Cyanine compounds and photoelectric conversion elements

Abstract

To provide a novel cyanine compound that more selectively absorbs incident light beyond 800 nm and also excels in light resistance and heat resistance.SOLUTION: Provided is a cyanine compound that is a counterion conjugate comprising an anion and a cation, the anion being represented by formula (I-1). (In formula (I-1), R1 and R2 each independently denote a hydrogen atom or a monovalent organic group; R3 and R4 each independently denote a monovalent group such as a phenyl group; X denotes a hydrogen atom, a halogen atom, or a monovalent organic group; and Y denotes a divalent group such as an n-propenyl group or the like).SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a cyanine compound and a photoelectric conversion element using the same. [Background technology]

[0002] Conventionally, technologies for converting visible light into an electric signal or electric energy by photoelectric conversion have been known. The former is widely used in imaging elements, and the latter is widely used in solar cells, etc. In addition, technologies for photoelectric conversion of near-infrared light are also used in dark cameras, various sensors for distance measurement, communication applications, analytical devices, etc.

[0003] On the other hand, it is expected that new value can be added to conventional technology by using elements that transmit visible light but selectively convert near-infrared light into electricity. For example, by placing such a photoelectric conversion element on the light-receiving front surface of an image sensor, it is possible to use the same element for imaging and sensing (e.g., 3D measurement) at the same time. This will enable the imaging element to be multi-functional, miniaturized, and cost-reduced. Alternatively, by placing such a photoelectric conversion element on the front surface of a display, it will be possible to simultaneously provide supplementary electrical energy for image display and realize power saving and battery-free operation when outdoors.

[0004] As a photoelectric conversion element that selectively converts near-infrared light into electricity, a stacked organic thin film element is promising in terms of the degree of freedom in designing organic materials, thin film thickness, and high sensitivity (quantum efficiency). For such a stacked organic thin film photoelectric conversion element, it is essential to use a material in the photosensitive portion that absorbs only near-infrared light and has minimal absorption in the visible light region. In addition to the above, such near-infrared absorbing materials can also be used in optical information recording media, organic solar cells, photosensitive materials for flash toner fixation, heat-shielding films, infrared cut filters, anti-counterfeiting inks, and preform heating aids for plastic bottles.

[0005] As an example of a laminated organic thin film element that absorbs only near-infrared light and transmits a portion of visible light, Patent Document 1 reports an example in which a metal naphthalocyanine derivative is used to selectively absorb light with a material having an absorption maximum wavelength in the range of 600 to 800 nm. Patent Documents 2 to 4 describe photoelectric conversion elements having an absorption maximum wavelength of around 700 nm in the range of visible light and near-infrared light combined. Of these, Patent Document 3 describes providing a material whose absorption intensity in the range of 400 to 550 nm is 1 / 10 or less of that in the near-infrared region. Non-Patent Document 1 describes a photoelectric conversion element in which a cyanine dye with specific absorption for near-infrared light is used in the photosensitive layer. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 186251 / 1983 [Patent Document 2] Patent No. 5270114 [Patent Document 3] Japanese Patent Application Laid-Open No. 2012-169676 [Patent Document 4] Japanese Patent Application Laid-Open No. 2017-34112 [Non-patent literature]

[0007] [Non-Patent Document 1] Org. Lett., Vol. 11, No. 21, 2009 Summary of the Invention [Problem to be solved by the invention]

[0008] However, silicon metal, a typical material for photoelectric conversion elements, is also sensitive to infrared light in the wavelength range of 600 to 800 nm, making it difficult to determine the superiority of the photoelectric conversion elements described in Patent Documents 1 to 4 over existing technologies. Furthermore, when a photoelectric conversion element is used as a light-receiving element for infrared LEDs or infrared lasers for imaging in dark places or three-dimensional distance measurement, the wavelength of the light-emitting device is generally 800 nm or longer. Therefore, using the elements described in Patent Documents 1 to 4 requires the use of special light-emitting devices, which leads to increased costs. Furthermore, the material and photoelectric conversion element described in Non-Patent Document 5 use a cyanine dye with a maximum wavelength of 800 nm or longer, and Non-Patent Document 5 describes its quantum efficiency. However, Non-Patent Document 5 does not describe the durability performance (e.g., light resistance and heat resistance) of the dye, which significantly affects the manufacturing process of the photoelectric conversion element or the durability of the element itself, making the practical feasibility unclear.

[0009] The present invention has been made in view of at least part of the above circumstances, and an object of the present invention is to provide a novel cyanine compound that selectively absorbs incident light having a wavelength exceeding 800 nm and has excellent light resistance and heat resistance, and a photoelectric conversion element using the cyanine compound. [Means for solving the problem]

[0010] As a result of extensive research aimed at achieving the above object, the present inventors have discovered a novel cyanine compound having an absorption maximum wavelength exceeding 800 nm, leading to the completion of the present invention.

[0011] That is, the present invention is as follows. [1] A cyanine compound which is a counterion bond consisting of an anion and a cation, wherein the anion is represented by the following formula (I-1): [ka] (In formula (I-1), R 1 and R 2each independently represents a hydrogen atom or a monovalent organic group, and R 3 and R 4 each independently represents a monovalent group represented by the following formula (I-1-1), X represents a hydrogen atom, a halogen atom or a monovalent organic group, and Y represents a divalent group represented by the following formula (I-1-2) or (I-1-3): [ka] (In formula (I-1-1), R a , R b , R c , R d and R e each independently represents a hydrogen atom, a monovalent hydrocarbon group, or a monovalent electron-withdrawing group; R a , R b , R c , R d and R e At least one of R represents the monovalent electron-withdrawing group; a , R b , R c , R d and R e When one of R is a halogen atom, the other R a , R b , R c , R d and R e At least one of the groups represents the monovalent hydrocarbon group or the monovalent electron-withdrawing group. [ka] (In formula (I-1-2), R f , R g , R h , R i , R j and R k each independently represents a hydrogen atom or a monovalent hydrocarbon group which may have an oxygen atom, a nitrogen atom or a sulfur atom. [ka] (In formula (I-1-3), R l , R m , R n and Ro each independently represents a hydrogen atom or a monovalent hydrocarbon group which may have an oxygen atom, a nitrogen atom or a sulfur atom. [2] The cyanine compound as described above, wherein the cation comprises at least one selected from the group consisting of alkali metal cations, alkaline earth metal cations, ammonium cations, sulfonium cations, phosphonium cations, and cationic cyanines. [3] The cyanine compound as described above, wherein the cation includes at least one selected from the group consisting of an alkali metal cation, an ammonium cation, and a cationic cyanine. [4] The above cyanine compound, wherein the cationic cyanine is a cation represented by the following formula (I-2-1), (I-2-2), (I-2-3), or (I-2-4): [ka] In formulas (I-2-1), (I-2-2), (I-2-3), and (I-2-4), E each independently represents a carbon atom, a nitrogen atom, an oxygen atom, or a sulfur atom; R p , R q , R r , R s , R t , R u , R v , R w and R x are each independently a hydrogen atom, a halogen atom, a hydroxyl group, a carboxyl group, a nitro group, an amino group, an amido group, an imido group, a cyano group, a silyl group, -L 1 , -SL 2 , -SS-L 2 , -SO2-L 3 , -N=NL 4 , or R q and R r , R s and R t , R t and R u , R u and R v , R v and R w and R w and R xand one or more groups selected from the group consisting of groups represented by the following formulae (A), (B), (C), (D), (E), (F), (G), and (H), to which one or more combinations of the following are bonded: The amino group, amido group, imido group and silyl group may be further substituted with one or more groups L selected from the group consisting of monovalent aliphatic hydrocarbon groups having 1 to 12 carbon atoms, monovalent halogen-substituted alkyl groups having 1 to 12 carbon atoms, monovalent alicyclic hydrocarbon groups having 3 to 14 carbon atoms, monovalent aromatic hydrocarbon groups having 6 to 14 carbon atoms, and monovalent heterocyclic groups having 3 to 14 carbon atoms; Said L 1 and L 4 represents a monovalent aliphatic hydrocarbon group having 1 to 12 carbon atoms, a monovalent halogen-substituted alkyl group having 1 to 12 carbon atoms, a monovalent alicyclic hydrocarbon group having 3 to 14 carbon atoms, a monovalent aromatic hydrocarbon group having 6 to 14 carbon atoms, or a heterocyclic group having 3 to 14 carbon atoms, each of which may be further substituted by the group L; Said L 2 represents a hydrogen atom, or a monovalent aliphatic hydrocarbon group having 1 to 12 carbon atoms, a monovalent halogen-substituted alkyl group having 1 to 12 carbon atoms, a monovalent alicyclic hydrocarbon group having 3 to 14 carbon atoms, a monovalent aromatic hydrocarbon group having 6 to 14 carbon atoms, or a heterocyclic group having 3 to 14 carbon atoms, which may be further substituted by the group L; Said L 3 represents a hydroxyl group, or a monovalent aliphatic hydrocarbon group having 1 to 12 carbon atoms, a monovalent halogen-substituted alkyl group having 1 to 12 carbon atoms, a monovalent alicyclic hydrocarbon group having 3 to 14 carbon atoms, a monovalent aromatic hydrocarbon group having 6 to 14 carbon atoms, or a heterocyclic group having 3 to 14 carbon atoms, which may be further substituted by the group L; Q 1 indicates an acetyl group, and Q 2 represents a structure represented by the following formula (q1), (q2), or (q3). [ka] (In formulas (A), (B), (C), (D), (E), (F), (G), and (H), the combination of Rx and Ry is R q and R r , R s and R t , Rt and R u , R u and R v , R v and R w or R w and R x It is a combination of R A , R B , R C , R D , R E , R F , R G , R H , R I , R J , R K and R L are each independently a hydrogen atom, a halogen atom, a hydroxyl group, a carboxyl group, a nitro group, an amino group, an amido group, an imido group, a cyano group, a silyl group, -L 1 , -SL 2 , -SS-L 2 , -SO2-L 3 or -N=NL 4 indicates L 1 , L 2 , L 3 and L 4 represents L in the formulas (I-2-1) and (I-2-2). 1 , L 2 , L 3 and L 4 The amino group, amido group, imido group and silyl group may be substituted with the group L. -C m H m+1 (q1) -C a H a+1 -OC b H b+1 (q2) (In formula (q1), m represents an integer of 1 to 5, and in formula (q2), a and b each represent an integer of 1 to 5.) [ka] In formula (q3), n represents an integer of 1 to 5, and T1, T2, T3, T4, and T5 each independently represent a hydrogen atom or —OC p H p+1and p represents an integer of 1 to 5. [5] R 1 and R 2 The above cyanine compound, wherein the monovalent organic group is a monovalent aliphatic hydrocarbon group having 1 to 12 carbon atoms, a monovalent halogen-substituted alkyl group having 1 to 12 carbon atoms, a monovalent alicyclic hydrocarbon group having 3 to 14 carbon atoms, a monovalent aromatic hydrocarbon group having 6 to 14 carbon atoms, or a heterocyclic group having 3 to 14 carbon atoms, which may be further substituted with a monovalent hydrocarbon group or a monovalent electron-withdrawing group. [6] R 1 and R 2 are each independently a hydrogen atom, a monovalent aliphatic hydrocarbon group having 1 to 3 carbon atoms, or a monovalent group represented by the formula (I-1-1). [7] The monovalent organic group in X is a hydroxyl group, a carboxyl group, a nitro group, an amino group, an amido group, an imido group, a cyano group, a silyl group, -L 1 , -SL 2 , -SS-L 3 , -SO2-L 3 , or -N=NL 4 indicates, The amino group, amido group, imido group and silyl group may be further substituted with one or more groups L selected from the group consisting of monovalent aliphatic hydrocarbon groups having 1 to 12 carbon atoms, monovalent halogen-substituted alkyl groups having 1 to 12 carbon atoms, monovalent alicyclic hydrocarbon groups having 3 to 14 carbon atoms, monovalent aromatic hydrocarbon groups having 6 to 14 carbon atoms, and monovalent heterocyclic groups having 3 to 14 carbon atoms; Said L 1 and L 4 represents a monovalent aliphatic hydrocarbon group having 1 to 12 carbon atoms, a monovalent halogen-substituted alkyl group having 1 to 12 carbon atoms, a monovalent alicyclic hydrocarbon group having 3 to 14 carbon atoms, a monovalent aromatic hydrocarbon group having 6 to 14 carbon atoms, or a heterocyclic group having 3 to 14 carbon atoms, each of which may be further substituted by the group L; Said L 2represents a hydrogen atom, or a monovalent aliphatic hydrocarbon group having 1 to 12 carbon atoms, a monovalent halogen-substituted alkyl group having 1 to 12 carbon atoms, a monovalent alicyclic hydrocarbon group having 3 to 14 carbon atoms, a monovalent aromatic hydrocarbon group having 6 to 14 carbon atoms, or a heterocyclic group having 3 to 14 carbon atoms, which may be further substituted by the group L; Said L 3 represents a hydroxyl group, or a monovalent aliphatic hydrocarbon group having 1 to 12 carbon atoms, a monovalent halogen-substituted alkyl group having 1 to 12 carbon atoms, a monovalent alicyclic hydrocarbon group having 3 to 14 carbon atoms, a monovalent aromatic hydrocarbon group having 6 to 14 carbon atoms, or a heterocyclic group having 3 to 14 carbon atoms, which may be further substituted with the group L; The cyanine compound described above. [8] The cyanine compound as described above, wherein X is a halogen atom. [9] R a , R b , R c , R d and R e wherein the monovalent hydrocarbon group is a monovalent aliphatic hydrocarbon group having 1 to 12 carbon atoms, a monovalent alicyclic hydrocarbon group having 3 to 14 carbon atoms, or a monovalent aromatic hydrocarbon group having 6 to 14 carbon atoms, which may be further substituted with one or more groups selected from the group consisting of monovalent aliphatic hydrocarbon groups having 1 to 12 carbon atoms, monovalent alicyclic hydrocarbon groups having 3 to 14 carbon atoms, and monovalent aromatic hydrocarbon groups having 6 to 14 carbon atoms.

