Interfacial Electronic and Photovoltaic Performance of a Novel Lead-Free Z-Scheme CsSnBr3/MoSe2 Perovskite Heterostructure: A Theoretical and Experimental Study

Sn-based perovskite materials with nontoxic, low cost, and unique structure have attracted much attention. However, their efficiency only reaches 14.09% due to the higher carrier recombination rate and short carrier lifetime in photovoltaic applications. Herein, the interfacial electronic structure, optical absorption, interfacial charge transfer mechanism, and photovoltaic performance of the CsSnBr3/MoSe2 perovskite heterostructure are systematically investigated by theoretical calculation and experimental observation. The results indicate that the strong coupling and hybridization of interfacial electronic states can lead to a narrowing bandgap, which induces an excellent optical absorption of the CsSnBr3/MoSe2 perovskite heterostructure in the visible spectrum. Excitingly, the charge transfer at the interface forms a built-in electric field, which can effectively promote the interfacial charge transfer between CsSnBr3 (001) and MoSe2 monolayer, complying with a Z-scheme mechanism. Moreover, the photovoltaic performance of the CsSnBr3/MoSe2 heterostructure significantly enhances due to excellent light absorption and Z-scheme system for extending carrier lifetime. An effective strategy for designing highly efficient Sn-based perovskite solar cells is reported.