Classifications

• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
  • Y02E10/00—Energy generation through renewable energy sources
  • Y02E10/50—Photovoltaic [PV] energy
  • Y02E10/549—Organic PV cells

Definitions

• the present invention relates to a photoelectric conversion material, as well as a photoelectric conversion element, an optical sensor, and a display device that use the same.
• An optical sensor generally comprises a photoelectric conversion element that converts light into electrical energy and a light-emitting element, and senses by irradiating an object with light from the light-emitting element and receiving the light that is transmitted through or reflected from the object with the photoelectric conversion element.
• a photoelectric conversion element that converts light into electrical energy
• a light-emitting element that senses by irradiating an object with light from the light-emitting element and receiving the light that is transmitted through or reflected from the object with the photoelectric conversion element.
• biometric information such as fingerprints, vein shapes, and blood oxygen levels.
• pyrromethene compounds are being considered as photoelectric conversion materials for use in photoelectric conversion elements in organic solar cells, organic photodetectors, and the like (see, for example, Patent Documents 1 to 4).
• Pyrromethene compounds generally have a high absorption coefficient, and are characterized by the fact that the absorption wavelength region can be designed to a desired range by selecting the substituent.
• Patent Documents 1 to 4 are sensitive in the range from red light to near-infrared light, they have the problem of being susceptible to thermal decomposition during vacuum deposition to manufacture organic devices and during the preceding high-purity process, sublimation purification.
• conjugation expansion is required to absorb long-wavelength light such as red and near-infrared light, but the substitution and condensation of aromatic rings required for conjugation expansion leads to an increase in the sublimation temperature due to the high molecular weight, making them susceptible to thermal decomposition during vacuum deposition and sublimation purification.
• the present invention aims to provide a photoelectric conversion material that is sensitive to the red light region, has high heat resistance, and is suitable for processing.
• Ar 1 is an aromatic carbocyclic ring or an aromatic heterocyclic ring.
• Ar 2 is an aryl group or a heteroaryl group, and may form a ring structure with an adjacent group.
• R 1 is selected from the group consisting of a hydrogen atom, an alkyl group, a cycloalkyl group, an aryl group, a heteroaryl group, an alkoxy group, a halogen atom, a cyano group, a nitro group, a silyl group, and a boryl group.
• R 2 and R 3 are each independently selected from the group consisting of a hydrogen atom, an alkyl group, a cycloalkyl group, an aryl group, a heteroaryl group, an alkoxy group, a halogen atom, a cyano group, a nitro group, a silyl group, and a boryl group, and a ring structure between the adjacent group.
• R 4 is an unsubstituted phenyl group.
• Y 1 is CR 5 R 6 , NR 7 , an oxygen atom, or a sulfur atom.
• R5 to R7 are each independently selected from the group consisting of a hydrogen atom, an alkyl group, a cycloalkyl group, an aryl group, a heteroaryl group, an alkoxy group, a halogen atom, a cyano group, a nitro group, a silyl group, and a boryl group.
• R5 and R6 may be bonded to each other to form a ring structure.
• X1 and X2 are each independently selected from the group consisting of an alkyl group, an aryl group, an alkoxy group, an aryloxy group, a halogen atom, and a cyano group.
• R 1 to R 6 are the same as those in general formula (1).
• R 8 to R 16 are each independently selected from the group consisting of a hydrogen atom, an alkyl group, a cycloalkyl group, an aryl group, a heteroaryl group, an alkoxy group, a halogen atom, a cyano group, a nitro group, a silyl group, a boryl group, and a ring structure formed between adjacent substituents.
• Ar 3 is an aromatic carbon ring or an aromatic heterocycle.
• Y 2 is CR 5 R 6 , NR 7 , an oxygen atom or a sulfur atom.
• R 1 , R 2 , R 4 to R 7 , Ar 1 , X 1 , X 2 and Y 1 are the same as those in general formula (1).
