Suppressing lead leakage in perovskite solar cells via a lead-scavenger and glass encapsulation

Abstract

Over the past 15 years, the rapid increase in the efficiency of perovskite solar cells (PSCs) and the ability to tailor their optoelectronic properties have made this photovoltaic (PV) technology one of the most promising for the PV market. A key barrier to the commercialisation of PSCs is the presence of toxic lead (Pb) in their composition, which is leached into the environment when devices are damaged. We report monopotassium phosphate (KH2PO4) loaded into a poly(vinyl alcohol)/hydroxypropyl cellulose (PVA/HPC) film applied on the cover glass as a Pb-scavenger coating to sequester Pb2+ released from damaged PSCs. Outdoor operation was simulated by subjecting the samples to a hail-impact test (modified FM 44787 standard) followed by a high-intensity rainfall simulation. Pb-scavenger coating reduced Pb release by >3700-fold relative to reference devices, without compromising PV performance. Devices with the mitigation layer also exhibited 5000 h of stability under dark, ambient-air storage. This simple, biocompatible, and process-friendly approach provides an effective route to address Pb leakage risk in perovskite PVs while preserving device performance.