Photoelectric conversion material and photoelectric conversion element using the same

Abstract

To provide a photoelectric conversion element having high photoelectric conversion efficiency of green light.SOLUTION: A photoelectric conversion material has a structure represented by a following general formula (1). In the general formula (1), R1, R3, R4 and R6 may be the same or different, and each represent a hydrogen atom, an alkyl group or a cycloalkyl group; R2 and R5 each represent a hydrogen atom, an alkyl group, an aryl group or a heteroaryl group, while at least one of R2 and R5 is an aryl group or a heteroaryl group and R2 and R5 are groups different from each other; R7 represents an aryl group or a heteroaryl group; and X1 and X2 may be the same or different and each represent an alkyl group, an aryl group, an alkoxy group, an aryloxy group, a halogen atom or a cyano group.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a photoelectric conversion material, a photoelectric conversion element using the same, an optical sensor, an imaging element, and a fingerprint authentication device. [Background technology]

[0002] In recent years, IoT (Internet of Things) and big data have been attracting attention, and sensing technology to acquire the various data that supports them is becoming increasingly important. There are various sensing technologies, but optical sensing in particular is a highly useful sensing technology that can be deployed in a variety of applications, such as by changing the sensing target by selecting the target wavelength.

[0003] Optical sensors generally comprise a photoelectric conversion element that converts light into electrical energy and a light-emitting element, and sense an object by irradiating the object with light from the light-emitting element and receiving the light that is transmitted through or reflected by the object with the photoelectric conversion element. Such optical sensors can acquire biometric information such as fingerprints, vein patterns, and blood oxygen levels by using, for example, green, red, or near-infrared light. Furthermore, by forming the substrate, light-emitting element, and light-receiving element primarily from organic materials, it is possible to construct a thin, flexible device (see, for example, Non-Patent Document 1).

[0004] Pyrromethene compounds have been investigated as photoelectric conversion materials for use in such photoelectric conversion elements (see, for example, Patent Documents 1 to 4). Pyrromethene compounds generally have a high absorption coefficient, and are characterized in that the absorption wavelength region can be designed to a desired range by selecting a substituent. [Prior art documents] [Non-patent literature]

[0005] [Non-Patent Document 1] Science Advances, 2016, Vol. 2, p. e1501856 [Patent documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2020-72270 [Patent Document 2] International Publication No. 2015 / 119039 [Patent Document 3] Japanese Patent Application Laid-Open No. 2008-109097 [Patent Document 4] International Publication No. 2017 / 018351 Summary of the Invention [Problem to be solved by the invention]

[0007] However, the pyrromethene compounds described in Patent Documents 1 to 4 have a very narrow half-width of the absorption spectrum, and therefore have high wavelength selectivity, but have a problem of insufficient photoelectric conversion efficiency because the wavelength range of incident light available for photoelectric conversion is limited. Therefore, an object of the present invention is to provide a photoelectric conversion material that can provide a photoelectric conversion element with a wide half-width of the absorption spectrum and high photoelectric conversion efficiency for green light. [Means for solving the problem]

[0008] The present invention is a photoelectric conversion material having a structure represented by the following general formula (1).

[0009] [ka]

[0010] In the above general formula (1), R 1 , R 3 , R 4 and R 6 may be the same or different and represent a hydrogen atom, an alkyl group, or a cycloalkyl group. 2 and R 5 represents a hydrogen atom, an alkyl group, an aryl group, or a heteroaryl group. 2 and R5 at least one of R is an aryl group or a heteroaryl group, and 2 and R 5 are different groups. 7 represents an aryl group or a heteroaryl group. 1 and X 2 may be the same or different and represent an alkyl group, an aryl group, an alkoxy group, an aryloxy group, a halogen atom or a cyano group. [Effects of the Invention]

[0011] The photoelectric conversion material of the present invention has a wide half-width of the absorption spectrum, and the photoelectric conversion material of the present invention can provide a photoelectric conversion element with high photoelectric conversion efficiency for green light. DETAILED DESCRIPTION OF THE INVENTION

[0012] The photoelectric conversion material of the present invention has a structure represented by the following general formula (1).

[0013] [ka]

[0014] R 1 , R 3 , R 4 and R 6 may be the same or different and represent a hydrogen atom, an alkyl group, or a cycloalkyl group. By selecting these groups, it becomes easier to adjust the absorption peak wavelength of the thin film to the region of 490 nm or more and 580 nm or less, thereby enabling efficient absorption of green light and increasing photoelectric conversion efficiency.

[0015] In all groups, hydrogen may be replaced with deuterium, as well as in the substituents, compounds, and partial structures thereof described below.

[0016] The alkyl group refers to a saturated aliphatic hydrocarbon group such as a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, a sec-butyl group, or a tert-butyl group, which may or may not have a substituent. Examples of the substituent include an alkoxy group, an alkoxycarbonyl group, a halogen atom, an aryl group, and a heteroaryl group. From the viewpoints of ease of raw material availability and vapor deposition stability, the number of carbon atoms in the alkyl group is preferably 1 to 20, more preferably 1 to 10, and even more preferably 1 to 6. Here, the number of carbon atoms in the alkyl group does not include the number of carbon atoms in the substituent, and this point is also applicable to the following description.

[0017] The cycloalkyl group refers to a saturated alicyclic hydrocarbon group such as a cyclopropyl group, a cyclopentyl group, a cyclohexyl group, a norbornyl group, or an adamantyl group, which may or may not have a substituent. Examples of the substituent include the groups exemplified as the substituent for the alkyl group. The number of ring carbon atoms of the cycloalkyl group is preferably in the range of 3 to 20.

[0018] From the viewpoints of chemical stability, electrochemical stability, and photostability, R 1 , R 3 , R 4 , R 6 Preferably, two or more of these groups are alkyl groups, and more preferably, three or more of these groups are alkyl groups.

[0019] R 2 and R 5 represents a hydrogen atom, an alkyl group, an aryl group, or a heteroaryl group.

[0020] The aryl group refers to an aromatic hydrocarbon group such as a phenyl group, a biphenyl group, a terphenyl group, a naphthyl group, a fluorenyl group, a benzofluorenyl group, a dibenzofluorenyl group, a phenanthryl group, an anthracenyl group, a benzophenanthryl group, a benzanthracenyl group, a chrysenyl group, a pyrenyl group, a fluoranthenyl group, a triphenylenyl group, a benzofluoranthenyl group, a dibenzoanthracenyl group, a perylenyl group, or a helicenyl group. Among these, a phenyl group, a biphenyl group, a terphenyl group, a naphthyl group, a fluorenyl group, a phenanthryl group, an anthracenyl group, a pyrenyl group, a fluoranthenyl group, or a triphenylenyl group is preferred. The aryl group may or may not have a substituent. Examples of the substituent include an alkyl group, an alkoxy group, an aryloxy group, an amino group, a monoalkylamino group, a dialkylamino group, a monoarylamino group, a diarylamino group, a cyano group, an alkoxycarbonyl group, a halogen atom, a hydroxy group, a thiol group, a thioalkyl group, a nitro group, and a heteroaryl group. The number of ring carbon atoms in the aryl group is preferably from 6 to 40, more preferably from 6 to 30. In addition, in a phenyl group, when two adjacent carbon atoms in the phenyl group each have a substituent, the substituents may together form a ring structure.

