and is preferably a 5-membered ring, a 6-membered ring, or a fused ring containing at least one of a 5-membered ring and a 6-membered ring. The number of carbon atoms in the fused ring containing at least one of a 5-membered ring and a 6-membered ring is preferably 6 to 20, more preferably 6 to 15, and even more preferably 8 to 10.

[0055] The ring may have a heteroatom. 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, and a sulfur atom, a nitrogen atom, or an oxygen atom is preferred. The number of heteroatoms in the ring is preferably 0 to 10, and more preferably 0 to 5. １ Among the carbon atoms constituting the ring represented by the formula (A-1), the carbon atom at the bonding position marked with * and Z １Carbon atoms other than the carbon atom bonded to may be substituted with a carbonyl carbon (>C=O) or a thiocarbonyl carbon (>C=S).

[0056] Above B １The ring represented by the formula (I) is preferably a ring used as an acidic nucleus (for example, the acidic nucleus in a merocyanine dye), and examples thereof include the following nuclei: (a) 1,3-dicarbonyl nucleus: for example, a 1,3-indandione nucleus, 1,3-cyclohexanedione, 5,5-dimethyl-1,3-cyclohexanedione, and 1,3-dioxane-4,6-dione; (b) pyrazolinone nucleus: for example, 1-phenyl-2-pyrazolin-5-one, 3-methyl-1-phenyl-2-pyrazolin-5-one, and 1-(2-benzothiazolyl)-3-methyl-2-pyrazolin-5-one; (c) isoxazolinone nucleus: for example, 3-phenyl-2-isoxazolin-5-one and 3-methyl-2-isoxazolin-5-one; (d) oxindole nucleus: for example, 1-alkyl-2,3-dihydro-2-oxindole; (e) 2,4,6-trioxohexahydropyrimidine nucleus: for example, barbituric acid, 2-thiobarbituric acid, and derivatives thereof. Examples of the derivatives include 1-alkyl compounds such as 1-methyl and 1-ethyl, 1,3-dialkyl compounds such as 1,3-dimethyl, 1,3-diethyl, and 1,3-dibutyl, 1,3-diaryl compounds such as 1,3-diphenyl, 1,3-di(p-chlorophenyl), and 1,3-di(p-ethoxycarbonylphenyl), 1-alkyl-1-aryl compounds such as 1-ethyl-3-phenyl, and 1,3-diheteroaryl compounds such as 1,3-di(2-pyridyl). (f) 2-thio-2,4-thiazolidinedione nucleus: for example, rhodanine and derivatives thereof. Examples of the derivatives include 3-alkylrhodanines such as 3-methylrhodanine, 3-ethylrhodanine, and 3-allylrhodanine, 3-arylrhodanines such as 3-phenylrhodanine, and 3-heteroarylrhodanines such as 3-(2-pyridyl)rhodanine. (g) 2-thio-2,4-oxazolidinedione nucleus (2-thio-2,4-(3H,5H)-oxazoledione nucleus): for example, 3-ethyl-2-thio-2,4-oxazolidinedione. (h) thianaphthenone nucleus: for example, 3(2H)-thianaphthenone-1,1-dioxide. (i) 2-thio-2,5-thiazolidinedione nucleus: for example, 3-ethyl-2-thio-2,5-thiazolidinedione.(j) 2,4-thiazolidinedione nucleus: for example, 2,4-thiazolidinedione, 3-ethyl-2,4-thiazolidinedione, and 3-phenyl-2,4-thiazolidinedione. (k) thiazolin-4-one nucleus: for example, 4-thiazolinone and 2-ethyl-4-thiazolinone. (l) 2,4-imidazolidinedione (hydantoin) nucleus: for example, 2,4-imidazolidinedione and 3-ethyl-2,4-imidazolidinedione. (m) 2-thio-2,4-imidazolidinedione (2-thiohydantoin) nucleus: for example, 2-thio-2,4-imidazolidinedione and 3-ethyl-2-thio-2,4-imidazolidinedione. (n) Imidazolin-5-one nucleus: for example, 2-propylmercapto-2-imidazolin-5-one, etc. (o) 3,5-pyrazolidinedione nucleus: for example, 1,2-diphenyl-3,5-pyrazolidinedione and 1,2-dimethyl-3,5-pyrazolidinedione, etc. (p) Benzothiophen-3(2H)-one nucleus: for example, benzothiophen-3(2H)-one, oxobenzothiophen-3(2H)-one, and dioxobenzothiophen-3(2H)-one, etc. (q) Indanone nucleus: for example, 1-indanone, 3-phenyl-1-indanone, 3-methyl-1-indanone, 3,3-diphenyl-1-indanone, and 3,3-dimethyl-1-indanone, etc. (r) Benzofuran-3-(2H)-one nucleus: for example, benzofuran-3-(2H)-one, etc. (s) 2,2-dihydrophenalene-1,3-dione nucleus, etc.

[0057] In formula (A-1), Z １ represents an oxygen atom, a sulfur atom, and ═NR Ｚ１ or = C(R Ｚ２ ) (R Ｚ３ ) represents Z. １ is an oxygen atom or ═C(R Ｚ２ ) (R Ｚ３ ) is preferred, and an oxygen atom is more preferred. Ｚ１ represents a hydrogen atom or a substituent. Examples of the substituent include the substituents exemplified above for the substituent W. Ｚ２ and R Ｚ３ each independently represents a cyano group, —SO ２ RＺ４ , -COOR Ｚ５ , or -COR Ｚ６ Represents R Ｚ２ and R Ｚ３ A cyano group is preferred as R Ｚ４ ~R Ｚ６ R each independently represent an aliphatic hydrocarbon group which may have a substituent, an aromatic ring group which may have a substituent, or an aliphatic heterocyclic group which may have a substituent. The aliphatic hydrocarbon group is defined as above, and an aliphatic hydrocarbon group having 1 to 3 carbon atoms is preferred. The aromatic ring group is defined as above, and an aromatic hydrocarbon group is preferred, and a phenyl group is more preferred. The aliphatic heterocyclic group is defined as above, and the heteroatom contained in the aliphatic heterocyclic group is preferably an oxygen atom, a sulfur atom, or a nitrogen atom. R Ｚ４ ~R Ｚ６ Examples of the substituent that each group represented by the following formula may have include the substituents exemplified for the substituent W above.

[0058] In formula (A-2), R ａ１ and R ａ２ each independently represents a cyano group, —SO ２ R ｂ１ , -COOR ｂ２ , or -COR ｂ３ Represents R ａ１ and R ａ２ is a cyano group or -COR ｂ３ is preferred. ｂ１ , R ｂ２ and R ｂ３ R each independently represents an aliphatic hydrocarbon group which may have a substituent, an aromatic ring group which may have a substituent, or an aliphatic heterocyclic group which may have a substituent. ｂ１ , R ｂ２ and R ｂ３ The definitions and preferred embodiments of each group represented by R Ｚ４ ~R Ｚ６ Among these, an aliphatic hydrocarbon group having 1 to 4 carbon atoms or a phenyl group is preferred.

