Multifunctionally Reusing Waste Solder to Prepare Highly Efficient Sn-Pb Perovskite Solar Cells.

The preparation of perovskite components (PbI2 and SnI2 ) using waste materials is of great significance for the commercialization of perovskite solar cells (PSCs). However, this goal is difficult to achieve due to the purity of the recovered products and the easy oxidation of Sn2+ . Here, a simple one-step synthetic process to convert waste Sn-Pb solder into SnI2 /PbI2 and then applied as-prepared SnI2 /PbI2 to PSCs for high additional value is adopted. During fabrication, Sn-Pb waste solder is also employed to serve as a reducing agent to reduce the Sn4+ in Sn-Pb mixed narrow perovskite precursor and hence remove the deep trap states in perovskite. The target PSCs achieved an efficiency of 21.04%, which is better than the efficiency of the device with commercial SnI2 /PbI2 (20.10%). Meanwhile, the target PSC maintained an initial efficiency of 80% even after 800 h under continuous illumination, which is significantly better than commercial devices. In addition, the method achieved a recovery rate of 90.12% for Sn-Pb waste solder, with a lab-grade purity (over 99.8%) for SnI2 /PbI2 , and the cost of perovskite active layer reduced to 39.81% through this recycling strategy through calculation.