Alternating multi-source vapor transport deposition

A method of making a perovskite film, comprising the steps of:

• (a) heating a metal halide in a first source tube at a first temperature from about 350° C. to about 480° C. at a first pressure from about 1×10−4 Torr to about 1×102 Torr, thereby producing a sublimated metal halide;
• (b) flowing a first carrier gas from a first inlet through the first source tube and exposing a substrate to the sublimated metal halide and the first carrier gas at a second pressure from about 1×104 Torr to about 1×102 Torr, thereby forming a metal halide-coated substrate;
• (c) heating an organic halide in a second source tube at a second temperature from about 100° C. to about 250° C. at a third pressure from about 1×10−4 Torr to about 1×102 Torr, thereby producing a sublimated organic halide;
• and
• (d) flowing a second carrier gas from a second inlet through the second source tube and exposing the metal halide-coated substrate to the sublimated organic halide and a second carrier gas at the second pressure from about 1×10−4 Torr to about 1×102 Torr, thereby forming the perovskite film,
• wherein the metal halide is disposed between a first filter disc and a second filter disc in the first source tube;
• the organic halide is disposed between a first filter disc and a second filter disc in the second source tube;
• and each first filter disc and each second filter disc comprises silicon carbide (SiC),
• steps (b) and (d) are alternatingly repeated at least 3 times, and the perovskite film comprises an alternating sequence of deposited layer pairs.