WO2014157238A1 - Photoelectric conversion material, photoelectric conversion element and method for using same, optical sensor, and image pickup element - Google Patents

Abstract

The present invention addresses the problem of providing a photoelectric conversion material that excels in heat resistance and vapor-deposition stability, a photoelectric conversion element using the photoelectric conversion material, a method for using the photoelectric conversion element, and an optical sensor and an image pickup element that include the photoelectric conversion element. This photoelectric conversion material is a compound (A) represented by formula (1).

Description

Photoelectric conversion material, photoelectric conversion element and method of using the same, optical sensor, imaging element

The present invention relates to a photoelectric conversion material, a photoelectric conversion element, a method for using the photoelectric conversion element, an optical sensor, and an imaging element.

A conventional optical sensor is an element in which a photodiode (PD) is formed in a semiconductor substrate such as silicon (Si). As a solid-state image sensor, signal charges generated in each PD are arranged in two dimensions. Are widely used.

In order to realize a color solid-state imaging device, a structure in which a color filter that transmits light of a specific wavelength is arranged on the light incident surface side of the flat solid-state imaging device is generally used. Color filters that transmit blue (B) light, green (G) light, and red (R) light are regularly arranged on each two-dimensionally arranged PD that is currently widely used in digital cameras and the like. Single-plate solid-state imaging devices are well known.

In recent years, development of solid-state imaging devices having a structure in which an organic photoelectric conversion film is formed on a signal readout substrate has been advanced.
In solid-state imaging devices and photoelectric conversion devices using such an organic photoelectric conversion film, responsiveness and photoelectric conversion efficiency are particularly problematic.

Among these, for example, Patent Document 1 and Patent Document 2 disclose materials having a specific structure as a photoelectric conversion material used for a photoelectric conversion element.

JP 2011-119745 A JP 2012-77064 A

Considering high productivity from the viewpoint of the manufacturing process, it is desirable that the vapor deposition process can be carried out continuously at a high vapor deposition rate for a long time. When the heat load applied to the material at a low vapor deposition rate is compared with the heat load applied to the material at a high vapor deposition rate, the latter heat load is greater. Therefore, in order to maintain a high vapor deposition rate, it is necessary that the photoelectric conversion material in the crucible be difficult to be decomposed even when exposed to a high temperature environment for a long time. That is, the photoelectric conversion material is required to have excellent heat resistance.
Moreover, when vapor deposition is continuously performed in the same batch, the stability of vapor deposition decreases as the latter half of the batch progresses, and the responsiveness of the resulting element may decrease. Therefore, excellent vapor deposition stability is required for the photoelectric conversion material.

The inventors of the present invention have studied the photoelectric conversion materials disclosed in Patent Document 1 and Patent Document 2, and have not yet reached the level required recently in terms of heat resistance and vapor deposition stability, and further improvements are necessary. I found out.

An object of this invention is to provide the photoelectric conversion material which is excellent in heat resistance and vapor deposition stability in view of the said situation.
Another object of the present invention is to provide a photoelectric conversion element using the photoelectric conversion material, a method for using the photoelectric conversion element, and an optical sensor and an imaging element including the photoelectric conversion element.

As a result of intensive studies to solve the above problems, the present inventor has found that the photoelectric conversion material, which is the compound (A) represented by the formula (1) described later, is excellent in heat resistance and vapor deposition stability. Was completed. That is, the present inventors have found that the above problem can be solved by the following configuration.

(1) A photoelectric conversion material which is a compound (A) represented by the following formula (1).

(In the formula (1), Ar ¹¹ and Ar ¹² represent an aryl group or a heteroaryl group which may have a substituent. At least one of Ar ¹¹ and Ar ¹² represents the following formula (2 Ar ¹¹ and Ar ¹² may be bonded to each other through a divalent organic group to form a ring.
Z ₁ represents a ring containing at least three carbon atoms and a 5-membered ring, a 6-membered ring, or a condensed ring containing at least one of a 5-membered ring and a 6-membered ring. )

(In the formula (2), Ar ¹³ and Ar ¹⁴ represent an aryl group or a heteroaryl group which may have a substituent. Ar ¹³ and / or Ar ¹⁴ represents Ar ¹¹ in the above formula (1). or Ar ¹² and may be bonded to each other to form a ring.
* Represents a binding position.
L ¹ represents a single bond, an alkenylene group which may have a substituent, a divalent aryl group which may have a substituent, or a divalent heteroaryl group which may have a substituent. . When L ¹ is a single bond, the nitrogen atom in formula (2) is directly bonded to Ar ¹¹ and / or Ar ¹² . )

(2) The photoelectric conversion material according to (1), wherein the compound (A) is a compound (a1) represented by the following formula (3).

(In the formula (3), R ¹¹ to R ²⁴ represent a hydrogen atom or a substituent. At least one of R ¹¹ to R ²⁴ is a group represented by the following formula (4): R ¹⁷ and R ¹⁸ may be bonded to each other via a divalent organic group to form a ring.
a and b represent an integer of 0 or more.
Z ₁ represents a ring containing at least three carbon atoms and a 5-membered ring, a 6-membered ring, or a condensed ring containing at least one of a 5-membered ring and a 6-membered ring. )

(In the formula (4), Ar ¹³ and Ar ¹⁴ represent an aryl group or a heteroaryl group which may have a substituent. Ar ¹³ and / or Ar ¹⁴ represents R ¹¹ in the above formula (3). At least one of -R ²⁴ may be bonded to each other to form a ring.
* Represents a binding position.
L ¹ represents a single bond, an alkenylene group which may have a substituent, a divalent aryl group which may have a substituent, or a divalent heteroaryl group which may have a substituent. . When L ¹ is a single bond, the nitrogen atom in the formula (4) is directly bonded to at least one of R ¹¹ to R ²⁴ . )

(3) The photoelectric conversion material according to (2), wherein at least one of R ¹⁴ and R ^{21 in} the formula (3) is a group represented by the formula (4).

(4) The photoelectric conversion material according to any one of (1) to (3), wherein Z ₁ is a ring represented by the following formula (Z1).

(In the formula (Z1), Z ₂ represents a ring containing at least 3 carbon atoms and represents a 5-membered ring, a 6-membered ring, or a condensed ring containing at least one of a 5-membered ring and a 6-membered ring. (* Represents a bonding position.)

(5) The photoelectric conversion material according to any one of (2) to (4), wherein the compound (a1) is a compound (a2) represented by the following formula (5).

(In formula (5), R ¹¹ to R ²⁴ represent a hydrogen atom or a substituent. At least one of R ¹¹ to R ²⁴ is a group represented by the following formula (6): R ¹⁷ and R ¹⁸ may be bonded to each other via a divalent organic group to form a ring.
a and b represent an integer of 0 or more.
R ⁵¹ to R ⁵⁴ represent a hydrogen atom or a substituent. R ⁵¹ and R ⁵² , R ⁵² and R ⁵³ , and R ⁵³ and R ⁵⁴ may be bonded to each other to form a ring. )

(In the formula (6), Ar ¹³ and Ar ¹⁴ represent an aryl group or a heteroaryl group which may have a substituent. Ar ¹³ and / or Ar ¹⁴ represents R ¹¹ in the above formula (5). At least one of -R ²⁴ may be bonded to each other to form a ring.
* Represents a binding position.
L ¹ represents a single bond, an alkenylene group which may have a substituent, a divalent aryl group which may have a substituent, or a divalent heteroaryl group which may have a substituent. . When L ¹ is a single bond, the nitrogen atom in the formula (6) is directly bonded to at least one of R ¹¹ to R ²⁴ . )

(6) The photoelectric conversion material according to any one of (1) to (5), wherein Ar ¹³ and Ar ¹⁴ are aryl groups which may have a substituent.

(7) The above (1) to (1), wherein L ¹ is a single bond, a divalent aryl group which may have a substituent, or a divalent heteroaryl group which may have a substituent. The photoelectric conversion material according to any one of 6).

(8) The photoelectric conversion material according to any one of (2) to (7), wherein a and b are 0.

(9) The photoelectric conversion material according to any one of (1) to (8), wherein Ar ¹¹ and Ar ¹² are not bonded to each other to form a ring.

(10) The photoelectric conversion material according to any one of (1) to (9), wherein Ar ¹³ and / or Ar ¹⁴ is bonded to Ar ¹¹ and / or Ar ¹² to form a ring. .

(11) A photoelectric conversion element using the photoelectric conversion material according to any one of (1) to (10) above.

(12) A photoelectric conversion element comprising a conductive film, a photoelectric conversion film containing the photoelectric conversion material according to any one of (1) to (10), and a transparent conductive film in this order.

(13) The photoelectric conversion element according to (12), wherein the photoelectric conversion film further contains an organic n-type semiconductor.

(14) The photoelectric conversion element according to (13), wherein the organic n-type semiconductor includes fullerenes selected from the group consisting of fullerenes and derivatives thereof.

(15) Content of the fullerenes with respect to the total content of the compound (A) and the fullerenes (= film thickness of the fullerenes as a single layer / (monolayer conversion of the compound (A)) The film thickness + the film thickness of the fullerenes in terms of a single layer)) is 50% by volume or more.