[0059] In formula (1) and formula (2), A is preferably a group represented by formula (A-3) or formula (A-4) in that the effects of the present invention are more excellent.

[0060]

[0061] In formula (A-3), D １ represents an aromatic ring which may have a substituent. The aromatic ring may be either a monocyclic or polycyclic ring. The number of ring members in the aromatic ring is preferably 4 to 30, more preferably 5 to 12, and even more preferably 5 to 8. The number of ring members in the aromatic ring is the number including the two carbon atoms specified in the formula. The aromatic ring may be either an aromatic hydrocarbon ring or an aromatic heterocyclic ring, and an aromatic hydrocarbon ring is preferred. The above D １ The aromatic ring represented by the formula (I) is as described above, and is preferably a benzene ring, a naphthalene ring, an anthracene ring, a pyrene ring, a thiophene ring, a furan ring, a thiazole ring, an oxazole ring, a pyridine ring, a thienothiophene ring, a benzothiophene ring, a benzofuran ring, a pyrazine ring, a pyrimidine ring, a thienothiophene ring, or a pyridazine ring, more preferably a benzene ring, a naphthalene ring, or a thiophene ring, and even more preferably a thiophene ring. Examples of the substituent that the aromatic ring may have include the groups exemplified by the substituent W, and an alkyl group or a halogen atom is preferred. The number of substituents that the aromatic ring may have is not particularly limited, but is preferably 0 to 8, and more preferably 0 to 4.

[0062] In formula (A-3), Z １ and Z ２ each independently represents an oxygen atom, a sulfur atom, or ═NR Ｚ１ or = C(R Ｚ２ ) (R Ｚ３ ) is represented. In terms of the effects of the present invention being more excellent, Z １ and Z ２ each independently represents an oxygen atom or ═C(R Ｚ２ ) (R Ｚ３ ) is preferably Z １ and Z ２ One of the groups represents an oxygen atom, and the other group represents an oxygen atom or ═C(R Ｚ２ ) (R Ｚ３) is more preferable. Ｚ１ , R Ｚ２ and R Ｚ３ represents R in formula (A-1). Ｚ１ , R Ｚ２ and R Ｚ３ The same applies to preferred embodiments.

[0063] In formula (A-4), Z ３ ~Z ５ each independently represents an oxygen atom, a sulfur atom, or ═NR Ｚ１ or = C(R Ｚ２ ) (R Ｚ３ ) is represented. In terms of the effects of the present invention being more excellent, Z ３ and Z ５ is preferably an oxygen atom, and Z ３ ~Z ５ It is more preferable that R is an oxygen atom. Ｚ１ , R Ｚ２ and R Ｚ３ represents R in formula (A-1). Ｚ１ , R Ｚ２ and R Ｚ３ The same applies to preferred embodiments.

[0064] In formula (A-4), R ｃ１ and R ｃ２ R each independently represents a hydrogen atom, an optionally substituted aliphatic hydrocarbon group, an optionally substituted aromatic ring group, or an optionally substituted aliphatic heterocyclic group. ｃ１ and R ｃ２ Among these, an alkyl group or an aryl group is preferred, and an alkyl group is more preferred. The alkyl group may be linear, branched, or cyclic, and a linear group is preferred. The alkyl group preferably has 1 to 20 carbon atoms, more preferably 1 to 6, even more preferably 1 to 3, and particularly preferably 1 or 2. The aryl group may be monocyclic or polycyclic, and a phenyl group is preferred. The aryl group may further have a substituent, and examples of the substituent include the groups exemplified for the substituent W above.

[0065] In formula (1) and formula (2), A more preferably represents a group represented by formula (A-5) in that the effects of the present invention are more excellent.

[0066]

[0067] In formula (A-5), X ５ and X ７ One of the groups represents an oxygen atom or a sulfur atom, and the other represents a nitrogen atom or -C(Rx)=. ６ represents -C(Rx)= or a nitrogen atom. Rx represents a hydrogen atom or a substituent, and is preferably a hydrogen atom. X ５ preferably represents -C(Rx)=, and X ７ preferably represents a sulfur atom. ６ It is preferable that X represents -C(Rx)=. ５ and X ６ When X represents -C(Rx)=, Rx's may be bonded to each other to form a ring. ６ and X ７ When represents -C(Rx)=, Rx's may be bonded to each other to form a ring. Examples of the ring formed by bonding Rx's to each other include aromatic rings, and among these, a benzene ring is preferable.

[0068] In formula (A-5), Z １ is a sulfur atom, =NR Ｚ１ or = C(R Ｚ２ ) (R Ｚ３ ) and =C(R Ｚ２ ) (R Ｚ３ ) is preferred. Ｚ１ , R Ｚ２ and R Ｚ３ represents R in formula (A-1). Ｚ１ , R Ｚ２ and R Ｚ３ The same applies to preferred embodiments. Ｚ２ and R Ｚ３ Among these, a cyano group is preferred.

[0069] Specific examples of the specific compound are shown below, but the present invention is not limited to these.

[0070]

[0071]

[0072]

[0073]

[0074] In the specific compounds exemplified above, A represents any of the following groups.

[0075]

[0076]

[0077]

[0078]

[0079]

[0080]

[0081]

[0082] The molecular weight of the specific compound is preferably 400 to 1200, more preferably 400 to 1000, and even more preferably 400 to 800. When the molecular weight is within the above range, the sublimation temperature of the specific compound is lowered, and it is presumed that the specific compound has excellent suitability for production.

[0083] The specific compound preferably has an ionization potential of −5.0 to −6.0 eV in a single film from the viewpoints of stability when used as a p-type organic semiconductor and matching of the energy level with an n-type organic semiconductor.

[0084] The maximum absorption wavelength of the specific compound is preferably in the wavelength range of 400 to 550 nm, more preferably in the range of 400 to 500 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 insoluble in chloroform, the maximum absorption wavelength of the specific compound is determined by evaporating the specific compound and measuring the value using the specific compound in a film state.

[0085] The specific compound is particularly useful as a material for a photoelectric conversion film used in an imaging device, an optical sensor, or a photovoltaic cell. The specific compound often functions as a dye in the photoelectric conversion film. The specific compound can also be used as a coloring material, a liquid crystal material, an organic semiconductor material, a charge transport material, a pharmaceutical material, and a fluorescent diagnostic material.

[0086] The specific compound may be purified as 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, and purification using an adsorbent such as activated carbon and recrystallization purification.

[0087] 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 not particularly limited, but is preferably 15 to 75% by volume, more preferably 20 to 60% by volume, and even more preferably 20 to 50% by volume. Only one type of specific compound may be used, or two or more types may be used. When two or more types are used, it is preferable that the total amount thereof is in the above range.

