Classifications

• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
  • H10K30/00—Organic devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation
  • H10K30/40—Organic devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation comprising a p-i-n structure, e.g. having a perovskite absorber between p-type and n-type charge transport layers
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
  • H10K30/00—Organic devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation
  • H10K30/50—Photovoltaic [PV] devices
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
  • H10K30/00—Organic devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation
  • H10K30/80—Constructional details
  • H10K30/84—Layers having high charge carrier mobility
  • H10K30/86—Layers having high hole mobility, e.g. hole-transporting layers or electron-blocking layers
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
  • H10K85/00—Organic materials used in the body or electrodes of devices covered by this subclass
  • H10K85/60—Organic compounds having low molecular weight

Definitions

• the present invention relates to a hole transport material that can be used in organic solar cells, such as dye-sensitized solar cells and perovskite solar cells. It also relates to a hole transport material that can be vapor-deposited.
• methylammonium lead iodide NH3CH3PbI3
• PbI2 lead iodide
• CH3NH3I methylammonium iodide
• Perovskite solar cells use perovskite crystals of methylammonium lead iodide ( NH3CH3PbI3 ) as a solar light absorber, joined to an electron transport layer that collects photogenerated electrons and sends them to the anode , and a hole transport layer that transports photogenerated holes to the cathode.
• examples of electron-withdrawing substituents include halogen groups such as F, Cl, Br, and I, cyano groups, nitro groups, and acyl groups, while examples of electron-donating substituents include amino groups, N-monosubstituted amino groups, and N,N-disubstituted amino groups. More specifically, the formula (III):
• Compound 101 is synthesized by referring to Patent Document 4.
• Compound B is synthesized by reacting compound A, which is either synthetic or commercially available, with compound 101.
• Another object of the present invention is to provide a hole transport material capable of forming a hole transport layer by vapor deposition.
• the present inventors have conducted extensive research into hole transport materials capable of forming a hole transport layer by vapor deposition, and as a result have surprisingly found that a hole transport material having an unbalanced structure in which N,N-di-(substituted phenyl)amino groups are bonded to at least one of the four phenyl rings of a spirobifluorene skeleton represented by formula (I) as a core structure, rather than a structure in which N,N-di-(substituted phenyl)amino groups are bonded in a balanced manner to all of the four phenyl rings, is bonded to a hydrogen atom, a C1-4 alkyl group or an alkoxy group, i.e., a structure in which N,N-di-(substituted phenyl)amino groups are bonded
• R 31 and R 32 are independently a hydrogen atom, a substituted or unsubstituted linear or branched C 1-4 alkyl group, a substituted or unsubstituted phenyl group, a nitrogen-containing heteroaromatic group, or a group represented by formula (IX):
• R 33 is a substituted or unsubstituted linear or branched C 1-4 alkyl group, a substituted or unsubstituted linear or branched C 1-4 alkoxy group, an amino group, or an N-substituted or N,N-disubstituted amino group substituted with a substituted or unsubstituted phenyl group, if said linear or branched C1-4 alkyl group, said linear or branched C1-4 alkoxy group or said phenyl group is substituted, the substituents are selected from the group consisting of halogen atoms selected from F, Cl, Br and I, hydroxyl groups, carbonyl groups, nitro groups, cyano groups, sulfonyl groups; or R 31 and R 32 together with the nitrogen atom to which they are bonded form a substituted or unsubstituted 5- to 8-membered heterocycloalkyl group, wherein the heterocycloalkyl group may contain, in
• the substituents which are not an amino group, an N-substituted amino group or an N,N-disubstituted amino group represented by the above formula (V) are independently a hydrogen atom, a halogen atom selected from F, Cl, Br and I, a hydroxyl group, a carbonyl group, a nitro group, a cyano group, a sulfonyl group, a trifluoromethyl group, a substituted or unsubstituted linear or branched chain C 1-4 alkyl group, a substituted or unsubstituted linear or branched chain C 1-4 alkoxy group, or a nitrogen-containing aromatic ring group; If the linear or branched C 1-4 alkyl group, the linear or branched C 1-4 alkoxy group, or the nitrogen-containing aromatic ring group is substituted, the substituent is selected from the group consisting of a halogen atom selected from F, Cl, Br, and
• the present invention provides a hole transport material with properties superior to spiro-OMeTAD, particularly in nip-type (forward-current) solar cells ( Figure 1) that employ mp- TiO2 as a scaffold for forming perovskite crystals.