(16) The photoelectric conversion element according to any one of (12) to (15) above, wherein an electron blocking layer is disposed between the conductive film and the transparent conductive film.

(17) The photoelectric conversion element according to any one of (12) to (16), wherein the photoelectric conversion film is formed by a vacuum vapor deposition method.

(18) The photoelectric conversion element according to any one of (12) to (17), wherein light is incident on the photoelectric conversion film through the transparent conductive film.

(19) The photoelectric conversion element according to any one of (12) to (18), wherein the transparent conductive film is made of a transparent conductive metal oxide.

(20) An optical sensor including the photoelectric conversion element according to any one of (11) to (19) above.

(21) An imaging device including the photoelectric conversion device according to any one of (11) to (19) above.

(22) A method of using the photoelectric conversion element according to any one of (11) to (19) above,
A method of using a photoelectric conversion element, wherein the conductive film and the transparent conductive film are a pair of electrodes, and an electric field of 1 × 10 ⁻⁴ to 1 × 10 ⁷ V / cm is applied between the pair of electrodes.

As shown below, according to the present invention, a photoelectric conversion material excellent in heat resistance and vapor deposition stability can be provided.
Moreover, this invention can provide the photoelectric conversion element using the said photoelectric conversion material, the usage method of the said photoelectric conversion element, and the optical sensor and imaging device containing a photoelectric conversion element.

FIG. 1A and FIG. 1B are schematic cross-sectional views each showing a configuration example of a photoelectric conversion element. It is a cross-sectional schematic diagram for 1 pixel of an image pick-up element. 1 is a ¹ H-NMR spectrum of a compound (1). (5) it is a ¹ H-NMR spectrum of the compound of. It is a ¹ H-NMR spectrum of compound (12).

[Photoelectric conversion material]
The photoelectric conversion material of this invention is a compound (A) represented by Formula (1) mentioned later.
As can be seen from the formula (1) described later, the compound (A) has two aromatic hydrocarbon rings and / or aromatic heterocycles bonded to the ring represented by Z _1. There are no hydrogen atoms with high acidity or hydrogen atoms on alkyl groups with relatively high acidity. For this reason, even when exposed to a high temperature environment for a long time, structural changes such as decomposition hardly occur, and it is considered that excellent heat resistance and vapor deposition stability are exhibited.
This indicates that the heat resistance and the deposition stability are insufficient when a hydrogen atom is present at the site where both are bonded, or when a hydrogen atom is present on the alkyl group, as shown in a comparative example described later. It is guessed from that.
In addition, the photoelectric conversion element manufactured using the said compound (A) excellent in heat resistance and vapor deposition stability has a small performance (responsiveness) difference between manufacturing lots, and is excellent in manufacturing aptitude.

The compound (A) which is the photoelectric conversion material of the present invention is represented by the following formula (1).

In said formula (1), Ar < ¹¹ > and Ar < ¹² > represent the aryl group or heteroaryl group which may have a substituent. Especially, the aryl group which may have a substituent is preferable from the reason which heat resistance and vapor deposition stability are more excellent.

When Ar ¹¹ or Ar ¹² is an aryl group, an aryl group having 6 to 30 carbon atoms is preferable, and an aryl group having 6 to 20 carbon atoms is more preferable. Preferred examples of the aryl group include, for example, a phenyl group, a naphthyl group, an anthracenyl group, a pyrenyl group, a fluorenyl group, a phenanthrenyl group, a methylphenyl group, a dimethylphenyl group, and a biphenyl group (two phenyl groups can be connected in any connection manner). Or a terphenyl group (three phenyl groups may be connected in an arbitrary connection manner), and a phenyl group or a naphthyl group is more preferable.
Examples of the substituent of the aryl group include a substituent W described later.

When Ar ¹¹ or Ar ¹² is a heteroaryl group, a heteroaryl group consisting of a 5-membered, 6-membered or 7-membered ring or a condensed ring thereof is preferred. Examples of the hetero atom contained in the heteroaryl group include an oxygen atom, a sulfur atom, and a nitrogen atom. Specific examples of the ring constituting the heteroaryl group include a furan ring, a thiophene ring, a pyrrole ring, a pyrroline ring, a pyrrolidine ring, an oxazole ring, an isoxazole ring, a thiazole ring, an isothiazole ring, an imidazole ring, an imidazoline ring, and an imidazolidine. Ring, pyrazole ring, pyrazoline ring, pyrazolidine ring, triazole ring, furazane ring, tetrazole ring, pyran ring, thiine ring, pyridine ring, piperidine ring, oxazine ring, morpholine ring, thiazine ring, pyridazine ring, pyrimidine ring, pyrazine ring, Piperazine ring, triazine ring, benzofuran ring, isobenzofuran ring, benzothiophene ring, indole ring, indoline ring, isoindole ring, benzoxazole ring, benzothiazole ring, indazole ring, benzimidazole ring, quinoline ring, iso Norrin ring, cinnoline ring, phthalazine ring, quinazoline ring, quinoxaline ring, dibenzofuran ring, dibenzothiophene ring, carbazole ring, xanthene ring, acridine ring, phenanthridine ring, phenanthroline ring, phenazine ring, phenoxazine ring, thianthrene ring, India A lysine ring, a quinolidine ring, a quinuclidine ring, a naphthyridine ring, a purine ring, a pteridine ring, etc. are mentioned.
Examples of the substituent for the heteroaryl group include a substituent W described later.

At least one of Ar ¹¹ and Ar ¹² has a group represented by the following formula (2) as a substituent.

In said formula (2), Ar < ¹³ > and Ar < ¹⁴ > represent the aryl group or heteroaryl group which may have a substituent. Specific examples and preferred embodiments of Ar ¹³ and Ar ¹⁴ are the same as Ar ¹¹ and Ar ¹² described above. Ar ¹³ and Ar ¹⁴ are preferably aryl groups which may have a substituent.

Ar ¹³ and / or Ar ¹⁴ may combine with Ar ¹¹ or Ar ¹² in the above formula (1) to form a ring. Examples of the ring formed include a ring R described later. The ring formed may have a substituent. Examples of the substituent include a substituent W described later.
For reasons of better heat resistance and vapor deposition stability, Ar ¹³ and / or Ar ¹⁴ are preferably bonded to Ar ¹¹ and / or Ar ^{12 in} formula (1) to form a ring.

In the above formula (2), * represents a bonding position.

In the above formula (2), L ¹ is a single bond, an alkenylene group (preferably having 2 to 4 carbon atoms) which may have a substituent, a divalent aryl group which may have a substituent, or The divalent heteroaryl group which may have a substituent is represented. Examples of the substituent include a substituent W described later.
When L ¹ is a divalent aryl group, an aryl group having 6 to 30 carbon atoms is preferable, and an aryl group having 6 to 20 carbon atoms is more preferable. Specific examples of the ring constituting the aryl group include a benzene ring, a naphthalene ring, an anthracene ring, a phenanthrene ring, a fluorene ring, a triphenylene ring, a naphthacene ring, and a biphenyl ring. Or a terphenyl ring (the three phenyl groups may be connected in any connection manner). The aryl group may be bonded to Ar ¹¹ or Ar ¹² to form a ring.
When L ¹ is a divalent heteroaryl group, a heteroaryl group consisting of a 5-membered, 6-membered or 7-membered ring or a condensed ring thereof is preferred. Specific examples of the hetero atom contained in the heteroaryl group are the same as those in the case where Ar ¹¹ or Ar ¹² described above is a heteroaryl group. Specific examples of the ring constituting the heteroaryl group are the same as those in the case where Ar ¹¹ or Ar ¹² described above is a heteroaryl group. The heteroaryl group may be bonded to Ar ¹¹ or Ar ¹² to form a ring.
L ¹ may be a single bond, a divalent aryl group that may have a substituent, or a divalent heteroaryl group that may have a substituent, because the deposition stability is more excellent. A single bond or a divalent aryl group which may have a substituent is more preferable, and a single bond is more preferable.

When L ¹ is a single bond, the nitrogen atom in the above formula (2) is directly bonded to Ar ¹¹ and / or Ar ¹² .

In the above formula (1), Ar ¹¹ and Ar ¹² may be bonded to each other via a divalent organic group to form a ring.
Examples of the divalent organic group include a substituted or unsubstituted divalent aliphatic hydrocarbon group (for example, an alkylene group, preferably 1 to 8 carbon atoms), a substituted or unsubstituted divalent aromatic hydrocarbon group ( For example, an arylene group, preferably having 6 to 12 carbon atoms, —O—, —S—, —SO ₂ —, —NR— (R: substituent W described later), —SiR ¹ R ² — (R ¹ and R ² : Substituent W), -CO-, -NH-, -COO-, -CONH-, or a combination thereof (for example, an alkyleneoxy group, an alkyleneoxycarbonyl group, an alkylenecarbonyloxy group, etc.) Etc. Of these, a substituted or unsubstituted alkylene group, —O—, —S—, —NR—, or a combination thereof is preferable.

Ar ¹¹ and Ar ¹² are preferably not bonded to each other to form a ring for the reason that photoelectric conversion efficiency is excellent and heat resistance and vapor deposition stability are more excellent.