[0088] <n-Type Organic Semiconductor> The photoelectric conversion film preferably further contains an n-type organic semiconductor in addition to the specific compound. The n-type organic semiconductor is a compound different from the specific compound. The n-type organic semiconductor is an acceptor organic semiconductor material (compound) and refers to an organic compound that has the property of easily accepting electrons. In other words, the n-type organic semiconductor refers to the organic compound that has a larger electron affinity when two organic compounds are used in contact with each other. In other words, any organic compound can be used as the acceptor organic semiconductor as long as it is an organic compound with electron-accepting properties. Examples of n-type organic semiconductors include fullerenes selected from the group consisting of fullerenes and derivatives thereof; fused aromatic carbocyclic compounds (e.g., naphthalene derivatives, anthracene derivatives, phenanthrene derivatives, tetracene derivatives, pyrene derivatives, perylene derivatives, and fluoranthene derivatives); and 5- to 7-membered heterocyclic compounds having at least one atom 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, pyrazole, imidazole, and thiazole). polyarylene compounds; fluorene compounds; cyclopentadiene compounds; silyl compounds; 1,4,5,8-naphthalenetetracarboxylic acid anhydride; 1,4,5,8-naphthalenetetracarboxylic acid diimide 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; 3,4,9,10-perylenetetracarboxylic acid dianhydride; 3,4,9,10-perylenetetracarboxylic acid diimide derivatives; and the compounds described in paragraphs

[0056] to

[0057] of JP-A No. 2006-100767.

[0089] As the n-type organic semiconductor (compound), fullerenes selected from the group consisting of fullerenes and derivatives thereof are preferred. For example, fullerene C ６０ , fullerene C ７０, fullerene C ７６ , fullerene C ７８ , fullerene C ８０ , fullerene C ８２ , fullerene C ８４ , fullerene C ９０ , fullerene C ９６ , fullerene C ２４０ , fullerene C ５４０ and mixed fullerenes. Examples of fullerene derivatives include compounds in which a substituent is added to the above-mentioned fullerenes. 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.

[0090] The n-type organic semiconductor may be an organic dye. Examples of the organic dye include cyanine dyes, styryl dyes, hemicyanine dyes, merocyanine dyes (including zeromethine merocyanine (simple merocyanine)), rhodacyanine dyes, allopolar dyes, oxonol dyes, hemioxonol dyes, squarylium 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.

[0091] The molecular weight of the n-type organic semiconductor is preferably 200 to 1,200, more preferably 200 to 900.

[0092] The maximum absorption wavelength of the n-type organic semiconductor is preferably 400 nm or less, or in the range of more than 400 nm and 600 nm or less.

[0093] The photoelectric conversion film preferably has a bulk heterostructure formed by mixing a specific compound and an n-type organic semiconductor. The bulk heterostructure is a layer in the photoelectric conversion film in which the specific compound and the n-type organic semiconductor are mixed and dispersed. The photoelectric conversion film having a bulk heterostructure can be formed by either a wet method or a dry method. The bulk heterostructure is described in detail in paragraphs

[0013] to

[0014] of JP 2005-303266 A.

[0094] The difference in electron affinity between the specific compound and the n-type organic semiconductor is preferably 0.1 eV or more.

[0095] When the photoelectric conversion film contains an n-type organic semiconductor, the content of the n-type organic semiconductor in the photoelectric conversion film (thickness of the n-type organic semiconductor in terms of a single layer / thickness of the photoelectric conversion film × 100) is preferably 15 to 75 vol%, more preferably 20 to 60 vol%, and still more preferably 20 to 50 vol%.

[0096] When the n-type organic semiconductor contains fullerenes, the content of the fullerenes relative to the total content of the n-type organic semiconductors (film thickness of fullerenes converted into a single layer / total film thickness of each n-type organic semiconductor 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.

[0097] In terms 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 in monolayer equivalent of the specific compound / (film thickness in monolayer equivalent of the specific compound + film thickness in monolayer equivalent of the n-type organic semiconductor) x 100) is preferably 20 to 80% by volume, more preferably 40 to 80% by volume. 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 in monolayer equivalent of the specific compound / (film thickness in monolayer equivalent of the specific compound + film thickness in monolayer equivalent of the n-type organic semiconductor + film thickness in monolayer equivalent of the p-type organic semiconductor) x 100) is preferably 15 to 75% by volume, more preferably 30 to 75% by volume. It is preferable that the photoelectric conversion film is substantially composed of the specific compound, the n-type organic semiconductor, and a p-type organic semiconductor that is included as desired. "Substantially" means that the total content of the specific compound, n-type organic semiconductor, and p-type organic semiconductor relative to the total mass of the photoelectric conversion film is 90 to 100% by volume, preferably 95 to 100% by volume, and more preferably 99 to 100% by volume.

[0098] <p-Type Organic Semiconductor> The photoelectric conversion film preferably further contains a p-type organic semiconductor in addition to the specific compound. The p-type organic semiconductor is a compound different from the specific compound. The p-type organic semiconductor is a donor organic semiconductor material (compound) and refers to an organic compound that has the property of easily donating electrons. In other words, the p-type organic semiconductor refers to the organic compound that has a 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 types.

[0099] Examples of p-type organic semiconductors include triarylamine compounds (e.g., N,N'-diphenyl-N,N'-bis(3-methylphenyl)-(1,1'-biphenyl)-4,4'-diamine (TPD), 4,4'-bis[N-(naphthyl)-N-phenyl-amino]biphenyl (α-NPD), compounds described in paragraphs

[0128] to

[0148] of JP-A No. 2011-228614, compounds described in paragraphs

[0052] to

[0063] of JP-A No. 2011-176259, compounds described in paragraphs

[0119] to

[0158] of JP-A No. 2011-225544, compounds, compounds described in paragraphs

[0044] to

[0051] of JP-A No. 2015-153910 and compounds described in paragraphs

[0086] to

[0090] of JP-A No. 2012-094660, 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][1]benzothiophene (BTBT) derivatives, thieno[3,2-f:4,5-f']bis[1]benzthiophene benzothiophene (TBBT) derivatives, compounds described in paragraphs

