Pb‐Reduced CsPb0.9Zn0.1I2Br Thin Films for Efficient Perovskite Solar Cells

Abstract Fabrication of efficient Pb reduced inorganic CsPbI 2 Br perovskite solar cells (PSC) are an important part of environment‐friendly perovskite technology. In this work, 10% Pb reduction in CsPb 0.9 Zn 0.1 I 2 Br promotes the efficiency of PSCs to 13.6% (AM1.5, 1sun), much higher than the 11.8% of the pure CsPbI 2 Br solar cell. Zn 2+ has stronger interaction with the anions to manipulate crystal growth, resulting in size‐enlarged crystallite with enhanced growth orientation. Moreover, the grain boundaries (GBs) are passivated by the Cs‐Zn‐I/Br compound. The high quality CsPb 0.9 Zn 0.1 I 2 Br greatly diminishes the GB trap states and facilitates the charge transport. Furthermore, the Zn4s‐I5p states slightly reduce the energy bandgap, accounting for the wider solar spectrum absorption. Both the crystalline morphology and energy state change benefit the device performance. This work highlights a nontoxic and stable Pb reduction method to achieve efficient inorganic PSCs.