In the above formula (1), Z ₁ represents a ring containing at least 3 carbon atoms and represents a 5-membered ring, a 6-membered ring, or a condensed ring containing at least one of a 5-membered ring and a 6-membered ring. .
As such a ring, what is normally used as an acidic nucleus with a merocyanine dye is preferable, and specific examples thereof include the following.

(A) 1,3-dicarbonyl nucleus: for example, 1,3-indandione nucleus, 1,3-cyclohexanedione, 5,5-dimethyl-1,3-cyclohexanedione, 1,3-dioxane-4,6 -Dione etc.
(B) pyrazolinone nucleus: for example, 1-phenyl-2-pyrazolin-5-one, 3-methyl-1-phenyl-2-pyrazolin-5-one, 1- (2-benzothiazoyl) -3-methyl- 2-pyrazolin-5-one and the like.
(C) isoxazolinone nucleus: for example, 3-phenyl-2-isoxazolin-5-one, 3-methyl-2-isoxazolin-5-one, etc.
(D) Oxindole nucleus: For example, 1-alkyl-2,3-dihydro-2-oxindole and the like.
(E) 2,4,6-triketohexahydropyrimidine nucleus: for example, barbituric acid or 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 diphenyl, 1,3-di (p-chlorophenyl), 1,3-di (p-ethoxycarbonylphenyl), 1-alkyl-1-aryl such as 1-ethyl-3-phenyl And 1,3-di (2-pyridyl) 1,3-diheterocyclic substituents and the like.
(F) 2-thio-2,4-thiazolidinedione nucleus: for example, rhodanine and derivatives thereof. Examples of the derivatives include 3-alkyl rhodanine such as 3-methylrhodanine, 3-ethylrhodanine and 3-allylrhodanine, 3-arylrhodanine such as 3-phenylrhodanine, and 3- (2-pyridyl). ) 3-position heterocyclic substituted rhodanine such as rhodanine.

(G) 2-thio-2,4-oxazolidinedione (2-thio-2,4- (3H, 5H) -oxazoledione nucleus: for example, 3-ethyl-2-thio-2,4-oxazolidinedione and the like.
(H) Tianaphthenone nucleus: For example, 3 (2H) -thianaphthenone-1,1-dioxide and the like.
(I) 2-thio-2,5-thiazolidinedione nucleus: for example, 3-ethyl-2-thio-2,5-thiazolidinedione and the like.
(J) 2,4-thiazolidinedione nucleus: for example, 2,4-thiazolidinedione, 3-ethyl-2,4-thiazolidinedione, 3-phenyl-2,4-thiazolidinedione and the like.
(K) Thiazolin-4-one nucleus: for example, 4-thiazolinone, 2-ethyl-4-thiazolinone, etc.
(L) 2,4-imidazolidinedione (hydantoin) nucleus: for example, 2,4-imidazolidinedione, 3-ethyl-2,4-imidazolidinedione, etc.
(M) 2-thio-2,4-imidazolidinedione (2-thiohydantoin) nucleus: for example, 2-thio-2,4-imidazolidinedione, 3-ethyl-2-thio-2,4-imidazolidine Zeon etc.
(N) Imidazolin-5-one nucleus: For example, 2-propylmercapto-2-imidazolin-5-one and the like.
(O) 3,5-pyrazolidinedione nucleus: for example, 1,2-diphenyl-3,5-pyrazolidinedione, 1,2-dimethyl-3,5-pyrazolidinedione, etc.
(P) Benzothiophen-3-one nucleus: for example, benzothiophen-3-one, oxobenzothiophen-3-one, dioxobenzothiophen-3-one and the like.
(Q) Indanone nucleus: for example, 1-indanone, 3-phenyl-1-indanone, 3-methyl-1-indanone, 3,3-diphenyl-1-indanone, 3,3-dimethyl-1-indanone, etc.

Z ₁ may have a substituent. Examples of the substituent include a substituent W described later.

Z ₁ is preferably a group represented by the following formula (Z1) from the viewpoint that the characteristics of the photoelectric conversion element such as response, sensitivity, and heat resistance are more excellent.

In formula (Z1), Z ₂ represents a ring containing at least 3 carbon atoms, and represents a 5-membered ring, a 6-membered ring, or a condensed ring containing at least one of a 5-membered ring and a 6-membered ring.
In formula (Z1), * represents a bonding position with the carbon atom to which Ar ¹¹ and Ar ¹² in the above formula (1) are bonded.

A preferred embodiment of the compound (A) is, for example, a compound (a1) represented by the following formula (3).

In the above formula (3), R ¹¹ to R ²⁴ represent a hydrogen atom or a substituent. Examples of the substituent include a substituent W described later.

At least one of R ¹¹ to R ²⁴ is a group represented by the following formula (4).

In said formula (4), Ar < ¹³ > and Ar < ¹⁴ > represent the aryl group or heteroaryl group which may have a substituent. Specific examples and preferred embodiments of Ar ¹³ and Ar ¹⁴ is the same as Ar ¹³ and Ar ¹⁴ in the formula (2).

Ar ¹³ and / or Ar ¹⁴ may be bonded to at least one of R ¹¹ to R ^{24 in} the above formula (3) to form a ring. Examples of the ring formed include a ring R described later. The ring formed may have a substituent. Examples of the substituent include a substituent W described later.
For reasons of better heat resistance and deposition stability, Ar ¹³ and / or Ar ¹⁴ are preferably bonded to at least one of R ¹¹ to R ^{24 in} the above formula (3) to form a ring.

In the above formula (4), * represents a bonding position.

In the above formula (4), L ¹ is a single bond, an alkenylene group which may have a substituent, a divalent aryl group which may have a substituent, or 2 which may have a substituent. Represents a valent heteroaryl group. Specific examples and preferred embodiments of L ¹ are as described above.
When L ¹ is a single bond, the nitrogen atom in the formula (4) is directly bonded to at least one of R ¹¹ to R ²⁴ .

In the above formula (3), R ¹⁷ and R ¹⁸ may be bonded to each other via a divalent organic group to form a ring. Specific examples and preferred embodiments of the divalent organic group are as described above.
R ¹⁷ and R ¹⁸ are preferably not bonded to each other to form a ring for the reason of better heat resistance and vapor deposition stability.

In said formula (3), a and b represent an integer greater than or equal to 0. Among these, an integer of 0 to 2, preferably 0 to 1, and more preferably 0 is preferable because the heat resistance and the deposition stability are more excellent.
In addition, a and b represent the number of connected benzene rings. For example, the aromatic ring containing R ¹⁸ to R ²⁴ in the above formula (3) represents a benzene ring when a = 0, and a naphthalene ring when a = 1.

In the above formula (3), Z ₁ represents a ring containing at least 3 carbon atoms and represents a 5-membered ring, a 6-membered ring, or a condensed ring containing at least one of a 5-membered ring and a 6-membered ring. . Specific examples and preferred embodiments of Z ₁ are as described above.

Z ₁ is preferably a group represented by the following formula (Z1) from the viewpoint that the characteristics of the photoelectric conversion element such as response, sensitivity, and heat resistance are more excellent.

In the formula (Z1), the definition of Z ₂ is as described above.
In formula (Z1), * represents a bonding position with a quaternary carbon atom to which an aromatic ring containing R ¹¹ to R ¹⁷ and an aromatic ring containing R ¹⁸ to R ²⁴ are bonded.

A preferred embodiment of the compound (a1) is, for example, a compound (a2) represented by the following formula (5).

In the above formula (5), R ¹¹ to R ²⁴ represent a hydrogen atom or a substituent. Examples of the substituent include a substituent W described later.

At least one of R ¹¹ to R ²⁴ is a group represented by the following formula (6).

In the above formula (6), the definitions, specific examples and preferred embodiments of Ar ¹³ and Ar ¹⁴ are the same as those in the above-described formula (4).
In the above formula (6), * represents a bonding position.
In the above formula (6), the definition, specific examples and preferred embodiments of L ¹ are the same as those in the above-described formula (4).

In the above formula (5), R ¹⁷ and R ¹⁸ may be bonded to each other via a divalent organic group to form a ring. Specific examples and preferred embodiments of the divalent organic group are as described above.
R ¹⁷ and R ¹⁸ are preferably not bonded to each other to form a ring for the reason of better heat resistance and vapor deposition stability.

In the above formula (5), the definitions, specific examples, and preferred aspects of a and b are the same as the above formula (3).

In the above formula (5), R ⁵¹ to R ⁵⁴ represent a hydrogen atom or a substituent. Examples of the substituent include a substituent W described later.
R ⁵¹ and R ⁵² , R ⁵² and R ⁵³ , and R ⁵³ and R ⁵⁴ may be bonded to each other to form a ring. Examples of the ring formed include a ring R described later. The ring formed may have a substituent. Examples of the substituent include a substituent W described later.

