Micro-strain regulation strategy to stabilize perovskite lattice based on the categories and impact of strain on perovskite solar cells

Photovoltaic metal halide perovskite solar cells (PSCs) convert light to electricity more efficiently than crystalline silicon cells, and the cost of materials used to make them is lower than that of silicon cells. Conversion efficiency is not a core issue affecting the application of perovskite solar cells in special scenarios. At present, stability is the major technical encounters that hinders its further commercial development. Micro-strain in PSCs is currently a significant factor responsible for the device’s instability. Strain-induced ion migration is widely believed to accelerate perovskite degradation even when external stimuli are excluded. Undoubtedly, it is imperative to study strain to enhance the stability of PSCs. This paper reviews recent developments to understand strain’s origin and effect mechanisms on performance of PSCs, including ion migration, failure behavior, defect formation, and its effect on photoelectric properties, stability, and reliability. Additionally, several well-known strain management strategies are systematically introduced based on the strain effect mechanism and strain engineering on the film, providing more clues for further preparation with increased stability. The manipulation of external physical strain applied from films to entire devices has been extensively studied. Furthermore, recommendations for future research directions and chemical approaches have been provided. It is emphasized that strain engineering plays a crucial role in improving the efficiency and longevity of PSCs. Tensile strain causes rapid degradation, while moderate compressive strain and external strain control could improve properties and stability. Efforts should focus on controlling compressive strain to mitigate residual tensile strain and introducing it in a controlled manner. Future research endeavors may focus on exploring these pathways to improve the efficiency and lifespan of PSCs.