[0021] The heteroaryl group refers to a cyclic aromatic group having one or more atoms other than carbon in the ring, such as a pyridyl group, a furanyl group, a thiophenyl group, a quinolinyl group, an isoquinolinyl group, a pyrazinyl group, a pyrimidyl group, a pyridazinyl group, a triazinyl group, a naphthyridinyl group, a cinnolinyl group, a phthalazinyl group, a quinoxalinyl group, a quinazolinyl group, a benzofuranyl group, a benzothiophenyl group, an indolyl group, a dibenzofuranyl group, a dibenzothiophenyl group, a carbazolyl group, a benzocarbazolyl group, a carbolinyl group, an indolocarbazolyl group, a benzofurocarbazolyl group, a benzothienocarbazolyl group, a dihydroindenocarbazolyl group, a benzoquinolinyl group, an acridinyl group, a dibenzoacridinyl group, a benzimidazolyl group, an imidazopyridyl group, a benzoxazolyl group, a benzothiazolyl group, or a phenanthrolinyl group. Here, the naphthyridinyl group refers to any of 1,5-naphthyridinyl, 1,6-naphthyridinyl, 1,7-naphthyridinyl, 1,8-naphthyridinyl, 2,6-naphthyridinyl, and 2,7-naphthyridinyl groups. The heteroaryl group may or may not have a substituent. Examples of the substituent include an alkyl group, an alkoxy group, an aryloxy group, an amino group, a monoalkylamino group, a dialkylamino group, a monoarylamino group, a diarylamino group, a cyano group, an ester group, a halogen atom, a hydroxy group, a thiol group, a thioalkyl group, a nitro group, and an aryl group. The number of ring carbon atoms of the heteroaryl group is preferably 2 to 40, more preferably 2 to 30.

[0022] However, R 2 and R 5 at least one of R is an aryl group or a heteroaryl group, and 2 and R 5are different groups. In this description, "different groups" refers to groups with different structures. For example, a methyl group and an ethyl group are both alkyl groups, but because they have different structures, they are considered "different groups" in this description. By selecting the substituents in this way, the absorption peak wavelength of the light absorption spectrum of the thin film is 490 nm to 580 nm, and the half-width is 45 nm to 130 nm. This allows the thin film to efficiently absorb and photoelectrically convert various green light beams with different peak wavelengths, thereby improving the photoelectric conversion efficiency. It is more preferable that the absorption peak wavelength is 500 nm to 570 nm, and the half-width is 50 nm to 125 nm.

[0023] R 7 represents an aryl group or a heteroaryl group. When a photoelectric conversion element or the like is produced using the photoelectric conversion material of the present invention, it is expected that a heating step such as vapor deposition will be performed, as will be described later. From the viewpoint of suppressing decomposition due to heating, it is preferable that the molecular weight of the photoelectric conversion material of the present invention is appropriately small. For this reason, R 7 The sum of the atomic weights of the atoms constituting R is preferably 350 or less, more preferably 250 or less, and even more preferably 150 or less. 7 By setting the total atomic weight of the atoms constituting R within the above range, the width of the absorption spectrum can be further widened. 7 The sum of the atomic weights of the atoms constituting the group is preferably 70 or more.

[0024] X 1 and X 2 may be the same or different and represent an alkyl group, an aryl group, an alkoxy group, an aryloxy group, a halogen atom or a cyano group.

[0025] The alkoxy group refers to a functional group in which an aliphatic hydrocarbon group is bonded via an ether bond, such as a methoxy group, an ethoxy group, or a propoxy group, and this aliphatic hydrocarbon group may or may not have a substituent. Examples of the substituent include the groups exemplified as the substituent for the alkyl group. The number of carbon atoms in the alkoxy group is preferably in the range of 1 to 20.

[0026] The aryloxy group refers to a functional group, such as a phenoxy group, in which an aromatic hydrocarbon group is bonded via an oxygen atom, and this aromatic hydrocarbon group may or may not have a substituent. Examples of the substituent include the groups exemplified as the substituent for the alkyl group. The number of ring carbon atoms of the aryloxy group is preferably in the range of 6 to 40.

[0027] The halogen atom refers to fluorine, chlorine, bromine, or iodine.

[0028] A cyano group is a functional group whose structure is represented by -C≡N.

[0029] X 1 and X 2 is preferably fluorine from the viewpoints of ease of synthesis, chemical stability, electrochemical stability, and photostability.

[0030] Examples of the structure represented by general formula (1) are shown below, but the invention is not limited to these.

[0031] [ka]

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[0055] A pyrromethene boron complex having a pyrrole with an asymmetric structure represented by general formula (1) can be synthesized by referring to, for example, Tetrahedron Lett., vol. 56, pp. 3919-3922 (2015), Chem. Cent. J., 12:60 (2018), and J. Phys. Chem. B, vol. 123, pp. 5601 (2019). 2 or R5 When an aryl or heteroaryl group is to be introduced into the compound, a pyrromethene boron complex to which a halogen atom has been introduced is used as a substrate. This can be synthesized by referring to the method described in, for example, Chem. Phys. Chem., vol. 17, pp. 433-442 (2016).

[0056] The pyrromethene boron complex having the structure represented by general formula (1) is preferably purified by organic synthesis techniques such as recrystallization or column chromatography, and then further purified by heating under reduced pressure, generally known as sublimation purification, to remove low-boiling components and improve purity. The heating temperature in sublimation purification is preferably 350°C or lower, more preferably 330°C or lower, from the viewpoint of preventing thermal decomposition of the pyrromethene boron complex.

[0057] The purity of the pyrromethene boron complex having the structure represented by general formula (1) is preferably 99% by weight or more from the viewpoint of stabilizing photoelectric conversion characteristics.

[0058] The photoelectric conversion material of the present invention is a material that is composed of a pyrromethene boron complex represented by general formula (1) and is used as a material for constituting a photoelectric conversion layer in a photoelectric conversion element having a photoelectric conversion layer between an anode and a cathode. In other words, the photoelectric conversion material refers to the use of the pyrromethene boron complex represented by the general formula (1).

[0059] The photoelectric conversion material of the present invention may be composed solely of a photoelectric conversion material having a structure represented by general formula (1), but may further contain other photoelectric conversion materials in order to further increase the photoelectric conversion efficiency.

[0060] Next, the photoelectric conversion element of the present invention will be described. The photoelectric conversion element of the present invention is a photoelectric conversion element that has a photoelectric conversion layer between an anode and a cathode, converts light into electrical energy, and contains the photoelectric conversion material of the present invention in the photoelectric conversion layer.