• [6] A photoelectric conversion element having a photoelectric conversion layer between an anode and a cathode, which converts light into electrical energy, the photoelectric conversion layer containing the photoelectric conversion material according to any one of [1] to [5].
• R 17 is selected from the group consisting of a hydrogen atom, an alkyl group, a cycloalkyl group, an aryl group, a heteroaryl group, an alkoxy group, a halogen atom, a cyano group, a nitro group, a silyl group, and a boryl group.
• R 18 to R 23 each independently represent a hydrogen atom or a methyl group.
• the present invention makes it possible to provide a photoelectric conversion material that is sensitive to the red light region, has high heat resistance, and is suitable for processing.
• the photoelectric conversion material according to the embodiment of the present invention has a structure represented by the following general formula (1).
• Ar 1 is an aromatic carbocycle or aromatic heterocycle.
• This aromatic carbocycle or aromatic heterocycle may be unsubstituted or substituted.
• the aromatic carbocycle is a cyclic structure that exhibits aromaticity in which the atoms constituting the ring are composed only of carbon, and examples thereof include a benzene ring, a naphthalene ring, a phenanthrene ring, and an anthracene ring.
• the aromatic heterocycle is a cyclic structure that exhibits aromaticity in which the atoms constituting the ring are composed of carbon and atoms other than carbon, and examples thereof include a furan ring, a pyrrole ring, a thiophene ring, a benzofuran ring, an indole ring, and a benzothiophene ring.
• a furan ring a pyrrole ring
• a thiophene ring a benzofuran ring
• an indole ring an indole ring
• a benzothiophene ring an aromatic carbocycle is preferred, and a benzene ring and a naphthalene ring are more preferred.
• Ar2 is an aryl group or a heteroaryl group.
• This aryl group or heteroaryl group may be unsubstituted or substituted, and may form a ring structure with adjacent groups.
• an aryl group is preferred, specifically, a substituted or unsubstituted phenyl group is more preferred, and an unsubstituted phenyl group is even more preferred.
• R 1 is selected from the group consisting of a hydrogen atom, an alkyl group, a cycloalkyl group, an aryl group, a heteroaryl group, an alkoxy group, a halogen atom, a cyano group, a nitro group, a silyl group, and a boryl group.
• R2 and R3 are each independently selected from the group consisting of a hydrogen atom, an alkyl group, a cycloalkyl group, an aryl group, a heteroaryl group, an alkoxy group, a halogen atom, a cyano group, a nitro group, a silyl group, a boryl group, and a ring structure between the adjacent groups.
• R 1 to R 3 are each preferably independently a hydrogen atom, an alkyl group, a cycloalkyl group, an aryl group, a heteroaryl group, or an alkoxy group.
• R 1 and R 2 are aryl groups
• R 3 is a hydrogen atom.
• R 4 is an unsubstituted phenyl group.
• R 4 is a substituted aryl group or a fused aryl group such as a naphthyl group
• the aryl group is twisted due to the steric repulsion between these substituents or fused ring parts and adjacent substituents (R 1 and R 2 ) in the pyrromethene skeleton, and the conformation of the molecule becomes three-dimensional.
• the intermolecular interaction between the compounds having the structure represented by the general formula (1) is reduced, and the half-width of the absorption spectrum becomes narrow. If the half-width is narrow, red light cannot be sufficiently absorbed, and the photoelectric conversion efficiency of the optical sensor is impaired.
• R 4 is an unsubstituted phenyl group.
• Y 1 is CR 5 R 6 , NR 7 , an oxygen atom, or a sulfur atom.
• CR 5 R 6 is preferred from the viewpoints of low-cost production, reduced deposition temperature, and electrochemical stability.
• R 5 to R 7 are each independently selected from the group consisting of a hydrogen atom, an alkyl group, a cycloalkyl group, an aryl group, a heteroaryl group, an alkoxy group, a halogen atom, a cyano group, a nitro group, a silyl group, and a boryl group.
