Boric Acid Mediated Formation and Doping of NiO<sub><i>x</i></sub> Layers for Perovskite Solar Cells with Efficiency over 21%
Bing Ge, Ze Qing Lin, Zi Ren Zhou, Hong Qiao, Ai Ping Chen, Yu Hou, Shuang Yang, Hua Gui Yang
Abstract
Metal halide perovskite solar cells (PSCs) have emerged as one of the most promising photovoltaic technologies. For inverted planar PSCs, nickel oxide (NiO x ) layers, as inorganic p‐type semiconductors, are competitive hole transport layers (HTLs) because of their low cost, chemical stability, and easy preparation. However, their inferior device performance still lags behind the devices using organic HTLs. Herein, a boric acid‐assisted strategy for NiO x HTLs is reported that enables compact film deposition and electronic modulation. Boron doping can enhance conductivity and deepen the valence band edge, leading to efficient hole extraction and transport. A methylammonium lead iodide (MAPbI 3 ) photovoltaic device based on our strategy achieves an optimized efficiency of 21.40% with a high open voltage of 1.131 V and a high fill factor of 80.9% with negligible hysteresis, as well as excellent stability.