1D Pyrrolidinium Lead Iodide for Efficient and Stable Perovskite Solar Cells

Due to their superior environmental stability, utilization of low‐dimensional perovskites in organometal halide solar cells (OMHSCs) has seen a sharp increase. Herein, a method to form 1D pyrrolidinium lead iodide (PyPbI 3 ) in situ atop photoactive 3D methylammonium lead iodide (MAPbI 3 ) using pyrrolidine posttreatment is reported. As compared with 3D MAPbI 3 , 1D PyPbI 3 has a wider bandgap and is more environmentally stable, and it serves as a tunneling contact to mitigate charge carrier recombination and as a robust barrier against environmental degradation when incorporated into OMHSCs. Accordingly, power conversion efficiencies of the resulting MAPbI 3 devices are enhanced from an average of 14.86% ± 0.65% to 15.9% ± 0.58% and their shelf‐life stability is significantly prolonged.