• R 5 and R 6 may be bonded to each other to form a ring structure.
• R 5 to R 7 are each independently more preferably a hydrogen atom, an alkyl group, a cycloalkyl group, an aryl group, and a heteroaryl group, and further preferably an alkyl group.
• X1 and X2 are each independently selected from the group consisting of an alkyl group, an aryl group, an alkoxy group, an aryloxy group, a halogen atom, and a cyano group.
• X1 and X2 are preferably halogen atoms, and more preferably fluorine atoms.
• the alkyl group refers to a saturated aliphatic hydrocarbon group, which may or may not have a substituent, such as 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, etc.
• the number of carbon atoms in the alkyl group is not particularly limited, but from the viewpoints of availability and cost, it is preferably from 1 to 20, and more preferably from 1 to 8.
• Cycloalkyl groups refer to saturated alicyclic hydrocarbon groups such as cyclopropyl, cyclopentyl, cyclohexyl, norbornyl, and adamantyl groups, which may or may not have a substituent.
• substituent include alkyl groups and the groups exemplified as the substituents for alkyl groups.
• the number of ring carbon atoms of the cycloalkyl group is preferably in the range of 3 to 20.
• the number of carbon atoms of the cycloalkyl group is preferably 5 to 10.
• 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 benzoanthracenyl 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.
• an aromatic hydrocarbon group such as a phenyl group, a biphenyl group, a terphenyl group, a naphthyl group, a fluor
• 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.
• substituents examples 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, a hydroxy group, a thiol group, a thioalkyl group, a nitro group, and a heteroaryl group.
• the number of ring carbon atoms of the aryl group is preferably in the range of 6 to 40, more preferably 6 to 30.
• the substituents may form a ring structure together.
• the number of carbon atoms of the aryl group is preferably 6 to 40.
• Heteroaryl groups include, for example, pyridyl, pyrrolyl, furanyl, thiophenyl, quinolinyl, isoquinolinyl, pyrazinyl, pyrimidyl, pyridazinyl, triazinyl, naphthyridinyl, cinnolinyl, phthalazinyl, quinoxalinyl, quinazolinyl, benzofuranyl, benzothiophenyl, indolyl, dibenzofuranyl, dibenzothiophenyl, carbazolyl, benzophenyl, and the like.
• a cyclic aromatic group having one or more atoms other than carbon in the ring such as a cycloaryl 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.
• a cycloaryl group such as a cycloaryl group, a carbolinyl group, an indolocarbazolyl group, a benzofurocarbazolyl group, a benzothienocarbazolyl group, a dihydroindenocarbazol
• the naphthyridinyl group refers to any of a 1,5-naphthyridinyl group, a 1,6-naphthyridinyl group, a 1,7-naphthyridinyl group, a 1,8-naphthyridinyl group, a 2,6-naphthyridinyl group, and a 2,7-naphthyridinyl group.
• the heteroaryl group may or may not have a substituent.
• substituents examples 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, 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 in the range of 2 to 40, more preferably 2 to 30.
• the number of carbon atoms of the heteroaryl group is preferably 2 to 40.
• alkoxy group refers to a functional group in which an aliphatic hydrocarbon group is bonded via an ether bond, such as a methoxy group, ethoxy group, or propoxy group, and this aliphatic hydrocarbon group may or may not have a substituent.
• 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.
• Halogen atoms include fluorine, chlorine, bromine and iodine atoms.
• sil group refers to a group to which a substituted or unsubstituted silicon atom is bonded, and examples thereof include alkylsilyl groups such as trimethylsilyl group, triethylsilyl group, tert-butyldimethylsilyl group, propyldimethylsilyl group, and vinyldimethylsilyl group, and arylsilyl groups such as phenyldimethylsilyl group, tert-butyldiphenylsilyl group, triphenylsilyl group, and trinaphthylsilyl group.
• the substituent on the silicon may be further substituted.
• the number of carbon atoms in the silyl group is not particularly limited, but is preferably in the range of 1 to 30.
