Internal Encapsulation Strategy Using a Polymer Enables Efficient, Stable, and Lead‐Safe Inverted Perovskite Solar Cells

Abstract Significant progress is made in perovskite solar cells (PSCs) with high power conversion efficiency (PCE). However, the potential issue of lead leakage creates a critical challenge to its commercialization. Therefore, a convenient internal encapsulation strategy is proposed by introducing a polyvinyl butyral (PVB) polymer at the perovskite/electron transport layer interface. This strategy enhances the performance of PSCs and effectively suppresses lead leakage. The introduced PVB layer plays a crucial role in mitigating ion migration, optimizing energy levels, and preventing moisture penetration. Thus, PSCs with PVB modifications generally perform better, with an improved PCE of 22.47% and reduced hysteresis. Furthermore, these modified devices exhibit enhanced stability under light soaking and thermal stress, effectively mitigating lead leakage. This innovative approach not only enhances the efficiency of PSCs but also addresses the challenges associated with lead leakage, paving the way for more sustainable and commercially viable solar cell technologies.