Solvent-free, solid phase synthesis of hybrid lead halide perovskites with superior purity

A method of synthesizing a mixed-halide perovskite, comprising the steps of:

• mixing a first single-halide perovskite and a second single-halide perovskite to form a solid- phase mixture, wherein the first single-halide perovskite and the second single-halide perovskite are both in the solid phase during mixing;
• and
• heating the solid phase mixture at a temperature below a first decomposition temperature of the first single-halide perovskite and below a second decomposition temperature of the second single-halide perovskite for a time sufficient to form the mixed-halide perovskite;
• wherein the heating step comprises forming a mixed-halide perovskite with a formula of CH3NH3PbX3-aX′a, wherein X and X′ are selected from the group consisting of I, Br, and Cl, and wherein 0>a>3.

A method of synthesizing a mixed-halide perovskite, comprising the steps of:

• mixing a first single-halide perovskite and a second single-halide perovskite to form a solid- phase mixture, wherein the first single-halide perovskite and the second single-halide perovskite are both in the solid phase during mixing;
• and
• heating the solid phase mixture at a temperature below a first decomposition temperature of the first single-halide perovskite and below a second decomposition temperature of the second single-halide perovskite for a time sufficient to form the mixed-halide perovskite;
• wherein the heating step comprises forming a mixed-halide perovskite with a formula of HC(NH2)2PbX3-aX′a, wherein X and X′ are selected from the group consisting of I, Br, and Cl, and wherein 0>a>3.

A method of synthesizing a mixed-halide perovskite, comprising the steps of:

• mixing a first single-halide perovskite and a second single-halide perovskite to form a solid- phase mixture, wherein the first single-halide perovskite and the second single-halide perovskite are both in the solid phase during mixing;
• and
• heating the solid phase mixture at a temperature below a first decomposition temperature of the first single-halide perovskite and below a second decomposition temperature of the second single-halide perovskite for a time sufficient to form the mixed- halide perovskite;
• wherein the heating step comprises forming a mixed-halide perovskite with a formula of APbX3-aX′a, wherein A is an alkali metal, wherein X and X′ are selected from the group consisting of I, Br, and Cl, and wherein 0>a>3.

A method of synthesizing a mixed-halide perovskite, comprising the steps of:

• mixing a first single-halide perovskite and a second single-halide perovskite to form a solid- phase mixture, wherein the first single-halide perovskite and the second single-halide perovskite are both in the solid phase during mixing;
• and
• heating the solid phase mixture at a temperature below a first decomposition temperature of the first single-halide perovskite and below a second decomposition temperature of the second single-halide perovskite for a time sufficient to form the mixed-halide perovskite;
• wherein the heating step comprises forming a mixed-halide perovskite with a formula of A1-bA′bPbX3-aX′a, wherein A is an alkali metal and A′ is an organic cation, wherein X and X′ are selected from the group consisting of I, Br, and Cl, and wherein 0>a>3.