• boryl group refers to a group to which a substituted or unsubstituted boron atom is bonded, and examples thereof include arylboryl groups such as diphenylboryl and dinaphthylboryl groups, alkoxyboryl groups such as dimethoxyboryl, diethoxyboryl and pinacolatoboryl groups, and aryloxyboryl groups such as diphenoxyboryl groups.
• the substituent on the boron may be further substituted.
• the number of carbon atoms in the boryl group is not particularly limited, but is preferably in the range of 1 to 30.
• photoelectric conversion materials having a structure represented by the above general formula (1) photoelectric conversion materials having a structure represented by the following general formula (2) are more preferred.
• R 1 to R 6 are the same as those in general formula (1).
• R 8 to R 16 are each independently selected from the group consisting of a hydrogen atom, an alkyl group, a cycloalkyl group, an aryl group, a heteroaryl group, an alkoxy group, a halogen atom, a cyano group, a nitro group, a silyl group, a boryl group, and a ring structure formed between adjacent substituents. The explanation of these substituents is as described above.
• a photoelectric conversion material having a structure represented by the above general formula (1) a photoelectric conversion material having a structure represented by the following general formula (3) is more preferable.
• Ar 3 is an aromatic carbon ring or an aromatic heterocycle.
• Y 2 is CR 5 R 6 , NR 7 , an oxygen atom or a sulfur atom.
• R 1 , R 2 , R 4 to R 7 , Ar 1 , X 1 , X 2 and Y 1 are the same as those in general formula (1). The explanation of these substituents is as described above.
• the photoelectric conversion material having the structure represented by general formula (1) can be synthesized by known methods, such as those described in U.S. Pat. Nos. 4,774,339, 5,187,288, 5,248,782, 5,433,896, and 5,451,663.
• the photoelectric conversion material having the structure represented by general formula (1) is preferably purified by organic synthesis methods such as recrystallization or column chromatography, and then further purified by reduced pressure heating, generally known as sublimation purification, to remove low boiling point components and improve purity.
• the heating temperature in sublimation purification is preferably 350°C or less, more preferably 330°C or less, from the viewpoint of preventing thermal decomposition.
• the purity of the photoelectric conversion material having the structure represented by general formula (1) is preferably 99% by weight or more from the viewpoint of stabilizing the photoelectric conversion characteristics.
• the photoelectric conversion material according to the embodiment of the present invention may be composed only of a photoelectric conversion material having a structure represented by general formula (1), but may also contain other photoelectric conversion materials in order to further increase the photoelectric conversion efficiency.
• the photoelectric conversion element according to the embodiment of the present invention is a photoelectric conversion element in which a photoelectric conversion layer is present between an anode and a cathode and converts light into electrical energy, and the photoelectric conversion layer contains the above-mentioned photoelectric conversion material.
• the photoelectric conversion layer preferably contains two or more types of photoelectric conversion materials, and for example, it is preferable to combine a photoelectric conversion material having a structure represented by general formula (1) with another photoelectric conversion material.
• the photoelectric conversion material to be combined is preferably an electron donor material (p-type organic semiconductor) or an electron acceptor material (n-type organic semiconductor), and more preferably an electron acceptor material.
• the photoelectric conversion material having a structure represented by general formula (1) is an electron donor material
• the photoelectric conversion layer contains a photoelectric conversion material having a structure represented by general formula (1) and an electron acceptor material.
• Electron acceptor materials include, for example, 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-naphthyltetracarboxydiimide (PTCDI-C8H); 2-(4-biphenylyl)-5-(4-t-butylphenyl)-1,3 ,4-oxadiazole (PBD), oxazole derivatives such as 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-
• fullerene compounds are preferably used because of their fast charge separation rate and electron transfer rate.
• fullerene compounds include unsubstituted fullerenes such as C60, C70, C76, C78, C82, C84, C90, and C94, [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).