[0061] The photoelectric conversion layer preferably contains two or more photoelectric conversion materials, for example, a photoelectric conversion material having a structure represented by general formula (1) of the present invention is preferably combined with another photoelectric conversion material, and the photoelectric conversion material to be combined is preferably an organic semiconductor exhibiting p-type or n-type semiconductor properties.

[0062] Examples of n-type semiconductors include 1,4,5,8-naphthalenetetracarboxylic dianhydride (NTCDA), 3,4,9,10-perylenetetracarboxylic dianhydride (PTCDA), 3,4,9,10-perylenetetracarboxylic bisbenzimidazole (PTCBI), N,N'-dioctyl-3,4,9,10-naphthyltetracarboxylic diimide (PTCDI-CH); 2-(4-biphenylyl)-5-(4-t-butylphenyl)-1,3,4-diol; Examples of suitable materials include oxazole derivatives such as oxadiazole (PBD) and 2,5-di(1-naphthyl)-1,3,4-oxadiazole (BND), triazole derivatives such as 3-(4-biphenylyl)-4-phenyl-5-(4-t-butylphenyl)-1,2,4-triazole (TAZ), phenanthroline derivatives, phosphine oxide derivatives, fullerene compounds, carbon nanotubes (CNT), and derivatives of poly-p-phenylene vinylene polymers with cyano groups (CN-PPV). Two or more of these may be used. Among these, fullerene compounds are preferred due to their fast charge separation and electron transfer rates. Examples of fullerene compounds include unsubstituted fullerenes such as C60, C70, C76, C78, ​​C82, C84, C90, and C94, as well as [6,6]-phenyl C61 butyric acid methyl ester ([6,6]-PCBM), [5,6]-phenyl C61 butyric acid methyl ester ([5,6]-PCBM), [6,6]-phenyl C61 butyric acid hexyl ester ([6,6]-PCBH), [6,6]-phenyl C61 butyric acid dodecyl ester ([6,6]-PCBD), phenyl C71 butyric acid methyl ester (PC70BM), and phenyl C85 butyric acid methyl ester (PC84BM).

[0063] Examples of p-type semiconductors include oligothiophene compounds such as terthiophene, quarterthiophene, sexithiophene, and octithiophene, phenylene vinylene compounds, p-phenylene compounds, polyfluorene compounds, phthalocyanine derivatives such as H2 phthalocyanine (H2Pc), copper phthalocyanine (CuPc), and zinc phthalocyanine (ZnPc), porphyrin derivatives, triarylamine derivatives such as N,N'-diphenyl-N,N'-di(3-methylphenyl)-4,4'-diphenyl-1,1'-diamine (TPD) and N,N'-dinaphthyl-N,N'-diphenyl-4,4'-diphenyl-1,1'-diamine (NPD), and carbazole derivatives such as 4,4'-di(carbazol-9-yl)biphenyl (CBP). Two or more of these may be used.

[0064] As described above, by combining a photoelectric conversion material having a structure represented by general formula (1) with an organic semiconductor having different HOMO-LUMO levels, the excitons generated by absorbing light are efficiently separated and dissociated at the interface between the different materials, thereby further increasing the photoelectric conversion efficiency.

[0065] When the photoelectric conversion layer contains two or more types of photoelectric conversion materials, these materials may be mixed or stacked, but stacking is preferred from the viewpoint of rectification. When stacked, it is preferable that the layer containing the material exhibiting p-type semiconductor properties be located on the anode side and the layer containing the material exhibiting n-type semiconductor properties be located on the cathode side. Furthermore, when stacked, a mixed layer (i-layer) may be present at the stacking interface. This configuration is called a pin structure, in which the i-layer is primarily responsible for charge separation, and the p-layer and n-layer are primarily responsible for hole transport and electron transport, respectively, thereby further improving photoelectric conversion efficiency. When mixed, it is preferable that the materials combined with the photoelectric conversion material having the structure represented by general formula (1) are compatible at the molecular level or phase-separated at the nanolevel. When phase-separated, the domain size of the phase-separated structure is preferably 1 nm or more and 50 nm or less.

[0066] The thickness of the photoelectric conversion layer is preferably 10 nm to 500 nm, more preferably 20 nm to 100 nm. When the photoelectric conversion layer has a laminated structure, the thickness of the layer containing the photoelectric conversion material having the structure represented by general formula (1) and the thickness of the laminated layer, out of the total thickness of the photoelectric conversion layer, are each preferably 5 nm to 495 nm, more preferably 10 nm to 50 nm. When a mixed layer (i-layer) is present at the laminate interface, the thickness of the i-layer is preferably 1 nm to 100 nm, more preferably 5 nm to 50 nm.

[0067] In a photoelectric conversion element, it is preferable that the anode and / or cathode have optical transparency. The optical transparency of the electrode is not particularly limited as long as it is sufficient for incident light to reach the photoelectric conversion layer and generate an electromotive force. Here, optical transparency is defined as the transmitted light intensity (W / m 2 ) / incident light intensity (W / m 2 The thickness of the light-transmitting electrode is determined by the following formula: )]×100(%). The thickness of the light-transmitting electrode may be within a range that provides light transparency and conductivity, and although it differs depending on the electrode material, a thickness of 20 nm to 300 nm is preferred. The other electrode does not necessarily need to be light-transmitting as long as it is conductive, and there are no particular restrictions on its thickness.

[0068] As for the electrode materials, it is preferable to use a conductive material with a large work function for one electrode and a conductive material with a small work function for the other electrode.

[0069] An electrode made of a conductive material with a large work function serves as an anode. Examples of conductive materials with a large work function include metals such as gold, platinum, chromium, and nickel, as well as transparent metal oxides such as indium, tin, and molybdenum, and composite metal oxides such as indium tin oxide (ITO) and indium zinc oxide (IZO). The conductive material used for the anode preferably forms an ohmic junction with the photoelectric conversion layer. Furthermore, as described below, when a hole transport layer is provided between the anode and the photoelectric conversion layer, the conductive material used for the anode preferably forms an ohmic junction with the hole transport layer. The anode can be formed using an optimal method depending on the material used for the anode. Examples include sputtering, vapor deposition, and inkjet printing. For example, sputtering is preferably used when forming an anode using a metal oxide, and vapor deposition is preferably used when forming an anode using a metal.

[0070] An electrode using a conductive material with a small work function serves as a cathode. Examples of conductive materials with a small work function that are preferably used include alkali metals such as lithium, alkaline earth metals such as magnesium and calcium, tin, silver, aluminum, and alloys thereof. A laminate using two or more of these may also be used. Here, the conductive material used for the cathode preferably forms an ohmic junction with the photoelectric conversion layer. Furthermore, as described below, when an electron transport layer is provided between the cathode and the photoelectric conversion layer, the conductive material used for the cathode preferably forms an ohmic junction with the electron transport layer. Furthermore, by introducing a metal fluoride such as lithium fluoride or cesium fluoride into the interface between the cathode and the electron transport layer, it is possible to improve the extracted current.