• the present invention also provides a hole transport material that can form a hole transport layer by vapor deposition.
• HTMs we fabricated perovskite solar cells using various spiro-OMeTAD analogues as HTMs by adjusting the highest occupied molecular orbital (E HOMO ) by changing the type and position of the substituents on the phenyl ring of the N,N-di-(substituted phenyl)amino group of spiro-OMeTAD, and measured the photoelectric conversion efficiency (PCE) in the presence or absence of dopants such as LiTFSI and TBP.
• E HOMO highest occupied molecular orbital
• PCE photoelectric conversion efficiency
• N,N-di-(substituted phenyl)amino group is selected from the group consisting of the following formula:
• Perovskite crystals which are useful for obtaining highly efficient photoelectric conversion elements, are known to have a three-dimensional structure and are represented by the composition formula: ABX3 (wherein A is an amine compound or a monovalent cation of an alkali metal element, B is a divalent cation of a metal element, and X is a monovalent anion of a halogen element).
• the hole transport material 3 of the present invention was synthesized according to reaction formula (1) and reaction formula (4).
• the hole transport material for solving the other object of the present invention can be synthesized by various synthetic routes. Hereinafter, an example of an embodiment for synthesizing the hole transport material of the present invention will be described.
• Compound 107 was synthesized with reference to Patent Document 4.
• Compound 107 (2.0 g, 4.2 mmol, 1.0 equivalent), compound 108 (1.8 g, 9.3 mmol, 2.2 equivalent), tris(dibenzylideneacetone)dipalladium(0) (Tokyo Chemical Industry, 39 mg, 0.04 mmol, 0.01 equivalent), 2-dicyclohexylphosphino-2',4',6'-triisopropylbiphenyl (Sigma-Aldrich, 40 mg, 0.08 mmol, 0.02 equivalent), cesium carbonate (Tokyo Chemical Industry, 4.1 g, 12.7 mmol, 3.0 equivalent), and 30 g of diethylene glycol dimethyl ether were charged and heated to 120 ° C.
• a perovskite solar cell 1 having the structure shown in Figure 1 was manufactured.
• a glass plate 11 having a fluorine-doped tin oxide (FTO)-coated FTO transparent electrode 12 was prepared.
• A. Formation of electron transport layer and mesoporous TiO2 layer The FTO film is subjected to oxygen plasma treatment, and then a film of amorphous compact TiO2 (c- TiO2 ) is formed on the FTO film by spray pyrolysis to form an electron transport layer 13. Next, titanium oxide nanoparticle colloid is spin-coated (at 2,000 rpm for 30 seconds), and then heated at 450°C for 30 minutes to form a mesoporous TiO2 (mp- TiO2 ) layer 14.
• c- TiO2 amorphous compact TiO2
• mp- TiO2 mesoporous TiO2
• a perovskite layer is formed.
• PbI2 lead iodide
• CH3NH3I methylammonium iodide
• a perovskite layer 15 was formed on the mp- TiO2 layer by spin coating.
• the solution was dropped, the solution was stopped for 15 seconds, accelerated to 5,000 rpm over 2 seconds, maintained at 5,000 rpm for 5 seconds, and stopped for 1 second. In addition, 20 seconds after the start, 200 ⁇ L of additional chlorobenzene was dropped.
• the resulting laminate is then thermally annealed with a temperature profile of 40° C. for 5 minutes, 60° C. for 5 minutes, 70° C. for 5 minutes, 100° C. for 10 minutes, and 120° C. for 10 minutes to form a MAPbI3 perovskite layer.
• Interface treatment of the perovskite layer surface is not essential in the present invention, but may be appropriately performed depending on the materials constituting the laminate and the method for forming the hole transport layer.
• the interface treatment is performed by dissolving 1-octylamine hydroiodide (OAI) in 2-propanol to prepare an OAI solution, dropping the OAI solution onto the perovskite layer 15, and spin coating (at 3,000 rpm for 30 seconds).
• OAI 1-octylamine hydroiodide
• hole transport material 0 is dissolved in chlorobenzene to prepare dopant-free HTM solution 0a (71 mM, 87 g/L).