• C60, C70, C76, C78, C82, C84, C90, and C94 [6,6]-phenyl
• Electron donor materials include, for example, oligothiophene compounds such as terthiophene, quarterthiophene, sexithiophene, and octithiophene, phenylenevinylene compounds, p-phenylene compounds, polyfluorene compounds, phthalocyanine derivatives such as the compound 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)bi
• the electron donor material and the electron acceptor material have different HOMO-LUMO levels.
• 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 charge separated and dissociated at the interface between the different materials, thereby further increasing the photoelectric conversion efficiency.
• the photoelectric conversion layer contains two or more types of photoelectric conversion materials
• these materials may be mixed in one layer, or layers containing each photoelectric conversion material may be stacked, but from the viewpoint of rectification, it is preferable that the layers are stacked.
• the layer containing the electron donor material is located on the anode side, and the layer containing the electron acceptor material is located on the cathode side.
• a mixed layer may be present at the stacking interface. This type of configuration is called a p-i-n 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 increasing the photoelectric conversion efficiency.
• the material to be combined with the photoelectric conversion material having the structure represented by general formula (1) is compatible at the molecular level, or is phase-separated at the nano level.
• the domain size of the phase-separated structure is preferably 1 nm or more and 50 nm or less.
• the thickness of the photoelectric conversion layer is preferably 10 nm to 500 nm, more preferably 20 nm to 100 nm.
• 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.
• the thickness of the i layer is preferably 1 nm to 100 nm, more preferably 5 nm to 50 nm.
• the anode and/or cathode have light transparency.
• the light transparency of the electrode is not particularly limited as long as the incident light reaches the photoelectric conversion layer and generates an electromotive force.
• the light transparency is an index indicated by a value calculated by [transmitted light intensity (W/m 2 )/incident light intensity (W/m 2 )] ⁇ 100 (%) (this is called "light transmittance").
• the light transmittance is preferably 50% or more at a wavelength of 350 nm or more, more preferably 70% or more, and even more preferably 90% or more.
• the thickness of the electrode having light transparency may be in a range having light transparency and conductivity, and varies depending on the electrode material, but is preferably 20 nm to 300 nm.
• the other electrode does not necessarily need to be light transparent as long as it is conductive, and the thickness is not particularly limited.
• the materials used for the electrodes 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.
• an electrode made of a conductive material with a large work function As the anode, it is preferable to use an electrode made of a conductive material with a large work function as the anode.
• 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 is one that forms an ohmic junction with the photoelectric conversion layer. Furthermore, as described below, in the case where a hole transport layer is provided between the anode and the photoelectric conversion layer, it is preferable that the conductive material used for the anode is one that forms an ohmic junction with the hole transport layer.
• the method for forming the anode can be selected optimally depending on the material used, but examples include sputtering, vapor deposition, and inkjet methods.
• sputtering is preferably used when the anode is made of metal oxide
• vapor deposition is preferably used when the anode is made of metal.
• an electrode made of a conductive material with a small work function As the cathode, it is preferable to use an electrode made of a conductive material with a small work function as the cathode.
• conductive materials with a small work function include alkali metals such as lithium, alkaline earth metals such as magnesium and calcium, tin, silver, aluminum, and alloys of these. A laminate using two or more of these materials may also be used.
• the conductive material used in 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 in the cathode preferably forms an ohmic junction with the electron transport layer. It is also possible to improve the extraction current by introducing a metal fluoride such as lithium fluoride or cesium fluoride into the interface between the cathode and the electron transport layer.
• a metal fluoride such as lithium fluoride or cesium fluoride
• the method for forming the cathode can be selected optimally depending on the material used, but examples include sputtering, vapor deposition, and inkjet methods.
• sputtering is preferably used when forming a cathode from a metal oxide
• vapor deposition is preferably used when forming an anode from a metal.
• the photoelectric conversion element 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.
• substrates include glass plates, ceramic plates, resin films, thin resin films made from cured varnish, and thin metal plates.
• glass substrates are preferably used because they are transparent and easy to process.
