Boosting Photovoltaic Performance and Stability of Super-Halogen-Substituted Perovskite Solar Cells by Simultaneous...

Perovskite solar cells (PSCs) are susceptible to intrinsic structural instability associated with the presence of inorganic halide anions and organic cation vacancies, thus leading to the deterioration or even premature failure of devices. Herein, we develop an efficient strategy using super-halogen BH₄^- substitution to simultaneously immobilize methylammonium and substitute iodide vacancy for high-performance PSCs based on the dihydrogen bonding interactions. The introduced super-halogen BH₄^- groups not only significantly reduce the vacancy density but also effectively inhibit the decomposition of the CH₃NH₃⁺ group by forming perovskite CH₃NH₃PbI_3-(BH₄^-). The power conversion efficiency (PCE) of the assembled mesoporous devices is remarkably promoted from 18.43 to 21.10%, accompanied by significant increase of both J_sc and V_oc without obvious hysteresis. The superior PSCs can retain 90 and 80% of their initial PCE even after being stored for 1200 h under environmental conditions (50 ± 10% RH) and 240 h at 85 °C in the dark, respectively. Moreover, it delivers excellent optical stability under ultraviolet illumination. This work provides an avenue to improve both the long-term stability and photovoltaic performance of PSCs.