Low-cost biodegradable lead sequestration film for perovskite solar cells

Despite the high efficiency that has been achieved for the perovskite solar cells (PSCs), the hazardous lead leakage from the perovskite absorber layer is one of the crucial barriers still hindering its penetration into the commercial market for a large-scale installation. Herein, we report a novel low-cost and biodegradable lead sequestration layer with high compatibility for up-scalable encapsulation of PSCs. Through a precisely designed cross-linking reaction of chemical agents, the as-made biodegradable chitosan composite film shows enhanced mechanical strength, chemical stability, and lead adsorption capacity. The designed encapsulation strategy reduces over 99.99% lead leakage to <2 ppb under varied simulations of weather conditions (hail, rain, or flood), which meet the safe level of drinking water set by the US Environmental Protection Agency (EPA). Moreover, the PSC efficiency is improved from 21.91% to 22.82% due to the improved light absorption from the printed biodegradable lead absorption film. Finally, we present a prototype process of accumulation and recycling of lead compounds in PSCs derbies via the biodegradation process. Based on the low-cost biodegradable lead sequestration film, this environmental-friendly encapsulation strategy could address the lead leakage issue for further commercialization of PSCs.