[10] R a , R b , R c , R d and R e wherein the monovalent electron-withdrawing group is a halogen atom, a carboxy group, a nitro group, a cyano group, a group represented by -COR, a group represented by -CONR2, a group represented by -S2R, or a group represented by -S3R, and R is the same as the monovalent hydrocarbon group or is a hydrogen atom.

[11] R a , R b , R c , R d and R e each independently represents a hydrogen atom or a halogen atom, and R a , R b, R c , R d and R e The above cyanine compound, wherein two or more of the above are halogen atoms.

[12] R f , R g , R h , R i , R j , R k , R l , R m , R n and R o The above cyanine compound, wherein the monovalent hydrocarbon group which may have an oxygen atom, a nitrogen atom or a sulfur atom is a monovalent aliphatic hydrocarbon group having 1 to 12 carbon atoms, a monovalent alicyclic hydrocarbon group having 3 to 14 carbon atoms or a monovalent aromatic hydrocarbon group having 6 to 14 carbon atoms which may be further substituted with one or more groups selected from the group consisting of monovalent aliphatic hydrocarbon groups having 1 to 12 carbon atoms, monovalent alicyclic hydrocarbon groups having 3 to 14 carbon atoms and monovalent aromatic hydrocarbon groups having 6 to 14 carbon atoms, which may have an oxygen atom, a nitrogen atom or a sulfur atom.

[13] R f , R g , R h , R i , R j , R k , R l , R m , R n and R o each independently represents a hydrogen atom or a monovalent aliphatic hydrocarbon group having 1 to 12 carbon atoms.

[14] A photoelectric conversion element having an infrared photoelectric conversion unit including a pair of electrodes and an organic infrared photoelectric conversion film provided between the pair of electrodes, The organic infrared photoelectric conversion film comprises the cyanine compound.

[15] The photoelectric conversion element as described above, wherein the organic infrared photoelectric conversion film contains an organic n-type semiconductor and / or an organic p-type semiconductor.

[16] The photoelectric conversion element as described above, wherein the infrared photoelectric conversion section contains one or more layers selected from the group consisting of a hole transport layer, an electron transport layer, a hole blocking layer, and an electron blocking layer between the electrode and the organic infrared photoelectric conversion film.

[17] The photoelectric conversion element as described above, wherein the infrared photoelectric conversion section has a maximum absorption wavelength in the light absorption spectrum in the infrared region of 800 nm or more and 2500 nm or less.

[18] The photoelectric conversion element as described above, further comprising a visible photoelectric conversion section having sensitivity to light in the visible range. [Effects of the Invention]

[0012] According to the present invention, it is possible to provide a cyanine compound that selectively absorbs incident light exceeding 800 nm and has excellent light resistance and heat resistance, and a photoelectric conversion element using the cyanine compound. [Brief explanation of the drawings]

[0013] [Figure 1] FIG. 2 is a schematic cross-sectional view partially illustrating an example of a photoelectric conversion section of the present invention. [Figure 2] 1 is an absorption spectrum of an example of a cyanine compound of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0014] Hereinafter, a mode for carrying out the present invention (hereinafter simply referred to as "the present embodiment") will be described in detail with reference to the drawings as necessary, but the present invention is not limited to the present embodiment. The present invention can be modified in various ways without departing from the gist of the invention. In the drawings, the same elements are given the same reference numerals, and redundant explanations will be omitted. Furthermore, positional relationships such as up, down, left, and right are based on the positional relationships shown in the drawings unless otherwise specified. Furthermore, the dimensional ratios of the drawings are not limited to those shown.

[0015] (cyanine compounds) The cyanine compound of this embodiment is a counterion conjugate consisting of an anion and a cation, and the anion is represented by the following formula (I-1). [ka] Here, in formula (I-1), R 1 and R 2 each independently represents a hydrogen atom or a monovalent organic group, and R 3 and R 4 each independently represents a monovalent group represented by the following formula (I-1-1), X represents a hydrogen atom, a halogen atom or a monovalent organic group, and Y represents a divalent group represented by the following formula (I-1-2) or (I-1-3): [ka] Here, in formula (I-1-1), R a , R b , R c , R d and R e each independently represents a hydrogen atom, a monovalent hydrocarbon group, or a monovalent electron-withdrawing group; R a , R b , R c , R d and R e At least one of the above represents the monovalent electron-withdrawing group, and R a , R b , R c , R d and R e When one of R is a halogen atom, the other R a , R b , R c , R d and R e At least one of the groups represents the monovalent hydrocarbon group or the monovalent electron-withdrawing group. [ka] Here, in formula (I-1-2), R f , R g , R h , R i , R j and R k each independently represents a hydrogen atom or a monovalent hydrocarbon group which may have an oxygen atom, a nitrogen atom or a sulfur atom. [ka] Here, in formula (I-1-3), R l , R m , R n and R o each independently represents a hydrogen atom or a monovalent hydrocarbon group which may have an oxygen atom, a nitrogen atom or a sulfur atom.

[0016] (anion) The anion in this embodiment is represented by the above formula (I-1). 1 , R 2 , R 3 , R 4 The total number of carbon atoms of each of X and Y, including substituents, is preferably 60 or less, more preferably 50 or less, and particularly preferably 40 or less. When the number of carbon atoms is within this range, the synthesis of the cyanine compound becomes easier and the absorption intensity per unit weight tends to be higher.

[0017] R 1 and R 2 The monovalent organic group in is not particularly limited, and examples thereof include a monovalent aliphatic hydrocarbon group having 1 to 12 carbon atoms, which may be further substituted with a monovalent hydrocarbon group or a monovalent electron-withdrawing group, a monovalent halogen-substituted alkyl group having 1 to 12 carbon atoms, a monovalent alicyclic hydrocarbon group having 3 to 14 carbon atoms, a monovalent aromatic hydrocarbon group having 6 to 14 carbon atoms, or a heterocyclic group having 3 to 14 carbon atoms.

[0018] Examples of the monovalent aliphatic hydrocarbon group having 1 to 12 carbon atoms include alkyl groups such as methyl (Me), ethyl (Et), n-propyl (n-Pr), isopropyl (i-Pr), n-butyl (n-Bu), sec-butyl (s-Bu), tert-butyl (t-Bu), pentyl, hexyl, octyl, nonyl, decyl, and dodecyl; alkenyl groups such as vinyl, 1-propenyl, 2-propenyl, butenyl, 1,3-butadienyl, 2-methyl-1-propenyl, 2-pentenyl, hexenyl, and octenyl; and alkynyl groups such as ethynyl, propynyl, butynyl, 2-methyl-1-propynyl, hexynyl, and octynyl. Among these, monovalent aliphatic hydrocarbon groups having 1 to 3 carbon atoms are preferred, and specifically, alkyl groups having 1 to 3 carbon atoms such as a methyl group (Me), an ethyl group (Et), an n-propyl group (n-Pr), and an isopropyl group (i-Pr) are preferred.

[0019] Examples of the monovalent halogen-substituted alkyl group having 1 to 12 carbon atoms include monovalent halogen-substituted alkyl groups having 1 to 3 carbon atoms. More specific examples of such halogen-substituted alkyl groups include a trichloromethyl group, a trifluoromethyl group, a 1,1-dichloroethyl group, a pentachloroethyl group, a pentafluoroethyl group, a heptachloropropyl group, and a heptafluoropropyl group.

[0020] Examples of the monovalent alicyclic hydrocarbon group having 3 to 14 carbon atoms include monovalent alicyclic hydrocarbon groups having 4 to 10 carbon atoms. More specific examples of such alicyclic hydrocarbon groups include cycloalkyl groups such as a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, and a cyclooctyl group; and polycyclic alicyclic groups such as a norbornane group and an adamantane group.

[0021] Examples of the monovalent aromatic hydrocarbon group having 6 to 14 carbon atoms include a phenyl group, a tolyl group, a xylyl group, a mesityl group, a cumenyl group, a 1-naphthyl group, a 2-naphthyl group, an anthracenyl group, a phenanthryl group, an acenaphthyl group, a phenalenyl group, a tetrahydronaphthyl group, an indanyl group, and a biphenylyl group. The aromatic hydrocarbon group may also be a monovalent group represented by formula (I-1-1) described in detail later, in which case R 1 and R 3 Or R 2 and R 4 may be the same or different from each other.

[0022] Examples of the heterocyclic group having 3 to 14 carbon atoms include groups consisting of heterocycles such as furan, thiophene, pyrrole, pyrazole, imidazole, triazole, oxazole, oxadiazole, thiazole, thiadiazole, indole, indoline, indolenine, benzofuran, benzothiophene, carbazole, dibenzofuran, dibenzothiophene, pyridine, pyrimidine, pyrazine, pyridazine, quinoline, isoquinoline, acridine, morpholine, and phenazine.

[0023] The monovalent hydrocarbon group as a substituent is not particularly limited, and examples thereof include monovalent aliphatic hydrocarbon groups having 1 to 12 carbon atoms, monovalent alicyclic hydrocarbon groups having 3 to 14 carbon atoms, and monovalent aromatic hydrocarbon groups having 6 to 14 carbon atoms. Examples and preferred embodiments of these are the same as those described above, and therefore further explanation will be omitted here.

[0024] The monovalent electron-withdrawing group as a substituent is not particularly limited as long as it is a monovalent group that exhibits electron-withdrawing properties in the anion of this embodiment. Here, whether or not the substituent is an "electron-withdrawing group" can be determined as follows. That is, for an anionic molecule having the substituent, molecular simulation using density functional theory (e.g., molecular simulation using Gaussian, a quantum chemistry calculation program manufactured by Gaussian) is performed to optimize the structure, and the electron affinity or ionization energy is determined. This is referred to as the electron affinity or ionization energy before substitution. Next, for an anionic molecule in which the substituent of the above-mentioned anionic molecule is substituted with a hydrogen atom or a monovalent hydrocarbon group, the electron affinity or ionization energy is determined in the same manner. This is referred to as the electron affinity or ionization energy after substitution. If the electron affinity or ionization energy after substitution is greater than the electron affinity or ionization energy before substitution, the substituent is determined to be an electron-withdrawing group. Such monovalent electron-withdrawing groups will be described in detail later, and therefore will not be described here.

[0025] In the monovalent group represented by the above formula (I-1-1), R a , R b , R c , R d and R e (Hereafter, simply "R a ~R e ". Each of the groups R independently represents a hydrogen atom, a monovalent hydrocarbon group, or a monovalent electron-withdrawing group. a ~R e At least one of R represents the monovalent electron-withdrawing group, that is, the monovalent group represented by the formula (I-1-1) necessarily has a monovalent electron-withdrawing group. a ~R e When one of R is a halogen atom, the other R a ~R e At least one of R represents the monovalent hydrocarbon group or the monovalent electron-withdrawing group. a ~R e When one of R is a halogen atom, the other R a ~R eThere is no embodiment in which all of are hydrogen atoms. As the monovalent hydrocarbon group, the same groups as those mentioned above can be used, and therefore, the explanation here will be omitted.

