Methods for producing perovskite halide films
An aspect of the present disclosure is a method that includes exchanging at least a portion of a first cation of a perovskite solid with a second cation, where the exchanging is performed by exposing the perovskite solid to a precursor of the second cation, such that the precursor of the second cation oxidizes to form the second cation and the first cation reduces to form a precursor of the first cation.
1. A method comprising:
exposing a first perovskite comprising a first cation, lead, and iodine to a gas comprising at least one of formylimidamide, guanidine, acetamidine, ethylamine, or methylammonia, wherein:
the exposing results in an exchange of the first cation with a second cation comprising at least one of methylammonium, formamidinium, guanidinium, acetamidinium, or ethylammonium, and
the exchange converts the first perovskite to a second perovskite comprising lead, iodine, and the second cation.
2. The method of claim 1 , wherein the exposing is performed with the gas at a pressure between 0.1 atmospheres and 5 atmospheres.
3. The method of claim 1 , wherein the first perovskite is in a form comprising at least one of a particle or a film.
4. The method of claim 1 , wherein the second cation comprises methylammonium.
5. The method of claim 1 , wherein the first perovskite comprises methylammonium lead triiodide and the second perovskite comprises formamidinium lead triiodide.
6. The method of claim 1 , further comprising, prior to the exposing, forming the first perovskite by at least one of a solution deposition method or a vapor deposition method.
7. The method of claim 1 , further comprising, prior to the exposing, producing the precursor by reacting a salt-precursor with a hydroxide salt.
8. The method of claim 7 , wherein the salt-precursor comprises formamidine acetate.
9. The method of claim 7 , wherein the hydroxide salt comprises sodium hydroxide.
10. The method of claim 1 , wherein exposing is performed at a temperature above the boiling point of the at least one of formylimidamide, guanidine, acetamidine, ethylamine, or methylammonia.