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

초록

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)I-3, MA(Sn0.6Pb0.4)I-3, and Cs(Sn0.6Pb0.4)I-3 is formed, and a promising composition window of (FA(0.6-x)MA(0.4)Cs(x))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 FA(0.55)MA(0.4)Cs(0.05)Sn(0.6)Pb(0.4)I(3) 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.

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