[0071] In order to maintain the mechanical strength of the photoelectric conversion element, suppress thermal deformation, and impart barrier properties that suppress the intrusion of water vapor and oxygen into the photoelectric conversion layer, it is preferable to form the photoelectric conversion element on a substrate. Examples of the substrate include a glass plate, a ceramic plate, a resin film, a resin thin film obtained by curing varnish, and a thin metal plate. Among these, a glass substrate is preferably used from the viewpoint of transparency and ease of processing. Furthermore, flexible displays and foldable displays are becoming increasingly common, mainly in mobile devices such as smartphones, and resin films and resin thin films are suitable for this application, for example, heat-resistant films such as polyimide films and polyethylene naphthalate films.

[0072] The photoelectric conversion element of the present invention may have a hole transport layer between the anode and the photoelectric conversion layer. Examples of materials for forming the hole transport layer include the above-mentioned oligothiophene compounds, phenylene vinylene compounds, p-phenylene compounds, polyfluorene compounds, phthalocyanine derivatives such as H2 phthalocyanine (H2Pc), copper phthalocyanine (CuPc), and zinc phthalocyanine (ZnPc), porphyrin derivatives, triarylamine derivatives such as N,N'-diphenyl-N,N'-di(3-methylphenyl)-4,4'-diphenyl-1,1'-diamine (TPD) and N,N'-dinaphthyl-N,N'-diphenyl-4,4'-diphenyl-1,1'-diamine (NPD), carbazole derivatives such as 4,4'-di(carbazol-9-yl)biphenyl (CBP), and metal oxides exhibiting p-type semiconductor properties such as molybdenum oxide and tungsten oxide. The thickness of the hole transport layer is preferably 1 nm to 200 nm, and more preferably 5 nm to 100 nm.

[0073] Furthermore, the photoelectric conversion element of the present invention may have a hole extraction layer between the anode and the hole transport layer. Examples of materials for forming the hole extraction layer include charge transfer complexes such as tris(4-bromophenyl)aminium hexachloroantimonate (TBPAH), 1,4,5,8,9,11-hexaazatriphenylene-hexacarbonitrile (HAT-CN6), 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane (F4-TCNQ), tetracyanoquinodimethane derivatives, radialene derivatives, and fluorinated copper phthalocyanine.

[0074] The photoelectric conversion element of the present invention may also include an electron transport layer between the photoelectric conversion layer and the cathode. Examples of materials for forming the electron transport layer include the n-type organic semiconductors described above, as well as polycyclic aromatic derivatives, styryl aromatic ring derivatives, quinone derivatives, phosphorus oxide derivatives, and various metal complexes such as quinolinol complexes of tris(8-quinolinolato)aluminum(III), benzoquinolinol complexes, hydroxyazole complexes, azomethine complexes, tropolone metal complexes, and flavonol metal complexes. To further improve electron transport efficiency, it is preferable to use a compound having a heteroaryl group containing electron-accepting nitrogen. Here, electron-accepting nitrogen refers to a nitrogen atom that forms a multiple bond with an adjacent atom. Heteroaryl groups containing electron-accepting nitrogen have a high electron affinity, which facilitates electron transport and contributes to improved photoelectric conversion efficiency. Examples of compounds having a heteroaryl group structure containing electron-accepting nitrogen include pyridine derivatives, triazine derivatives, pyrazine derivatives, pyrimidine derivatives, quinoline derivatives, quinoxaline derivatives, quinazoline derivatives, naphthyridine derivatives, benzoquinoline derivatives, phenanthroline derivatives, imidazole derivatives, oxazole derivatives, thiazole derivatives, triazole derivatives, oxadiazole derivatives, thiadiazole derivatives, benzimidazole derivatives, benzoxazole derivatives, benzthiazole derivatives, phenanthroimidazole derivatives, and oligopyridine derivatives such as bipyridine and terpyridine. Two or more of these may be used. Furthermore, electron transport materials having a condensed polycyclic aromatic skeleton are preferred because they have an improved glass transition temperature and high electron mobility. Examples of such condensed polycyclic aromatic skeletons include quinolinol complexes, triazine derivatives, fluoranthene skeletons, anthracene skeletons, pyrene skeletons, and phenanthroline skeletons.

[0075] The electron transport layer may contain an electron donor material. Here, the electron donor material is a compound that improves the electrical conductivity of the electron transport layer. Preferred examples of electron donor materials include alkali metals such as Li, inorganic salts containing alkali metals such as LiF, complexes of alkali metals and organic substances such as lithium quinolinol, alkaline earth metals, inorganic salts containing alkaline earth metals, complexes of alkaline earth metals and organic substances, rare earth metals such as Eu and Yb, inorganic salts containing rare earth metals, and complexes of rare earth metals and organic substances. Two or more of these may be used. Among these, metallic lithium, rare earth metals, and lithium quinolinol (Liq) are preferred.

[0076] The thickness of the electron transport layer is preferably 1 nm to 200 nm, and more preferably 5 nm to 100 nm.

[0077] The method for forming each of the layers constituting the photoelectric conversion element may be either a dry process or a wet process, and examples thereof include resistance heating evaporation, electron beam evaporation, sputtering, molecular lamination, coating, inkjet printing, etc. Among these, resistance heating evaporation is preferred from the viewpoint of element characteristics.

[0078] The photoelectric conversion element of the present invention has a function of converting light into electrical energy. From the viewpoint of highly efficient photoelectric conversion of green light having different wavelengths, the absorption spectrum of the photoelectric conversion layer of the photoelectric conversion element of the present invention preferably has an absorption peak wavelength of 490 nm to 580 nm and a half width of 45 nm to 130 nm, more preferably an absorption peak wavelength of 500 nm to 570 nm and a half width of 50 nm to 125 nm, and even more preferably a half width of 70 nm to 125 nm.

[0079] The photoelectric conversion element of the present invention can be applied to various electronic devices and optical sensing devices that utilize its ability to selectively and efficiently photoelectrically convert green light. For example, it can be used as an optical sensor, optical switch, or imaging element, and can acquire biometric information such as fingerprints, veins, pulse waves, and blood oxygen levels with high sensitivity. It can also be used in a display device that includes the photoelectric conversion element of the present invention and an organic light-emitting element, and performs fingerprint authentication using the light from the organic light-emitting element. For example, by configuring some of the pixels of an organic EL display that displays in a matrix and / or segment format with the photoelectric conversion element of the present invention, fingerprint authentication functionality can be added to the organic EL display. That is, green light emitted from the organic light-emitting element of the organic EL display is reflected and scattered by a finger touching the display, and the light is received and photoelectrically converted by the photoelectric conversion element of the present invention, thereby enabling fingerprint information to be acquired with high accuracy. [Example]

[0080] The present invention will be described below with reference to examples, but the present invention is not limited to these examples.

