In-Situ Spatially-Resolved Analysis of Degradation in Perovskite Solar Cells

Long-term durability of metal halide perovskite solar cells (PSCs) can be impacted by both the intrinsic nature of the as-designed device stack as well as unintentional local nonuniformities. Here, we present methods for spatially-resolved in-situ degradation analysis during perovskite stress testing. We use repeated bias/rest cycles from timescales of minutes up to 100 hours to separately assess metastability in comparison to irreversible degradation. We visualize device evolution in-situ under light or electrical bias, either in surface view using electro-optical imaging or in cross-section using kelvin probe force microscopy. We further demonstrate multi-scale investigation of defects, from rapid electro-optical screening of the full device area down to nanoscale microscopic characterization to reveal the underlying chemical or structural nature of defects. Our results inform methods to screen for defects in PSCs, as well as further development of accelerated stress testing and degradation analysis which will become essential for perovskite devices to improve their durability and enter the commercial market.