(Substituent W)
It describes about the substituent W in this specification.
Examples of the substituent W include a halogen atom, 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, Heterocyclic group (may be referred to as heterocyclic group), cyano group, hydroxy group, nitro group, carboxy group, alkoxy group, aryloxy group, silyloxy group, heterocyclic oxy group, acyloxy group, carbamoyloxy group, alkoxycarbonyl Oxy group, aryloxycarbonyloxy group, amino group (including anilino group), ammonio group, acylamino group, aminocarbonylamino group, alkoxycarbonylamino group, aryloxycarbonylamino group, sulfamoylamino group, alkyl or arylsulfo Ruamino group, mercapto group, alkylthio group, arylthio group, heterocyclic thio group, sulfamoyl group, sulfo group, alkyl or arylsulfinyl group, alkyl or arylsulfonyl group, acyl group, aryloxycarbonyl group, alkoxycarbonyl group, carbamoyl group, Aryl or heterocyclic azo group, imide group, phosphino group, phosphinyl group, phosphinyloxy group, phosphinylamino group, phosphono group, silyl group, hydrazino group, ureido group, boronic acid group (-B (OH) ₂ ), A phosphato group (—OPO (OH) ₂ ), a sulfato group (—OSO ₃ H), and other known substituents.
Details of the substituent are described in paragraph [0023] of JP-A-2007-234651.

(Ring R)
It describes about the ring R in this specification.
Examples of the ring R include an aromatic hydrocarbon ring, an aromatic heterocycle, a non-aromatic hydrocarbon ring, a non-aromatic heterocycle, or a polycyclic fused ring formed by combining these. More specifically, benzene ring, naphthalene ring, anthracene ring, phenanthrene ring, fluorene ring, triphenylene ring, naphthacene ring, biphenyl ring, pyrrole ring, furan ring, thiophene ring, imidazole ring, oxazole ring, thiazole ring, pyridine ring , Pyrazine ring, pyrimidine ring, pyridazine ring, indolizine ring, indole ring, benzofuran ring, benzothiophene ring, isobenzofuran ring, quinolidine ring, quinoline ring, phthalazine ring, naphthyridine ring, quinoxaline ring, quinoxazoline ring, isoquinoline ring, carbazole Ring, phenanthridine ring, acridine ring, phenanthroline ring, thianthrene ring, chromene ring, xanthene ring, phenoxathiin ring, phenothiazine ring, phenazine ring, cyclopentane ring, cyclohexane ring, pyro Jin ring, piperidine ring, a tetrahydrofuran ring, tetrahydropyran ring, a tetrahydrothiophene ring, a tetrahydrothiopyran ring.
The ring R may have the substituent W.

Compound (A) can be produced by carrying out a partial modification according to a known method. Specific examples of the compound represented by the compound (A) are shown below, but the present invention is not limited thereto.

The ionization potential (hereinafter sometimes abbreviated as IP) of the compound (A) is preferably 6.0 ev or less, more preferably 5.8 eV or less, and particularly preferably 5.6 eV or less. If it is this range, when an electrode and another material exist, it is preferable in order to perform transfer of the electron with the material with small electrical resistance. IP can be obtained using AC-2 manufactured by Riken Keiki Co., Ltd.

The compound (A) preferably has an absorption maximum at 400 nm or more and less than 720 nm in the UV-visible absorption spectrum, and the peak wavelength (absorption maximum wavelength) of the absorption spectrum is 450 nm or more and 700 nm from the viewpoint of broadly absorbing light in the visible region. The following is preferable, 480 nm to 700 nm is more preferable, and 510 nm to 680 nm is further preferable.
The absorption maximum wavelength of the compound (A) can be measured with a chloroform solution of the compound (A) using, for example, UV-2550 manufactured by Shimadzu Corporation. Concentration of the chloroform solution is preferably from ^{5 × 10 -5 ~ 1 × 10} -7 mol / l, more preferably ^{3 × 10 -5 ~ 2 × 10} -6 mol / l, 2 × 10 -5 ~ 5 × 10 - ⁶ mol / l is particularly preferred.

The compound (A) preferably has an absorption maximum at 400 nm or more and less than 720 nm in the ultraviolet-visible absorption spectrum, and the molar extinction coefficient at the absorption maximum wavelength is 10,000 mol ⁻¹ · l · cm ⁻¹ or more. In order to reduce the film thickness of the photoelectric conversion film and to obtain an element having high charge collection efficiency and high sensitivity characteristics, a material having a large molar extinction coefficient is preferable. Preferably 10000mol ^-1 · l · cm ^-1 or more molar extinction coefficient of the compound (A), more preferably 30000mol ^-1 · l · cm ^-1 or more, 50000mol ^-1 · l · cm ^-1 or more is particularly preferred . The molar extinction coefficient of compound (A) is measured with a chloroform solution.

The larger the difference between the melting point and the deposition temperature (melting point−deposition temperature), the more preferable the compound (A) is, and the higher the temperature, the higher the deposition rate. The difference between the melting point and the deposition temperature (melting point−deposition temperature) is preferably 40 ° C. or higher, more preferably 50 ° C. or higher, and still more preferably 60 ° C. or higher.
Moreover, 240 degreeC or more is preferable, as for melting | fusing point of a compound (A), 280 degreeC or more is more preferable, and 300 degreeC or more is further more preferable. A melting point of 300 ° C. or higher is preferable because it hardly melts before vapor deposition and can stably form a film, and a decomposition product of the compound is relatively less likely to occur, so that the photoelectric conversion performance is not easily lowered.
The vapor deposition temperature of the compound is such that the crucible is heated at a vacuum of 4 × 10 ⁻⁴ Pa or less and the vapor deposition rate reaches 0.4 angstrom / s (0.4 × ^{10 −10} m / s).

The glass transition point (Tg) of the compound (A) is preferably 95 ° C. or higher, more preferably 110 ° C. or higher, further preferably 135 ° C. or higher, particularly preferably 150 ° C. or higher, and most preferably 160 ° C. or higher.

The molecular weight of the compound (A) is preferably 300 to 1500, more preferably 400 to 1000, and particularly preferably 500 to 900. When the molecular weight of the compound is 1500 or less, the deposition temperature does not increase and the compound is hardly decomposed. If the molecular weight of the compound is 300 or more, the glass transition point of the deposited film is not lowered, and the heat resistance of the device is hardly lowered.

Compound (A) is particularly useful as a material for a photoelectric conversion film used for an image sensor, a photosensor, or a photovoltaic cell. In general, the compound (A) functions as an organic p-type semiconductor (compound) in the photoelectric conversion film. As other applications, it can also be used as a coloring material, liquid crystal material, organic semiconductor material, organic light emitting device material, charge transport material, pharmaceutical material, fluorescent diagnostic material, and the like.

[Photoelectric conversion element]
The photoelectric conversion element of this invention will not be restrict | limited especially if it is a photoelectric conversion element using the photoelectric conversion material (compound (A)) of this invention mentioned above.
As a suitable aspect of the photoelectric conversion element of this invention, a photoelectric conversion element provided with the conductive film, the photoelectric conversion film containing the photoelectric conversion material of this invention, and a transparent conductive film in this order is mentioned.

In FIG. 1, the cross-sectional schematic diagram of one Embodiment of the photoelectric conversion element of this invention is shown.
A photoelectric conversion element 10a shown in FIG. 1A includes a conductive film (hereinafter also referred to as a lower electrode) 11 that functions as a lower electrode, an electron blocking layer 16A formed on the lower electrode 11, and an electron blocking layer 16A. The photoelectric conversion film 12 formed above and a transparent conductive film (hereinafter also referred to as an upper electrode) 15 functioning as an upper electrode are stacked in this order.
FIG. 1B shows a configuration example of another photoelectric conversion element. The photoelectric conversion element 10b shown in FIG. 1B has a configuration in which an electron blocking layer 16A, a photoelectric conversion film 12, a hole blocking layer 16B, and an upper electrode 15 are stacked in this order on a lower electrode 11. Have. Note that the stacking order of the electron blocking layer 16A, the photoelectric conversion film 12, and the hole blocking layer 16B in FIGS. 1A and 1B may be reversed depending on the application and characteristics.

In the configuration of the photoelectric conversion element 10 a (10 b), it is preferable that light is incident on the photoelectric conversion film 12 through the transparent conductive film 15.
Moreover, when using the photoelectric conversion element 10a (10b), an electric field can be applied. In this case, it is preferable that the conductive film 11 and the transparent conductive film 15 form a pair of electrodes, and an electric field of 1 × 10 ⁻⁵ to 1 × 10 ⁷ V / cm is applied between the pair of electrodes, It is more preferable to apply an electric field of 1 × 10 ⁻⁴ to 1 × 10 ⁷ V / cm. From the viewpoint of performance and power consumption, an electric field of 1 × 10 ⁻⁴ to 1 × 10 ⁶ V / cm is preferably applied, and an electric field of 1 × 10 ⁻³ to 5 × 10 ⁵ V / cm is preferably applied. More preferred.
In addition, about the voltage application method, in FIG. 1 (a) and (b), it is preferable to apply so that the electron blocking layer 16A side may become a cathode and the photoelectric converting film 12 side may become an anode. When the photoelectric conversion element 10a (10b) is used as an optical sensor, or when it is incorporated into an image sensor, voltage can be applied by the same method.

Below, the aspect of each layer (a photoelectric conversion film, a lower electrode, an upper electrode, an electron blocking layer, a hole blocking layer, etc.) which comprises the photoelectric conversion element 10a (10b) is explained in full detail.
First, the photoelectric conversion film will be described in detail.