[0081] First, the evaluation methods used in each of the examples and comparative examples will be described below.

[0082] ( 1 H-NMR) The pyrromethene boron complexes obtained in Examples 1 to 6 were analyzed in deuterated chloroform solution using a superconducting FTNMR JNM-ECZ400R (manufactured by JEOL Ltd.). 1 The structure was identified by H-NMR measurement.

[0083] (Solution absorption characteristics) The pyrromethene boron complexes obtained in the examples and the pyrromethene boron complexes used in the comparative examples were each dissolved in toluene at a concentration of 10 -5 The absorption spectrum of the diluted solution of 1 mol / L was measured using a spectrophotometer (U-3010) manufactured by Hitachi High-Tech Science Corporation with an optical path length of 1 cm, and the peak wavelength and half-width were determined.

[0084] In addition, the absorbance A, solution concentration c, and optical path length l obtained by measuring the absorption spectrum were substituted into the following conversion formula 1 to determine the molar absorption coefficient ε in the solution state. Conversion formula 1: ε[L / (mol·cm)]=A / c[mol / L] / l[cm].

[0085] (ionization potential) A 100 nm ITO film was formed on non-alkali glass, and the substrate was cut into 1 cm squares. The surface was cleaned for 10 minutes using a UV ozone cleaner (manufactured by Sen Special Light Sources). Next, using a vapor deposition machine, the pyrromethene boron complex obtained in each example and the pyrromethene obtained in the comparative example were vapor deposited at a film formation rate of 10 nm / s to produce a 30 nm thick thin film.

[0086] The ionization potential Ip of the obtained thin film was measured in air using a photoelectron spectrometer (manufactured by Riken Keiki Co., Ltd.: AC-2).

[0087] (thin film absorption characteristics) A 3 cm square quartz plate was surface-cleaned for 10 minutes using a UV ozone cleaner (manufactured by Sen Special Light Sources). Subsequently, using a vapor deposition machine, the pyrromethene boron complex obtained in each example and the pyrromethene obtained in the comparative example were vapor-deposited at a film-forming rate of 10 nm / s to produce a 30 nm-thick thin film. The absorption spectrum of the obtained thin film was measured using a spectrophotometer (U-3010) manufactured by Hitachi High-Tech Science Corporation, and the peak wavelength and half-width were determined.

[0088] In addition, a tangent line was drawn to the falling edge on the long wavelength side of the obtained absorption spectrum, and the wavelength value λedge [nm] at the intersection of the tangent line and the horizontal axis was substituted into the following conversion formula 2 to calculate the energy gap Eg. Conversion formula 2: Eg[eV]=1239.85 / λedge The absorbance A and film thickness x obtained from the absorption spectrum were substituted into the following conversion formula 3 to determine the absorption coefficient α. Conversion formula 3: α[m -1 ]=A / log10 (e / x)[m].

[0089] (HOMO level, LUMO level) The electron affinity Af was calculated from the Ip and Eg values ​​measured or calculated by the above method, and used as an index of the LUMO level. Ip was also used as an index of the HOMO level.

[0090] Example 1 Synthesis of Compound A-1 3.80 g of 2,4-dimethylpyrrole and 267 mL of dehydrated diethyl ether were placed in a flask and purged with nitrogen. The mixed solution was cooled to 0°C, and 26.2 mL of 1.6 M n-butyllithium was added dropwise and stirred at room temperature for 1.5 hours. 2.70 mL of 2,6-dimethylaniline was added to the reaction solution and stirred at room temperature for 30 minutes. 31.2 g of aldehyde was added to the reaction solution and stirred at 35°C for 5.5 hours. The reaction solution was cooled to room temperature, saturated aqueous ammonium chloride solution was added, and the mixture was stirred to extract the organic layer. This organic layer was dried over magnesium sulfate, filtered, and the solvent was distilled off. The resulting reaction product was purified by silica gel column chromatography to obtain 11.3 g of brown liquid A-1A.

[0091] 8.01 g of A-1A and 350 mL of toluene were placed in a flask and purged with nitrogen. 3.31 g of 2,4-dimethylpyrrole and 6.11 g of methanesulfonic anhydride were added to the reaction solution, which was then heated and stirred at 80°C for 7.5 hours. The reaction solution was cooled to room temperature, water was added, and the mixture was stirred to extract the organic layer. This organic layer was dried over magnesium sulfate, filtered, and the solvent was removed by distillation to obtain A-1B.

[0092] 250 mL of methylene chloride was added to A-1B in a flask and the atmosphere was replaced with nitrogen. 24.0 mL of diisopropylethylamine and 17.5 mL of boron trifluoride diethyl ether complex were added and stirred at room temperature for 17.5 hours. Water was then added and stirred to extract the organic layer. This organic layer was dried over magnesium sulfate, filtered, and the solvent was distilled off. The resulting reaction product was purified by silica gel column chromatography to obtain 8.92 g of orange powder A-1C.

[0093] 2.50 g of A-1C and 43 mL of methylene chloride were placed in a flask and purged with nitrogen. 960 mg of N-iodosuccinimide was added and stirred at room temperature for 2 hours, after which water was added and stirred to extract the organic layer. This organic layer was dried over magnesium sulfate, filtered, and the solvent was distilled off. The resulting reaction product was purified by silica gel column chromatography to obtain 2.33 g of orange powder A-1D.

[0094] A flask was charged with 2.30 g of A-1D, 790 mg of phenylboronic acid, 64 mL of toluene, 64 mL of ethanol, and 32 mL of water, and the atmosphere was replaced with nitrogen. 2.67 g of potassium carbonate and 370 mg of tetrakistriphenylphosphine palladium were added, and the mixture was heated and stirred at 78°C for 1 hour. The reaction solution was cooled to room temperature, and water was added and stirred to extract the organic layer. This organic layer was dried over magnesium sulfate, filtered, and the solvent was distilled off. The resulting reaction product was purified by silica gel column chromatography to obtain 2.17 g of orange powder A-1. The resulting powder 1 The results of H-NMR analysis are as follows, and it was confirmed that the orange powder obtained above was compound A-1 having a structure represented by general formula (1). 1 H-NMR(CDCl3(d=ppm)):7.95(t,1H),7.62(d,4H),7.56(d,2H),7.49(d,4H),7.37(t,2H),7.30(d,1H ),7.16-7.14(m,2H),6.03(s,1H),2.60(s,3H),2.54(s,3H),1.53(s,3H),1.43(s,3H),1.37(s,18H).

[0095] [ka]

[0096] To further increase the purity, sublimation purification was performed. The metal container containing compound A-1 was placed in a glass tube, and 1 × 10 -3The solid was sublimated by heating at 300°C under a pressure of 10 Pa. The solid adhering to the wall of the glass tube was collected and analyzed by LC-MS, revealing a purity of 99%.

