Lead Immobilization Using Tetrabutylammonium Alginate for Passivation Defect in Sustainable Stable Inverted Perovskite Solar Cells

<b>Abstract</b><br/>Despite advancements in power conversion efficiency (PCE) of lead halide perovskite solar cells (PSCs), stability issues still hinder the commercialization of PSCs. Unbound lead can cause defects in perovskite crystallization, leading to instability and even lead leakage. In this study, we synthesized an amphiphilic polymer, tetrabutylammonium alginate (TBA-Alg), which cross-links at the perovskite surface and grain boundaries to effectively manage lead ions and passivate defects. Incorporating TBA-Alg polymer into perovskite, the hydrophilic alginate groups anchor free lead ions, forming ordered crystallization sites, while the hydrophobic tetrabutylammonium groups with alkyl chains provide waterproof properties. This process optimizes perovskite crystallization, reduces charge recombination losses, and enhances moisture resistance, thereby improving the stability of the perovskite film. As a result, the polymer-incorporated inverted PSCs achieve 25.01% efficiency and maintain 95% of their initial performance for 2,000 hours under continuous illumination. Exhibited high stability under thermal and ambient conditions.