[0026] The monovalent electron-withdrawing group is not particularly limited as long as it is a monovalent group that exhibits electron-withdrawing properties in the anion of this embodiment. Examples of such monovalent electron-withdrawing groups include a halogen atom, a carboxy group (-COOH), a nitro group (-NO), a cyano group (-CN), a group represented by -COR, a group represented by -CONR, a group represented by -SOR, or a group represented by -SOR. Here, R is a hydrogen atom or a monovalent hydrocarbon group, and the monovalent hydrocarbon group has the same meaning as the monovalent hydrocarbon group described above, so a detailed description thereof will be omitted here.

[0027] Examples of halogen atoms include fluorine atom (F), chlorine atom (Cl), bromine atom (Br) and iodine atom (I).

[0028] Examples of the group (acyl group) represented by —COR include an acetyl group, a propionyl group, a butyryl group, an isobutyryl group, a benzoyl group, an acryloyl group, and a methacryloyl group, where R may have 1 to 6 carbon atoms.

[0029] Examples of the group (amide group) represented by -CONR2 include an amide group, a methylamide group, a dimethylamide group, a diethylamide group, a dipropylamide group, a diisopropylamide group, and a dibutylamide group. The group represented by -CONR2 here may be a lactam in which one of the Rs is bonded to a carbon atom of a carboxy group. Examples of lactams include an α-lactam group, a β-lactam group, a γ-lactam group, and a δ-lactam group. Here, the number of carbon atoms in R may be 1 to 4.

[0030] Examples of the group represented by —SO 2 R include a mesyl group, an ethylsulfonyl group, an n-butylsulfonyl group, a phenylsulfonyl group, and a p-toluenesulfonyl group, where R may have 1 to 7 carbon atoms.

[0031] Examples of groups represented by -SO3R include sulfo groups (-SO3H), methylsulfonic acid groups (-SO3CH3), ethylsulfonic acid groups (-SO3C2H5), n-butylsulfonic acid groups (-SO3C3H7), and phenylsulfonic acid groups (-SO3C6H5). Here, the number of carbon atoms in R may be 1 to 6.

[0032] In this embodiment, from the viewpoint of more selectively absorbing incident light exceeding 800 nm, R a ~R e Preferably, two or more of R are electron-withdrawing groups, more preferably three or more of R are electron-withdrawing groups, and particularly preferably all of R are electron-withdrawing groups. From the same viewpoint, the electron-withdrawing group is preferably a halogen atom, and R a ~R e When two or more of the groups are electron-withdrawing groups, it is more preferable that all of them are halogen atoms.

[0033] R in the above formula (I-1-1) a ~R e For the combination of a ~R e At least one of the groups represents the monovalent electron-withdrawing group, and R a ~R e If one of the R is a halogen atom, the other R a ~R e Any combination of the above-exemplified substituents may be used as long as one or more of the above represents the monovalent hydrocarbon group or the monovalent electron-withdrawing group.

[0034] X represents a hydrogen atom, a halogen atom, or a monovalent organic group, of which a halogen atom is preferred. As the halogen atom, the same as those mentioned above can be used, and therefore further explanation will be omitted here.

[0035] The monovalent organic group for X is not particularly limited, but examples thereof include a hydroxyl group, a carboxyl group, a nitro group, an amino group, an amide group, an imide group, a cyano group, a silyl group, -L1 , -SL 2 , -SS-L 3 , -SO2-L 3 , or -N=NL 4 The amino group, amido group, imido group and silyl group may be further substituted with one or more groups L selected from the group consisting of monovalent aliphatic hydrocarbon groups having 1 to 12 carbon atoms, monovalent halogen-substituted alkyl groups having 1 to 12 carbon atoms, monovalent alicyclic hydrocarbon groups having 3 to 14 carbon atoms, monovalent aromatic hydrocarbon groups having 6 to 14 carbon atoms and monovalent heterocyclic groups having 3 to 14 carbon atoms.

[0036] Also, L 1 and L 4 is a monovalent aliphatic hydrocarbon group having 1 to 12 carbon atoms, a monovalent halogen-substituted alkyl group having 1 to 12 carbon atoms, a monovalent alicyclic hydrocarbon group having 3 to 14 carbon atoms, a monovalent aromatic hydrocarbon group having 6 to 14 carbon atoms, or a heterocyclic group having 3 to 14 carbon atoms, which may be further substituted with a group L. 2 is a hydrogen atom, or a monovalent aliphatic hydrocarbon group having 1 to 12 carbon atoms, a monovalent halogen-substituted alkyl group having 1 to 12 carbon atoms, a monovalent alicyclic hydrocarbon group having 3 to 14 carbon atoms, a monovalent aromatic hydrocarbon group having 6 to 14 carbon atoms, or a heterocyclic group having 3 to 14 carbon atoms, which may be further substituted with a group L. 3 is a hydroxyl group, or a monovalent aliphatic hydrocarbon group having 1 to 12 carbon atoms, a monovalent halogen-substituted alkyl group having 1 to 12 carbon atoms, a monovalent alicyclic hydrocarbon group having 3 to 14 carbon atoms, a monovalent aromatic hydrocarbon group having 6 to 14 carbon atoms, or a monovalent heterocyclic group having 3 to 14 carbon atoms, which may be further substituted with a group L.

[0037] Examples of the monovalent aliphatic hydrocarbon group having 1 to 12 carbon atoms, the monovalent halogen-substituted alkyl group having 1 to 12 carbon atoms, the monovalent alicyclic hydrocarbon group having 3 to 14 carbon atoms, the monovalent aromatic hydrocarbon group having 6 to 14 carbon atoms, and the monovalent heterocyclic group having 3 to 14 carbon atoms include the same groups as those described above, and therefore further description thereof will be omitted here.

[0038] The monovalent aliphatic hydrocarbon group having 1 to 12 carbon atoms which may be further substituted with a group L is preferably a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, a sec-butyl group, a tert-butyl group, a pentyl group, a hexyl group, an octyl group, a 4-phenylbutyl group, or a 2-cyclohexylethyl group, and more preferably a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, a sec-butyl group, a tert-butyl group, or a hexyl group.

[0039] The monovalent halogen-substituted alkyl group having 1 to 12 carbon atoms which may be further substituted with a group L is preferably a trichloromethyl group, a pentachloroethyl group, a trifluoromethyl group, a pentafluoroethyl group, or a 5-cyclohexyl-2,2,3,3-tetrafluoropentyl group, and more preferably a trichloromethyl group, a pentachloroethyl group, a trifluoromethyl group, or a pentafluoroethyl group.

[0040] The monovalent alicyclic hydrocarbon group having 3 to 14 carbon atoms which may be further substituted with a group L is preferably a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, a 4-ethylcyclohexyl group, a cyclooctyl group, or a 4-phenylcycloheptyl group, more preferably a cyclopentyl group, a cyclohexyl group, or a 4-ethylcyclohexyl group.

[0041] The monovalent aromatic hydrocarbon group having 6 to 14 carbon atoms which may be further substituted with a group L is preferably a phenyl group, a 1-naphthyl group, a 2-naphthyl group, a tolyl group, a xylyl group, a mesityl group, a cumenyl group, a 3,5-di-tert-butylphenyl group, a 4-cyclopentylphenyl group, a 2,3,6-triphenylphenyl group, or a 2,3,4,5,6-pentaphenylphenyl group, more preferably a phenyl group, a tolyl group, a xylyl group, a mesityl group, a cumenyl group, or a 2,3,4,5,6-pentaphenylphenyl group.

[0042] The monovalent heterocyclic group having 3 to 14 carbon atoms which may be further substituted with a group L is preferably a group consisting of furan, thiophene, pyrrole, indole, indoline, indolenine, benzofuran, benzothiophene, or morpholine, and more preferably a group consisting of furan, thiophene, pyrrole, or morpholine.

[0043] The monovalent aliphatic hydrocarbon group having 1 to 12 carbon atoms, the monovalent halogen-substituted alkyl group having 1 to 12 carbon atoms, the monovalent alicyclic hydrocarbon group having 3 to 14 carbon atoms, the monovalent aromatic hydrocarbon group having 6 to 14 carbon atoms, or the heterocyclic group having 3 to 14 carbon atoms, which may be further substituted with a group L, may further have one or more groups selected from the group consisting of a halogen atom, a sulfo group, a hydroxyl group, a cyano group, a nitro group, a carboxy group, a phosphate group, and an amino group. Examples of these include 4-sulfobutyl, 4-cyanobutyl, 5-carboxypentyl, 5-aminopentyl, 3-hydroxypropyl, 2-phosphorylethyl, 6-amino-2,2-dicyclohexyl, 2-chloro-4-hydroxybutyl, 2-cyanocyclobutyl, 3-hydroxycyclopentyl, 3-carboxycyclopentyl, 4-aminocyclohexyl, 4-hydroxycyclohexyl, 4-hydroxyphenyl, 2-hydroxynaphthyl, 4-aminophenyl, 2,3,4,5,6-pentafluorophenyl, 4-nitrophenyl, 3-methylpyrrole, 2-hydroxyethoxy, 3-cyanopropoxy, 4-fluorobenzoyl, 2-hydroxyethoxycarbonyl, and 4-cyanobutoxycarbonyl.

[0044] Examples of the amino group which may have a group L include an amino group, an ethylamino group, a dimethylamino group, a methylethylamino group, a dibutylamino group, and a diisopropylamino group.

[0045] Examples of the amide group which may have the group L include an amide group, a methylamide group, a dimethylamide group, a diethylamide group, a dipropylamide group, a diisopropylamide group, a dibutylamide group, an α-lactam group, a β-lactam group, a γ-lactam group, and a δ-lactam group.

[0046] Examples of the imido group which may have the group L include an imido group, a methylimido group, an ethylimido group, a diethylimido group, a dipropylimido group, a diisopropylimido group, and a dibutylimido group.

[0047] Examples of the silyl group which may have the group L include a trimethylsilyl group, a tert-butyldimethylsilyl group, a triphenylsilyl group, and a triethylsilyl group.

[0048] Y represents a divalent group represented by the above formula (I-1-2) or (I-1-3). f , R g , R h , R i , R j and R k (Hereafter, simply "R f ~R k ") each independently represent a hydrogen atom or a monovalent hydrocarbon group which may have an oxygen atom, a nitrogen atom or a sulfur atom. In formula (I-1-3), R l , R m , R n and R o (Hereafter, simply "R l ~R o ") each independently represent a hydrogen atom or a monovalent hydrocarbon group which may have an oxygen atom, a nitrogen atom or a sulfur atom.

[0049] Examples of the monovalent hydrocarbon group which may have an oxygen atom, a nitrogen atom, or a sulfur atom include a monovalent aliphatic hydrocarbon group having 1 to 12 carbon atoms, a monovalent alicyclic hydrocarbon group having 3 to 14 carbon atoms, or a monovalent aromatic hydrocarbon group having 6 to 14 carbon atoms, which may be further substituted with one or more groups selected from the group consisting of a monovalent aliphatic hydrocarbon group having 1 to 12 carbon atoms, a monovalent alicyclic hydrocarbon group having 3 to 14 carbon atoms, and a monovalent aromatic hydrocarbon group having 6 to 14 carbon atoms, which may have an oxygen atom, a nitrogen atom, or a sulfur atom.

[0050] Examples of monovalent hydrocarbon groups that do not contain oxygen atoms, nitrogen atoms, or sulfur atoms, more specifically, monovalent aliphatic hydrocarbon groups having 1 to 12 carbon atoms, monovalent alicyclic hydrocarbon groups having 3 to 14 carbon atoms, and monovalent aromatic hydrocarbon groups having 6 to 14 carbon atoms, as well as monovalent aliphatic hydrocarbon groups having 1 to 12 carbon atoms, monovalent alicyclic hydrocarbon groups having 3 to 14 carbon atoms, and monovalent aromatic hydrocarbon groups having 6 to 14 carbon atoms as substituents, include the same monovalent hydrocarbon groups as described above, and therefore further description here will be omitted.

