Superior SnO2 electron transport layer via bifunctional interfacial regulation using cesium sulfate for efficient perovskite solar cell

SnO2-based perovskite solar cells (PSCs) suffer severe nonradiative recombination owing to inefficient carrier extraction and poor perovskite film quality hindering their device performance. It is highly necessary to develop a desirable strategy to minimize nonradiative recombination losses by modifying SnO2 interface and optimizing perovskite film quality. Herein, Cesium Sulfate (Cs2SO4) is used to modify SnO2 interface and regulate the crystal growth process of perovskite. The Cs2SO4-modified SnO2 demonstrates superior charge extraction and enhanced conductivity as compared to untreated SnO2 (control). Furthermore, SnO2/Cs2SO4 fabricated perovskite film exhibits reduced defect density and suppressed no-radiative recombination. Through this interface modification strategy, effective carrier extraction and recombination suppression are achieved synchronously. These favorable results translate into an efficiency enhancement from 21.51% to 22.66%. In addition, SnO2/Cs2SO4-based PSCs also display improved device stability owing to the chemical interconnection between the SnO2/Cs2SO4 and the light absorption layer. This work provides a way of enhancing carrier extraction and suppressing nonradiative recombination to realize efficiency and stability enhancement.