High-throughput compositional mapping of triple-cation tin–lead perovskites for high-efficiency solar cells

Abstract

Mixed tin–lead perovskites suffer from structural instability and rapid tin oxidation; thus, the investigation of their optimal composition ranges is important to address these inherent weaknesses. The critical role of triple cations in mixed Sn–Pb iodides is studied by performing a wide range of compositional screenings over mechanochemically synthesized bulk and solution-processed thin films. A ternary phase map of FA (Sn0.6Pb0.4)I3, MA(Sn0.6Pb0.4)I3, and Cs(Sn0.6Pb0.4)I3 is formed, and a promising composition window of (FA0.6−xMA0.4Csx)Sn0.6Pb0.4I3 (0 ≤ x ≤ 0.1) is demonstrated through phase, photoluminescence, and stability evaluations. Solar cell performance and chemical stability across the targeted compositional space are investigated, and FA0.55MA0.4Cs0.05Sn0.6Pb0.4I3 with strain-relaxed lattices, reduced defect densities, and improved oxidation stability is demonstrated. The inverted perovskite solar cells with the optimal composition demonstrate a power conversion efficiency of over 22% with an open-circuit voltage of 0.867 V, which corresponds to voltage loss of 0.363 V, promising for the development of narrow-bandgap perovskite solar cells. © 2022 The Authors. InfoMat published by UESTC and John Wiley & Sons Australia, Ltd.