Sustainable up-cycling of lead-acid battery waste for hybrid perovskite solar cells

Despite strict regulations about the use of lead in several countries, large amounts of waste lead-acid batteries are generated worldwide every year, seriously polluting the environment, and constituting a persistent threat to human health. Here, we focus on the use of lead recycled by established industrial methods to obtain lead-halide perovskite, a highly studied material for future photovoltaic and optoelectronic technology. Recycled lead is purified to obtain a lead-iodide (PbI2) precursor for CH3NH3PbI3 lead-halide perovskite, where a re-crystallization route was developed to eliminate impurities and refine the PbI2. The refined lead-iodide enables the synthesis of high-quality CH3NH3PbI3 perovskite thin films, which exhibit comparable photoluminescence emission and photocarrier diffusion length to those obtained from commercially available PbI2. This result is further corroborated by 830 mV open-circuit voltage achieved with a basic solar cell device utilizing the recycled material. Our results demonstrate that lead obtained from industrial recycling methods, together with tailored synthesis and recrystallization of lead-iodide precursor, is able to deliver optoelectronic-grade CH3NH3PbI3 perovskite. The recycled lead thus avoids further depletion of lead from virgin natural resources, reinforcing the sustainability of this material for photovoltaic and optoelectronic technology.