[0031] to

[0036] of JP 2018-014474 A, compounds described in paragraphs

[0043] to

[0045] of WO 2016 / 194630 A, compounds described in paragraphs

[0025] to

[0037] and

[0099] to

[0109] of WO 2017 / 159684 A, compounds described in paragraphs

[0029] to

[0034] of JP 2017-076766 A, compounds described in paragraphs

[0015] to

[0025] of WO 2018 / 207722 A, compounds described in paragraph [004 5] to

[0053] , compounds described in paragraphs

[0045] to

[0055] of WO2019 / 058995, compounds described in paragraphs

[0063] to

[0089] of WO2019 / 081416, compounds described in paragraphs

[0033] to

[0036] of JP2019-080052A, compounds described in paragraphs

[0044] to

[0054] of WO2019 / 054125, compounds described in paragraphs

[0041] to

[0046] of WO2019 / 093188, compounds described in paragraphs

[0034] to

[0037] of JP2019-050398A,The compounds described in paragraphs

[0033] to

[0036] of JP-A No. 2018-206878, the compounds described in paragraph

[0038] of JP-A No. 2018-190755, the compounds described in paragraphs

[0019] to

[0021] of JP-A No. 2018-026559, the compounds described in paragraphs

[0031] to

[0056] of JP-A No. 2018-170487, the compounds described in paragraphs

[0036] to

[0041] of JP-A No. 2018-16620 Compounds described in paragraphs

[0055] to

[0082] of JP-A No. 2018-113425, compounds described in paragraphs

[0041] to

[0050] of JP-A No. 2018-113425, compounds described in paragraphs

[0044] to

[0048] of JP-A No. 2018-085430, compounds described in paragraphs

[0041] to

[0045] of JP-A No. 2018-056546, compounds described in paragraphs

[0042] to

[0049] of JP-A No. 2018-046267, compounds described in paragraphs

[0043] to

[0044] of JP-A No. 2018-014474 Compounds described in paragraphs

[0031] to

[0036] of WO2018 / 016465, compounds described in paragraphs

[0036] to

[0046] of JP2020-016465A, compounds described in paragraphs

[0045] to

[0048] of JP2020-010024A, etc.), cyanine compounds, oxonol compounds, polyamine compounds, indole compounds, pyrrole compounds, pyrazole compounds, polyarylene compounds, fused aromatic carbocyclic compounds (e.g., naphthalene derivatives, 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. As p-type organic semiconductors, in addition to the above-mentioned compounds, JP 2021-163968 A, JP 2022-027575 A, JP 2022-123944 A, JP 2022-122839 A, JP 2022-120323 A, JP 2022-120273 A, JP 2022-115832 A, JP 2022-108268 A, JP 2022-100258 A,Compounds described in JP-A Nos. 2022-181226 and 2023-005703 can also be used, and these compounds are incorporated herein by reference. Examples of p-type organic semiconductors include compounds with 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 listed below.

[0100]

[0101]

[0102]

[0103]

[0104] The difference in ionization potential between the specific compound and the p-type organic semiconductor is preferably 0.1 eV or more.

[0105] When the photoelectric conversion film contains a p-type organic semiconductor, the content of the p-type organic semiconductor in the photoelectric conversion film (thickness of the p-type organic semiconductor in terms of a single layer / 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%.

[0106] The photoelectric conversion film containing the specific compound is a non-luminescent film and has characteristics different from those of an organic electroluminescent device (OLED: Organic Light Emitting Diode). A non-luminescent film means a film having a luminescence quantum efficiency of 1% or less, preferably 0.5% or less, more preferably 0.1% or less. The lower limit is often 0% or more.

[0107] <Dye> The photoelectric conversion film may further contain a dye in addition to the specific compound. The dye is a compound different from the specific compound. The dye is preferably an organic dye. Examples of the organic dye include cyanine dyes, styryl dyes, hemicyanine dyes, merocyanine dyes (including zeromethine merocyanine (simple merocyanine)), rhodacyanine dyes, allopolar dyes, oxonol dyes, hemioxonol dyes, squarylium 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, Examples of the organic dye include acridinone dyes, diphenylamine dyes, quinophthalone dyes, phenoxazine dyes, phthaloperylene dyes, dioxane dyes, porphyrin dyes, chlorophyll dyes, phthalocyanine dyes, subphthalocyanine dyes and metal complex dyes, imidazoquinoxaline dyes described in WO 2020 / 013246, WO 2022 / 168856, JP 2023-10305 A, and JP 2023-10299 A, acceptor-donor-acceptor type dyes in which two acidic nuclei are bonded to a donor, and donor-acceptor-donor type dyes in which two donors are bonded to an acceptor. Among these, cyanine dyes, imidazoquinoxaline dyes, or acceptor-donor-acceptor type dyes are preferred as organic dyes, as they have a maximum absorption wavelength in the preferred range described below.

[0108] The maximum absorption wavelength of the dye is preferably in the visible light region, more preferably from 400 to 700 nm, and even more preferably from 400 to 650 nm.

[0109] The content of the dye in the photoelectric conversion film relative to the total content of the specific compound and the dye (=(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 20 to 50 vol%.

[0110] <Film formation method> Examples of the film formation method for the photoelectric conversion film include dry film formation methods. 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, and vacuum deposition methods are preferred. When forming the photoelectric conversion film by vacuum deposition, manufacturing conditions such as the degree of vacuum and deposition temperature can be set according to conventional methods.

[0111] The thickness of the photoelectric conversion film is preferably from 10 to 1,000 nm, more preferably from 50 to 800 nm, and even more preferably from 50 to 500 nm.

[0112] [Electrodes] The photoelectric conversion element preferably has electrodes. The electrodes (upper electrode (transparent conductive film) 15 and lower electrode (conductive film) 11) are made of a conductive material. Examples of conductive materials include metals, alloys, metal oxides, electrically conductive compounds, and mixtures thereof. Since light is incident through the upper electrode 15, it is preferable that the upper electrode 15 is transparent to the light to be detected. Examples of materials constituting the upper electrode 15 include conductive metal oxides such as tin oxide doped with antimony or fluorine (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); thin metal films such as gold, silver, chromium, and nickel; mixtures or laminates of these metals and conductive metal oxides; and organic conductive materials such as polyaniline, polythiophene, and polypyrrole; and nanocarbon materials such as carbon nanotubes and graphene. Of these, conductive metal oxides are preferred in terms of high conductivity and transparency.

[0113] Typically, when the conductive film is made thinner than a certain range, the resistance value often increases rapidly. 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 wide degree of freedom in the range of film thickness that can be reduced. Furthermore, the thinner the film thickness of 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 desirable 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 reduction in film thickness, the thickness of the upper electrode 15 is preferably 5 to 100 nm, and more preferably 5 to 20 nm.

[0114] Depending on the application, the lower electrode 11 may be made transparent or may be made non-transparent and reflect light. Examples of materials constituting the lower electrode 11 include conductive metal oxides such as tin oxide (ATO, FTO) doped with antimony or fluorine, etc., 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; organic conductive materials such as polyaniline, polythiophene, and polypyrrole; and carbon materials such as carbon nanotubes and granphenes.

[0115] The method for forming the electrodes can be appropriately selected depending on the electrode material. 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, examples include electron beam methods, sputtering, resistance heating deposition, chemical reaction methods (such as the sol-gel method), and coating of a dispersion of indium tin oxide.

[0116] [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. Examples of the intermediate layer include a charge-blocking film. When the photoelectric conversion element has this film, the properties (quantum efficiency, response speed, etc.) of the resulting photoelectric conversion element are more excellent. Examples of the charge-blocking film include an electron-blocking film and a hole-blocking film.

[0117] [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. Polymer materials can also be used as the electron blocking film. Examples of polymer materials include polymers of phenylene vinylene, fluorene, carbazole, indole, pyrene, pyrrole, picoline, thiophene, acetylene, diacetylene, and the like, and derivatives thereof.

[0118] The electron blocking film may be composed of multiple films. The electron blocking film may be composed of an inorganic material. In general, 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 quantum 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.

[0119] [Hole-Blocking Film] The hole-blocking film is an acceptor organic semiconductor material (compound), and the n-type organic semiconductors described above can be used. The hole-blocking film may be composed of multiple films.