• flexible and foldable displays are becoming more common, mainly in mobile devices such as smartphones, and resin films and thin resin films are suitable for this application, including heat-resistant films such as polyimide films and polyethylene naphthalate films.
• the photoelectric conversion element according to the embodiment of the present invention may have a hole transport layer between the anode and the photoelectric conversion layer.
• 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-y
• the photoelectric conversion element according to the embodiment of the present invention may have a hole extraction layer between the anode and the hole transport layer.
• 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.
• TPAH tris(4-bromophenyl)aminium hexachloroantimonate
• HAT-CN6 1,4,5,8,9,11-hexaazatriphenylene-hexacarbonitrile
• F4-TCNQ 2,3,5,6-tetrafluor
• the photoelectric conversion element according to the embodiment of the present invention may also have an electron transport layer between the photoelectric conversion layer and the cathode.
• materials for forming the electron transport layer include the above-mentioned n-type organic semiconductors, as well as various metal complexes such as polycyclic aromatic derivatives, styryl aromatic ring derivatives, quinone derivatives, phosphorus oxide derivatives, quinolinol complexes such as tris(8-quinolinolato)aluminum(III), benzoquinolinol complexes, hydroxyazole complexes, azomethine complexes, tropolone metal complexes, and flavonol metal complexes.
• 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 large electron affinity, making it easier to transport electrons, which contributes to improving the 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.
• the electron transport material has a condensed polycyclic aromatic skeleton
• the glass transition temperature is improved and the electron mobility is large, which is more preferable.
• a condensed polycyclic aromatic skeleton a quinolinol complex, a triazine derivative, a fluoranthene skeleton, an anthracene skeleton, a pyrene skeleton, or a phenanthroline skeleton is preferable.
• the electron transport layer may contain an electron donor material.
• 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.
• the thickness of the electron transport layer is preferably 1 nm to 200 nm, and more preferably 5 nm to 100 nm.
• the method for forming each of the above layers constituting the photoelectric conversion element may be a dry process or a wet process, such as resistance heating deposition, electron beam deposition, sputtering, molecular lamination, coating, inkjet, and printing. Among these, resistance heating deposition is preferred from the viewpoint of element characteristics.
• the photoelectric conversion element according to the embodiment of the present invention has a function of converting light into electrical energy.
• the photoelectric conversion element according to the embodiment of the present invention preferably has an absorption peak wavelength of 570 nm or more and 670 nm or less and a half-width of 45 nm or more and 140 nm or less in the absorption spectrum of the photoelectric conversion layer, and more preferably has an absorption peak wavelength of 580 nm or more and 660 nm or less and a half-width of 50 nm or more and 130 nm or less.
• the photoelectric conversion element according to the embodiment of the present invention can be applied to various electronic devices and optical sensing devices that utilize the function of selectively and highly efficiently converting red light into electric signals.
• it can be used as an optical sensor, an optical switch, and an image sensor, and can obtain biological information such as fingerprints, veins, pulse waves, and blood oxygen concentration with high sensitivity.
• the biological information in the present invention is not particularly limited as long as it is information obtained from a living body, but examples include information obtained as reflected or transmitted light when a living body is irradiated with radiant light, and information obtained as light emitted from the living body.
• examples of objects to be measured include the iris, face shape, skin dryness, and blood sugar level.
• the optical sensor of the present invention is preferably used as a fingerprint authentication device for a display device.
• One aspect of this is a display device that uses a combination of an optical sensor according to an embodiment 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, it is possible to impart a fingerprint authentication function to the organic EL display.
• the optical sensor according to the embodiment of the present invention has excellent photoelectric conversion characteristics for red light, so when used in combination with a red light source, it is possible to perform sensing with high accuracy and sensitivity.
• red light emitted from an organic light-emitting element of an organic EL display is reflected and scattered by a finger touching the display, and the light is received and photoelectrically converted by an optical sensor according to an embodiment of the present invention, thereby making it possible to obtain fingerprint information with high accuracy.