<Photoelectric conversion film>
The photoelectric conversion film is a film containing the compound (A) as a photoelectric conversion material.
The compound (A) is as described above.

(Other materials)
The photoelectric conversion film may further contain an organic p-type semiconductor (compound) or an organic n-type semiconductor (compound) photoelectric conversion material.
The organic p-type semiconductor (compound) is a donor-type organic semiconductor (compound), which is mainly represented by a hole-transporting organic compound and refers to an organic compound having a property of easily donating electrons. More specifically, an organic compound having a smaller ionization potential when two organic materials are used in contact with each other. Therefore, any organic compound can be used as the donor organic compound as long as it is an electron-donating organic compound. For example, a triarylamine compound, a benzidine compound, a pyrazoline compound, a styrylamine compound, a hydrazone compound, a triphenylmethane compound, a carbazole compound, or the like can be used.

Organic n-type semiconductors (compounds) are acceptor organic semiconductors, which are typically represented by electron-transporting organic compounds and refer to organic compounds that easily accept electrons. More specifically, the organic compound having the higher electron affinity when two organic compounds are used in contact with each other. Therefore, any organic compound may be used as the acceptor organic semiconductor as long as it is an organic compound having an electron accepting property. Preferably, fullerenes selected from the group consisting of fullerenes and derivatives thereof, condensed aromatic carbocyclic compounds (naphthalene derivatives, anthracene derivatives, phenanthrene derivatives, tetracene derivatives, pyrene derivatives, perylene derivatives, fluoranthene derivatives), nitrogen atoms, oxygen Heterocyclic compounds containing atoms and sulfur atoms (eg, pyridine, pyrazine, pyrimidine, pyridazine, triazine, quinoline, quinoxaline, quinazoline, phthalazine, cinnoline, isoquinoline, pteridine, acridine, phenazine, phenanthroline, tetrazole, pyrazole, imidazole, thiazole , Oxazole, indazole, benzimidazole, benzotriazole, benzoxazole, benzothiazole, carbazole, purine, triazo Pyridazine, triazolopyrimidine, tetrazaindene, oxadiazole, imidazopyridine, pyralidine, pyrrolopyridine, thiadiazolopyridine, dibenzazepine, tribenzazepine, etc.), polyarylene compounds, fluorene compounds, cyclopentadiene compounds, silyl compounds, Examples thereof include a metal complex having a nitrogen heterocyclic compound as a ligand.

As the organic n-type semiconductor (compound), fullerenes selected from the group consisting of fullerenes and derivatives thereof are preferable. The fullerene, 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, mixed Fullerene is represented, and its derivative (fullerene derivative) represents a compound having a substituent added thereto. As the substituent, an alkyl group, an aryl group, or a heterocyclic group is preferable. As the fullerene derivative, compounds described in JP-A-2007-123707 are preferred.

The photoelectric conversion film preferably has a bulk heterostructure formed by mixing the compound (A) and fullerenes. A bulk heterostructure is a film in which an organic p-type compound (for example, compound (A)) and an organic n-type compound are mixed and dispersed in a photoelectric conversion film, and can be formed by either a wet method or a dry method. Those formed by vapor deposition are preferred. By including the heterojunction structure, it is possible to make up for the disadvantage that the carrier diffusion length of the photoelectric conversion film is short, and to improve the photoelectric conversion efficiency of the photoelectric conversion film. The bulk heterojunction structure is described in detail in JP-A-2005-303266, [0013] to [0014].

From the viewpoint of the responsiveness of the photoelectric conversion element, the content of fullerenes relative to the total content of the compound (A) and fullerenes (= film thickness in terms of a single layer of fullerenes / (single layer of compound (A) The film thickness in terms of conversion + the film thickness in terms of a single layer of fullerenes)) is preferably 50% by volume or more, and more preferably 60% by volume or more. The upper limit is not particularly limited, but is preferably 95% by volume or less, and more preferably 90% by volume or less.

The photoelectric conversion film (in which an organic n-type compound may be mixed) containing the compound (A) of the present invention is a non-light-emitting film and has characteristics different from those of an organic electroluminescent element (OLED). The non-light-emitting film is a film having an emission quantum efficiency of 1% or less, more preferably 0.5% or less, and still more preferably 0.1% or less.

(Film formation method)
The photoelectric conversion film 12 can be formed by a dry film formation method or a wet film formation method. Specific examples of the dry film forming method include a physical vapor deposition method such as a vacuum deposition method, a sputtering method, an ion plating method, and an MBE method, or a CVD method such as plasma polymerization. As the wet film forming method, a casting method, a spin coating method, a dipping method, an LB method, or the like is used. A dry film forming method is preferred, and a vacuum deposition method is more preferred. In the case of forming a film by a vacuum deposition method, the production conditions such as the degree of vacuum and the deposition temperature can be set according to conventional methods.

The thickness of the photoelectric conversion film 12 is preferably 10 nm to 1000 nm, more preferably 50 nm to 800 nm, and particularly preferably 100 nm to 500 nm. By setting it to 10 nm or more, a suitable dark current suppressing effect is obtained, and by setting it to 1000 nm or less, suitable photoelectric conversion efficiency is obtained.

<Electrode>
The electrodes (upper electrode (transparent conductive film) 15 and lower electrode (conductive film) 11) are made of a conductive material. As the conductive material, a metal, an alloy, a metal oxide, an electrically conductive compound, or a mixture thereof can be used.
Since light is incident from the upper electrode 15, the upper electrode 15 needs to be sufficiently transparent to the light to be detected. Specifically, conductive metal oxides such as tin oxide (ATO, FTO) doped with antimony or fluorine, tin oxide, zinc oxide, indium oxide, indium tin oxide (ITO), indium zinc oxide (IZO), Metal thin films such as gold, silver, chromium, nickel, etc., and mixtures or laminates of these metals and conductive metal oxides, inorganic conductive materials such as copper iodide and copper sulfide, organics such as polyaniline, polythiophene, and polypyrrole Examples thereof include conductive materials and laminates of these with ITO. Among these, a transparent conductive metal oxide is preferable from the viewpoint of high conductivity, transparency, and the like.

When a transparent conductive film such as TCO is used as the upper electrode 15, a DC short circuit or an increase in leakage current may occur. One reason for this is considered to be that fine cracks introduced into the photoelectric conversion film 12 are covered by a dense film such as TCO, and conduction with the lower electrode 11 on the opposite side is increased. Therefore, in the case of an electrode having a relatively poor film quality such as aluminum, an increase in leakage current is unlikely to occur. By controlling the film thickness of the upper electrode 15 with respect to the film thickness of the photoelectric conversion film 12 (that is, the crack depth), an increase in leakage current can be largely suppressed. The thickness of the upper electrode 15 is desirably 1/5 or less, preferably 1/10 or less of the thickness of the photoelectric conversion film 12.

Usually, when the conductive film is made thinner than a certain range, the resistance value is rapidly increased. However, in the solid-state imaging device incorporating the photoelectric conversion device according to this embodiment, the sheet resistance is preferably 100 to 10,000 Ω / □. Well, the degree of freedom in the range of film thickness that can be made thin is great. Further, as the thickness of the upper electrode (transparent conductive film) 15 decreases, the amount of light absorbed decreases, and the light transmittance generally increases. An increase in light transmittance is very preferable because it increases the light absorption in the photoelectric conversion film 12 and increases the photoelectric conversion ability. In consideration of the suppression of leakage current, the increase in the resistance value of the thin film, and the increase in transmittance due to the thinning, the thickness of the upper electrode 15 is preferably 5 to 100 nm, and more preferably 5 to 20 nm. It is desirable.

Depending on the application, the lower electrode 11 may have transparency, or conversely, may use a material that does not have transparency and reflects light. Specifically, conductive metal oxides such as tin oxide (ATO, FTO) doped with antimony or fluorine, tin oxide, zinc oxide, indium oxide, indium tin oxide (ITO), indium zinc oxide (IZO), Metals such as gold, silver, chromium, nickel, titanium, tungsten, and aluminum, and conductive compounds such as oxides and nitrides of these metals (for example, titanium nitride (TiN)), and these metals and conductivity Examples include mixtures or laminates with metal oxides, inorganic conductive materials such as copper iodide and copper sulfide, organic conductive materials such as polyaniline, polythiophene, and polypyrrole, and laminates of these with ITO or titanium nitride. .

The method for forming the electrode is not particularly limited, and can be appropriately selected in consideration of suitability with the electrode material. Specifically, it can be formed by a wet method such as a printing method or a coating method, a physical method such as a vacuum deposition method, a sputtering method or an ion plating method, or a chemical method such as CVD or plasma CVD method.
When the electrode material is ITO, it can be formed by a method such as an electron beam method, a sputtering method, a resistance heating vapor deposition method, a chemical reaction method (such as a sol-gel method), or a dispersion of indium tin oxide. Furthermore, UV-ozone treatment, plasma treatment, or the like can be performed on a film formed using ITO. When the electrode material is TiN, various methods including a reactive sputtering method can be used, and further, UV-ozone treatment, plasma treatment, and the like can be performed.