[0120] Examples of methods for producing a charge blocking film include dry film formation and wet film formation. Examples of dry film formation include vapor deposition and sputtering. Vapor deposition may be either physical vapor deposition (PVD) or chemical vapor deposition (CVD), with physical vapor deposition such as vacuum deposition being preferred. Examples of wet film formation include inkjet printing, spray printing, nozzle printing, spin coating, dip coating, casting, die coating, roll coating, bar coating, and gravure coating, with the inkjet method being preferred in terms of high-precision patterning.

[0121] The thickness of each of the charge blocking films (electron blocking film and hole blocking film) is preferably from 3 to 200 nm, more preferably from 5 to 100 nm, and even more preferably from 5 to 30 nm.

[0122] [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 stacked in this order on the substrate.

[0123] [Sealing Layer] The photoelectric conversion element may further have a sealing layer. The performance of photoelectric conversion materials may be significantly degraded in the presence of degrading factors such as water molecules. Therefore, the degradation can be prevented by covering and sealing the entire photoelectric conversion film with a sealing layer made of a ceramic such as a dense metal oxide, metal nitride, or metal nitride oxide, or diamond-like carbon (DLC), which does not allow water molecules to penetrate. Examples of sealing layers include those described in paragraphs

[0210] to

[0215] of JP 2011-082508 A, the contents of which are incorporated herein by reference.

[0124] [Method for manufacturing photoelectric conversion element] Examples of methods for manufacturing photoelectric conversion elements include known manufacturing methods. Specifically, for example, a method for manufacturing a photoelectric conversion element includes a step of forming a conductive film on a substrate, a step of forming a photoelectric conversion film, and a step of forming a transparent conductive film. The method for manufacturing a photoelectric conversion element may include other steps (for example, a step of forming a charge blocking film and a step of forming a sealing layer) in addition to the above. The method for forming each layer is as described above.

[0125] [Imaging element] An example of an application of a photoelectric conversion element is an imaging element. 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. For this reason, each pixel is composed of one or more photoelectric conversion elements and one or more transistors. The manufacturing method of an imaging element is not particularly limited, but examples include a method including the step of manufacturing the photoelectric conversion element described above.

[0126] [Optical Sensor] Other applications 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.

[0127] [Compound] The present invention also includes the invention of a compound. The compound of the present invention is the above-mentioned specific compound.

[0128] The present invention will be described in more detail below with reference to the following examples. The materials, amounts used, ratios, treatment details, treatment procedures, etc. shown in the following examples can be changed as appropriate without departing from the spirit of the present invention. Therefore, the scope of the present invention should not be construed as being limited by the following examples.

[0129] [Compounds used in photoelectric conversion film] The materials used in the photoelectric conversion film are shown below.

[0130] [Synthesis of Compound (D-1)] Compound (D-1) was synthesized according to the following scheme.

[0131]

[0132] 2.0 mmol of compound (D-1-1), 2.4 mmol of compound (D-1-2), and 14 mL of acetic anhydride were placed in a glass reaction vessel and reacted at 110°C for 4 hours under a nitrogen atmosphere. The precipitated solid was filtered, and the resulting solid was purified by column chromatography (eluted with dichloromethane:ethyl acetate = 95:5). The resulting crude product was purified by sublimation to obtain 1.44 mmol of compound (D-1) (yield 72%). Since compound (D-1) has low solubility, its structure was confirmed by LDI-MS (laser desorption ionization mass spectrometry). The LDI-MS measurement results for compound (D-1) are shown below. Compound (D-1): LDI-MS 481.2 (M ＋ )

[0133] The compounds used in the photoelectric conversion film of each of the Examples and Comparative Examples other than the compound (D-1) were synthesized according to the synthesis method of the compound (D-1).

[0134] [Specific Compounds] The specific compounds used in the photoelectric conversion film and comparative compounds for comparison are shown below. Compounds (D-1) to (D-36) are specific compounds, and compounds (C-1) and (C-2) are comparative compounds.

[0135]

[0136]

[0137]

[0138] [n-type organic semiconductor] Fullerene (C ６０ )

[0139] [p-type organic semiconductor]

[0140]

[0141] [Dye] In Test Y described later, the dye shown below was used.

[0142]

[0143] [Evaluation: Test X] The quantum efficiency, response speed, and stability over time of the photoelectric conversion element when receiving blue light (wavelength 450 nm) were evaluated by the following methods.

[0144] [Fabrication of Photoelectric Conversion Element] A photoelectric conversion element having the configuration shown in FIG. 2 was fabricated using the various components shown above. Here, 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 formed on a glass substrate by sputtering to form a lower electrode 11 (thickness: 30 nm), and compound (EB-1) was further formed on the lower electrode 11 by vacuum heating deposition to form an electron blocking film 16A (thickness: 30 nm). Next, with the glass substrate at room temperature, each specific compound or each comparative compound shown in Tables 1 and 2, and a p-type organic semiconductor and an n-type organic semiconductor (fullerene (C ６０ )) were co-deposited by vacuum deposition to form a film having a thickness of 80 nm in terms of a single layer. This resulted in the formation of a photoelectric conversion film 12 having a bulk heterostructure of 240 nm. 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 deposited on the hole blocking film 16B by sputtering to form an upper electrode 15 (transparent conductive film) (thickness: 10 nm). After a SiO film was formed as a sealing layer on the upper electrode 15 by vacuum deposition, aluminum oxide (Al ２ O ３ The resulting laminate was heated in a glove box at 150° C. for 30 minutes to obtain a photoelectric conversion element.

[0145]

[0146] [Dark Current] The dark current of each of the obtained photoelectric conversion elements was measured by the following method. ５A voltage was applied to the photoelectric conversion element so as to obtain an electric field strength of 50 nA / cm. The current value in a dark place (dark current) was measured. As a result, the dark current was 50 nA / cm for all the photoelectric conversion elements. ２ It was confirmed that the dark current was sufficiently low.

[0147] [Quantum Efficiency] The quantum efficiency of each photoelectric conversion element was measured when blue light was received by the following method. ５ After applying a voltage to achieve an electric field strength of 1000 V / cm, light was irradiated from the upper electrode (transparent conductive film) side to evaluate the quantum efficiency (photoelectric conversion efficiency) at a wavelength of 450 nm, and the quantum efficiency (relative ratio) was calculated according to formula (S1). From the obtained value, the quantum efficiency was evaluated according to the following evaluation criteria. Formula (S1): Quantum efficiency (relative ratio) = (photoelectric conversion efficiency of each photoelectric conversion element) / (photoelectric conversion efficiency of the photoelectric conversion element in Example 1-1)

[0148] A: Quantum efficiency (relative ratio) is 0.95 or more. B: Quantum efficiency (relative ratio) is 0.80 or more and less than 0.95. C: Quantum efficiency (relative ratio) is 0.60 or more and less than 0.80. D: Quantum efficiency (relative ratio) is less than 0.60.

