Unraveling the Role of Environmental Stress in Potential-Induced Degradation of Perovskite Solar Cells

Potential-induced degradation (PID) is a critical failure mechanism that compromises the outdoor stability of photovoltaic devices, yet its underlying causes remain inadequately understood in perovskite solar cells (PSCs). This study examines the degradation of PSCs under PID stress, followed by exposure to ambient air containing water and oxygen. We found that corrosion initiates at the interface between the transparent conductive oxide (TCO) and glass. Notably, fluorine-doped tin oxide (FTO) substrates exhibited a dramatic 290-fold increase in sheet resistance, compared to just a twofold increase in indium tin oxide (ITO) substrates. Surface chemical analyses reveal that the corrosion is driven by a series of electrochemical reactions, including the voltage-driven migration of sodium ions, oxidation of tin oxide, and the ingress of atmospheric moisture. Both FTO- and ITO-based PSCs experienced significant performance degradation when exposed to air, with FTO-based cells suffering more severe damage, including electrochemical corrosion and delamination, ultimately leading to near-zero current density and complete device failure. Isolating the cells from air for 20 days after PID stress significantly mitigated performance degradation. Module-level investigations revealed similar corrosion patterns, particularly at the P3 scribe lines, where FTO is exposed. This study highlights the crucial role of environmental factors in PID and underscores the need for improved encapsulation strategies to enhance the long-term stability of PSCs in real-world applications.