<Charge blocking layer: electron blocking layer, hole blocking layer>
The photoelectric conversion element of the present invention may have a charge blocking layer. By having this layer, the characteristics (photoelectric conversion efficiency, response speed, etc.) of the obtained photoelectric conversion element are more excellent. Examples of the charge blocking layer include an electron blocking layer and a hole blocking layer. Below, each layer is explained in full detail.

(Electronic blocking layer)
An electron donating organic material can be used for the electron blocking layer. Specifically, for low molecular weight materials, N, N′-bis (3-methylphenyl)-(1,1′-biphenyl) -4,4′-diamine (TPD) or 4,4′-bis [N Aromatic diamine compounds such as-(naphthyl) -N-phenyl-amino] biphenyl (α-NPD), oxazole, oxadiazole, triazole, imidazole, imidazolone, stilbene derivative, pyrazoline derivative, tetrahydroimidazole, polyarylalkane, butadiene 4,4 ', 4 "tris (N- (3-methylphenyl) N-phenylamino) triphenylamine (m-MTDATA), porphyrin, tetraphenylporphyrin copper, phthalocyanine, copper phthalocyanine, titanium phthalocyanine oxide, etc. Compounds, triazole derivatives, oxazizazole derivatives, Midazole derivatives, polyarylalkane derivatives, pyrazoline derivatives, pyrazolone derivatives, phenylenediamine derivatives, arylamine derivatives, amino-substituted chalcone derivatives, oxazole derivatives, styrylanthracene derivatives, fluorenone derivatives, hydrazone derivatives, silazane derivatives, etc. can be used. As the molecular material, polymers such as phenylene vinylene, fluorene, carbazole, indole, pyrene, pyrrole, picoline, thiophene, acetylene, diacetylene, and derivatives thereof can be used. From the viewpoint of dark current suppression, the electron affinity of the n-type semiconductor used for the photoelectric conversion film and the electron block adjacent to the photoelectric conversion film can be used. The difference from the ionization potential of the material used for the rocking layer is preferably 1 eV or more When fullerene (C60) is used as the n-type semiconductor, the electron affinity of fullerene (C60) is 4.2 eV, so that adjacent electron blocking is performed. The material used for the layer preferably has an ionization potential of 5.2 eV or more, specifically, [0083] to [0089] of JP-A-2008-72090, and [0049] to [0049] of JP-A-2011-176259. [0063] The compounds described in JP2011-228614A [0121] to [0156] and JP2011-228615A [0108] to [0156] are preferred.

The electron blocking layer may be composed of a plurality of layers.
An inorganic material can also be used as the electron blocking layer. In general, since an inorganic material has a dielectric constant larger than that of an organic material, when used in an electron blocking layer, a large voltage is applied to the photoelectric conversion film, and the photoelectric conversion efficiency can be increased. Materials that can be used as an electron blocking layer include calcium oxide, chromium oxide, chromium oxide copper, manganese oxide, cobalt oxide, nickel oxide, copper oxide, gallium copper oxide, strontium copper oxide, niobium oxide, molybdenum oxide, indium copper oxide, and oxide. Examples include indium silver and iridium oxide. In the case where the electron blocking layer is a single layer, the layer can be a layer made of an inorganic material, or in the case of a plurality of layers, one or more layers can be a layer made of an inorganic material. .

(Hole blocking layer)
An electron-accepting organic material can be used for the hole blocking layer.
Examples of electron-accepting materials include 1,3-bis (4-tert-butylphenyl-1,3,4-oxadiazolyl) phenylene (OXD-7) and other oxadiazole derivatives, anthraquinodimethane derivatives, and diphenylquinone derivatives. , Bathocuproine, bathophenanthroline, and derivatives thereof, triazole compounds, tris (8-hydroxyquinolinato) aluminum complexes, bis (4-methyl-8-quinolinato) aluminum complexes, distyrylarylene derivatives, silole compounds, etc. Can do. Moreover, even if it is not an electron-accepting organic material, it can be used if it is a material which has sufficient electron transport property. A porphyrin compound or a styryl compound such as DCM (4-dicyanomethylene-2-methyl-6- (4- (dimethylaminostyryl))-4H pyran) or a 4H pyran compound can be used. Specifically, compounds described in [0073] to [0078] of JP-A-2008-72090 are preferable.

The method for producing the charge blocking layer is not particularly limited, and can be formed by a dry film forming method or a wet film forming method. As a dry film forming method, a vapor deposition method, a sputtering method, or the like can be used. The vapor deposition may be either physical vapor deposition (PVD) or chemical vapor deposition (CVD), but physical vapor deposition such as vacuum vapor deposition is preferred. As the wet film forming method, an inkjet method, a spray method, a nozzle printing method, a spin coating method, a dip coating method, a casting method, a die coating method, a roll coating method, a bar coating method, a gravure coating method, etc. can be used. From the viewpoint of high-precision patterning, the inkjet method is preferable.

The thickness of the charge blocking layer (electron blocking layer and hole blocking layer) is preferably 10 to 200 nm, more preferably 20 to 150 nm, and particularly preferably 30 to 50 nm. This is because if the thickness is too thin, the dark current suppressing effect is lowered, and if it is too thick, the photoelectric conversion efficiency is lowered.

<Board>
The photoelectric conversion element of the present invention may further include a substrate. The type of the substrate used is not particularly limited, and a semiconductor substrate, a glass substrate, or a plastic substrate can be used.
The position of the substrate is not particularly limited, but usually a conductive film, a photoelectric conversion film, and a transparent conductive film are laminated on the substrate in this order.

<Sealing layer>
The photoelectric conversion element of the present invention may further include a sealing layer. The performance of photoelectric conversion materials may deteriorate significantly due to the presence of deterioration factors such as water molecules. Ceramics such as dense metal oxides, metal nitrides, and metal nitride oxides that do not penetrate water molecules and diamond-like materials Covering and sealing the entire photoelectric conversion film with a sealing layer such as carbon (DLC) can prevent the deterioration.
The material for the sealing layer may be selected and manufactured according to paragraphs [0210] to [0215] of JP2011-082508A.

[Optical sensor]
Examples of the use of the photoelectric conversion element include a photovoltaic cell and an optical sensor, but the photoelectric conversion element of the present invention is preferably used as an optical sensor. As an optical sensor, the photoelectric conversion element used alone may be used, or a line sensor in which the photoelectric conversion elements are arranged linearly or a two-dimensional sensor arranged on a plane is preferable. The photoelectric conversion element of the present invention converts optical image information into an electrical signal using an optical system and a drive unit like a scanner in a line sensor, and optically converts optical image information like an imaging module in a two-dimensional sensor. The system functions as an image sensor by forming an image on a sensor and converting it into an electrical signal.
Since the photovoltaic cell is a power generation device, the efficiency of converting light energy into electrical energy is an important performance, but dark current, which is a current in a dark place, is not a functional problem. Further, a subsequent heating step such as installation of a color filter is not necessary. Since it is important for optical sensors to convert light and dark signals to electrical signals with high accuracy, the efficiency of converting light intensity into current is also important, but noise is generated when signals are output in the dark. Low dark current is required. In addition, resistance to subsequent processes is also important.

[Image sensor]
Next, a configuration example of an image sensor including the photoelectric conversion element 10a will be described.
In the configuration examples described below, members having the same configuration / action as those already described are denoted by the same or corresponding reference numerals in the drawings, and the description is simplified or omitted.
An image sensor is an element that converts optical information of an image into an electric signal. A plurality of photoelectric conversion elements are arranged on a matrix in the same plane, and an optical signal is converted into an electric signal in each photoelectric conversion element (pixel). That can be output to the outside of the imaging device for each pixel sequentially. Therefore, one pixel is composed of one photoelectric conversion element and one or more transistors.
FIG. 2 is a schematic cross-sectional view showing a schematic configuration of an image sensor for explaining an embodiment of the present invention. This imaging device is used by being mounted on an imaging device such as a digital camera or a digital video camera, an imaging module such as an electronic endoscope or a mobile phone, or the like.
This imaging element has a plurality of photoelectric conversion elements having the configuration shown in FIG. 1 and a circuit board on which a readout circuit for reading a signal corresponding to the charge generated in the photoelectric conversion film of each photoelectric conversion element is formed. A plurality of photoelectric conversion elements are arranged one-dimensionally or two-dimensionally on the same surface above the circuit board.

2 includes a substrate 101, an insulating layer 102, a connection electrode 103, a pixel electrode (lower electrode) 104, a connection portion 105, a connection portion 106, a photoelectric conversion film 107, and a counter electrode. (Upper electrode) 108, buffer layer 109, sealing layer 110, color filter (CF) 111, partition 112, light shielding layer 113, protective layer 114, counter electrode voltage supply 115, and readout circuit 116.

The pixel electrode 104 has the same function as the electrode 11 of the photoelectric conversion element 10a shown in FIG. The counter electrode 108 has the same function as the electrode 15 of the photoelectric conversion element 10a shown in FIG. The photoelectric conversion film 107 has the same configuration as the layer provided between the electrode 11 and the electrode 15 of the photoelectric conversion element 10a illustrated in FIG.

