Fig. 4. Enhancement of MAPbI₃ transistor performance with positive azeotrope, Lewis base solvent treatments.

Variation in the transfer characteristics of MAPbI₃ perovskite FETs (L = 100 μm, W = 1 mm) (A) when exposed to a CoCl₂ desiccant layer. Also shown are treatments with a different class of orthogonal solvents: (B) Lewis bases (ethyl acetate, methyl acetate, and diethyl ether) that also form a low boiling azeotropic mixture with water and (C) Lewis bases (pyridine and acetic acid) that do not form a low boiling azeotropic mixture with water. (D) Shift in the XRD peak corresponding to (110) depicting the increase in lattice size upon treatment of MAPbI₃ films with methyl acetate solvent. Diethyl ether was avoided because of its low boiling point.