Abstract
Designing post-formed two-dimensional(2D)perovskite on the surface of three-dimensional(3D)per-ovskite with matched energy levels and high stability is crucial for improving the performance and sta-bility of perovskite solar cells(PSCs).Herein,a long alkyl chain dodecylammonium bromide(DABr)was applied to react with excessive lead iodide(PbI2)on the grain boundary of metal halide perovskite pref-erentially,forming DA2PbI4(n=1)to constitute a clear 2D/3D heterojunction.The existence of hetero-junction increases the intensity of the built-in electric field of the device to enhance carrier separation and extraction,and the amino group of dodecylammonium cation passivates defects,which jointly con-tribute to the improvement of the power conversion efficiency(PCE)from 20.35 to 21.81％.The long alkyl chain endows the 2D perovskite with good hydrophobic properties,improving the humidity and thermal stability of the device.The unencapsulated device can maintain 64％of its initial efficiency after 1065 h storage in ambient air.
维普
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