[0051] Examples of monovalent hydrocarbon groups containing an oxygen atom, a nitrogen atom, or a sulfur atom include monovalent aliphatic hydrocarbon groups having 1 to 12 carbon atoms, monovalent alicyclic hydrocarbon groups having 3 to 14 carbon atoms, and monovalent aromatic hydrocarbon groups having 6 to 14 carbon atoms, which may be further substituted with one or more groups selected from the group consisting of monovalent aliphatic hydrocarbon groups having 1 to 12 carbon atoms, monovalent alicyclic hydrocarbon groups having 3 to 14 carbon atoms, and monovalent aromatic hydrocarbon groups having 6 to 14 carbon atoms, and which contain one or more groups selected from the group consisting of oxygen atoms, nitrogen atoms, and sulfur atoms (hereinafter, in the description of Y, these will be simply referred to as "substituents"). Examples of groups containing an oxygen atom include groups containing a hydroxyl group, an ether group, a carbonyl group, or a carboxy group. Examples of groups containing a nitrogen atom include groups containing a cyano group or an amino group. Examples of groups containing a sulfur atom include groups containing a thioether group. Examples of groups containing both an oxygen atom and a nitrogen atom include groups containing a nitro group. An example of a compound having an oxygen atom and a sulfur atom is a compound having a sulfo group.

[0052] The monovalent hydrocarbon group which may have a hydrogen atom, an oxygen atom, a nitrogen atom, or a sulfur atom is preferably a hydrogen atom or a monovalent aliphatic hydrocarbon group having 1 to 12 carbon atoms, and the monovalent aliphatic hydrocarbon group having 1 to 12 carbon atoms is more preferably a monovalent aliphatic hydrocarbon group having 1 to 6 carbon atoms, and even more preferably a monovalent aliphatic hydrocarbon group having 1 to 4 carbon atoms.

[0053] R f ~R k and R l ~R o Preferred combinations include, for example, the combinations shown in the table below. [Table 1]

[0054] (cation) The cation in this embodiment is not particularly limited, but preferably includes at least one selected from the group consisting of alkali metal cations, alkaline earth metal cations, ammonium cations, sulfonium cations, phosphonium cations, and cationic cyanines, and more preferably includes at least one selected from the group consisting of alkali metal cations, ammonium cations, and cationic cyanines.

[0055] Examples of alkali metal cations include lithium cations (Li + ), sodium cation (Na + ), potassium cation (K + ), rubidium cation (Rb + ) and cesium cation (Cs + ) are listed.

[0056] Examples of alkaline earth metal cations include beryllium cations (Be 2+ ), magnesium cation (Mg 2+ ), calcium cation (Ca 2+ ), strontium cation (Sr 2+) and barium cation (Ba 2+ ) are listed.

[0057] The ammonium cation is ammonium ion (NH4 + ), primary ammonium cation (NH3R + ), secondary ammonium cation (NH2R2 + ), tertiary ammonium cation (NHR3 + ) and quaternary ammonium cations such as tetraalkylammonium cations, typified by tetrabutylammonium cation (HR4 + Here, R represents a monovalent aliphatic hydrocarbon group having 1 to 12 carbon atoms, such as an alkyl group having 1 to 12 carbon atoms, a monovalent alicyclic hydrocarbon group having 3 to 14 carbon atoms, or a monovalent aromatic hydrocarbon group having 6 to 14 carbon atoms.

[0058] The sulfonium cation is a sulfonium ion (SH3 + ), primary sulfonium cation (SH2R + ), secondary sulfonium cation (SHR2 + ) and tertiary sulfonium cations (SR3 + Here, R represents a monovalent aliphatic hydrocarbon group having 1 to 12 carbon atoms, such as an alkyl group having 1 to 12 carbon atoms, a monovalent alicyclic hydrocarbon group having 3 to 14 carbon atoms, or a monovalent aromatic hydrocarbon group having 6 to 14 carbon atoms.

[0059] The phosphonium cation is phosphonium ion (PH4 + ), primary phosphonium cation (PH3R + ), secondary phosphonium cation (PH2R2 + ), tertiary phosphonium cation (PHR3 + ) and quaternary phosphonium cations (PR4 + Here, R represents a monovalent aliphatic hydrocarbon group having 1 to 12 carbon atoms, such as an alkyl group having 1 to 12 carbon atoms, a monovalent alicyclic hydrocarbon group having 3 to 14 carbon atoms, or a monovalent aromatic hydrocarbon group having 6 to 14 carbon atoms.

[0060] Examples of cationic cyanines include cations represented by the following formulas (I-2-1), (I-2-2), (I-2-3) and (I-2-4). [ka] In the formulae (I-2-1), (I-2-2), (I-2-3) and (I-2-4), E each independently represents a carbon atom, a nitrogen atom, an oxygen atom or a sulfur atom. p , R q , R r , R s , R t , R u , R v , R w and R x are each independently a hydrogen atom, a halogen atom, a hydroxyl group, a carboxyl group, a nitro group, an amino group, an amido group, an imido group, a cyano group, a silyl group, -L 1 , -SL 2 , -SS-L 2 , -SO2-L 3 , -N=NL 4 , or R q and R r , R s and R t , R t and R u , R u and R v , R v and R w and R w and R x and a combination of one or more of the following is bonded to the group consisting of groups represented by the following formulae (A), (B), (C), (D), (E), (F), (G), and (H):

[0061] The amino group, amido group, imido group and silyl group may be further substituted with one or more groups L selected from the group consisting of monovalent aliphatic hydrocarbon groups having 1 to 12 carbon atoms, monovalent halogen-substituted alkyl groups having 1 to 12 carbon atoms, monovalent alicyclic hydrocarbon groups having 3 to 14 carbon atoms, monovalent aromatic hydrocarbon groups having 6 to 14 carbon atoms and monovalent heterocyclic groups having 3 to 14 carbon atoms.

[0062] L 1 and L 4 is a monovalent aliphatic hydrocarbon group having 1 to 12 carbon atoms, a monovalent halogen-substituted alkyl group having 1 to 12 carbon atoms, a monovalent alicyclic hydrocarbon group having 3 to 14 carbon atoms, a monovalent aromatic hydrocarbon group having 6 to 14 carbon atoms, or a heterocyclic group having 3 to 14 carbon atoms, which may be further substituted with a group L.

[0063] L 2 is a hydrogen atom, or a monovalent aliphatic hydrocarbon group having 1 to 12 carbon atoms, a monovalent halogen-substituted alkyl group having 1 to 12 carbon atoms, a monovalent alicyclic hydrocarbon group having 3 to 14 carbon atoms, a monovalent aromatic hydrocarbon group having 6 to 14 carbon atoms, or a heterocyclic group having 3 to 14 carbon atoms, which may be further substituted with a group L.

[0064] L 3 is a hydroxyl group, or a monovalent aliphatic hydrocarbon group having 1 to 12 carbon atoms, a monovalent halogen-substituted alkyl group having 1 to 12 carbon atoms, a monovalent alicyclic hydrocarbon group having 3 to 14 carbon atoms, a monovalent aromatic hydrocarbon group having 6 to 14 carbon atoms, or a heterocyclic group having 3 to 14 carbon atoms, which may be further substituted with a group L.

[0065] Q 1 indicates an acetyl group, and Q 2 represents a structure represented by the following formula (q1), (q2) or (q3). [ka] In the formulas (A), (B), (C), (D), (E), (F), (G), and (H), the combination of Rx and Ry is R q and R r , R s and R t , R t and R u , R u and R v , R v and R w or R w and R x It is a combination of:

[0066] R A , RB , R C , R D , R E , R F , R G , R H , R I , R J , R K and R L are each independently a hydrogen atom, a halogen atom, a hydroxyl group, a carboxyl group, a nitro group, an amino group, an amido group, an imido group, a cyano group, a silyl group, -L 1 , -SL 2 , -SS-L 2 , -SO2-L 3 or -N=NL 4 Indicates L 1 , L 2 , L 3 and L 4 represents L in the above formulas (I-2-1) and (I-2-2). 1 , L 2 , L 3 and L 4 The amino group, the amido group, the imido group and the silyl group may be substituted with a group L. -C m H m+1 (q1) -C a H a+1 -OC b H b+1 (q2) Here, in formula (q1), m represents an integer of 1 to 5, and in formula (q2), a and b each represent an integer of 1 to 5. [ka] In formula (q3), n represents an integer of 1 to 5, and T1, T2, T3, T4, and T5 each independently represent a hydrogen atom or -OC p H p+1 and p represents an integer of 1 to 5.

[0067] The aliphatic hydrocarbon group having 1 to 12 carbon atoms, the halogen-substituted alkyl group having 1 to 12 carbon atoms, the alicyclic hydrocarbon group having 3 to 14 carbon atoms, the aromatic hydrocarbon group having 6 to 14 carbon atoms, and the heterocyclic group having 3 to 14 carbon atoms, which may have a group L, each preferably has a total carbon number including substituents of 50 or less, more preferably 40 or less, and particularly preferably 30 or less. When the carbon number is within this range, the synthesis of the cyanine compound becomes easier and the absorption intensity per unit weight tends to be higher.

[0068] Examples of the aliphatic hydrocarbon group having 1 to 12 carbon atoms, the halogen-substituted alkyl group having 1 to 12 carbon atoms, the alicyclic hydrocarbon group having 3 to 14 carbon atoms, the aromatic hydrocarbon group having 6 to 14 carbon atoms, the heterocyclic group having 3 to 14 carbon atoms, and the group L are the same as those described above, and therefore further explanation will be omitted here.

[0069] -SL 2 Examples of the alkyl group include a thiol group, a methyl sulfide group, an ethyl sulfide group, a propyl sulfide group, a butyl sulfide group, an isobutyl sulfide group, a sec-butyl sulfide group, a tert-butyl sulfide group, a phenyl sulfide group, a 2,6-di-tert-butylphenyl sulfide group, a 2,6-diphenylphenyl sulfide group, and a 4-cumylphenyl sulfide group.

[0070] -SS-L 2 Examples of the disulfide group include a disulfide group, a methyl disulfide group, an ethyl disulfide group, a propyl disulfide group, a butyl disulfide group, an isobutyl disulfide group, a sec-butyl disulfide group, a tert-butyl disulfide group, a phenyl disulfide group, a 2,6-di-tert-butylphenyl disulfide group, a 2,6-diphenylphenyl disulfide group, and a 4-cumylphenyl disulfide group.

[0071] -SO2-L 3 Examples of the sulfonyl group include a sulfoxyl group, a mesyl group, an ethylsulfonyl group, an n-butylsulfonyl group, and a p-toluenesulfonyl group.

[0072] -N=NL 4 Examples of the azo group include a methylazo group, a phenylazo group, a p-methylphenylazo group, and a p-dimethylaminophenylazo group.

[0073] The anion in the cyanine compound of this embodiment can be prepared according to or with reference to the methods described in the Examples below, and the cation in the cyanine compound of this embodiment can be prepared by conventionally known methods.

[0074] The cyanine compound of this embodiment, particularly by containing the above-mentioned anion, is likely to have an absorption maximum wavelength exceeding 800 nm, and thus can more selectively absorb incident light exceeding 800 nm (particularly infrared light) while suppressing absorption of visible light. This is thought to be due to the fact that the above-mentioned anion has a structure that tends to narrow the energy gap, but the cause is not limited to this. Furthermore, the cyanine compound of this embodiment, particularly by containing the above-mentioned anion, is likely to exhibit higher durability (e.g., light resistance and heat resistance). This is due to the fact that the above-mentioned anion has a molecular orbital that is more stable, and in particular, R 1 ~R 4 When the compound is bulky, it is thought that this is because it inhibits the approach of active oxygen and the like to the methine moiety, which is susceptible to autoxidation, thereby suppressing the deterioration of the anion, but the factors are not limited to these.

[0075] (Photoelectric conversion element) The photoelectric conversion element of this embodiment has a photoelectric conversion unit (hereinafter also referred to as an infrared photoelectric conversion unit) that generates charges according to the amount of incident light in the infrared range, and outputs the generated charges to the outside of the photoelectric conversion element via a capacitor (also referred to as a storage unit) for storing the generated charges and a transistor circuit (also referred to as a readout unit) for reading them out. Here, the infrared photoelectric conversion unit refers to an organic infrared photoelectric conversion film disposed between a pair of opposing electrodes, and light is incident on the photoelectric conversion unit from above the electrodes. Furthermore, the organic infrared photoelectric conversion film is a photosensitive thin film containing a material that absorbs at least a portion of incident light in the infrared range (hereinafter referred to as an "organic infrared absorbing material"), and generates holes and electrons as a result of the incident light.

