Highly Efficient Perovskite Solar Cells Based on Zn₂ Ti₃ O₈ Nanoparticles as Electron Transport Material

Developing ternary metal oxides as electron transport layers (ETLs) for perovskite solar cells is a great challenge in the field of third-generation photovoltaics. In this study, a highly mesoporous Zn₂ Ti₃ O₈ (m-ZTO) scaffold is synthesized by ion-exchange method and used as ETL for the fabrication of methyl ammonium lead halide (CH₃ NH₃ PbI₃ ) perovskite solar cells. The optimized devices exhibit 17.21 % power conversion efficiency (PCE) with an open circuit voltage (V_oc ) of 1.02 V, short-circuit current density (J_sc ) of 21.97 mA cm^-2 and fill factor (FF) of 0.77 under AM 1.5G sunlight (100 mW cm^-2 ). The PCE is significantly higher than that based on mesoporous ST01 (m-ST01; 10 nm TiO₂ powder) layer (η=14.93 %), which is ascribed to the deeper conductive band of ZTO nanoparticles, better light absorption and smaller charge recombination. The devices stored for 100 days at ambient temperature with humidity of 10 % showed excellent stability with only 12 % reduction of the PCE. The charge transmission kinetic and long-term stability parameters of the ZTO-based perovskite film growth are discussed as well.