Textured MAPbI₃ Thin Films Achieved via Solvent Engineering in the Solution‐Shearing Process

Abstract

Solvent mixtures for making uniform, crystalline methylammonium lead iodide (MAPbI3) perovskite films are provided. The solvents dimethyl sulfoxide (DMSO), γ‐butyrolactone (GBL), and 1‐methyl‐2‐pyrrolidinone (NMP) are examined as well as their binary combinations to prepare solution‐sheared perovskite films at higher than 150 °C temperatures. Characterization methods such as imaging, X‐ray diffraction, grazing‐incidence wide‐angle X‐ray scattering, and photoluminescence (PL) to evaluate the crystal size, quality, and ordering that determine the viability of these films for device applications are explored and then a perovskite solar cell is made to test the stability of the most promising film. Excellent macroscopic crystals, over 1 mm in length, are achieved using a solvent mixture containing equal volumes of DMSO and NMP. These superior 3D MAPbI3 films, which retain solvent–perovskite intermediate phases and exhibit high crystalline ordering, are essential for high‐performing and stable optoelectronic devices.