[0097] The results of evaluation of A-1 after sublimation purification by the above-mentioned method are shown below. Absorption spectrum (solvent: toluene): λmax 516nm, half width 27nm Absorption spectrum (thin film): λmax 530nm, half width 47nm Ionization potential: 5.81 eV Electron affinity: 3.59eV As described above, the absorption spectrum of the thin film has an absorption peak wavelength of 490 nm or more and 580 nm or less, and a half-width of 45 nm or more and 130 nm or less, so A-1 can photoelectrically convert green light with high efficiency.

[0098] The structures of the pyrromethene boron complex precursor A-1E and the pyrromethene boron complexes A-2 to A-6 and B-1 used in each of the Examples and Comparative Examples are shown below.

[0099] [ka]

[0100] Example 2 Synthesis of Compound A-2 8.92 g of A-1C and 150 mL of methylene chloride were placed in a flask and purged with nitrogen. 2.83 g of N-bromosuccinimide was added and stirred at room temperature for 2 hours, after which the solvent was distilled off. The resulting reaction product was purified by silica gel column chromatography to obtain 5.82 g of orange powder A-1E.

[0101] A flask was charged with 504 mg of A-1E, 231 mg of 4-methoxyphenylboronic acid, 15 mL of toluene, 15 mL of methanol, and 10 mL of water, and the atmosphere was replaced with nitrogen. 642 mg of potassium carbonate and 11.6 mg of tetrakistriphenylphosphine palladium were added, and the mixture was heated and stirred at 69°C for 19 hours. The reaction solution was cooled to room temperature, water was added, and the mixture was stirred, and the organic layer was extracted. This organic layer was dried over magnesium sulfate, filtered, and the solvent was distilled off. The resulting reaction product was purified by silica gel column chromatography, yielding 301 mg of orange powder A-2. 1 The H-NMR analysis results are as follows, and it was confirmed that the orange powder obtained above was Compound A-2 having a structure represented by general formula (1). 1 H-NMR(CDCl3(d=ppm)):7.95(t,1H),7.62(dd,4H),7.55(d,2H),7.49(dd,4H),7.06(dd,2H),6.91(d d,2H),6.02(s,1H),3.82(s,3H),2.60(s,3H),2.53(s,3H),1.52(s,3H),1.42(s,3H),1.37(s,18H).

[0102] To further increase the purity, sublimation purification was performed. The metal container containing compound A-2 was placed in a glass tube, and 1 × 10 -3 The solid was sublimated by heating at 300°C under a pressure of 10 Pa. The solid adhering to the wall of the glass tube was collected and analyzed by LC-MS, revealing a purity of 99%.

[0103] The results of evaluation of A-2 after sublimation purification by the above-mentioned method are shown below. Absorption spectrum (solvent: toluene): λmax 518nm, half width 39nm Absorption spectrum (thin film): λmax 533nm, half width 56nm Ionization potential: 5.73 eV Electron affinity: 3.55eV As described above, the absorption spectrum of the thin film has an absorption peak wavelength of 490 nm or more and 580 nm or less, and a half-width of 45 nm or more and 130 nm or less, so A-2 can photoelectrically convert green light with high efficiency.

[0104] Example 3 Synthesis of Compound A-3 A flask was charged with 444 mg of A-1E, 401 mg of 4-diphenylaminophenylboronic acid, 7 mL of toluene, 7 mL of ethanol, and 4 mL of water, and the atmosphere was replaced with nitrogen. 567 mg of potassium carbonate and 73.5 mg of tetrakistriphenylphosphine palladium were added, and the mixture was heated and stirred at 69°C for 19 hours. The reaction solution was cooled to room temperature, water was added, and the mixture was stirred to extract the organic layer. This organic layer was dried over magnesium sulfate, filtered, and the solvent was distilled off. The resulting reaction product was purified by silica gel column chromatography to obtain 417 mg of a red powder, A-3. 1 The results of H-NMR analysis are as follows, and it was confirmed that the red powder obtained above was compound A-3 having a structure represented by general formula (1). 1 H-NMR(CDCl3(d=ppm)):7.95(t,1H),7.61(d,4H),7.54(d,2H),7.49(d,4H),7.26-7.22(m,4H),7.00(d, 4H),7.06-6.98(m,6H),6.01(s,1H),2.59(s,3H),2.57(s,3H),1.52(s,3H),1.46(s,3H),1.36(s,18H).

[0105] To further increase the purity, sublimation purification was performed. The metal container containing compound A-3 was placed in a glass tube, and 1 × 10 -3 The solid was sublimated by heating at 320°C under a pressure of 10 Pa. The solid adhering to the wall of the glass tube was collected and analyzed by LC-MS, which revealed that it was 100% pure.

[0106] The results of evaluation of A-3 after sublimation purification by the above-mentioned method are shown below. Absorption spectrum (solvent: toluene): λmax 521nm, half width 45nm Absorption spectrum (thin film): λmax 533nm, half width 67nm Ionization potential: 5.43 eV Electron affinity: 3.34eV As described above, the absorption spectrum of the thin film has an absorption peak wavelength of 490 nm or more and 580 nm or less, and a half-width of 50 nm or more and 130 nm or less, so A-3 can photoelectrically convert green light with high efficiency.

[0107] Example 4 Synthesis of compound A-4 3.95 g of 2,4-dimethylpyrrole and 275 mL of dehydrated diethyl ether were placed in a flask and purged with nitrogen. The mixed solution was cooled to 0°C, and 29.5 mL of 1.6 M n-butyllithium was added dropwise and stirred at room temperature for 2 hours. 2.60 mL of 2,6-dimethylaniline was added to the reaction solution and stirred at room temperature for 45 minutes. 22.5 g of aldehyde was added to the reaction solution and stirred at 30°C for 1.5 hours. The reaction solution was cooled to room temperature, saturated aqueous ammonium chloride solution was added, and the mixture was stirred to extract the organic layer. This organic layer was dried over magnesium sulfate, filtered, and the solvent was evaporated. The resulting reaction product was purified by silica gel column chromatography to obtain 20.7 g of a brown solid, A-4A, as a mixture with difficult-to-separate impurities.

[0108] A mixture of 20.7 g of A-4A and impurities and 250 mL of toluene were placed in a flask and purged with nitrogen. 5.60 g of 2,4-dimethylpyrrole and 9.78 g of methanesulfonic anhydride were added to the reaction solution, which was then heated and stirred at 80°C for 7.5 hours. 1.96 g of 2,4-dimethylpyrrole and 6.62 g of methanesulfonic anhydride were then added to the reaction solution, which was then heated and stirred at 80°C for 1.5 hours. The reaction solution was cooled to room temperature, water was added, and the mixture was stirred to extract the organic layer. This organic layer was dried over magnesium sulfate, filtered, and the solvent was removed by distillation to obtain A-4B.

