A method for preparing photoactive perovskite materials. The method comprises the steps of: introducing a lead halide and a first solvent to a first vessel and contacting the lead halide with the first solvent to dissolve the lead halide to form a lead halide solution, introducing a Group 1 metal halide a second solvent into a second vessel and contacting the Group 1 metal halide with the second solvent to dissolve the Group 1 metal halide to form a Group 1 metal halide solution, and contacting the lead halide solution with the Group 1 metal halide solution to form a thin-film precursor ink. The method further comprises depositing the thin-film precursor ink onto a substrate, drying the thin-film precursor ink to form a thin film, annealing the thin film; and rinsing the thin film with a salt solution.

A method for preparing photoactive perovskite materials. The method comprises the steps of: introducing a lead halide and a first solvent to a first vessel and contacting the lead halide with the first solvent to dissolve the lead halide to form a lead halide solution, introducing a Group 1 metal halide a second solvent into a second vessel and contacting the Group 1 metal halide with the second solvent to dissolve the Group 1 metal halide to form a Group 1 metal halide solution, and contacting the lead halide solution with the Group 1 metal halide solution to form a thin-film precursor ink. The method further comprises depositing the thin-film precursor ink onto a substrate, drying the thin-film precursor ink to form a thin film, annealing the thin film; and rinsing the thin film with a salt solution.

A method for preparing photoactive perovskite materials. The method comprises the steps of: introducing a lead halide and a first solvent to a first vessel and contacting the lead halide with the first solvent to dissolve the lead halide to form a lead halide solution, introducing a Group 1 metal halide a second solvent into a second vessel and contacting the Group 1 metal halide with the second solvent to dissolve the Group 1 metal halide to form a Group 1 metal halide solution, and contacting the lead halide solution with the Group 1 metal halide solution to form a thin-film precursor ink. The method further comprises depositing the thin-film precursor ink onto a substrate, drying the thin-film precursor ink to form a thin film, annealing the thin film; and rinsing the thin film with a salt solution.

A method for preparing photoactive perovskite materials. The method comprises the steps of: introducing a lead halide and a first solvent to a first vessel and contacting the lead halide with the first solvent to dissolve the lead halide to form a lead halide solution, introducing a Group 1 metal halide a second solvent into a second vessel and contacting the Group 1 metal halide with the second solvent to dissolve the Group 1 metal halide to form a Group 1 metal halide solution, and contacting the lead halide solution with the Group 1 metal halide solution to form a thin-film precursor ink. The method further comprises depositing the thin-film precursor ink onto a substrate, drying the thin-film precursor ink to form a thin film, annealing the thin film; and rinsing the thin film with a salt solution.

Provided is a method for producing an alkali metal halide, including causing a reaction of an alkali metal sulfide and a substance represented by the following general formula (1) in the absence of a solvent or in a solvent except for water: X.sub.2 (1), wherein X represents a halogen element.

Disclosed are a method for supplying molten carbonate fuel cell with electrolyte and a molten carbonate fuel cell using the same, wherein a molten carbonate electrolyte is generated from a molten carbonate electrolyte precursor compound in a molten carbonate fuel cell and is supplied to the molten carbonate fuel cell.

A method for preparing photoactive perovskite materials. The method comprises the steps of: introducing a lead halide and a first solvent to a first vessel and contacting the lead halide with the first solvent to dissolve the lead halide to form a lead halide solution, introducing a Group 1 metal halide a second solvent into a second vessel and contacting the Group 1 metal halide with the second solvent to dissolve the Group 1 metal halide to form a Group 1 metal halide solution, and contacting the lead halide solution with the Group 1 metal halide solution to form a thin-film precursor ink. The method further comprises depositing the thin-film precursor ink onto a substrate, drying the thin-film precursor ink to form a thin film, annealing the thin film; and rinsing the thin film with a salt solution.

A method for preparing photoactive perovskite materials. The method comprises the steps of: introducing a lead halide and a first solvent to a first vessel and contacting the lead halide with the first solvent to dissolve the lead halide to form a lead halide solution, introducing a Group 1 metal halide a second solvent into a second vessel and contacting the Group 1 metal halide with the second solvent to dissolve the Group 1 metal halide to form a Group 1 metal halide solution, and contacting the lead halide solution with the Group 1 metal halide solution to form a thin-film precursor ink. The method further comprises depositing the thin-film precursor ink onto a substrate, drying the thin-film precursor ink to form a thin film, annealing the thin film; and rinsing the thin film with a salt solution.

Provided is a method for producing an alkali metal halide, including causing a reaction of an alkali metal sulfide and a substance represented by the following general formula (1) in the absence of a solvent or in a solvent except for water: X.sub.2 (1), wherein X represents a halogen element.

A method for preparing photoactive perovskite materials. The method comprises the steps of: introducing a lead halide and a first solvent to a first vessel and contacting the lead halide with the first solvent to dissolve the lead halide to form a lead halide solution, introducing a Group 1 metal halide a second solvent into a second vessel and contacting the Group 1 metal halide with the second solvent to dissolve the Group 1 metal halide to form a Group 1 metal halide solution, and contacting the lead halide solution with the Group 1 metal halide solution to form a thin-film precursor ink. The method further comprises depositing the thin-film precursor ink onto a substrate, drying the thin-film precursor ink to form a thin film, annealing the thin film; and rinsing the thin film with a salt solution.