A simple fabrication of high efficiency planar perovskite solar cells: controlled film growth with methylammonium iodide and green antisolvent sec-butyl alcohol

Abstract

Perovskite films can be prepared using sec-butyl alcohol (2-BA) by a one-step antisolvent assisted method. However, 2-BA dissolves a necessary perovskite precursor, methylammonium iodide, CH₃NH₃I, (MAI), which is lost during the fabrication, leaving behind residues of another perovskite precursor, PbI₂. The resulting perovskite films show reduced power conversion efficiency (PCE) and poor stability to ambient conditions. In this work, we propose an elegant strategy, i.e., the introduction of a small amount of MAI dissolved in the antisolvent 2-BA (1 mg mL⁻¹). The additional MAI can react with the residual PbI₂ during the fabrication to form the desired organic–inorganic hybrid perovskite material, CH₃NH₃PbI₃. The high-quality of the perovskite films obtained can provide larger grain sizes and smoother surfaces, with an ideal PCE of 19.29% and superior moisture stabilities.