[0149] [Response Speed] The response speed of each photoelectric conversion element when receiving blue light was evaluated by the following method. ５ A voltage was applied so that the intensity was 1000 V / cm. Thereafter, an LED (light emitting diode) was momentarily turned on to irradiate light from the upper electrode (transparent conductive film) side, and the photocurrent at a wavelength of 450 nm at that time was measured with an oscilloscope to measure the rise time from 0% signal intensity to 97% signal intensity, and the relative response speed was calculated according to formula (S2). From the obtained value, the response speed was evaluated according to the following evaluation criteria. Formula (S2): Relative response speed = (rise time of each photoelectric conversion element) / rise time of the photoelectric conversion element of Example 1-1

[0150] A: Relative response speed is less than 1.1 B: Relative response speed is 1.1 or more and less than 1.5 C: Relative response speed is 1.5 or more and less than 2.0 D: Relative response speed is 2.0 or more

[0151] [Stability over time] The stability over time of each photoelectric conversion element was evaluated by the following method. For each photoelectric conversion element prepared according to the procedure in [Preparation of photoelectric conversion element] above, the response speed was measured according to the procedure in [Response speed] above on the day after preparation and one month later, and the stability over time was calculated according to formula (S3). From the obtained values, the stability over time was evaluated according to the following evaluation criteria. Formula (S3): Stability over time = (rise time of each photoelectric conversion element measured one month after preparation) / (rise time of each photoelectric conversion element measured the day after preparation)

[0152] A: Stability over time is less than 1.1 B: Stability over time is 1.1 or more and less than 2.0 C: Stability over time is 2.0 or more

[0153] [Result: Rating X]

[0154] The evaluation results of Test X are shown in Tables 1 and 2 below. In the table, in the "Formula (2)" column, when the specific compound is a compound represented by formula (2), it is marked with "A", and in other cases it is marked with "B". １ = -C(R Ｙ１ ) (R Ｙ２ ) -" column indicates Y for specific compounds. １ But -C(R Ｙ１ ) (R Ｙ２ In the table, "Y" is used to indicate the presence of a γ-α. １ , Y ２ The "= aliphatic hydrocarbon group" column indicates the R Ｙ１ and R Ｙ２ each independently represents an aliphatic hydrocarbon group which may have a substituent, R Ｙ１ and R Ｙ２is represented by "A" when they may be bonded to each other to form a ring, and "B" otherwise. In the table, in the column "A = (A-1)", for a specific compound, "A" is represented when A represents a group represented by formula (A-1), and "B" is represented otherwise. In the table, in the column "A = (A-3) (A-4)", for a specific compound, "A" is represented when A represents a group represented by formula (A-3) or formula (A-4), and "B" is represented otherwise. In the table, in the column "A = (A-5)", for a specific compound, "A" is represented when A represents a group represented by formula (A-5), and "B" is represented otherwise.

[0155]

[0156]

[0157] From the results shown in Tables 1 and 2, it was confirmed that the photoelectric conversion element of the present invention has excellent stability over time in response speed to blue light. From the comparison between Examples 1-11 to 1-18 and Examples 1-23 and 1-24, it was confirmed that, for the specific compound, when the specific compound is a compound represented by formula (2), the quantum efficiency when blue light is received is more excellent. From the comparison between Examples 1-21 and 1-22 and Examples 1-29 and 1-30, it was confirmed that, for the specific compound, １ But -C(R Ｙ１ ) R Ｙ２ It was confirmed that the quantum efficiency when blue light was received was superior when R Ｙ１ and R Ｙ２are each independently an aliphatic hydrocarbon group which may have a substituent, the response speed when blue light is received was confirmed to be better. Comparison of Examples 1-19 and 1-20 with Examples 1-26 and 1-27, etc., confirmed that when A represents a group represented by formula (A-1) in a specific compound, the response speed and the stability of the response speed over time when blue light is received were better. Comparison of Examples 1-11 to 1-20, etc. confirmed that when A represents a group represented by formula (A-3) or formula (A-4) in a specific compound, the response speed when blue light is received was better. Comparison of Examples 1-1 to 1-18, etc. confirmed that when A represents a group represented by formula (A-5) in a specific compound, the quantum efficiency when blue light is received was better.

[0158] [Evaluation: Test Y] Subsequently, a photoelectric conversion element was prepared using a dye other than the specific compound in addition to the specific compound, and the quantum efficiency, response speed, and stability over time of the photoelectric conversion element when receiving blue light (wavelength 450 nm) were evaluated by the following methods.

[0159] [Fabrication of Photoelectric Conversion Device] Each specific compound or each comparative compound shown in Tables 3 and 4, a p-type organic semiconductor, an n-type organic semiconductor (fullerene (C ６０ )) and the dye were co-deposited by a vacuum deposition method in a ratio of compound (specific compound or comparative compound):dye:p-type organic semiconductor:n-type organic semiconductor=1:1:2:2 in terms of a single film, to form a film, thereby forming a photoelectric conversion film, and the other procedures were the same as in Test X, to prepare photoelectric conversion elements in each of the Examples and Comparative Examples.

[0160] [Dark Current] The dark current was measured in the same manner as in Test X. As a result, the dark current was 50 nA / cm in all the photoelectric conversion elements. ２ It was confirmed that the dark current was sufficiently low.

[0161] [Quantum Efficiency] The quantum efficiency of each of the obtained photoelectric conversion elements was measured by the following method. ５After applying a voltage to achieve an electric field strength of 1000 V / cm, light was irradiated from the upper electrode (transparent conductive film) side to evaluate the quantum efficiency (photoelectric conversion efficiency) at a wavelength of 450 nm or 600 nm, and the quantum efficiency (relative ratio) was calculated according to formula (S4). From the obtained values, the quantum efficiency was evaluated according to the following evaluation criteria. Formula (S4): Quantum efficiency (relative ratio) = (quantum efficiency of each photoelectric conversion element at a wavelength of 450 nm or 600 nm) / (quantum efficiency of Example 2-1 at a wavelength of 450 nm or 600 nm)

[0162] The evaluation criteria for quantum efficiency at wavelengths of 450 nm and 600 nm are as follows: A: Quantum efficiency (relative ratio) is 0.95 or more; B: Quantum efficiency (relative ratio) is 0.80 or more and less than 0.95; C: Quantum efficiency (relative ratio) is 0.60 or more and less than 0.80; D: Quantum efficiency (relative ratio) is less than 0.60.

[0163] [Response Speed] The response speed of each of the obtained photoelectric conversion elements was evaluated by the following method. ５ A voltage was applied to the device so that the intensity was 100 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 450 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, and the relative response speed was calculated according to formula (S5). From the obtained value, the response speed was evaluated according to the following evaluation criteria. Formula (S5): Relative response speed = (rise time at a wavelength of 450 nm or 600 nm for each Example or Comparative Example) / (rise time at a wavelength of 450 nm or 600 nm for Example 2-1)

[0164] The evaluation criteria for the response speed at wavelengths of 450 nm and 600 nm are as follows: A: Relative response speed less than 1.1 B: Relative response speed 1.1 or more and less than 1.5 C: Relative response speed 1.5 or more and less than 2.0 D: Relative response speed 2.0 or more

[0165] [Stability over time] The stability over time of each photoelectric conversion element was evaluated by the following method. For each photoelectric conversion element prepared according to the procedure in [Preparation of photoelectric conversion element] in Test Y, the response speed was measured the day after the preparation date and one month later according to the procedure in [Response speed] in Test Y, and the stability over time was calculated according to formula (S6). From the obtained values, the stability over time was evaluated according to the following evaluation criteria. Formula (S6): Stability over time = (rise time of each photoelectric conversion element at a wavelength of 450 nm, measured one month after the element preparation) / (rise time of each photoelectric conversion element at a wavelength of 450 nm, measured the day after the element preparation)

[0166] A: Stability over time is less than 1.1 B: Stability over time is 1.1 or more and less than 2.0 C: Stability over time is 2.0 or more

[0167] Tables 3 and 4 show the evaluation results of Test Y. The notations in Tables 3 and 4 are as described above for the notations in Tables 1 and 2.

