Efficient and Stable Ideal Bandgap Perovskite Solar Cell Achieved by a Small Amount of Tin Substituted Methylammonium Lead Iodide

Ideal bandgap ~ 1.4 eV of lead–tin (Pd–Sn) organic–inorganic hybrid perovskite absorber is essential to further enhance the power conversion efficiency of perovskite solar cells (PVSCs). However, due to the facile oxidation of Sn2+, large amount of Sn substituted Pb based PVSCs suffer with low stability in ambient environment. In this work, we realize an ideal bandgap perovskite by introducing a small amount (10 mol%) of Sn2+ to methylammonium lead iodide (MAPbI3). A large grain size MAPb0.9Sn0.1I3 films with strong absorbance can be obtained. As a result, the best performance up to 18.3% efficiency is achieved. Importantly, the MAPb0.9Sn0.1I3 cell retains 90% of its performance after operation at the maximum power point under full 1-sun illumination for 500 h, in contrast to the quick degradation of MAPbI3 cell. This study demonstrates the promising potential of stable and efficient ideal band-gap Pb–Sn PVSCs.