Guanidinium cation passivated Pb-Cu alloyed perovskite for efficient low-toxicity solar cells

Overcoming the toxicity of organic–inorganic perovskite materials is one of the main challenges in applying them to commercial optoelectronic devices, despite the amazing power conversion efficiency (PCE) of organic–inorganic hybrid perovskite solar cells (PSCs). In this work, we demonstrate a low-toxicity Pb-Cu alloyed perovskite film prepared by simple two-step methods and its integration in inverted PSCs. The formation of iodine defects was suppressed through the hydrogen bonding of guanidinium (Gua) cation (CH 6 N 3 + ), which greatly improves the quality of the film. It is demonstrated that introduction of GuaI additives leads to stronger photoluminescence (PL) intensity, and lower defects state density. The open circuit voltage (Voc) and PCE of Pb-Cu alloyed PSCs reached 0.95 V and 9.69%, respectively. This work helps to guide the preparation of efficient low-toxicity Pb-Cu alloyed optoelectronic devices.