Strain Regulation and Photophysical Properties in Halide Perovskite

Perovskite solar cells (PSCs) are regarded as the most promising new generation of green energy technology due to their outstanding device performance and simple processing technology. The strain in the active layer of PSCs is primarily caused by lower interionic and intercrystal forces, leading to an increase in defect density and high recombination of carriers, which can negatively impact the performance and stability of perovskite devices. Herein, the origins of strain in perovskite film of solution processing are revealed by conducting strain tests and characterizing photophysical processes. The impacts of strain on optical and electrical properties are summarized, including its effects on molecular interaction force, band structure, defect formation energy, activation energy of ion migration, phase segregation, and phase transition. To mitigate these negative effects, the review introduces several methods for modulating strain in perovskite films, including crystallization, component tailoring, adding additives, and modifying contact layers, which are aimed at improving carrier transport and collection efficiency. It is believed that these approaches will provide scientists with new ways of thinking and system schemes for improving the performance and stability of perovskite solar cells.