• the hole transport material 1 of the present invention is dissolved in a chlorobenzene/chloroform mixed solvent with a volume ratio of 1/1 to prepare dopant-free HTM solutions 1a (33 mM, 40 g/L) and 1b (8 mM, 10 g/L), respectively.
• the HTM solution 0a or the dopant-free HTM solution 1a or 1b is dropped, and a hole transport layer 16 is formed by spin coating (at 3,000 rpm for 30 seconds).
• a control hole transport material 0, 0.69 molar equivalents of LiTFSI as a dopant, and 2.96 molar equivalents of TBP are dissolved in chlorobenzene to prepare HTM solution 0b (71 mM, 87 g/L).
• the hole transport material 4 of the present invention is dissolved in a mixed solvent of chlorobenzene/chloroform in a volume ratio of 1/1 to prepare a dopant-free HTM solution 4 (8 mM, 8 g/L).
• Comparative hole transport material 5 is dissolved in a chlorobenzene/chloroform mixed solvent with a volume ratio of 1/1 to prepare dopant-free HTM solution 5 (3 mM, 6 g/L).
• B HTM solution 0b, dopant-free HTM solution 4 or dopant-free HTM solution 5 is dropped onto perovskite layer 15, and hole transport layer 16 is formed by spin coating (3,000 rpm for 30 seconds).
• Vapor Deposition Method A predetermined amount of hole transport material is weighed out into an alumina crucible C-3 (manufactured by Nilaco Corporation). Using an organic vapor deposition apparatus (apparatus number SV-C218, manufactured by Sunvac Corporation), the temperature of the seal heater of the vapor deposition source is heated to 400 to 550°C under reduced pressure of 7 x 10-4 Pa to 1 x 10-3 Pa, and vapor deposition of each of the control hole transport material 0, the hole transport material 4 of the present invention, and the comparative hole transport material 5 onto the perovskite layer 15 is performed to form a hole transport layer 16.
• an organic vapor deposition apparatus apparatus (apparatus number SV-C218, manufactured by Sunvac Corporation)
• the temperature of the seal heater of the vapor deposition source is heated to 400 to 550°C under reduced pressure of 7 x 10-4 Pa to 1 x 10-3 Pa, and vapor deposition of each of the control hole transport material 0, the hole transport material 4 of the present invention, and the comparative
• Terminals are provided so that the transparent FTO electrode 12 serves as the negative electrode (anode) and the metal electrode serves as the positive electrode (cathode), forming the perovskite solar cell 1.
• the addition of a dopant is necessary to adjust the electronic properties such as hole mobility and electrical conductivity.
• the layer thickness is moderate for conventional hole transport materials with added dopants.
• the hole transport material of the present invention does not require the addition of a dopant. However, this tends to result in a low conductivity of the hole transport layer (high resistance), and therefore, a measure to reduce the thickness of the hole transport layer is required.
• the hole transport material 1 of the present invention When the hole transport material 1 of the present invention was used, the measured electronic properties were similar when the layer thickness was similar to that of the control hole transport material 0 (about 125 nm), but when the thickness was reduced to 1/5 to 1/6 (about 25 nm), the photoelectric conversion efficiency (PCE) was improved. This indicates that by using the hole transport material of the present invention, the layer thickness of the hole transport material can be reduced, thereby improving the electronic properties of the solar cell while reducing the amount of material used.
• PCE photoelectric conversion efficiency
• an mp- TiO2 layer is formed using the same procedure as described in the above section [Fabrication of Solar Cell], and a perovskite layer is formed using this mp- TiO2 layer as a scaffold.
• Lead iodide ( PbI2 ), formamidine iodide (HC(NH2)2I), and methylammonium chloride (CH3NH3Cl) were mixed in a molar ratio of 1:1:0.35 and dissolved in a mixed solvent of DMF and DMSO (volume ratio 4:1) to prepare a solution of perovskite FAPbI3 .
• a perovskite layer was formed on the mp- TiO2 layer by spin coating.
• control hole transport material 0 Spiro-MeOTAD
• alumina crucible C-3 manufactured by Nilaco Corporation
• the temperature of the seal heater of the vapor deposition source was heated to 414-432°C under reduced pressure of 9.2 x 10-4 Pa, and vapor deposition was performed on the FAPbI3 perovskite layer 15 to form a hole transport layer 16.
