Fabrication of Methylammonium Bismuth Iodide Layers Employing Methylamine Vapor Exposure

Abstract

Methylammonium bismuth iodide (MBI) is a promising candidate for nontoxic perovskite solar cells because of its pronounced stability compared with other lead‐free compounds. Herein, the transformation of solution‐processed BiI 3 to MBI employing an exposure to methylamine (MA) vapor is demonstrated. The MA process features a very fast reaction, short process times, and atmospheric‐pressure conditions. The reaction of BiI 3 with MA is analyzed and discussed in detail, and the formation of MBI is confirmed via X‐ray diffraction (XRD). Devices based on MA‐treated solution‐deposited BiI 3 show performance figures comparable to those of conventionally solution‐processed cells. In conclusion, the results of this study demonstrate that exposure to MA is a promising route toward a fast, versatile, and resource‐efficient production of MA cation based perovskites for solar cell modules.