Oriented perovskite crystals and methods of making the same

1. A method comprising:

combining a first organic salt (A 1 X 1 ), a first metal salt (M 1 (X 2 ) 2 ) a second organic salt (A 2 X 3 ), a second metal salt (M 2 Cl 2 ), and a solvent to form a primary solution, wherein:

A 1 X 1 and M 1 (X 2 ) 2 are present in the primary solution at a first molar ratio between about 0.5 to 1.0 and about 1.5 to 1.0,

A 2 X 3 to M 2 Cl 2 are present in the primary solution at a second molar ratio between about 2.0 to 1.0 and about 4.0 to 1.0,

the primary solution is capable of producing a plurality of organic-inorganic perovskite crystals comprising A 1 ( 1−x )A 2 x M 1 z M 2 (1−z) X 1 a X 2 b X 3 c Cl d ,

a+b+c+d=3.0, d>0, and 0<x<1.

2. The method of claim 1 , wherein at least one of A 1 or A 2 independently comprises an alkyl ammonium, an alkyl diamine, cesium, or rubidium.

3. The method of claim 1 , wherein at least one of A 1 or A 2 comprises methylammonium (MA), ethylammonium, propylammonium, or butylammonium.

4. The method of claim 1 , wherein at least one of A 1 or A 2 comprises formamidinium (FA).

5. The method of claim 1 , wherein at least one of M 1 or M 2 comprises a metal having a 2+ valence state.

6. The method of claim 5 , wherein each of M 1 and M 2 independently comprises lead, tin, or germanium.

7. The method of claim 1 , wherein each of X 1 , X 2 , and X 3 comprises a halogen.

8. The method of claim 7 , wherein at least onceach of X 1 , X 2 , and X 3 independently comprises fluorine, bromine, iodine, or astatine.

9. The method of claim 1 , wherein the solvent comprises an organic solvent.

10. The method of claim 9 , wherein the organic solvent comprises at least one of dimethylformamide, dimethylacetamide, γ-butyrolactone, dimethyl sulfoxide, or N-methyl-2-pyrrolidone.

11. The method of claim 1 , wherein:

A 1 X 1 and M 1 (X 2 ) 2 form a first reactant pair,

A 2 X 3 to M 2 Cl 2 form a second reactant pair, and

the first reactant pair and the second reactant pair are present in the primary solution at a third molar ratio between about 1.0 to 1.0 and about 1.5 to 1.0.

12. The method of claim 1 , further comprising:

depositing at least a portion of the primary solution onto a solid surface, wherein:

the depositing forms a liquid layer comprising the primary solution on the solid surface.

13. The method of claim 12 , wherein the depositing is performed using at least one of spin coating, blade coating, curtain coating, or dip coating.

14. The method of claim 12 , further comprising, after the depositing:

treating at least the liquid layer, wherein:

the treating converts at least a portion of the liquid layer to a solid layer comprising the plurality of organic-inorganic perovskite crystals, and

the solid layer is adhered to the solid surface.

15. The method of claim 14 , wherein the treating is performed by thermal treating.

16. The method of claim 1 , wherein the plurality of organic-inorganic perovskite crystals comprises FA (1−x) MA x Pb z Cs 1−z I a Br b Cl d .

17. The method of claim 1 , wherein the plurality of organic-inorganic perovskite crystals comprises FA (1−x) MA x PbI a Cl d .

18. The method of claim 1 , wherein:

each crystal of the plurality of organic-inorganic perovskite crystals has a length dimension and a width dimension, and

the length dimension (L) and the width dimension (W) define an aspect ratio of L to W between about 1.5 to 1.0 and about 50 to 1.0.

19. The method of claim 18 , wherein L is between about 100 nm and about 3000 nm.

20. The method of claim 1 , wherein the plurality of organic-inorganic perovskite crystals form grains measuring between about 2 μm and about 5 μm.