[0109] 250 mL of methylene chloride was added to A-4B in a flask and the atmosphere was replaced with nitrogen. 40.0 mL of diisopropylethylamine and 30.0 mL of boron trifluoride diethyl etherate were added and stirred at room temperature for 17 hours. Water was then added and stirred, and the organic layer was extracted. This organic layer was dried over magnesium sulfate, filtered, and the solvent was distilled off. The resulting reaction product was purified by silica gel column chromatography to obtain 13.8 g of orange powder A-4C.

[0110] 13.8 g of A-4C and 300 mL of methylene chloride were placed in a flask and purged with nitrogen. 5.43 g of N-bromosuccinimide was added and stirred at room temperature for 22.5 hours, after which the solvent was distilled off. The resulting reaction product was purified by silica gel column chromatography to obtain 7.24 g of orange powder A-4D.

[0111] 3.52 g of A-4D, 3.69 g of diphenylaminophenylboronic acid, 60 mL of toluene, 60 mL of ethanol, and 30 mL of water were placed in a flask and purged with nitrogen. 5.25 g of potassium carbonate and 1.48 g of tetrakistriphenylphosphine palladium were added, and the mixture was heated and stirred at 78°C for 14 hours. The reaction solution was cooled to room temperature, water was added, and the mixture was stirred to extract the organic layer. This organic layer was dried over magnesium sulfate, filtered, and the solvent was distilled off. The resulting reaction product was purified by silica gel column chromatography and then recrystallized from butyl acetate, yielding 2.46 g of red powder A-4. 1 The results of H-NMR analysis are as follows, and it was confirmed that the red powder obtained above was compound A-4 having a structure represented by general formula (1). 1 H-NMR(CDCl3(d=ppm)):7.94(t,1H),7.66(d,4H),7.58(d,2H),7.47(t,4H),7.40(t,2H),7.24(t,6 H),7.10(d,2H),6.07-6.99(m,6H),6.03(s,1H)2.64(s,3H),2.58(s,3H),1.54(s,3H),1.48(s,3H).

[0112] [ka]

[0113] To further increase the purity, sublimation purification was performed. The metal container containing compound A-4 was placed in a glass tube, and 1 × 10 -3 The solid was sublimated by heating at 275°C under a pressure of 10 Pa. The solid adhering to the wall of the glass tube was collected and analyzed by LC-MS, revealing a purity of 99%.

[0114] The results of evaluation of A-4 after sublimation purification by the above-mentioned method are shown below. Absorption spectrum (solvent: toluene): λmax 521nm, half width 46nm Absorption spectrum (thin film): λmax 536nm, half width 72nm Ionization potential: 5.59 eV Electron affinity: 3.52eV As described above, the absorption spectrum of the thin film has an absorption peak wavelength of 490 nm or more and 580 nm or less, and a half-width of 45 nm or more and 130 nm or less, so A-4 can photoelectrically convert green light with high efficiency.

[0115] Example 5 Synthesis of Compound A-5 7.17 g of 2,4-dimethylpyrrole, 180 mL of dehydrated diethyl ether, and 22 mL of toluene were placed in a flask and purged with nitrogen. The mixed solution was cooled to 0°C, and 55.0 mL of 1.6 M n-butyllithium was added dropwise and stirred at room temperature for 1.5 hours. 4.80 mL of 2,6-dimethylaniline was added to the reaction solution and stirred at room temperature for 45 minutes. 25.5 g of aldehyde was added to the reaction solution and stirred at 35°C for 7.5 hours. The reaction solution was cooled to room temperature, saturated aqueous ammonium chloride solution was added, and the mixture was stirred to extract the organic layer. This organic layer was dried over magnesium sulfate, filtered, and the solvent was evaporated. The resulting reaction product was purified by silica gel column chromatography to obtain 20.1 g of a white solid, A-5A, as a mixture with difficult-to-separate impurities.

[0116] A mixture of 20.1 g of A-5A and impurities and 400 mL of toluene were placed in a flask and purged with nitrogen. 15.8 g of 2,4-dimethylpyrrole and 28.5 g of methanesulfonic anhydride were added to the reaction solution, which was then heated and stirred at 80°C for 5 hours. The reaction solution was cooled to room temperature, water was added, and the mixture was stirred to extract the organic layer. This organic layer was dried over magnesium sulfate, filtered, and the solvent was removed by distillation to obtain A-5B.

[0117] 400 mL of methylene chloride was added to A-5B in a flask and the atmosphere was purged with nitrogen. 121 mL of diisopropylethylamine and 81.0 mL of boron trifluoride diethyl etherate were added and stirred at room temperature for 21 hours, after which water was added and stirred, and the organic layer was extracted. This organic layer was dried over magnesium sulfate, filtered, and the solvent was distilled off. The resulting reaction product was placed in a flask, 400 mL of methylene chloride was added, and the atmosphere was purged with nitrogen. 120 mL of diisopropylethylamine and 74.0 mL of boron trifluoride diethyl etherate were added and stirred at room temperature for 18 hours, after which water was added and stirred, and the organic layer was extracted. This organic layer was dried over magnesium sulfate, filtered, and the solvent was distilled off. The resulting reaction product was purified by silica gel column chromatography to obtain 18.1 g of a black-green powder, A-5C, as a mixture with difficult-to-separate impurities.

[0118] A mixture of 18.1 g of A-5C and impurities and 250 mL of methylene chloride were placed in a flask and purged with nitrogen. 9.08 g of N-bromosuccinimide was added and stirred at room temperature for 1.5 hours, after which the solvent was distilled off. The resulting reaction product was purified by silica gel column chromatography to obtain 7.62 g of orange powder A-5D.

[0119] 2.89 g of A-5D, 3.37 g of diphenylaminophenylboronic acid, 60 mL of toluene, 60 mL of ethanol, and 30 mL of water were placed in a flask and purged with nitrogen. 5.47 g of potassium carbonate and 1.52 g of tetrakistriphenylphosphine palladium were added, and the mixture was heated and stirred at 78°C for 10.5 hours. The reaction solution was cooled to room temperature, water was added, and the mixture was stirred to extract the organic layer. This organic layer was dried over magnesium sulfate, filtered, and the solvent was distilled off. The resulting reaction product was purified by silica gel column chromatography and then recrystallized from butyl acetate, yielding 739 mg of red powder A-5. 1 The results of H-NMR analysis are as follows, and it was confirmed that the red powder obtained above was compound A-5 having a structure represented by general formula (1). 1 H-NMR(CDCl3(d=ppm)):7.99(d,1H),7.92(dd,1H),7.87(dd,1H),7.82(s,1H),7.59-7.55(m,2H),7.41(dd,1H),7. 24(t,4H),7.08(d,4H),7.02(t,3H),6.98(t,3H),5.99(s,1H),2.59(s,3H),2.57(s,3H),1.31(s,3H),1.25(s,3H).

