Multifunctional Interface Treatment of Phosphate for High-Efficiency Perovskite Solar Cells

An electron transport layer (ETL)/perovskite interface with abundant defects and energy level mismatch can lead to severe nonradiative recombination and reduce the efficiency in perovskite solar cells (PSCs). Thus, achieving an excellent ETL/perovskite interface is crucial for the development of high-efficiency PSCs. Herein, we present a method to enhance the interface between SnO₂ and the perovskite using an inorganic phosphate compound with appropriate functional groups. By leveraging the multifunctional effects of Sn⁴⁺ and Pb²⁺ ions and P═O bonds, as well as the formation of hydrogen bonds between the perovskite and phosphate, we successfully engineered an exceptional interface characterized by a reduced number of defect states and improved energy level alignment. The optimization of the SnO₂/perovskite interface led to an impressive power conversion efficiency of 21.84% for methylammonium lead triiodide (MAPbI₃) PSCs, with improved stability in the air environment. The findings of our work present an effective strategy for modifying the ETL/perovskite interface with suitable functional groups for high-performance and stable PSCs.