Ion Migration‐Induced Amorphization and Phase Segregation as a Degradation Mechanism in Planar Perovskite Solar Cells
The operation of halide perovskite optoelectronic devices, including solar
cells and LEDs, is strongly influenced by the mobility of ions comprising the
crystal structure. This peculiarity is particularly true when considering the
long-term stability of devices. A detailed understanding of the ion migrationdriven
degradation pathways is critical to design effective stabilization
strategies. Nonetheless, despite substantial research in this first decade
of perovskite photovoltaics, the long-term effects of ion migration remain
elusive due to the complex chemistry of lead halide perovskites. By linking
materials chemistry to device optoelectronics, this study highlights that
electrical bias-induced perovskite amorphization and phase segregation is a
crucial degradation mechanism in planar mixed halide perovskite solar cells.
Depending on the biasing potential and the injected charge, halide segregation
occurs, forming crystalline iodide-rich domains, which govern light
emission and participate in light absorption and photocurrent generation.
Additionally, the loss of crystallinity limits charge collection efficiency and
eventually degrades the device performance.