Perovskite material layer processing

1. A method for processing a perovskite photoactive layer comprising:

depositing a lead salt precursor onto a substrate to form a lead salt thin film;

depositing a second salt precursor onto the lead salt thin film; and

annealing the substrate to form a perovskite material, wherein annealing occurs in a controlled humidity environment at an absolute humidity greater than or equal to 0 g H 2 O/m 3 air and less than or equal to 20 g H 2 O/m 3 air.

2. The method of claim 1 , wherein the lead salt precursor is deposited by spin-coating, slot-die printing, sputtering, PE-CVD, thermal evaporation, or spray coating.

3. The method of claim 1 , wherein the second salt precursor is deposited by spin-coating, slot-die printing, sputtering, PE-CVD, thermal evaporation, or spray coating.

4. The method of claim 1 , wherein the lead salt precursor comprises one or more lead salts selected from the group consisting of lead (II) iodide, lead (II) thiocyanate, lead (II) chloride, lead (II) bromide, and combinations thereof.

5. The method of claim 1 , wherein the second salt comprises formamidinium iodide, formamidinium thiocyanate, or guanidinium thiocyanate.

6. The method of claim 1 , wherein the lead salt precursor comprises a solution comprising one or more solvents selected from the group consisting of N-cyclohexyl-2-pyrrolidone, alkyl-2-pyrrolidone, dimethylformamide, dialkylformamide, dimethylsulfoxide (DMSO), methanol, ethanol, propanol, butanol, tetrahydrofuran, formamide, tert-butylpyridine, pyridine, alkylpyridine, pyrrolidine, chlorobenzene, dichlorobenzene, dichloromethane, chloroform, and combinations thereof.

7. The method of claim 1 , wherein the lead salt precursor contains one or more additives selected from the group consisting of an amino acid, 5-aminovaleric acid hydroiodide, 1,8-diiodooctane, 1,8-dithiooctane, formamidinium halide, acetic acid, trifluoroacetic acid, a methylammonium halide, water, and combinations thereof.

8. The method of claim 1 , wherein the second salt precursor comprises a solution comprising one or more solvents selected from the group consisting of N-cyclohexyl-2-pyrrolidone, alkyl-2-pyrrolidone, dimethylformamide, dialkylformamide, dimethylsulfoxide (DMSO), methanol, ethanol, propanol, butanol, tetrahydrofuran, formamide, tert-butylpyridine, pyridine, alkylpyridine, pyrrolidine, chlorobenzene, dichlorobenzene, dichloromethane, chloroform, and combinations thereof.

9. The method of claim 1 , wherein annealing occurs at a temperature greater than or equal to 50° C. and less than or equal to 300° C.

10. The method of claim 1 , wherein annealing in a controlled humidity environment occurs at an absolute humidity between about 4 and 7 g H 2 O/m 3 air.

11. The method of claim 1 , further comprising drying the lead salt precursor in a substantially water-free atmosphere to form a lead salt thin film.

12. The method of claim 11 , further comprising annealing the lead salt thin film at a temperature between about 20° C. and about 300° C.

13. The method of claim 1 , wherein annealing the substrate occurs at about 125° C.

14. A method for processing a perovskite photoactive layer comprising:

depositing a PbI 2 precursor onto a substrate to form a PbI 2 thin film, wherein the PbI 2 precursor comprises a 90:10 mole ratio of PbI 2 to PbCl 2 dissolved in anhydrous DMF;

depositing a formamidinium iodide precursor onto the PbI 2 thin film, wherein the formamidinium iodide precursor comprises a 25-60 mg/mL concentration of formamidinium iodide dissolved in anhydrous isopropyl alcohol; and

annealing the substrate in a controlled humidity environment at an absolute humidity greater than or equal to 0 g H 2 O/m 3 air and less than or equal to 20 g H 2 O/m 3 air and at a temperature greater than or equal to 50° C. and less than or equal to 300° C. to form a formamidinium lead iodide (FAPbI 3 ) perovskite material.

15. The method of claim 14 , wherein the controlled humidity environment comprises an environment having between about 4 and 7 g H 2 O/m 3 air.

16. The method of claim 14 , wherein annealing the substrate occurs at about 125° C.

17. The method of claim 14 , wherein the PbI 2 precursor further comprises one or more additives selected from the group consisting of 5-aminovaleric acid hydroiodide, 1,8-diiodooctane, 1,8-dithiooctane, formamidinium halide, acetic acid, trifluoroacetic acid, a methylammonium halide, water, and combinations thereof.

18. The method of claim 14 , further comprising drying the PbI 2 precursor in a substantially water-free atmosphere for about one hour.

19. The method of claim 14 , further comprising annealing the PbI 2 thin film for about ten minutes at a temperature of about 50° C.

20. The method of claim 14 , wherein the formamidinium iodide precursor is deposited at a temperature between about 25° C. and about 125° C.