Strain regulation strategies of halide perovskite solar cells and optimization of flexible devices

Abstract

As the core material of the third-generation photovoltaic technology, perovskite solar cells (PSCs) have shown noteworthy performance in terms of photovoltaic properties. Nevertheless, concerns regarding stability have served as a significant impediment to the commercialisation of the subject. Perovskite materials possess the characteristics of soft ions, and under the influence of these characteristics, the strain effect on perovskite films has recently been identified as one of the key factors that have a significant impact on their optoelectronic properties and the stability of the devices. This paper systematically interprets the formation mechanism of residual strain and the applicable boundaries of its characterization methods from the perspective of multi-scale interactions, and focuses on discussing three core stress regulation strategies, including interface modification, additive engineering, and doping engineering. For flexible devices, strategies such as the selection of low-modulus substrates, the design of stress-relieving structures, and the development of flexible interfacial layers are summarized to balance the mechanical deformation tolerance and optoelectronic performance of flexible devices. Finally, we propose several potential methods for regulating stress and strain in the future, providing important references for constructing the theoretical system of strain regulation for perovskite films.