The substrate 101 is a glass substrate or a semiconductor substrate such as Si. An insulating layer 102 is formed on the substrate 101. A plurality of pixel electrodes 104 and a plurality of connection electrodes 103 are formed on the surface of the insulating layer 102.

The photoelectric conversion film 107 is a layer common to all the photoelectric conversion elements provided on the plurality of pixel electrodes 104 so as to cover them.

The counter electrode 108 is one electrode provided on the photoelectric conversion film 107 and common to all the photoelectric conversion elements. The counter electrode 108 is formed up to the connection electrode 103 disposed outside the photoelectric conversion film 107, and is electrically connected to the connection electrode 103.

The connection part 106 is embedded in the insulating layer 102 and is a plug or the like for electrically connecting the connection electrode 103 and the counter electrode voltage supply part 115. The counter electrode voltage supply unit 115 is formed on the substrate 101 and applies a predetermined voltage to the counter electrode 108 via the connection unit 106 and the connection electrode 103. When the voltage to be applied to the counter electrode 108 is higher than the power supply voltage of the image sensor, the power supply voltage is boosted by a booster circuit such as a charge pump to supply the predetermined voltage.

The readout circuit 116 is provided on the substrate 101 corresponding to each of the plurality of pixel electrodes 104, and reads out a signal corresponding to the charge collected by the corresponding pixel electrode 104. The readout circuit 116 is configured by, for example, a CCD, a CMOS circuit, a TFT circuit, or the like, and is shielded by a light shielding layer (not shown) disposed in the insulating layer 102. The readout circuit 116 is electrically connected to the corresponding pixel electrode 104 via the connection unit 105.

The buffer layer 109 is formed on the counter electrode 108 so as to cover the counter electrode 108. The sealing layer 110 is formed on the buffer layer 109 so as to cover the buffer layer 109. The color filter 111 is formed at a position facing each pixel electrode 104 on the sealing layer 110. The partition wall 112 is provided between the color filters 111 and is for improving the light transmission efficiency of the color filter 111.

The light shielding layer 113 is formed in a region other than the region where the color filter 111 and the partition 112 are provided on the sealing layer 110, and prevents light from entering the photoelectric conversion film 107 formed outside the effective pixel region. The protective layer 114 is formed on the color filter 111, the partition 112, and the light shielding layer 113, and protects the entire image sensor 100.

In the imaging device 100 configured as described above, when light is incident, the light is incident on the photoelectric conversion film 107, and charges are generated here. Holes in the generated charges are collected by the pixel electrode 104, and a voltage signal corresponding to the amount is output to the outside of the image sensor 100 by the readout circuit 116.

The manufacturing method of the image sensor 100 is as follows.
On the circuit board on which the common electrode voltage supply unit 115 and the readout circuit 116 are formed, the connection units 105 and 106, the plurality of connection electrodes 103, the plurality of pixel electrodes 104, and the insulating layer 102 are formed. The plurality of pixel electrodes 104 are arranged on the surface of the insulating layer 102 in a square lattice pattern, for example.

Next, a photoelectric conversion film 107 is formed on the plurality of pixel electrodes 104 by, for example, a vacuum heating deposition method. Next, the counter electrode 108 is formed on the photoelectric conversion film 107 under vacuum by, for example, sputtering. Next, the buffer layer 109 and the sealing layer 110 are sequentially formed on the counter electrode 108 by, for example, a vacuum heating deposition method. Next, after forming the color filter 111, the partition 112, and the light shielding layer 113, the protective layer 114 is formed, and the imaging element 100 is completed.

Even in the method of manufacturing the image sensor 100, a plurality of processes can be performed even when a step of placing the image sensor 100 being manufactured under non-vacuum is added between the process of forming the photoelectric conversion film 107 and the process of forming the sealing layer 110. The performance deterioration of the photoelectric conversion element can be prevented. By adding this step, it is possible to suppress the manufacturing cost while preventing the performance degradation of the image sensor 100.

Examples are shown below, but the present invention is not limited thereto.

<Example 1>
The following compound (1) (photoelectric conversion material) was synthesized according to the synthesis scheme shown below. The compound was identified by MS measurement and ¹ H-NMR measurement. FIG. 3 shows a ¹ H-NMR spectrum of the compound (1).

(Preparation of photoelectric conversion element)
Using the obtained photoelectric conversion material, a photoelectric conversion element in the form of FIG. Here, the photoelectric conversion element includes the lower electrode 11, the electron blocking layer 16 </ b> A, the photoelectric conversion film 12, and the upper electrode 15.
Specifically, an amorphous ITO film is formed on a glass substrate by sputtering to form the lower electrode 11 (thickness: 30 nm), and the following compound (EB-1) is vacuum-heated on the lower electrode 11 An electron blocking layer 16 </ b> A (thickness: 100 nm) was formed by a deposition method.
Furthermore, in a state where the temperature of the substrate is controlled at 25 ° C., the obtained photoelectric conversion material and fullerene (C ₆₀ ) are vacuum-heat-deposited on the electron blocking layer 16A so as to be 114 nm and 286 nm, respectively, in single layer conversion. The film was co-evaporated to form a photoelectric conversion film 12. Here, vapor deposition was performed by heating the crucible containing the obtained photoelectric conversion material (compound of the following (1)) under vacuum (degree of vacuum of 4 × 10 ⁻⁴ Pa or less). Moreover, it vapor-deposited so that the vapor deposition rate of the obtained photoelectric converting material (compound of following (1)) might be set to 0.4 (angstrom) / sec (0.4 * 10 < ^-10 > m / sec).
Further, an amorphous ITO film was formed on the photoelectric conversion film 12 by sputtering to form an upper electrode 15 (transparent conductive film) (thickness: 10 nm). An SiO film was formed as a sealing layer on the upper electrode 15 by heat evaporation, and then an aluminum oxide (Al ₂ O ₃ ) layer was formed thereon by ALCVD to produce a photoelectric conversion element (1st element).

Next, the crucible used when the 1st element was produced (the one containing the remaining photoelectric conversion material) was used as it was, and the deposition rate was 3.0 Å / second (3.0 × 10 ⁻¹⁰ m / second). Except for the above, a photoelectric conversion element (2nd) was produced according to the same procedure as the 1st element.

<Confirmation of element drive>
About the obtained photoelectric conversion element (1st element, 2nd element), it was confirmed whether it functions as a photoelectric conversion element. Specifically, a voltage was applied to the lower electrode and the upper electrode of the obtained photoelectric conversion element so that the electric field strength was 2.5 × 10 ⁵ V / cm, and the current values in the dark place and the bright place were determined. It was measured. As a result, although a dark current of 100 nA / cm ² or less was shown in the dark place, a current of 10 μA / cm ² or more was shown in the bright place, and it was confirmed that it functions as a photoelectric conversion element.

<Crucible residual purity maintenance ratio>
The material remaining in the crucible after producing the 1st element was subjected to HPLC measurement to determine the purity of the photoelectric conversion material (photoelectric conversion material of Example). Similarly, HPLC measurement of the material remaining in the crucible after producing the 2nd element was performed, and the purity of the photoelectric conversion material (photoelectric conversion material of the example) was obtained. And the "crucible residual purity maintenance ratio" was calculated | required from the following formula.
Crucible residual purity maintenance ratio = (purity after 2nd device fabrication) / (purity after 1st device fabrication)
The results are shown in Table 1. The higher the crucible residual purity maintenance rate, the better the heat resistance of the photoelectric conversion material. In practice, it is preferable that the residual crucible purity is 0.90 or more.

<Change in responsiveness (rise time to 98% signal strength)>
When an electric field of 1.5 × 10 ⁵ V / cm is applied to the photoelectric conversion element (1st element) and light is irradiated from the upper electrode (transparent conductive film) side, the photocurrent is measured and is 0 to 98%. The rise time to signal intensity (1st element) was determined. Similarly, the rise time (2nd element) from 0 to 98% signal intensity was determined for the photoelectric conversion element (2nd element). Then, “change in rise time” was obtained from the following equation.
Change in rise time = (rise time of 2nd element) / (rise time of 1st element)
The results are shown in Table 1. The smaller the rise time change, the better the deposition stability. Practically, the change in the rise time is preferably 1.20 or less.

<Examples 2 to 9, Comparative Examples 1 to 3>
By using a known method, the following compounds (2) to (9) (photoelectric conversion materials of Examples 2 to 9) and comparative compounds (1) to (3) (photovoltaic materials of Comparative Examples 1 to 3) Conversion material) was synthesized. The compound was identified by MS measurement and ¹ H-NMR measurement. 4, the ¹ H-NMR spectrum of the compound of the synthesized (5), a ¹ H-NMR spectrum of the compound of synthesized 5 (12).
Moreover, according to the procedure similar to Example 1 using each photoelectric conversion material, the photoelectric conversion element was produced and various evaluation was performed. The results are summarized in Table 1.
Note that it was confirmed from the confirmation of element driving that any element functions as a photoelectric conversion element.