• an organic EL display by configuring some of the pixels of an organic EL display with an optical sensor according to an embodiment of the present invention as described above, it is possible to impart a biosensing function to the organic EL display. That is, by receiving and photoelectrically converting the red light emitted from the organic light-emitting elements of the organic EL display, which is absorbed and scattered by a finger touching the display, using the photoelectric conversion element of the present invention, it is possible to obtain biological information such as veins, pulse waves, and blood oxygen concentration with high accuracy.
• examples of compounds according to embodiments of the present invention include compounds having a structure represented by the following formula (4) or formula (5).
• R 17 is selected from the group consisting of a hydrogen atom, an alkyl group, a cycloalkyl group, an aryl group, a heteroaryl group, an alkoxy group, a halogen atom, a cyano group, a nitro group, a silyl group, and a boryl group.
• R 18 to R 23 are each independently a hydrogen atom or a methyl group. It is preferable that R 18 to R 23 are all methyl groups.
• the compounds represented by the above formulas (4) and (5) are materials that combine deposition stability and heat resistance of thin films, and can be used for applications such as organic light-emitting devices, organic transistors, organic thin-film solar cells, and biosensors in addition to the optical sensors described above.
• Example 1 The pyrromethene boron complex obtained in Example 1 was subjected to 1 H-NMR measurement in a deuterated chloroform solution using a superconducting FT-NMR JNM-ECZ400R (manufactured by JEOL Ltd.) to identify the chemical structure.
• Example 1 Synthesis of Compound A-1 The following reaction was carried out under a nitrogen atmosphere. Chalcone (A-1A, 100 g) was dissolved in ethanol (400 mL), and nitromethane (80.0 mL) and diethylamine (150 mL) were added, followed by stirring at 80°C for 1.5 hours. The reaction solution was cooled to room temperature and concentrated under reduced pressure. The precipitated solid was washed with methanol to obtain 95.1 g (74%) of Compound A-1B as a white solid.
• the 1 H-NMR analysis results of the obtained powder are as follows, and it was confirmed that the above obtained black-green powder was compound A-1 having a structure represented by general formula (1).
• a photoelectric conversion element was produced using compound A-1 as a red light absorbing material.
• a 46 mm x 38 mm transparent glass substrate was prepared, with an ITO electrode layer of 125 nm thickness as the anode. This substrate was immersed in pure water and ultrasonically cleaned for 10 minutes, then ultrasonically cleaned with isopropyl alcohol for 10 minutes, and thoroughly dried. It was then subjected to UV ozone cleaning for 20 minutes.
• PEDOT:PSS poly3,4-ethylenedioxythiophene doped with poly4-styrenesulfonic acid
• isopropyl alcohol in a volume ratio of 6:4 was spin-coated at 3,000 rpm for 30 seconds onto the ITO electrode layer of the substrate, and then heated on a hot plate at 150°C for 10 minutes to form a hole extraction layer with a thickness of 55 nm.
• the substrate on which the hole extraction layer was formed was placed in a vacuum deposition apparatus (manufactured by Eiko Engineering Co., Ltd.), and the pressure was reduced to approximately 3 ⁇ 10 ⁇ 3 Pa.
• N-[1,1'-biphenyl]-4-yl-9,9-dimethyl-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-9H-fluoren-2-amine 60 nm
• A-1 23 nm
• fullerene C 60 , 23 nm
• the vacuum deposition apparatus was once opened to the atmosphere, and then the deposition source was replaced and the pressure was reduced again to about 3 ⁇ 10 ⁇ 3 Pa.
• Lithium quinolinol (7.5 nm) and aluminum (69 nm) were sequentially deposited on the photoelectric conversion layer to form an electron transport layer and a cathode, respectively.
• the obtained laminate was sealed with a barrier film (manufactured by TESA) in a glove box to obtain a photoelectric conversion element.
