Depth‐Resolved Photo‐Degradation of Perovskite Layer in Solar Cells Stressed Under ISOS Light‐Aging Protocol Conditions: The Role of Substrate, Electron‐Transport‐Layer and Perovskite Deposition Method

Photo‐stability of perovskite photovoltaics is widely considered the major hurdle hindering their commercial viability. Notwithstanding advancements in the field, mechanistic pathways and inhomogeneity in light‐induced degradation of perovskite layer remain unraveled. This disclosure provides a direct comparison of depth‐dependent photo‐degradation of ambient‐air‐processed perovskite layers developed using one/two‐step deposition methods on rigid‐glass/flexible‐plastic substrates and mesoporous/planar TiO 2 /SnO 2 ‐based electron‐transport‐layers, for carbon‐based hole‐transport‐layer‐free solar cells stressed under ISOS‐L‐1 and ISOS‐L‐2 protocol conditions. Using grazing incidence X‐ray crystallography combined with nanomechanical analysis and a series of extra materials characterization techniques, the gradient distribution of damage in the perovskite layer after aging is mapped. The results showed that the light‐induced degradation starts near both top and buried interfaces for all types of solar cells and spreads into the bulk, affecting perovskite crystals quality, size and micro‐strain, as well as turning the nanomechanical behavior of perovskite from elastic to viscoelastic. Subsequently, the performance of the photovoltaics decreases in terms of light harvesting efficiency, quantum efficiency and charge carrier dynamics. This study provides significance to the field since it gives in‐depth evidence on light‐induced degradation of a series of industry‐compatible‐designed photovoltaics subjected to accelerated aging according to established protocols, giving important insights from a multiscale and industrial perspective.