[0076] (organic infrared absorbing material) The organic infrared absorbing material in this embodiment contains the above-mentioned cyanine compound.

[0077] The organic infrared-absorbing material in this embodiment preferably has a maximum absorption wavelength in the infrared region of its light absorption spectrum of 800 nm to 2500 nm. That is, when the organic infrared-absorbing material is formed into an organic photoelectric conversion film in a thin film state, the light absorption peak exhibits a maximum absorption peak in the wavelength range of 800 nm to 2500 nm. In particular, the absorptance of the infrared light absorption peak is preferably 50% or more.

[0078] Furthermore, it is preferable that the organic infrared absorbing material in this embodiment has minimal absorption in wavelength regions other than 800 nm to 2500 nm. However, the organic infrared absorbing material in this embodiment exhibits a maximum absorption wavelength and a maximum absorption wavelength in the light absorption spectrum in the infrared region of 800 nm to 2500 nm, but when used as a photoelectric conversion element, it is sufficient that the material achieves absorption of these wavelengths in a solid state. In general, the higher the molar absorption coefficient of the photoelectric conversion material used in the photoelectric conversion element, the more the sensitivity can be improved, so it is preferable that the molar absorption coefficient is high.

[0079] The organic infrared-absorbing material in this embodiment may be composed solely of the cyanine compound, or may contain other known infrared-absorbing substances, such as cyanine compounds other than those listed above, squarylium compounds, croconium compounds, immonium compounds, dithiolene compounds, bisdithiolene compounds, porphyrin compounds, phthalocyanine compounds, naphthalocyanine compounds, BODIPY compounds, and quaterrylene diimide.

[0080] (organic infrared photoelectric conversion film) The organic infrared photoelectric conversion film used in the photoelectric conversion element of this embodiment can be obtained by thinning the organic infrared absorbing material. Methods for forming the organic infrared photoelectric conversion film in this embodiment include general dry film formation methods and wet film formation methods. Specific examples of such formation methods include vacuum processes such as resistance heating evaporation, electron beam evaporation, sputtering, and molecular lamination; solution processes such as casting, spin coating, dip coating, blade coating, wire bar coating, and spray coating; printing methods such as inkjet printing, screen printing, offset printing, and relief printing; and soft lithography methods such as microcontact printing. A combination of these methods may be used to form each layer.

[0081] For example, in a dry film-forming method, the cyanine compound of this embodiment and, if necessary, a compound appropriate for the application of the photoelectric conversion element are mixed to form a composition, and the composition is vapor-deposited under vacuum onto an electrode or an organic thin film layer described below, thereby obtaining an organic infrared photoelectric conversion film. In a wet film-forming method, the cyanine compound of this embodiment and, if necessary, a compound appropriate for the application of the photoelectric conversion element are mixed with a solvent to form a liquid composition, which is coated or printed on an electrode or an organic thin film, and then dried, thereby obtaining an organic infrared photoelectric conversion film.

[0082] The thickness of the organic infrared photoelectric conversion film prepared to contain the above cyanine compound cannot be limited because it depends on the resistance value and charge mobility of each substance, but is usually 0.5 nm or more and 5000 nm or less, preferably 1 nm or more and 1000 nm or less, and more preferably 5 nm or more and 500 nm or less.

[0083] The organic infrared photoelectric conversion film of this embodiment may contain an organic substance other than the cyanine compound. Among these, a p-type and / or n-type organic semiconductor is preferred because it can convert incident light energy into an electrical signal more efficiently. Among these, an organic p-type semiconductor that readily donates electrons (has a small ionization potential) or an organic n-type semiconductor that readily accepts electrons (has a large electron affinity) is preferred because it can convert incident light energy into an electrical signal more efficiently. More specifically, the ionization potential (HOMO level) of the thin film solid is preferably −5.5 eV or higher. Furthermore, the electron affinity (LUMO level) of the thin film solid is preferably −3.0 eV or lower. Here, the ionization potential (HOMO level) refers to a value measured by photoelectron yield spectroscopy in air. Furthermore, the electron affinity (LUMO level) refers to a value obtained by subtracting the energy band gap calculated from the longest wavelength absorption edge of the near-infrared spectrum from the HOMO level.

[0084] When an organic semiconductor is used, both an embodiment in which the cyanine compound of the present embodiment and an organic semiconductor are mixed and used, and an embodiment in which a layer made only of the cyanine compound of the present embodiment (hereinafter referred to as a "cyanine compound layer") and a layer made only of an organic semiconductor (hereinafter referred to as an "organic semiconductor layer") are multilayered and used.

[0085] When an organic semiconductor layer is used, the layer may be one layer or two or more layers. The organic semiconductor layer may be an organic p-type semiconductor film, an organic n-type semiconductor film, or a mixed film thereof (bulk heterostructure). In particular, the organic semiconductor layer preferably has a bulk heterojunction structure layer. In such a case, by incorporating a bulk heterojunction structure into the organic infrared photoelectric conversion film, the drawback of the organic infrared photoelectric conversion film being short in carrier diffusion length can be compensated for, and the photoelectric conversion efficiency can be improved.

[0086] When the cyanine compound layer and the organic semiconductor layer are used in combination, the thickness of the laminate obtained by laminating them cannot be limited because it depends on the resistivity and charge mobility of each substance, but it is usually 0.5 nm to 5000 nm, preferably 1 nm to 1000 nm, and more preferably 5 to 500 nm. In this case, the organic semiconductor layer preferably has about 2 to 10 layers.

[0087] The organic semiconductor will be described in detail below.

[0088] (organic p-type semiconductor) An organic p-type semiconductor (compound) is a donor organic semiconductor (hereinafter also referred to as a "donor organic compound"), and is mainly represented by a hole-transporting organic compound, and refers to an organic compound that has the property of readily donating electrons. More specifically, it refers to the organic compound that has the smaller ionization potential when two organic materials are used in contact. Therefore, any organic compound that has electron-donating properties can be used as a donor organic compound.

[0089] Examples of such donor organic compounds include triarylamine compounds, benzidine compounds, pyrazoline compounds, styrylamine compounds, hydrazone compounds, triphenylmethane compounds, carbazole compounds, polysilane compounds, thiophene compounds, phthalocyanine compounds, cyanine compounds, merocyanine compounds, oxonol compounds, polyamine compounds, indole compounds, pyrrole compounds, pyrazole compounds, polyarylene compounds, fused aromatic carbon ring compounds (naphthalene derivatives, anthracene derivatives, phenanthrene derivatives, tetracene derivatives, pyrene derivatives, perylene derivatives, fluoranthene derivatives), and metal complexes having nitrogen-containing heterocyclic compounds as ligands. Note that, without being limited to these, as described above, any organic compound having a smaller ionization potential than the organic compound used as the acceptor organic compound can be used as the donor organic semiconductor.

[0090] (organic n-type semiconductor) An organic n-type semiconductor (compound) is an acceptor organic semiconductor (hereinafter also referred to as an "acceptor organic compound"), and is mainly represented by an electron-transporting organic compound, and refers to an organic compound that has the property of readily accepting electrons. More specifically, when two organic compounds are used in contact with each other, it refers to the organic compound that has the greater electron affinity. Therefore, any organic compound that has electron-accepting properties can be used as an acceptor organic compound.

[0091] Examples of such acceptor organic compounds include fused aromatic carbocyclic compounds (naphthalene derivatives, anthracene derivatives, phenanthrene derivatives, tetracene derivatives, pyrene derivatives, perylene derivatives, fluoranthene derivatives, and fullerene derivatives), 5- to 7-membered heterocyclic compounds containing a nitrogen atom, an oxygen atom, or a sulfur atom (e.g., pyridine, pyrazine, pyrimidine, pyridazine, triazine, quinoline, quinoxaline, quinazoline, phthalazine, cinnoline, isoquinoline, pteridine, acridine, phenazine, phenanthroline, tetrazole, pyridine, and the like). Examples of the metal complexes having as a ligand include azole, imidazole, thiazole, oxazole, indazole, benzimidazole, benzotriazole, benzoxazole, benzothiazole, carbazole, purine, triazolopyridazine, triazolopyrimidine, tetrazaindene, oxadiazole, imidazopyridine, pyrazine, pyrrolopyridine, thiadiazolopyridine, dibenzazepine, and tribenzazepine), polyarylene compounds, fluorene compounds, cyclopentadiene compounds, silyl compounds, and nitrogen-containing heterocyclic compounds. Note that, without being limited to these, as described above, any organic compound having a larger electron affinity than the organic compound used as the donor organic compound can be used as the acceptor organic semiconductor.

[0092] (Infrared photoelectric conversion section) The infrared photoelectric conversion unit in this embodiment has a pair of electrodes and the organic infrared photoelectric conversion film provided between the pair of electrodes. This infrared photoelectric conversion unit may use an organic thin film layer in addition to the pair of electrodes and the organic infrared photoelectric conversion film. This infrared photoelectric conversion unit may have, as layers other than the organic infrared photoelectric conversion film, for example, an electron transport layer, a hole transport layer, an electron blocking layer, a hole blocking layer, an electron injection layer, a hole injection layer, a crystallization prevention layer, and an interlayer contact improving layer. It is particularly preferable for the infrared photoelectric conversion unit to have one or more layers selected from the group consisting of an electron transport layer, a hole transport layer, an electron blocking layer, and a hole blocking layer, because this allows for a device that can more efficiently convert even weak light energy into an electrical signal.

[0093] FIG. 1 is a cross-sectional schematic diagram partially illustrating an example of an infrared photoelectric conversion unit in this embodiment. The infrared photoelectric conversion unit 100 shown in FIG. 1 includes an organic infrared photoelectric conversion film 110 containing an organic infrared-absorbing material, a hole transport layer 120 and an electron transport layer 130 stacked so as to sandwich the organic infrared photoelectric conversion film 110, and electrodes 140 and 150 stacked so as to further sandwich them. This infrared photoelectric conversion unit 100 can selectively photoelectrically convert infrared wavelengths of 800 nm or more from incident light containing visible light and infrared light, mainly because the organic infrared photoelectric conversion film contains the organic infrared-absorbing material. Below, each component included in the infrared photoelectric conversion unit 100 will be described in detail.

[0094] (electrode) When the organic infrared photoelectric conversion film included in the infrared photoelectric conversion section has hole transport properties or when an organic thin film layer other than the organic infrared photoelectric conversion film is a hole transport layer having hole transport properties, the electrode plays a role of extracting holes from the organic infrared photoelectric conversion film and other organic thin film layers and collecting them. Also, when the organic infrared photoelectric conversion film included in the infrared photoelectric conversion section has electron transport properties or when an organic thin film layer other than the organic infrared photoelectric conversion film is an electron transport layer having electron transport properties, the electrode plays a role of extracting electrons from the organic infrared photoelectric conversion film and other organic thin film layers and ejecting them.

[0095] Materials that can be used as electrodes are not particularly limited as long as they have a certain degree of conductivity. However, it is preferable to select a material taking into consideration factors such as adhesion to adjacent organic infrared photoelectric conversion films and other organic thin film layers, electron affinity, ionization potential, and stability. Materials that can be used as electrodes include, for example, conductive metal oxides such as tin oxide (NESA), indium oxide, indium tin oxide (ITO), and indium zinc oxide (IZO); metals such as gold, silver, platinum, chromium, aluminum, iron, cobalt, nickel, and tungsten; inorganic conductive materials such as copper iodide and copper sulfide; conductive polymers such as polythiophene, polypyrrole, and polyaniline; and carbon. These materials may be used alone or in combination, or two or more layers of multiple materials may be stacked. The thickness of the electrode can be selected arbitrarily taking into consideration conductivity, but may be from 5 nm to 500 nm, preferably from 10 nm to 300 nm.

[0096] The conductivity of the material used for the electrode is not particularly limited as long as it does not unnecessarily interfere with the light reception of the photoelectric conversion element, but it is preferable that the conductivity be as high as possible from the viewpoint of the signal strength and power consumption of the photoelectric conversion element. For example, an ITO film having a conductivity of 300 Ω / □ or less as a transparent electrode will function satisfactorily as an electrode. However, commercially available substrates with ITO films having a conductivity of several Ω / □ (e.g., 5 to 9 Ω / □) are also available, and substrates with such high conductivity are desirable.