[0168]

[0169]

[0170] 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

1. A photoelectric conversion element having a conductive film, a photoelectric conversion film, and a transparent conductive film in this order, wherein the photoelectric conversion film contains a compound represented by formula (1). In formula (1), R １ and R ２ Each independently represents a hydrogen atom or a substituent. ３ represents a hydrogen atom, an aliphatic hydrocarbon group which may have a substituent other than an acid group and a salt thereof, an aromatic ring group which may have a substituent other than an acid group and a salt thereof, or an aliphatic heterocyclic group which may have a substituent other than an acid group and a salt thereof. １ and X ２ Each of Y independently represents a nitrogen atom or -C(Rx)=, where Rx represents a hydrogen atom or a substituent. １ is -C(R Ｙ１ ) (R Ｙ２ )-, an oxygen atom, a sulfur atom, or a selenium atom. Ｙ１ and R Ｙ２ each independently represents an aliphatic hydrocarbon group which may have a substituent, an aromatic ring group which may have a substituent, or an aliphatic heterocyclic group which may have a substituent. Ｙ１ and R Ｙ２ may be bonded to each other to form a ring. １ represents a monocyclic aromatic ring which may have a substituent. １ and X ２ In the case where both of these represent -C(Rx)=, A １ represents a nitrogen-containing 6-membered aromatic ring which may have a substituent. A represents a group represented by formula (A-1) or formula (A-2). In formula (A-1), B １ represents a ring containing two or more carbon atoms and which may have a substituent. １ is an oxygen atom, a sulfur atom, ═NR Ｚ１ Or = C(R Ｚ２ ) (R Ｚ３ ) represents R Ｚ１ represents a hydrogen atom or a substituent. Ｚ２ and R Ｚ３ each independently represents a cyano group, —SO ２ R Ｚ４ , -COOR Ｚ５ , or -COR Ｚ６ Represents R Ｚ４ ~R Ｚ６ each independently represents an aliphatic hydrocarbon group which may have a substituent, an aromatic ring group which may have a substituent, or an aliphatic heterocyclic group which may have a substituent. ａ１ and R ａ２ each independently represents a cyano group, —SO ２ R ｂ１ , -COOR ｂ２ , or -COR ｂ３ Represents R ｂ１ , R ｂ２ and R ｂ３ each independently represents an aliphatic hydrocarbon group which may have a substituent, an aromatic ring group which may have a substituent, or an aliphatic heterocyclic group which may have a substituent. * represents a bonding position.

2. The photoelectric conversion element according to claim 1, wherein the compound represented by formula (1) is a compound represented by formula (2). In formula (2), R １ , R ２ , R ３ , Y １ and A is R in the formula (1). １ , R ２ , R ３ , Y １ and A. ４ and R ５ Each of X independently represents a hydrogen atom or a substituent. １ represents a nitrogen atom. ２ ~X ４ each independently represents a nitrogen atom or -C(Rx)=, where Rx represents a hydrogen atom or a substituent.

3. Y １ But -C(R Ｙ１ ) (R Ｙ２ )-, R Ｙ１ and R Ｙ２ each independently represents an aliphatic hydrocarbon group which may have a substituent, an aromatic ring group which may have a substituent, or an aliphatic heterocyclic group which may have a substituent; R Ｙ１ and R Ｙ２ The photoelectric conversion element according to claim 1 , wherein:

4. R Ｙ１ and R Ｙ２ each independently represents an aliphatic hydrocarbon group which may have a substituent; R Ｙ１ and R Ｙ２ The photoelectric conversion element according to claim 3 , wherein:

5. The photoelectric conversion element according to claim 1, wherein A represents a group represented by formula (A-1).

6. The photoelectric conversion element according to claim 1, wherein A represents a group represented by formula (A-3) or formula (A-4). In formula (A-3), D １ represents an aromatic ring which may have a substituent. １ and Z ２ each independently represents an oxygen atom, a sulfur atom, or ═NR Ｚ１ Or = C(R Ｚ２ ) (R Ｚ３ ) represents R Ｚ１ represents a hydrogen atom or a substituent. Ｚ２ and R Ｚ３ each independently represents a cyano group, —SO ２ R Ｚ４ , -COOR Ｚ５ , or -COR Ｚ６ Represents R Ｚ４ ~R Ｚ６ each independently represents an aliphatic hydrocarbon group which may have a substituent, an aromatic ring group which may have a substituent, or an aliphatic heterocyclic group which may have a substituent. ３ ~Z ５ each independently represents an oxygen atom, a sulfur atom, or ═NR Ｚ１ Or = C(R Ｚ２ ) (R Ｚ３ ) represents R Ｚ１ represents a hydrogen atom or a substituent. Ｚ２ and R Ｚ３ each independently represents a cyano group, —SO ２ R Ｚ４ , -COOR Ｚ５ , or -COR Ｚ６ Represents R Ｚ４ ~R Ｚ６ R each independently represents an aliphatic hydrocarbon group which may have a substituent, an aromatic ring group which may have a substituent, or an aliphatic heterocyclic group which may have a substituent. ｃ１ and R ｃ２ each independently represents a hydrogen atom, an optionally substituted aliphatic hydrocarbon group, an optionally substituted aromatic ring group, or an optionally substituted aliphatic heterocyclic group. * represents a bonding position.

7. The photoelectric conversion element according to claim 1, wherein A represents a group represented by formula (A-5). In formula (A-5), X ５ and X ７ One of these represents an oxygen atom or a sulfur atom, and the other represents a nitrogen atom or -C(Rx)=. ６ represents -C(Rx)= or a nitrogen atom. Rx represents a hydrogen atom or a substituent. ５ and X ６ When represents -C(Rx)=, Rx may be bonded to each other to form a ring. ６ and X ７ When represents -C(Rx)=, Rx may be linked to each other to form a ring. １ is a sulfur atom, =NR Ｚ１ Or = C(R Ｚ２ ) (R Ｚ３ ) represents R Ｚ１ represents a hydrogen atom or a substituent. Ｚ２ and R Ｚ３ each independently represents a cyano group, —SO ２ R Ｚ４ , -COOR Ｚ５ , or -COR Ｚ６ Represents R Ｚ４ ~R Ｚ６ each independently represents an aliphatic hydrocarbon group which may have a substituent, an aromatic ring group which may have a substituent, or an aliphatic heterocyclic group which may have a substituent. * represents a bonding position.

