# US 12,006,574 B2 · Low temperature formation of perovskite films in supercritical fluids > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 12,006,574 B2 - Document ID: US12006574B2 - Status: Granted - Kind: B2 - Application number: 17/604,512 - Filed: 2020-02-27 - Published: 2022-06-30 - Granted: 2024-06-11 - Earliest claimed: 2019-04-18 - Assignees: Virginia Commonwealth University - Applicants: Virginia Commonwealth University - Inventors: Gary Tepper; Gilbert Annohene - Web page: https://patentgrep.com/patent/US12006574B2 ## CPC - C23C 18/1204: {inorganic material, e.g. non-oxide and non-metallic such as sulfides, nitrides based compounds} - C23C 18/125: {Process of deposition of the inorganic material} - H10K 30/50: Photovoltaic [PV] devices - H10K 85/50: Organic perovskites; Hybrid organic-inorganic perovskites [HOIP], e.g. CH3NH3PbI3 - H10K 71/15: characterised by the solvent used - C23C: COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL (making metal-coated products by extrusion B21C23/22; covering with metal by connecting pre-existing layers to articles, see the relevant places, e.g. B21D39/00, B23K; metallising of glass C03C; metallising mortars, concrete, artificial stone, ceramics or natural stone C04B41/00; enamelling of, or applying a vitreous layer to, metals C23D; treating metal surfaces or coating of metals by electrolysis or electrophoresis C25D; single-crystal film growth C30B; by metallising textiles D06M11/83; decorating textiles by locally metallising D06Q1/04) - H10K: ORGANIC ELECTRIC SOLID-STATE DEVICES ## Abstract Crystallization of perovskite films was performed in supercritical carbon dioxide with and without organic co-solvents. Post deposition crystallization of the films was performed in a binary, single phase supercritical fluid at constant conditions (45° C., 1200 psi) but with varying organic co-solvent volume fractions up to 2%. The co-solvents can provide selective interactions with one or both of the perovskite precursor compounds resulting in different film morphologies ranging from uniform films containing large grains to films exhibiting large cubic or hexagonal crystals or preferential crystallographic orientations. The use of supercritical fluids to enhance or tune crystallization in solid-state thin films could have broad applications toward the realization of high efficiency photovoltaic devices. ## Claims ### Claim 1 A method to produce perovskite films of the following formula: AMX3 comprising, depositing inorganic-organic or all inorganic precursors onto a substrate, wherein said depositing step produces a film of a perovskite precursor solution, then exposing the film of the perovskite precursor solution to a supercritical fluid at a temperature equal to or less than 50° C., and then inducing crystallization of perovskite crystals in the film of the perovskite precursor solution so as to produce a film with perovskite crystals, of the formula: AMX3, wherein, A is an organic cationic ammonium compound or an inorganic cation; M is at least one divalent metal; and X is halide selected from the group consisting of F, Cl, Br, and I. ### Claim 2 (depends on 1) The method of claim 1, wherein the organic cationic ammonium compound is selected from the group consisting of methylammonium, tetramethylammonium, formamidinium and guanidinium. ### Claim 3 (depends on 1) The method of claim 1, wherein the inorganic cation is selected from the group consisting of Cs+, Na+ and K+. ### Claim 4 (depends on 1) The method of claim 1, wherein the supercritical fluid exposure step is conducted at temperature in the range of from 10° C. to 50° C. ### Claim 5 (depends on 1) The method of claim 1 where the pressure of the supercritical fluid is in the range of 1100 Psi to 2000 Psi. ### Claim 6 (depends on 1) The method of claim 1 wherein the substrate coated with the film of the perovskite precursor solution are placed within a pressure vessel when exposed to the supercritical fluid. ### Claim 7 (depends on 1) The method of claim 1 where the substrate is comprised of a glass or other optically transparent material coated with one or more layers of a thin film photovoltaic device. ### Claim 8 (depends on 1) The method of claim 1 wherein the supercritical fluid is selected from the group consisting of CO2, methane, ethylene, propane, and propylene, alone or in combination with a co-solvent. ### Claim 9 (depends on 8) The method of claim 8 wherein the exposure step is conducted with a co-solvent selected from a group consisting of benzene, toluene, dichloromethane, hexane, xylene, tetrahydrofuran, acetone, dimethyl sulfoxide, dimethylformamide, ethanol, isopropanol, methanol, and ethylene glycol. ### Claim 10 (depends on 8) The method of claim 8, wherein the co-solvent is an organic solvent. ### Claim 11 (depends on 1) The method of claim 1 wherein the supercritical fluid is CO2. ### Claim 12 (depends on 1) The method of claim 1, wherein the exposure step is conducted with supercritical CO2 combined with a co-solvent. ### Claim 13 (depends on 12) The method of claim 12, wherein the co-solvent selected from a group consisting of benzene, toluene, dichloromethane, hexane, xylene, tetrahydrofuran, acetone, dimethyl sulfoxide, dimethylformamide, ethanol, isopropanol, methanol, and ethylene glycol. ### Claim 14 (depends on 12) The method of claim 12, wherein the exposure step is conducted in the co-solvent at a v/v % concentration in the range of 0.1 to 2.0%. ### Claim 15 (depends on 1) The method of claim 1, wherein the film with perovskite crystals has the formula CH3NH3PbX3, wherein, X is a halide selected from the group consisting of F, Cl, Br, and I. ### Claim 16 (depends on 15) The method of claim 15, wherein the film with perovskite crystals has the formula CH3NH3PbI3. ### Claim 17 (depends on 1) The method of claim 1, wherein the perovskite crystals possess an average grain size ranging from 200 to 1000 mm. ### Claim 18 (depends on 1) The method of claim 1, wherein the perovskite crystals possess an average grain size of 200 nm, 250 nm, 400 nm, or 600 nm.