As can be seen from Table 1, all of the examples of the present application which were the compound (A) exhibited excellent heat resistance and vapor deposition stability.
From the comparison of Examples 1 to 9, 11 and 12, Examples 1 to 9 and 11 in which Ar ¹¹ and Ar ¹² in the above formula (1) are both aryl groups which may have a substituent are more excellent. It showed high heat resistance and deposition stability. Among them, Examples 1 to 8 and 11 in which L ¹ in the above formula (2) is a single bond showed better vapor deposition stability. Among them, Examples 1, 2, 4 to 8 and 11 in which Ar ¹¹ and Ar ¹² in the above formula (1) are not bonded to each other to form a ring showed better heat resistance and vapor deposition stability. Among them, Examples 2 and 7 in which Ar ¹³ and / or Ar ¹⁴ in the above formula (2) are bonded to Ar ¹¹ and / or Ar ^{12 in} the above formula (1) to form a ring are as follows: Furthermore, it showed excellent heat resistance and deposition stability.
From the comparison between Examples 1 and 5 and the comparison between Examples 6 and 8, Examples 1 and 6 in which a and b in the above formula (3) are 0 are more excellent in heat resistance and vapor deposition. Showed stability.

On the other hand, Comparative Examples 1 to 4, which are compounds different from the compound (A), were insufficient in heat resistance and vapor deposition stability.

<Production of image sensor>
An image sensor similar to that shown in FIG. 2 was produced. That is, after forming amorphous TiN 30 nm on a CMOS substrate by sputtering, patterning is performed so that one pixel exists on each photodiode (PD) on the CMOS substrate by photolithography to form a lower electrode, After the formation of the electron blocking material, it was produced in the same manner as in Examples 1 to 9 and Comparative Examples 1 to 3. The evaluation was performed in the same manner, and the same results as in Table 1 were obtained.

10a, 10b Photoelectric conversion element 11 Lower electrode (conductive film)
12 Photoelectric conversion film 15 Upper electrode (transparent conductive film)
16A Electron blocking layer 16B Hole blocking layer 100 Image sensor 101 Substrate 102 Insulating layer 103 Connection electrode 104 Pixel electrode (lower electrode)
105 connecting portion 106 connecting portion 107 photoelectric conversion film 108 counter electrode (upper electrode)
109 Buffer layer 110 Sealing layer 111 Color filter (CF)
112 partition wall 113 light shielding layer 114 protective layer 115 counter electrode voltage supply unit 116 readout circuit

Claims (22)

1. The photoelectric conversion material which is a compound (A) represented by following formula (1).
   

   

   (In the formula (1), Ar ¹¹ and Ar ¹² represent an aryl group or a heteroaryl group which may have a substituent. At least one of Ar ¹¹ and Ar ¹² represents the following formula (2 Ar ¹¹ and Ar ¹² may be bonded to each other through a divalent organic group to form a ring.
   Z ₁ represents a ring containing at least three carbon atoms and a 5-membered ring, a 6-membered ring, or a condensed ring containing at least one of a 5-membered ring and a 6-membered ring. )
   

   

   (In the formula (2), Ar ¹³ and Ar ¹⁴ represent an aryl group or a heteroaryl group which may have a substituent. Ar ¹³ and / or Ar ¹⁴ represents Ar ¹¹ in the formula (1). or Ar ¹² and may be bonded to each other to form a ring.
   * Represents a binding position.
   L ¹ represents a single bond, an alkenylene group which may have a substituent, a divalent aryl group which may have a substituent, or a divalent heteroaryl group which may have a substituent. . When L ¹ is a single bond, the nitrogen atom in formula (2) is directly bonded to Ar ¹¹ and / or Ar ¹² . )
2. The photoelectric conversion material of Claim 1 whose said compound (A) is a compound (a1) represented by following formula (3).
   

   

   (In the formula (3), R ¹¹ to R ²⁴ represent a hydrogen atom or a substituent. At least one of R ¹¹ to R ²⁴ is a group represented by the following formula (4): R ¹⁷ and R ¹⁸ may be bonded to each other via a divalent organic group to form a ring.
   a and b represent an integer of 0 or more.
   Z ₁ represents a ring containing at least three carbon atoms and a 5-membered ring, a 6-membered ring, or a condensed ring containing at least one of a 5-membered ring and a 6-membered ring. )
   

   

   (In the formula (4), Ar ¹³ and Ar ¹⁴ represent an aryl group or a heteroaryl group which may have a substituent. Ar ¹³ and / or Ar ¹⁴ represents R ¹¹ in the formula (3). At least one of -R ²⁴ may be bonded to each other to form a ring.
   * Represents a binding position.
   L ¹ represents a single bond, an alkenylene group which may have a substituent, a divalent aryl group which may have a substituent, or a divalent heteroaryl group which may have a substituent. . When L ¹ is a single bond, the nitrogen atom in the formula (4) is directly bonded to at least one of R ¹¹ to R ²⁴ . )
3. The photoelectric conversion material according to claim 2, wherein at least one of R ¹⁴ and R ^{21 in} the formula (3) is a group represented by the formula (4).
4. The photoelectric conversion material according to any one of claims 1 to 3, wherein Z ₁ is a ring represented by the following formula (Z1).
   

   

   (In the formula (Z1), Z ₂ represents a ring containing at least 3 carbon atoms and represents a 5-membered ring, a 6-membered ring, or a condensed ring containing at least one of a 5-membered ring and a 6-membered ring. (* Represents a bonding position.)
5. The photoelectric conversion material according to any one of claims 2 to 4, wherein the compound (a1) is a compound (a2) represented by the following formula (5).
   

   

   (In formula (5), R ¹¹ to R ²⁴ represent a hydrogen atom or a substituent. At least one of R ¹¹ to R ²⁴ is a group represented by the following formula (6): R ¹⁷ and R ¹⁸ may be bonded to each other via a divalent organic group to form a ring.
   a and b represent an integer of 0 or more.
   R ⁵¹ to R ⁵⁴ represent a hydrogen atom or a substituent. R ⁵¹ and R ⁵² , R ⁵² and R ⁵³ , and R ⁵³ and R ⁵⁴ may be bonded to each other to form a ring. )
   

   

   (In the formula (6), Ar ¹³ and Ar ¹⁴ represent an aryl group or a heteroaryl group which may have a substituent. Ar ¹³ and / or Ar ¹⁴ represents R ¹¹ in the formula (5). At least one of -R ²⁴ may be bonded to each other to form a ring.
   * Represents a binding position.
   L ¹ represents a single bond, an alkenylene group which may have a substituent, a divalent aryl group which may have a substituent, or a divalent heteroaryl group which may have a substituent. . When L ¹ is a single bond, the nitrogen atom in the formula (6) is directly bonded to at least one of R ¹¹ to R ²⁴ . )
6. The photoelectric conversion material according to any one of claims 1 to 5, wherein Ar ¹³ and Ar ¹⁴ are aryl groups which may have a substituent.
7. The L ¹ is a single bond, a divalent aryl group which may have a substituent, or a divalent heteroaryl group which may have a substituent. The photoelectric conversion material according to item.
8. The photoelectric conversion material according to any one of claims 2 to 7, wherein a and b are 0.
9. The photoelectric conversion material according to any one of claims 1 to 8, wherein Ar ¹¹ and Ar ¹² are not bonded to each other to form a ring.
10. The photoelectric conversion material according to any one of claims 1 to 9, wherein Ar ¹³ and / or Ar ¹⁴ are bonded to Ar ¹¹ and / or Ar ¹² to form a ring.
11. A photoelectric conversion element using the photoelectric conversion material according to any one of claims 1 to 10.
12. A photoelectric conversion element comprising a conductive film, a photoelectric conversion film containing the photoelectric conversion material according to any one of claims 1 to 10, and a transparent conductive film in this order.
13. The photoelectric conversion element according to claim 12, wherein the photoelectric conversion film further contains an organic n-type semiconductor.
14. The photoelectric conversion element according to claim 13, wherein the organic n-type semiconductor contains fullerenes selected from the group consisting of fullerenes and derivatives thereof.
15. Content of the fullerenes relative to the total content of the compound (A) and the fullerenes (= film thickness in terms of a single layer of the fullerenes / (film thickness in terms of a single layer of the compound (A) + The photoelectric conversion element according to claim 14, wherein a film thickness of the fullerenes in terms of a single layer) is 50% by volume or more.
16. The photoelectric conversion element according to any one of claims 12 to 15, wherein an electron blocking layer is disposed between the conductive film and the transparent conductive film.
17. The photoelectric conversion element according to any one of claims 12 to 16, wherein the photoelectric conversion film is formed by a vacuum deposition method.
18. 18. The photoelectric conversion element according to claim 12, wherein light is incident on the photoelectric conversion film through the transparent conductive film.
19. The photoelectric conversion element according to any one of claims 12 to 18, wherein the transparent conductive film is made of a transparent conductive metal oxide.
20. An optical sensor including the photoelectric conversion element according to any one of claims 11 to 19.
21. An image pickup device comprising the photoelectric conversion device according to any one of claims 11 to 19.
22. A method for using the photoelectric conversion element according to any one of claims 12 to 19,
    A method for using a photoelectric conversion element, wherein the conductive film and the transparent conductive film are a pair of electrodes, and an electric field of 1 × 10 ⁻⁴ to 1 × 10 ⁷ V / cm is applied between the pair of electrodes.

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