Efficient Ideal-Bandgap Tin–Lead Alloyed Inorganic Perovskite Solar Cells Enabled by Structural Dimension Engineering

摘要

Inorganic tin–lead alloyed perovskite solar cells with optimal bandgap havegained increasing attention because of their higher theoretical efficiency limit,inherently robust stability, and potentials in all-inorganic perovskite tandems.However, their efficiency has far lagged from their Pb-based counterpartsowing to some intractable problems such as poor crystallization and facileSn~(2+) oxidation. Here, a small amount of 2D perovskite PEAPb_(0.7)Sn_(0.3)I_4 isutilized to regulate the crystallization process of 3D CsPb_(0.7)Sn_(0.3)I_3 based onthe temperature-gradient annealing method. The X-ray diffraction resultsshow that a stable intermediate phase composed of 3D perovskite seeds and2D phases is formed under a lower annealing temperature of 50 ℃, and thepre-crystallized 3D perovskites can promote the subsequent crystallizationupon 80 ℃ annealing to attain high quality film. It is interesting that the 2Dperovskite phase is ultimately mainly located between the 3D perovskitephase and hole transport layer as revealed by the time of flight-secondaryion mass spectrometry. The resulting perovskite exhibits a lower extent ofnon-radiative recombination and better stability. Consequently, the deviceachieves a champion efficiency of 14.6 setting a new record for inorganictin-lead perovskite solar cells (PSCs). This work sheds more light on thefuture progress of inorganic tin-lead PSC.