[0097] When an ITO film is used, the thickness of the electrode can be selected arbitrarily taking into account conductivity, but is usually 5 nm to 3000 nm, preferably 10 nm to 300 nm. Methods for forming ITO films include conventionally known vapor deposition methods, electron beam methods, sputtering methods, chemical reaction methods, and coating methods. The ITO film provided on the substrate may be subjected to UV-ozone treatment or plasma treatment, if necessary.

[0098] Furthermore, when multiple organic infrared photoelectric conversion films with different detection wavelengths are stacked, the electrode film (this is an electrode film other than the pair of electrodes) used between each organic infrared photoelectric conversion film needs to transmit light of wavelengths other than the light detected by each organic infrared photoelectric conversion film. From this perspective, it is preferable to use a material for the electrode film that transmits 90% or more of the incident light, and more preferably a material that transmits 95% or more of the light.

[0099] Furthermore, when a photoelectric conversion unit that senses light in the visible light range is further provided below the infrared photoelectric conversion unit in this embodiment, the electrode used in the infrared photoelectric conversion unit preferably has a transmittance of 90% or more for visible light and infrared light, and more preferably 95% or more.

[0100] A preferred electrode material that satisfies these conditions is a transparent conducting oxide (TCO), which has high transmittance to visible light and infrared light and low resistance. Thin metal films such as Au can also be used as electrodes, but increasing transmittance to 90% or more results in a dramatic increase in resistance. Therefore, TCO is preferred as the electrode. Particularly preferred TCO materials are ITO, IZO, AZO, FTO, SnO2, TiO2, and ZnO2.

[0101] The method for forming the electrode is not particularly limited and can be appropriately selected taking into consideration the suitability for the electrode material. When a transparent electrode is used, specific examples of the formation method 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 a transparent conductive metal oxide such as ITO, examples of the formation method include electron beam deposition, sputtering, resistance heating deposition, chemical reaction methods (such as the sol-gel method), and coating a dispersion of the metal oxide. Furthermore, a film of a transparent conductive metal oxide such as ITO can also be subjected to UV-ozone treatment and plasma treatment.

[0102] Next, the organic thin film layers other than the organic infrared photoelectric conversion film will be described.

[0103] The electron transport layer serves to transport electrons generated in the organic infrared photoelectric conversion film to the electrode and to block holes from moving from the electrode to which the electrons are transported to the organic infrared photoelectric conversion film.

[0104] The hole transport layer serves to transport generated holes from the organic infrared photoelectric conversion film to the electrode, and to block electrons from moving from the electrode to which the holes have been transported to the organic infrared photoelectric conversion film.

[0105] The electron blocking layer prevents electrons from moving from the electrode to the organic infrared photoelectric conversion film, prevents recombination within the organic infrared photoelectric conversion film, reduces dark current, reduces noise, and expands the dynamic range.

[0106] The hole-blocking layer has the functions of preventing the movement of holes from the electrode to the organic infrared photoelectric conversion film, preventing recombination within the organic infrared photoelectric conversion film, reducing dark current, reducing noise, and expanding the dynamic range.

[0107] (Hole transport layer) The material for the hole transport layer is not particularly limited as long as it is known as a material for a hole transport layer in a photoelectric conversion element such as a solid-state imaging element, and examples thereof include polyaniline and doped materials thereof, and the cyanide compounds described in WO 2006 / 019270.

[0108] More specifically, materials constituting the hole transport layer include selenium, iodides such as copper iodide (CuI), cobalt complexes such as layered cobalt oxides, CuSCN, molybdenum oxide (MoO, etc.), nickel oxide (NiO, etc.), 4CuBr·3S (C4H9), and organic hole transport materials. Among these, an example of an iodide is copper iodide (CuI). An example of a layered cobalt oxide is AxCoO2 (where A represents Li, Na, K, Ca, Sr, or Ba, and 0≦X≦1). Examples of organic hole transport materials include polythiophene derivatives such as poly-3-hexylthiophene (P3HT), poly(3,4-ethylenedioxythiophene), and PEDOT (for example, trade name "Baytron P" manufactured by Starck-V-Tech), fluorene derivatives such as 2,2',7,7'-tetrakis-(N,N-di-p-methoxyphenylamine)-9,9'-spirobifluorene (spiro-MeO-TAD), carbazole derivatives such as polyvinylcarbazole, triphenylamine derivatives, diphenylamine derivatives, polysilane derivatives, and polyaniline derivatives. Further, examples of materials for the hole transport layer include compound semiconductors containing monovalent copper, such as CuInSe2 and copper sulfide (CuS), gallium phosphide (GaP), nickel oxide (NiO), cobalt oxide (CoO), iron oxide (FeO), bismuth oxide (Bi2O3), molybdenum oxide (MoO2), and chromium oxide (Cr2O3).

[0109] Furthermore, it is preferable that the hole transport layer has a LUMO level shallower than that of the organic infrared photoelectric conversion film, since this layer has a rectifying effect that suppresses the movement of electrons generated in the organic infrared photoelectric conversion film toward the electrode, thereby imparting an electron blocking function. Such a hole transport layer is also called an electron blocking layer.

[0110] Among the materials constituting the electron blocking layer, examples of low molecular weight organic compounds include aromatic diamine compounds such as N,N'-bis(3-methylphenyl)-(1,1'-biphenyl)-4,4'-diamine (TPD) and 4,4'-bis[N-(naphthyl)-N-phenyl-amino]biphenyl (α-NPD), oxazole, oxadiazole, triazole, imidazole, imidazolone, stilbene derivatives, pyrazoline derivatives, tetrahydroimidazole, polyarylalkane, butadiene, methyl methacrylate ... Dienes, 4,4',4" tris(N-(3-methylphenyl)N-phenylamino)triphenylamine (m-MTDATA), porphyrins, tetraphenylporphyrin copper, phthalocyanines, porphyrin compounds such as copper phthalocyanine and titanium phthalocyanine oxide, triazole derivatives, oxadiazole derivatives, imidazole derivatives, polyarylalkane derivatives, pyrazoline derivatives, pyrazolone derivatives, phenylenediamine derivatives, arylamine derivatives, amino-substituted Examples of suitable materials for the electron blocking layer include chalcone derivatives, oxazole derivatives, styrylanthracene derivatives, fluorenone derivatives, hydrazone derivatives, and silazane derivatives. Examples of suitable polymeric organic compounds include polymers of phenylene vinylene, fluorene, carbazole, indole, pyrene, pyrrole, picoline, thiophene, acetylene, and diacetylene, as well as their derivatives. Even if the compound is not an electron-donating compound, any compound with sufficient hole transport properties can be used as a material for the electron blocking layer. Examples of suitable inorganic compounds for the electron blocking layer include metal oxides such as 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, as well as selenium, tellurium, and antimony sulfide. These compounds may be used alone or in combination of two or more.

[0111] From the viewpoint of suppressing dark current and preventing a decrease in photoelectric conversion efficiency, the thickness of the hole transport layer is preferably 10 nm or more and 300 nm or less, more preferably 30 nm or more and 250 nm or less, and even more preferably 50 nm or more and 200 nm or less.

[0112] The hole transport layer may be formed by a conventional method, such as a dry film-forming method like vacuum deposition, or a wet film-forming method like solution coating. However, wet film-forming methods are preferred because they allow for leveling of the coating surface. Examples of dry film-forming methods include vapor deposition methods like vacuum deposition and sputtering. Vapor deposition may be either physical vapor deposition (PVD) or chemical vapor deposition (CVD), with physical vapor deposition like vacuum deposition being preferred. Examples of wet film-forming methods include inkjet printing, spraying, nozzle printing, spin coating, dip coating, casting, die coating, roll coating, bar coating, and gravure coating.

[0113] (electron transport layer) The material for the electron transport layer is not particularly limited as long as it is known as an electron transport layer in a photoelectric conversion element such as a solid-state imaging element. Examples of the material include organic compounds such as octaazaporphyrin, perfluorinated p-type semiconductors (perfluoropentacene, perfluorophthalocyanine, etc.), fullerene, fullerene derivatives (e.g., [6,6]-phenyl-C61-butylic acid methyl ester; PCBM), perylene, indenoindene, and indenoindene derivatives, and inorganic oxides such as titanium oxide (TiO2, etc.), nickel oxide (NiO), tin oxide (SnO2), tungsten oxide (WO2, WO3, W2O3, etc.), zinc oxide (ZnO), niobium oxide (Nb2O5, etc.), tantalum oxide (Ta2O5, etc.), yttrium oxide (YO3, etc.), and strontium titanate (SrTiO3, etc.). The electron transport layer may be porous or dense, and when they are laminated, it is preferable that the porous electron transport layer and the dense electron transport layer are laminated in this order from the organic infrared photoelectric conversion film side.

[0114] Furthermore, it is preferable that the electron transport layer has a HOMO level deeper than that of the organic infrared photoelectric conversion film, because this layer has a rectifying effect that inhibits the migration of holes generated in the organic infrared photoelectric conversion film toward the counter electrode, thereby imparting a hole-blocking function. Such an electron transport layer is also called a hole-blocking layer.

[0115] Examples of materials constituting the hole blocking layer include oxadiazole derivatives such as 1,3-bis(4-tert-butylphenyl-1,3,4-oxadiazolyl)phenylene (OXD-7), anthraquinodimethane derivatives, diphenylquinone derivatives, bathocuproine, bathophenanthroline, and derivatives thereof, triazole compounds, tris(8-hydroxyquinolinato)aluminum complexes, bis(4-methyl-8-quinolinato)aluminum complexes, silole compounds, porphyrins, etc. Examples of suitable materials include styryl compounds such as styrene-based compounds, styryl compounds such as DCM (4-dicyanomethylene-2-methyl-6-(4-(dimethylaminostyryl))-4H-pyran), n-type semiconductor materials such as naphthalene tetracarboxylic anhydride, naphthalene tetracarboxylic diimide, perylene tetracarboxylic anhydride, and perylene tetracarboxylic diimide, n-type inorganic oxides such as titanium oxide, zinc oxide, and gallium oxide, and alkali metal fluorides such as lithium fluoride, sodium fluoride, and cesium fluoride. Furthermore, alkali metal compounds doped with organic semiconductor molecules are also preferred because they have the function of improving electrical connection with the counter electrode. These may be used alone or in combination of two or more.

[0116] From the viewpoint of suppressing dark current and preventing a decrease in photoelectric conversion efficiency, the thickness of the electron transport layer is preferably 10 nm or more and 300 nm or less, more preferably 30 nm or more and 250 nm or less, and even more preferably 50 nm or more and 200 nm or less.

[0117] The electron transport layer may be formed by a conventional method, such as a dry film-forming method like vacuum deposition, or a wet film-forming method like solution coating. However, wet film-forming methods are preferred because they allow for leveling of the coating surface. Examples of dry film-forming methods include vapor deposition methods like vacuum deposition and sputtering. Vapor deposition may be either physical vapor deposition (PVD) or chemical vapor deposition (CVD), with physical vapor deposition like vacuum deposition being preferred. Examples of wet film-forming methods include inkjet printing, spraying, nozzle printing, spin coating, dip coating, casting, die coating, roll coating, bar coating, and gravure coating.

[0118] (Interlayer contact improvement layer) The interlayer contact-improving layer functions to reduce damage to the film immediately below the upper electrode, such as an organic infrared photoelectric conversion film, during deposition of the upper electrode. In particular, high-energy particles present in the equipment used to deposit the upper electrode, such as sputtered particles, secondary electrons, Ar particles, and negative oxygen ions, can collide with the film immediately below, potentially resulting in performance degradation such as increased leakage current and reduced sensitivity. To prevent this, it is preferable to provide an interlayer contact-improving layer on top of the film immediately below. Preferred materials for the interlayer contact-improving layer include organic compounds such as copper phthalocyanine, PTCDA, acetylacetonate complex, and BCP, as well as organic-metal compounds and inorganic compounds such as MgAg and MgO. The appropriate thickness of the interlayer contact-improving layer varies depending on the composition of the photoelectric conversion film and the thickness of the electrode. However, a thickness of 2 nm to 50 nm is preferred, particularly from the viewpoint of selecting a material that does not absorb light in the visible range or using an extremely thin layer.