• 100 nm of Au was vapor-deposited on the surface of the hole transport layer 16 to form a metal electrode 17.
• control hole transport material 0 could be deposited, but because it was dopant-free, the electronic properties of the solar cell were inferior.
• hole transport material 1 of the present invention could be deposited, and it was found to exhibit excellent electronic properties depending on the type of perovskite.
• Table 5 shows the measurement results of the IV characteristics of the short circuit current density (J sc ), open circuit voltage (V oc ), fill factor (FF) and photoelectric conversion efficiency (PCE).
• Hole transport materials 1 to 3 according to the present invention exhibit a highest occupied molecular orbital level that is useful for perovskite solar cells, and when used in the hole transport layer of a solar cell, they exhibited PCE characteristics equivalent to those with a dopant even without a dopant.
• a hole transport layer was formed by a conventional solution method and a vapor deposition method, respectively, to prepare a solar cell.
• dopants LiTFSI and TBP
• the IV characteristics of each solar cell were measured, including short circuit current density ( Jsc ), open circuit voltage ( Voc ), fill factor (FF) and photoelectric conversion efficiency (PCE). The measurements were performed 6 days after the solar cell was manufactured. The results are shown in Table 6.
• the deposition method can form a hole transport layer with a smaller thickness (for example, in the range of 5 to 100 nm, or 5 to 25 nm, or even 10 to 20 nm) and less variation in thickness than the solution method, making it possible to reduce resistance in the thickness direction.
• ⁇ Measurement method> Short-circuit current density (Jsc) of a solar cell (2) Open circuit voltage of solar cell (Voc) (3) Solar Cell Fill Factor (FF) (4) Photoelectric conversion efficiency (PCE) of solar cells Using a solar simulator (XIL-05B100KP, manufactured by Ceric Corporation), the solar cell was irradiated with AM1.5G, 100 mW/ cm2 artificial sunlight, and the above-mentioned (1) to (4) IV characteristics were evaluated.
• Jsc Short-circuit current density
• Voc Open circuit voltage of solar cell
• FF Solar Cell Fill Factor
• PCE Photoelectric conversion efficiency
• E HOMO Highest occupied molecular orbital level
• PCE photoelectric conversion efficiency
• a perovskite solar cell using the hole transport material of the present invention exhibits high photoelectric conversion efficiency even without adding dopants such as LiTFSI and TBP to the hole transport layer, and can provide a solar cell with stable photoelectric characteristics.
• the hole transport material of the present invention can be easily adjusted to the highest occupied molecular orbital level (E HOMO ) and can be applied to various perovskites.
• E HOMO highest occupied molecular orbital level
• a hole transport layer can be formed by a vapor deposition method, and a solar cell exhibiting sufficient photoelectric conversion efficiency and stable photoelectric characteristics can be provided.
• the hole transport material of the present invention By using the hole transport material of the present invention, a thin hole transport layer free of pinhole defects can be formed, making it possible to manufacture highly reliable solar cells with a high yield. It is also possible to construct a tandem solar cell in which the perovskite utilizes light on the short wavelength side and the silicon utilizes light on the long wavelength side, thereby achieving higher photoelectric conversion efficiency.
• Such solar cells can be used in a wide variety of fields, including roof-mounted panels (for homes, buildings, factories), roof-integrated systems (for homes, buildings, factories, garages, greenhouses), wall-mounted systems (for homes, buildings, factories), window glass, blinds, shading sheets, solar power plants, power sources for IoT devices (RFID tags, sensors, small electronic devices), mobile solar chargers, artificial satellites, automobiles, drones, and solar planes.
• roof-mounted panels for homes, buildings, factories
• roof-integrated systems for homes, buildings, factories, garages, greenhouses
• wall-mounted systems for homes, buildings, factories
• window glass blinds, shading sheets
• solar power plants power sources for IoT devices (RFID tags, sensors, small electronic devices), mobile solar chargers, artificial satellites, automobiles, drones, and solar planes.
• IoT devices RFID tags, sensors, small electronic devices
• mobile solar chargers artificial satellites, automobiles, drones, and solar planes.
• Perovskite solar cell 11 Glass substrate 12 Transparent electrode 13 Electron transport layer 14 Mesoporous metal oxide 15 Perovskite layer 16 Hole transport layer 17 Metal electrode

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• 2023
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