Reverse‐Bias Breakdown Mechanisms and Mitigation Strategies in Perovskite Cells and Tandems

Abstract As a promising photovoltaic technology, perovskite solar cells and tandems face the critical challenge of reverse‐bias breakdown stability, which significantly hinders their commercialization. However, the fundamental mechanisms behind reverse‐bias breakdown remain poorly understood. To address this, the underlying mechanisms of reverse‐bias breakdown are systematically elucidated and targeted optimization strategies are proposed through a synergistic approach combining photoelectrical coupled simulations with well‐designed experiments. Notably, it is identified that the reverse‐bias breakdown is primarily governed by Zener tunneling, triggered by localized electric field amplification at the perovskite interfaces. Furthermore, misaligned energy band structures and ion migration further accelerate Zener breakdown and reduce the breakdown voltage. The pronounced ion accumulation of ion migration over extended operational periods also induces progressive degradation of device performance under fixed reverse bias over time. Additionally, narrow‐bandgap perovskite cells exhibit significantly higher breakdown voltages but lower robustness than wide‐bandgap perovskite cells, resulting in the breakdown characteristics of tandem cells being dominated by the narrow‐bandgap perovskite sub‐cells. These findings provide a solid theoretical basis for the design and industrialization of efficient and stable perovskite photovoltaics.