[0119] The photoelectric conversion element of this embodiment has an infrared photoelectric conversion unit that generates charges according to the amount of incident light in the infrared range. The generated charges are read out by a semiconductor as a signal according to the amount of charge. To this end, a capacitor for storing the generated charges (hereinafter also referred to as the "storage unit") and a transistor circuit for reading out the charges (hereinafter also referred to as the "readout unit") are connected to the photoelectric conversion element via connecting parts made of conductive materials. Furthermore, if necessary, the photoelectric conversion element may include a substrate for maintaining strength, a microlens for focusing light, etc.

[0120] (Storage section, readout section, and connection section) The readout section is provided to read out a signal corresponding to the charge generated in the organic infrared photoelectric conversion film. The readout section is composed of, for example, a CCD, CMOS circuit, or TFT circuit, and is preferably shielded from light by a light-shielding layer disposed within the insulating layer. The readout circuit is electrically connected to its corresponding electrode via a connection section. To ensure the amount of charge required for readout, a storage section composed of a capacitor or the like may be interposed between the electrode and the connection section. The connection section is embedded in the insulating layer and is, for example, a plug for electrically connecting an electrode (e.g., a transparent electrode or a counter electrode) to the readout section. When a component configured in this manner is a solid-state imaging element, when light is incident, the light is incident on the organic infrared photoelectric conversion film, where charge is generated. Electrons from the generated charge are collected (and stored) by one of the electrodes, and a voltage signal corresponding to the amount is output from the solid-state imaging element by the readout section.

[0121] (Visible light electric conversion part) The photoelectric conversion element of this embodiment preferably has a visible photoelectric conversion unit having an absorption spectrum in the visible light range, from the viewpoint of improving the sensitivity of photoelectric conversion and from the viewpoint of improving the image processing speed when infrared imaging or position information using infrared light is used in combination with visible imaging. When the infrared photoelectric conversion unit transmits light in the visible range, such as when the photoelectric conversion element of this embodiment has a transparent electrode, this visible photoelectric conversion unit can be provided below the infrared photoelectric conversion unit to photoelectrically convert the transmitted light in the visible light range and sense visible light and infrared light simultaneously.

[0122] The visible photoelectric conversion unit may sense light in the visible light range using a conventionally known silicon photodiode or a device having an organic photoelectric conversion material sensitive to visible light (for example, the device described in JP 2013-258168 A). For color imaging, a color filter or the like may be provided on the visible photoelectric conversion unit, or organic photoelectric conversion layers with different visible light wavelength sensitivities may be stacked.

[0123] The photoelectric conversion element of this embodiment, particularly because the organic infrared photoelectric conversion film contains a cyanine compound having the above-described anion, facilitates more selective absorption of incident light (particularly infrared light) exceeding 800 nm, resulting in excellent photoelectric conversion efficiency. This is thought to be due to the fact that the above-described anion has a structure that easily narrows the energy gap, but the cause is not limited to this. Furthermore, the photoelectric conversion element of this embodiment, particularly because the organic infrared photoelectric conversion film contains a cyanine compound having the above-described anion, is likely to exhibit higher durability (e.g., light resistance and heat resistance). This is thought to be due to the fact that the above-described anion has a molecular orbital that is more stable, but the cause is not limited to this.

[0124] (Solid-state imaging device) The solid-state imaging device of this embodiment includes a large number of photoelectric conversion elements of this embodiment arranged in an array. That is, by arranging a large number of photoelectric conversion elements in an array, a solid-state imaging device is configured that indicates not only the amount of incident light but also incident position information.

[0125] In a solid-state imaging element, if an infrared photoelectric conversion unit located closer to the light source does not block (transmits) the absorption wavelength of another photoelectric conversion unit (such as a visible photoelectric conversion unit) located behind it when viewed from the light source side, multiple photoelectric conversion units may be stacked.

[0126] In a solid-state imaging element, from the viewpoint of ease of molding, the infrared photoelectric conversion section or the visible photoelectric conversion section may be partially configured as a thin film on the same plane with no structural separation between adjacent photoelectric conversion elements.

[0127] The solid-state imaging device of this embodiment may further include a substrate. The substrate is used to manufacture the solid-state imaging device by stacking each layer thereon, or to increase the mechanical strength of the solid-state imaging device. The type of substrate is not particularly limited, and examples thereof include a semiconductor substrate, a glass substrate, and a plastic substrate. [Example]

[0128] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

[0129] Example 1 First, compound 1a was synthesized according to the following scheme. [ka]

[0130] Bromopentafluorobenzene was added to a dry tetrahydrofuran solution (approximately 14%) of isopropyl magnesium chloride-lithium chloride complex so that the molar ratio of the complex to bromopentafluorobenzene was 1.05:1.00, and the mixture was stirred at -78°C for 45 minutes to react. 2,3-butanedione was added to the resulting product so that the molar ratio of the product to 2,3-butanedione was 1.0:1.1, and the mixture was stirred at room temperature for 2.5 hours to produce compound 1a. The resulting compound 1a was purified, and its yield was measured to be 53%.

[0131] Next, fluorinated tricyanofuran 2a was synthesized according to the following scheme: Fluorinated tricyanofuran 2a was synthesized with reference to Chem. Mater. 2002, 14, pp. 2393-2400. [ka]

[0132] A 1M ethanol solution containing 5 mol% lithium ethoxide and malononitrile were added to dry tetrahydrofuran, and compound 1a was added thereto so that the molar ratio of malononitrile to compound 1a was 2:1. The mixture was refluxed overnight to produce fluorinated tricyanofuran 2a. The resulting fluorinated tricyanofuran 2a was purified and its yield was determined to be 10%.

[0133] Furthermore, the known dialdehyde 3 was synthesized according to the following scheme. [ka]

[0134] Excess dimethylformamide and cyclohexanone were mixed with 4 equivalents of phosphoryl chloride and reacted at 0°C for 30 minutes. Cyclohexanone was added to the resulting product, and the mixture was further stirred at 55°C for 3.5 hours to produce dialdehyde 3. The resulting dialdehyde 3 was purified and its yield was determined to be 52%.

[0135] Then, a cyanine compound 4a having a perfluorophenyl group was synthesized according to the following scheme. [ka]

[0136] Dialdehyde 3 and fluorinated tricyanofuran 2a were added to acetic anhydride containing sodium acetate in a molar ratio of 1.0:2.1:2.2, and the mixture was stirred at 120°C for 4 hours to synthesize cyanine compound 4a. The resulting cyanine compound 4a was purified and its yield was determined to be 40%. The results of NMR analysis (measurement device: JTM-ECS400, manufactured by JEOL Ltd.; the same applies hereinafter) are shown below. [ka]

[0137] Example 2 According to the following scheme, a cyanine compound 5a having a perfluorophenyl group was synthesized. [ka]

[0138] Cyanine compound 4a obtained in Example 1 was added to an acetone solution containing tetrabutylammonium iodide at a molar ratio of 1.0:1.1, and the mixture was stirred at room temperature for 1 hour to synthesize cyanine compound 5a. The resulting cyanine compound 5a was purified and its yield was measured to be 69%. The NMR measurement results are shown below. [ka]

[0139] (Reference example 1) Known compound 1b was synthesized according to the following scheme: Compound 1b was synthesized with reference to Angew. Chem. Int. Ed., 2017, 56, pp. 2478-2481. [ka]

[0140] To a dry tetrahydrofuran solution of phenylmagnesium bromide, 2,3-butanedione was added at 0°C so that the molar ratio of phenylmagnesium bromide to 2,3-butanedione was 1.05:1.00, and the mixture was stirred at room temperature for 3 hours to give compound 1b. The crude yield of the obtained compound 1b was measured to be 87%.

[0141] Next, tricyanofuran 2b was synthesized according to the following scheme. [ka]

[0142] A 1M ethanol solution containing 5 mol% lithium ethoxide and malononitrile were added to dry tetrahydrofuran, and the compound 1b obtained above was added without purification so that the molar ratio of malononitrile to compound 1b was 2:1. The mixture was refluxed overnight to produce tricyanofuran 2b. The resulting tricyanofuran 2b was purified and its yield was determined to be 25%.

[0143] Then, cyanine compound 4b was synthesized according to the following scheme. [ka]

[0144] Dialdehyde 3 and tricyanofuran 2b were added to acetic anhydride containing sodium acetate in a molar ratio of 1.0:2.1:2.2, and the mixture was stirred at 120°C for 4 hours to synthesize cyanine compound 4b. The resulting cyanine compound 4b was purified and its yield was determined to be 38%. The NMR analysis results are shown below. [ka]

[0145] (Reference example 2) Cyanine compound 5b was synthesized according to the following scheme. [ka]

[0146] Cyanine compound 4b obtained in Reference Example 1 was added to an acetone solution containing tetrabutylammonium iodide at a molar ratio of 1.0:1.1, and the mixture was stirred at room temperature for 1 hour to synthesize cyanine compound 5b. The resulting cyanine compound 5b was purified and its yield was measured to be 65%. The NMR measurement results are shown below. [ka]

[0147] (Comparative Example 1) The compound represented by the following formula was synthesized by a known method. [ka]

[0148] A dichloromethane solution (1×10 -6 The absorption maxima at 1000 nm (M) and the transmittance in each wavelength range were measured using a spectrophotometer (product name: U-4100) manufactured by Hitachi High-Technologies Corporation. As an example, the absorption spectrum of the compound of Example 2 is shown in FIG. 2. In the obtained absorption spectra, the absorption maxima wavelengths were 934 nm in Example 2, 920 nm in Reference Example 2, and 906 nm in Comparative Example 1.

[0149] <Light resistance> In a thermostatic bath at 25°C, a solution of each compound obtained in Example 2, Reference Example 2, and Comparative Example 1 in dehydrated dichloromethane (1 × 10 -6 M) was continuously irradiated with a white LED light (L-711), and the residual rate of the compound in the solution was measured (the concentration of the compound in the solution immediately before irradiation is taken as 100%). 13 days after the start of irradiation, the residual rate of the compound in Example 2 was 69%, while the residual rate of the compound in Reference Example 2 was 45%. Furthermore, the residual rate of the compound in Comparative Example 1 fell below the detection limit 12 days after the start of irradiation.

[0150] <Heat resistance> The decomposition temperature of each compound obtained in Example 2, Reference Example 2, and Comparative Example 1 was measured by TG-DTA (apparatus name: EXSTAR-6000 TG / DTA 6300, manufactured by Seiko Instruments Inc.). The samples used for the measurement were previously subjected to a heating and reduced pressure drying treatment (80°C, 3 × 10 2 The sample was subjected to 1000 kJ / min (Pa, overnight). The temperature was increased from 30°C to 400°C under a nitrogen atmosphere, and the temperature at which the sample lost 2% weight was measured. The compound of Example 2 lost 2% weight at a temperature of approximately 207°C, whereas the compound of Reference Example 2 lost 2% weight at a temperature of approximately 200°C and the compound of Comparative Example 1 lost 2% weight at a temperature of approximately 198°C. [Industrial Applicability]

[0151] The cyanine compound of the present invention has near-infrared absorption beyond 800 nm and has no or very little sensitivity to visible light. Furthermore, the cyanine compound of the present invention also has excellent durability, such as light resistance and heat resistance. Therefore, the cyanine compound of the present invention can be used as a material for a transparent, durable photoelectric conversion device that generates charges in response to near-infrared light. Therefore, the cyanine compound and photoelectric conversion device of the present invention have industrial applicability in fields requiring these properties. Specifically, they have industrial applicability as solid-state imaging devices, such as imaging devices in security cameras, vehicle-mounted cameras, unmanned aerial vehicles, agricultural cameras, industrial cameras, medical cameras such as endoscopic cameras, game console cameras, digital still cameras, digital video cameras, mobile phone cameras, and cameras for other mobile devices; image reading devices in facsimiles, scanners, copiers, and the like; and optical sensors in bio- and chemical sensors, etc. Furthermore, they have industrial applicability as displays, such as television monitors, touch monitors, digital signage, wearable displays, electronic paper, and head-up displays for mobility applications. In addition to the above, the cyanine compound of the present invention may also be industrially applicable as a material for optical information recording media, photosensitive materials for flash toner fixing, heat-shielding films, infrared cut filters, anti-counterfeiting inks, etc., or as a preform heating aid for plastic bottles. [Explanation of symbols]

[0152] 100... infrared photoelectric conversion section, 110... organic infrared photoelectric conversion film, 120... hole transport layer, 130... electron transport layer, 140, 150... electrodes.