8. The photoelectric conversion element according to claim 1, wherein the photoelectric conversion film further contains an n-type organic semiconductor, and the photoelectric conversion film has a bulk heterostructure formed by mixing the compound represented by formula (1) and the n-type organic semiconductor.

9. The photoelectric conversion element according to claim 8, wherein the n-type organic semiconductor contains a fullerene selected from the group consisting of fullerene and derivatives thereof.

10. The photoelectric conversion element according to claim 1, wherein the photoelectric conversion film further contains a p-type organic semiconductor.

11. The photoelectric conversion element according to claim 1, wherein the photoelectric conversion film further contains a dye.

12. The photoelectric conversion element according to claim 1, further comprising, in addition to said photoelectric conversion film, one or more intermediate layers between said conductive film and said transparent conductive film.

13. An imaging device comprising the photoelectric conversion element according to any one of claims 1 to 12.

14. An optical sensor comprising the photoelectric conversion element according to any one of claims 1 to 12.

15. A method for manufacturing an imaging element, comprising the step of manufacturing a photoelectric conversion element according to any one of claims 1 to 12.

16. A compound represented by formula (1). In formula (1), R １ and R ２ Each independently represents a hydrogen atom or a substituent. ３ represents a hydrogen atom, an aliphatic hydrocarbon group which may have a substituent other than an acid group and a salt thereof, an aromatic ring group which may have a substituent other than an acid group and a salt thereof, or an aliphatic heterocyclic group which may have a substituent other than an acid group and a salt thereof. １ and X ２ Each of Y independently represents a nitrogen atom or -C(Rx)=, where Rx represents a hydrogen atom or a substituent. １ is -C(R Ｙ１ ) (R Ｙ２ )-, an oxygen atom, a sulfur atom, or a selenium atom. Ｙ１ and R Ｙ２ each independently represents an aliphatic hydrocarbon group which may have a substituent, an aromatic ring group which may have a substituent, or an aliphatic heterocyclic group which may have a substituent. Ｙ１ and R Ｙ２ may be bonded to each other to form a ring. １ represents a monocyclic aromatic ring which may have a substituent. １ and X ２ In the case where both of these represent -C(Rx)=, A １ represents a nitrogen-containing 6-membered aromatic ring which may have a substituent. A represents a group represented by formula (A-1) or formula (A-2). In formula (A-1), B １ represents a ring containing two or more carbon atoms and which may have a substituent. １ is an oxygen atom, a sulfur atom, ═NR Ｚ１ Or = C(R Ｚ２ ) (R Ｚ３ ) represents R Ｚ１ represents a hydrogen atom or a substituent. Ｚ２ and R Ｚ３ each independently represents a cyano group, —SO ２ R Ｚ４ , -COOR Ｚ５ , or -COR Ｚ６ Represents R Ｚ４ ~R Ｚ６ each independently represents an aliphatic hydrocarbon group which may have a substituent, an aromatic ring group which may have a substituent, or an aliphatic heterocyclic group which may have a substituent. ａ１ and R ａ２ each independently represents a cyano group, —SO ２ R ｂ１ , -COOR ｂ２ , or -COR ｂ３ Represents R ｂ１ , R ｂ２ and R ｂ３ each independently represents an aliphatic hydrocarbon group which may have a substituent, an aromatic ring group which may have a substituent, or an aliphatic heterocyclic group which may have a substituent. * represents a bonding position.

17. The compound according to claim 16, wherein the compound represented by formula (1) is a compound represented by formula (2). In formula (2), R １ , R ２ , R ３ , Y １ and A is R in the formula (1). １ , R ２ , R ３ , Y １ and A. ４ and R ５ Each of X independently represents a hydrogen atom or a substituent. １ represents a nitrogen atom. ２ ~X ４ each independently represents a nitrogen atom or -C(Rx)=, where Rx represents a hydrogen atom or a substituent.

18. Y １ But -C(R Ｙ１ ) (R Ｙ２ )-, R Ｙ１ and R Ｙ２ each independently represents an aliphatic hydrocarbon group which may have a substituent, an aromatic ring group which may have a substituent, or an aliphatic heterocyclic group which may have a substituent; R Ｙ１ and R Ｙ２ The compound according to claim 16 , wherein:

19. R Ｙ１ and R Ｙ２ each independently represents an aliphatic hydrocarbon group which may have a substituent; R Ｙ１ and R Ｙ２ and optionally are bonded to each other to form a ring.

20. The compound according to claim 16, wherein A represents a group represented by formula (A-1).

21. The compound according to claim 16, wherein A represents a group represented by formula (A-3) or formula (A-4). In formula (A-3), D １ represents an aromatic ring which may have a substituent. １ and Z ２ each independently represents an oxygen atom, a sulfur atom, or ═NR Ｚ１ Or = C(R Ｚ２ ) (R Ｚ３ ) represents R Ｚ１ represents a hydrogen atom or a substituent. Ｚ２ and R Ｚ３ each independently represents a cyano group, —SO ２ R Ｚ４ , -COOR Ｚ５ , or -COR Ｚ６ Represents R Ｚ４ ~R Ｚ６ each independently represents an aliphatic hydrocarbon group which may have a substituent, an aromatic ring group which may have a substituent, or an aliphatic heterocyclic group which may have a substituent. ３ ~Z ５ each independently represents an oxygen atom, a sulfur atom, or ═NR Ｚ１ Or = C(R Ｚ２ ) (R Ｚ３ ) represents R Ｚ１ represents a hydrogen atom or a substituent. Ｚ２ and R Ｚ３ each independently represents a cyano group, —SO ２ R Ｚ４ , -COOR Ｚ５ , or -COR Ｚ６ Represents R Ｚ４ ~R Ｚ６ R each independently represents an aliphatic hydrocarbon group which may have a substituent, an aromatic ring group which may have a substituent, or an aliphatic heterocyclic group which may have a substituent. ｃ１ and R ｃ２ each independently represents a hydrogen atom, an optionally substituted aliphatic hydrocarbon group, an optionally substituted aromatic ring group, or an optionally substituted aliphatic heterocyclic group. * represents a bonding position.

22. The compound according to any one of claims 16 to 21, wherein A represents a group represented by formula (A-5). In formula (A-5), X ５ and X ７ One of these represents an oxygen atom or a sulfur atom, and the other represents a nitrogen atom or -C(Rx)=. ６ represents -C(Rx)= or a nitrogen atom. Rx represents a hydrogen atom or a substituent. ５ and X ６ When represents -C(Rx)=, Rx may be bonded to each other to form a ring. ６ and X ７ When represents -C(Rx)=, Rx may be linked to each other to form a ring. １ is a sulfur atom, =NR Ｚ１ Or = C(R Ｚ２ ) (R Ｚ３ ) represents R Ｚ１ represents a hydrogen atom or a substituent. Ｚ２ and R Ｚ３ each independently represents a cyano group, —SO ２ R Ｚ４ , -COOR Ｚ５ , or -COR Ｚ６ Represents R Ｚ４ ~R Ｚ６ each independently represents an aliphatic hydrocarbon group which may have a substituent, an aromatic ring group which may have a substituent, or an aliphatic heterocyclic group which may have a substituent. * represents a bonding position.