• the photoelectric conversion element obtained was evaluated using the method described above and was found to be sensitive in the red light region, with an external quantum efficiency of 21.2% and a spectral sensitivity peak wavelength of 614 nm.
• Example 2 Synthesis of Compound A-2 The following reaction was carried out under a nitrogen atmosphere. A-1K (4.00 g) was dissolved in toluene (50 mL), and benzoyl chloride (2.00 mL) was added thereto, followed by stirring for 3 hours under heating and reflux. The reaction solution was cooled to room temperature and concentrated under reduced pressure. The precipitated solid was washed with methanol to obtain 1.67 g (30%) of Compound A-2A as a light green solid.
• compound A-1K and A-2A were reacted under acidic conditions according to standard methods, and then reacted with boron trifluoride diethyl ether complex to obtain compound A-2.
• a photoelectric conversion element was fabricated in the same manner as in Example 1, except that Compound A-2 was used as the red light absorbing material and the thickness of the aluminum film was changed to 63 nm.
• Compound A-2 was used as the red light absorbing material and the thickness of the aluminum film was changed to 63 nm.
• it showed sensitivity in the red light region, with an external quantum efficiency of 20.1% and a spectral sensitivity peak wavelength of 648 nm.
• Example 3 Synthesis of Compound A-3 The following reaction was carried out under a nitrogen atmosphere.
• Compound A-3A 63.0 g was dissolved in ethanol (200 mL), and 3M aqueous potassium hydroxide solution (169 mL) and benzaldehyde (43.0 L) were added, followed by stirring at room temperature for 5 hours.
• the solid precipitated in the reaction solution was washed with methanol and water to quantitatively obtain compound A-3B (103 g) as a white solid.
• compound A-1K and A-3F were reacted under acidic conditions according to standard methods, and then reacted with boron trifluoride diethyl ether complex to obtain compound A-3.
• a photoelectric conversion element was fabricated in the same manner as in Example 1, except that Compound A-3 was used as the red light absorbing material and the thickness of the aluminum film was changed to 81 nm.
• Compound A-3 was used as the red light absorbing material and the thickness of the aluminum film was changed to 81 nm.
• it showed sensitivity in the red light region, with an external quantum efficiency of 30.9% and a spectral sensitivity peak wavelength of 632 nm.
• Example 4 Synthesis of Compound A-4 The following reaction was carried out under a nitrogen atmosphere.
• Compound A-4A (15.0 g) was dissolved in ethanol (170 mL), and 3M aqueous potassium hydroxide solution (60 mL) and benzaldehyde (12.5 mL) were added, followed by stirring at room temperature for 1 hour.
• the solid precipitated in the reaction solution was filtered and washed with methanol to obtain 22.1 g (89%) of compound A-4B as a white solid.
• a photoelectric conversion element was fabricated in the same manner as in Example 1, except that Compound A-4 was used as the red light absorbing material and the thickness of the aluminum film was changed to 75 nm.
• Compound A-4 was used as the red light absorbing material and the thickness of the aluminum film was changed to 75 nm.
• it showed sensitivity in the red light region, with an external quantum efficiency of 22.2% and a spectral sensitivity peak wavelength of 622 nm.
• Example 1 A photoelectric conversion element was prepared and evaluated in the same manner as in Example 1 except that Compound B-1 was used as the red light absorbent. The element showed sensitivity in the red light region, with an external quantum efficiency of 1.3% and a spectral sensitivity peak wavelength of 607 nm.
• Example 5 The current (I dark ) when a voltage of -3 V was applied to the photoelectric conversion element produced in Example 1 under light shielding, and the photocurrent (I photo ) when a voltage of -3 V was applied to the element under weak light (50 Lux) were measured, and I photo /I dark showed 100 or more. It was also confirmed that the photocurrent when a voltage of -3 V was applied to the element was directly proportional to the amount of light in the range of 1 to 300 Lux. From these results, it was confirmed that the photoelectric conversion element of the present invention functions as a photosensor.

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