[0120] [ka]

[0121] To further increase the purity, sublimation purification was performed. The metal container containing compound A-5 was placed in a glass tube, and 1 × 10 -3 The solid was sublimated by heating at 260°C under a pressure of 10 Pa. The solid adhering to the wall of the glass tube was collected and analyzed by LC-MS, revealing a purity of 99%.

[0122] The results of evaluation of A-5 after sublimation purification by the above-mentioned method are shown below. Absorption spectrum (solvent: toluene): λmax 521nm, half width 46nm Absorption spectrum (thin film): λmax 537nm, half width 75nm Ionization potential: 5.57 eV Electron affinity: 3.51eV As described above, the absorption spectrum of the thin film has an absorption peak wavelength of 490 nm or more and 580 nm or less, and a half-width of 45 nm or more and 130 nm or less, so A-5 can photoelectrically convert green light with high efficiency.

[0123] Example 6 Synthesis of compound A-6 11.7 g of 2,4-dimethylpyrrole and 500 mL of dehydrated diethyl ether were placed in a flask and purged with nitrogen. The mixed solution was cooled to 0°C, and 90.0 mL of 1.6 M n-butyllithium was added dropwise and stirred at room temperature for 2 hours. 7.50 mL of 2,6-dimethylaniline was added to the reaction solution and stirred at room temperature for 45 minutes. 27.0 mL of aldehyde was added to the reaction solution and stirred at 30°C for 4 hours. The reaction solution was cooled to room temperature, saturated aqueous ammonium chloride solution was added, and the mixture was stirred to extract the organic layer. This organic layer was dried over magnesium sulfate, filtered, and the solvent was distilled off. The resulting reaction product was washed with methanol to obtain 10.6 g of a yellow-white solid, A-6A.

[0124] 10.6 g of A-6A and 250 mL of toluene were placed in a flask and purged with nitrogen. 10.1 g of 2,4-dimethylpyrrole and 18.7 g of methanesulfonic anhydride were added to the reaction solution, which was then heated and stirred at 80°C for 5 hours. The reaction solution was cooled to room temperature, water was added, and the mixture was stirred to extract the organic layer. This organic layer was dried over magnesium sulfate, filtered, and the solvent was removed by distillation to obtain A-6B.

[0125] 300 mL of methylene chloride was added to A-6B in a flask and the atmosphere was replaced with nitrogen. 75.0 mL of diisopropylethylamine and 51.0 mL of boron trifluoride diethyl ether complex were added and stirred at room temperature for 16.5 hours. Water was then added and stirred, and the organic layer was extracted. This organic layer was dried over magnesium sulfate, filtered, and the solvent was distilled off. The resulting reaction product was purified by silica gel column chromatography to obtain 14.2 g of orange powder A-6C.

[0126] 14.1 g of A-6C and 400 mL of methylene chloride were placed in a flask and purged with nitrogen. 8.10 g of N-bromosuccinimide was added and the mixture was stirred at room temperature for 19 hours, after which the solvent was distilled off. The resulting reaction product was purified by silica gel column chromatography to obtain 9.55 g of orange powder A-6D.

[0127] A flask was charged with 3.00 g of A-6D, 4.31 g of diphenylaminophenylboronic acid, 70 mL of toluene, 70 mL of ethanol, and 35 mL of water, and the atmosphere was replaced with nitrogen. 6.29 g of potassium carbonate and 1.74 g of tetrakistriphenylphosphine palladium were added, and the mixture was heated and stirred at 78°C for 18 hours. The reaction solution was cooled to room temperature, water was added, and the mixture was stirred to extract the organic layer. This organic layer was dried over magnesium sulfate, filtered, and the solvent was distilled off. The resulting reaction product was purified by silica gel column chromatography and then recrystallized from methylene chloride / heptane, yielding 2.04 g of a red powder, E-1. 1 The H-NMR analysis results are as follows, and it was confirmed that the red powder obtained above was compound A-6 having a structure represented by general formula (1). 1 H-NMR(CDCl3(d=ppm)):7.51-7.47(m,3H),7.33-7.31(m,2H),7.25(t,4H),7.10(d,4H),7 .05(t,3H)7.00(t,3H),5.99(s,1H),2.58(s,3H),2.55(s,3H),1.38(s,3H),1.32(s,3H).

[0128] [ka]

[0129] To further increase the purity, sublimation purification was performed. The metal container containing compound A-6 was placed in a glass tube, and 1 × 10 -3The solid was sublimated by heating at 265°C under a pressure of 10 Pa. The solid adhering to the wall of the glass tube was collected and analyzed by LC-MS, revealing a purity of 99%.

[0130] The results of evaluation of A-6 after sublimation purification by the above-mentioned method are shown below. Absorption spectrum (solvent: toluene): λmax 520nm, half width 46nm Absorption spectrum (thin film): λmax 535nm, half width 79nm Ionization potential: 5.47 eV Electron affinity: 3.40eV As described above, the absorption spectrum of the thin film has an absorption peak wavelength of 490 nm or more and 580 nm or less, and a half-width of 45 nm or more and 130 nm or less, so A-6 can photoelectrically convert green light with high efficiency.

[0131] (Comparative Example 1) Compound B-1, which does not have the structure represented by general formula (1), was evaluated by the above-mentioned method.

[0132] Table 1 shows the solution properties of the compounds (photoelectric conversion materials) obtained in each of the Examples and Comparative Examples, and Table 2 shows the thin film properties, HOMO level, LUMO level, and energy gap.

[0133] [Table 1]

[0134] [Table 2]

Claims

1. A photoelectric conversion material having a structure represented by the following general formula (1): 【Chemistry 1】 In the above general formula (1), R １ , R ３ , R ４ and R ６ may be the same or different and represent a hydrogen atom, an alkyl group or a cycloalkyl group. R 2 represents a hydrogen atom, and R 5 represents an aryl group or a heteroaryl group. R ７ represents an aryl group or a heteroaryl group. １ and X ２ may be the same or different and represent an alkyl group, an aryl group, an alkoxy group, an aryloxy group, a halogen atom or a cyano group.

2. In the general formula (1), X １ and X ２ The photoelectric conversion material according to claim 1 , wherein is a fluorine atom.

3. A photoelectric conversion element for converting light into electrical energy, comprising a photoelectric conversion layer between an anode and a cathode, wherein the photoelectric conversion layer contains the photoelectric conversion material according to claim 1 or 2.

4. The photoelectric conversion element according to claim 3 , wherein the photoelectric conversion layer contains two or more types of photoelectric conversion materials.

5. An optical sensor comprising the photoelectric conversion element according to claim 3 or 4.

6. An imaging device comprising the photoelectric conversion element according to claim 3 or 4.

7. A fingerprint authentication device comprising the photoelectric conversion element according to claim 3 or 4 and an organic light-emitting element, and performing fingerprint authentication using light from the organic light-emitting element.

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