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

Fabrication of efficient Pb reduced inorganic CsPbI2Br perovskite solar cells (PSC) are an important part of environment-friendly perovskite technology. In this work, 10% Pb reduction in CsPb0.9Zn0.1I2Br promotes the efficiency of PSCs to 13.6% (AM1.5, 1sun), much higher than the 11.8% of the pure CsPbI2Br solar cell. Zn2+ 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 CsPb0.9Zn0.1I2Br 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.