Rapid fabrication of semiconductor thin films

A method of fabricating a semiconductor thin film comprising:

• depositing a perovskite precursor in a first solvent on a substrate, the precursor forming a first perovskite layer on a surface of the substrate;
• applying a recrystallization additive in a second solvent to the layer on the surface of the substrate to form a second layer on the substrate, wherein the first perovskite layer and the second layer are deposited sequentially without thermal treatment in between;
• and
• annealing the first layer and the second layer to exchange a cation of the recrystallization additive with a cation of the perovskite precursor to form a perovskite alloy film and a volatile byproduct.