Claims

1. A cyanine compound which is a counterion bond consisting of an anion and a cation, wherein the anion is represented by the following formula (I-1): 【Chemistry 1】 (In formula (I-1), R 1 and R 2 each independently represents a hydrogen atom or a monovalent organic group, R 3 and R 4 each independently represents a monovalent group represented by the following formula (I-1-1), X represents a hydrogen atom, a halogen atom or a monovalent organic group, and Y represents a divalent group represented by the following formula (I-1-2) or (I-1-3): 【Chemistry 2】 (In formula (I-1-1), R a , R b , R c , R d and R e each independently represents a hydrogen atom, a monovalent hydrocarbon group, or a monovalent electron-withdrawing group. a , R b , R c , R d and R e At least one of R represents the monovalent electron-withdrawing group. a , R b , R c , R d and R e When only one of R is a halogen atom, the other R a , R b , R c , R d and R e At least one of the groups represents the monovalent hydrocarbon group or the monovalent electron-withdrawing group (excluding halogen atoms). 【Transformation 3】 (In formula (I-1-2), R f , R g , R h , R i , R j and R k each independently represents a hydrogen atom or a monovalent hydrocarbon group which may have an oxygen atom, a nitrogen atom or a sulfur atom. 【Chemistry 4】 (In formula (I-1-3), R l , R m , R n and R o each independently represents a hydrogen atom or a monovalent hydrocarbon group which may have an oxygen atom, a nitrogen atom or a sulfur atom.

2. 2. The cyanine compound according to claim 1, wherein the cation comprises at least one selected from the group consisting of alkali metal cations, alkaline earth metal cations, ammonium cations, sulfonium cations, phosphonium cations, and cationic cyanines.

3. 3. The cyanine compound according to claim 2, wherein the cation comprises at least one selected from the group consisting of an alkali metal cation, an ammonium cation, and a cationic cyanine.

4. The cyanine compound according to claim 3, wherein the cationic cyanine is a cation represented by the following formula (I-2-1), (I-2-2), (I-2-3) or (I-2-4): 【Transformation 5】 (In formulas (I-2-1), (I-2-2), (I-2-3), and (I-2-4), E each independently represents a carbon atom, a nitrogen atom, an oxygen atom, or a sulfur atom; R p , R q , R r , R s , R t , R u , R v , R w and R x each independently represents a hydrogen atom, a halogen atom, a hydroxyl group, a carboxyl group, a nitro group, an amino group, an amido group, an imido group, a cyano group, a silyl group, -L 1 , -SL 2 , -SS-L 2 , -SO 2 -L 3 , -N=N-L 4 , or R q and R r , R s and R t , R t and R u , R u and R v , R v and R w and R w and R x and (B) represents one or more groups selected from the group consisting of groups represented by the following formulae (A), (B), (C), (D), (E), (F), (G), and (H), to which one or more combinations of: the amino group, amido group, imido group and silyl group may be further substituted with one or more groups L selected from the group consisting of monovalent aliphatic hydrocarbon groups having 1 to 12 carbon atoms, monovalent halogen-substituted alkyl groups having 1 to 12 carbon atoms, monovalent alicyclic hydrocarbon groups having 3 to 14 carbon atoms, monovalent aromatic hydrocarbon groups having 6 to 14 carbon atoms, and monovalent heterocyclic groups having 3 to 14 carbon atoms; Said L 1 and L 4 represents a monovalent aliphatic hydrocarbon group having 1 to 12 carbon atoms, a monovalent halogen-substituted alkyl group having 1 to 12 carbon atoms, a monovalent alicyclic hydrocarbon group having 3 to 14 carbon atoms, a monovalent aromatic hydrocarbon group having 6 to 14 carbon atoms, or a heterocyclic group having 3 to 14 carbon atoms, each of which may be further substituted by the group L; Said L 2 represents a hydrogen atom, or a monovalent aliphatic hydrocarbon group having 1 to 12 carbon atoms, a monovalent halogen-substituted alkyl group having 1 to 12 carbon atoms, a monovalent alicyclic hydrocarbon group having 3 to 14 carbon atoms, a monovalent aromatic hydrocarbon group having 6 to 14 carbon atoms, or a heterocyclic group having 3 to 14 carbon atoms, each of which may be further substituted by the group L; Said L 3 represents a hydroxyl group, or a monovalent aliphatic hydrocarbon group having 1 to 12 carbon atoms, a monovalent halogen-substituted alkyl group having 1 to 12 carbon atoms, a monovalent alicyclic hydrocarbon group having 3 to 14 carbon atoms, a monovalent aromatic hydrocarbon group having 6 to 14 carbon atoms, or a heterocyclic group having 3 to 14 carbon atoms, each of which may be further substituted by the group L; Q 1 represents an acetyl group, and Q 2 represents a structure represented by the following formula (q1), (q2) or (q3): 【Transformation 6】 (In formulas (A), (B), (C), (D), (E), (F), (G) and (H), the combination of Rx and Ry is R q and R r , R s and R t , R t and R u , R u and R v , R v and R w or R w and R x It is a combination of R A , R B , R C , R D , R E , R F , R G , R H , R I , R J , R K and R L each independently represents a hydrogen atom, a halogen atom, a hydroxyl group, a carboxyl group, a nitro group, an amino group, an amido group, an imido group, a cyano group, a silyl group, -L 1 , -SL 2 , -SS-L 2 , -SO 2 -L 3 or -N=N-L 4 indicates L 1 , L 2 , L 3 and L 4 represents L in the formulas (I-2-1) and (I-2-2). 1 , L 2 , L 3 and L 4 The amino group, the amido group, the imido group and the silyl group may be substituted with the group L. -C m H m+1 (q1) -C a H a+1 -OC b H b+1 (q2) (In formula (q1), m represents an integer of 1 to 5, and in formula (q2), a and b each represent an integer of 1 to 5.) 【Transformation 7】 (In formula (q3), n represents an integer of 1 to 5, and T 1 , T 2 , T 3 , T 4 and T 5 are each independently a hydrogen atom or —OC p H p+1 and p represents an integer of 1 to 5.

5. The R 1 and R 2 The cyanine compound according to any one of claims 1 to 4, wherein the monovalent organic group in the formula (I) is a monovalent aliphatic hydrocarbon group having 1 to 12 carbon atoms, a monovalent halogen-substituted alkyl group having 1 to 12 carbon atoms, a monovalent alicyclic hydrocarbon group having 3 to 14 carbon atoms, a monovalent aromatic hydrocarbon group having 6 to 14 carbon atoms, or a heterocyclic group having 3 to 14 carbon atoms, which may be further substituted with a monovalent hydrocarbon group or a monovalent electron-withdrawing group.

6. The R 1 and R 2 and each independently represent a hydrogen atom, a monovalent aliphatic hydrocarbon group having 1 to 3 carbon atoms, or a monovalent group represented by formula (I-1-1).

7. The monovalent organic group in X is a hydroxyl group, a carboxyl group, a nitro group, an amino group, an amido group, an imido group, a cyano group, a silyl group, -L 1 , -SL 2 , -SS-L 3 , -SO 2 -L 3 , or −N=N−L 4 indicates, the amino group, amido group, imido group and silyl group may be further substituted with one or more groups L selected from the group consisting of monovalent aliphatic hydrocarbon groups having 1 to 12 carbon atoms, monovalent halogen-substituted alkyl groups having 1 to 12 carbon atoms, monovalent alicyclic hydrocarbon groups having 3 to 14 carbon atoms, monovalent aromatic hydrocarbon groups having 6 to 14 carbon atoms, and monovalent heterocyclic groups having 3 to 14 carbon atoms; Said L 1 and L 4 represents a monovalent aliphatic hydrocarbon group having 1 to 12 carbon atoms, a monovalent halogen-substituted alkyl group having 1 to 12 carbon atoms, a monovalent alicyclic hydrocarbon group having 3 to 14 carbon atoms, a monovalent aromatic hydrocarbon group having 6 to 14 carbon atoms, or a heterocyclic group having 3 to 14 carbon atoms, each of which may be further substituted by the group L; Said L 2 represents a hydrogen atom, or a monovalent aliphatic hydrocarbon group having 1 to 12 carbon atoms, a monovalent halogen-substituted alkyl group having 1 to 12 carbon atoms, a monovalent alicyclic hydrocarbon group having 3 to 14 carbon atoms, a monovalent aromatic hydrocarbon group having 6 to 14 carbon atoms, or a heterocyclic group having 3 to 14 carbon atoms, each of which may be further substituted by the group L; Said L 3 represents a hydroxyl group, or a monovalent aliphatic hydrocarbon group having 1 to 12 carbon atoms, a monovalent halogen-substituted alkyl group having 1 to 12 carbon atoms, a monovalent alicyclic hydrocarbon group having 3 to 14 carbon atoms, a monovalent aromatic hydrocarbon group having 6 to 14 carbon atoms, or a heterocyclic group having 3 to 14 carbon atoms, which may be further substituted with the group L; The cyanine compound according to any one of claims 1 to 6.

8. 8. The cyanine compound according to claim 7, wherein X is a halogen atom.

9. The R a , R b , R c , R d and R e The cyanine compound according to any one of claims 1 to 8, wherein the monovalent hydrocarbon group in the formula (I) is a monovalent aliphatic hydrocarbon group having 1 to 12 carbon atoms, a monovalent alicyclic hydrocarbon group having 3 to 14 carbon atoms, or a monovalent aromatic hydrocarbon group having 6 to 14 carbon atoms, which may be further substituted with one or more groups selected from the group consisting of monovalent aliphatic hydrocarbon groups having 1 to 12 carbon atoms, monovalent alicyclic hydrocarbon groups having 3 to 14 carbon atoms, and monovalent aromatic hydrocarbon groups having 6 to 14 carbon atoms.

10. The R a , R b , R c , R d and R e The monovalent electron-withdrawing group in 2 a group represented by —SO 2 A group represented by R or —SO 3 10. The cyanine compound according to claim 1, wherein R is a group represented by R, wherein R is the same as the monovalent hydrocarbon group or a hydrogen atom.

11. The R a , R b , R c , R d and R e each independently represents a hydrogen atom or a halogen atom, R a , R b , R c , R d and R e 11. The cyanine compound according to claim 10, wherein two or more of the following are halogen atoms:

12. The R f , R g , R h , R i , R j , R k , R l , R m , R n and R o The cyanine compound according to any one of claims 1 to 11, wherein the monovalent hydrocarbon group which may have an oxygen atom, a nitrogen atom, or a sulfur atom in the formula (I) is a monovalent aliphatic hydrocarbon group having 1 to 12 carbon atoms, a monovalent alicyclic hydrocarbon group having 3 to 14 carbon atoms, or a monovalent aromatic hydrocarbon group having 6 to 14 carbon atoms, which may be further substituted with one or more groups selected from the group consisting of monovalent aliphatic hydrocarbon groups having 1 to 12 carbon atoms, monovalent alicyclic hydrocarbon groups having 3 to 14 carbon atoms, and monovalent aromatic hydrocarbon groups having 6 to 14 carbon atoms, which may have an oxygen atom, a nitrogen atom, or a sulfur atom.

13. R f , R g , R h , R i , R j , R k , R l , R m , R n and R o and each independently represent a hydrogen atom or a monovalent aliphatic hydrocarbon group having 1 to 12 carbon atoms.

14. A photoelectric conversion element including an infrared photoelectric conversion unit including a pair of electrodes and an organic infrared photoelectric conversion film provided between the pair of electrodes, A photoelectric conversion element, wherein the organic infrared photoelectric conversion film contains the cyanine compound according to any one of claims 1 to 13.

15. The photoelectric conversion element according to claim 14 , wherein the organic infrared photoelectric conversion film contains an organic n-type semiconductor and / or an organic p-type semiconductor.

16. The photoelectric conversion element according to claim 14 or 15, wherein the infrared photoelectric conversion section contains one or more layers selected from the group consisting of a hole transport layer, an electron transport layer, a hole blocking layer, and an electron blocking layer between the electrode and the organic infrared photoelectric conversion film.

17. The photoelectric conversion element according to any one of claims 14 to 16, wherein the infrared photoelectric conversion section has a maximum absorption wavelength in the light absorption spectrum in the infrared region of 800 nm to 2500 nm.

18. The photoelectric conversion element according to any one of claims 14 to 17, further comprising a visible photoelectric conversion part having sensitivity to light in the visible range.

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