Strain on perovskite solar cells: from origins and effects to device optimization.

Perovskite solar cells (PSCs) have achieved a remarkable power conversion efficiency (PCE) exceeding 27%. However, their long-term stability remains a significant obstacle to commercialization. Of particular concern is the strain effect arising from the soft lattice properties of perovskite materials, which has a substantial impact on the photoelectric performance and stability of PSCs. This review focuses on several key aspects. Firstly, the origins of strain are presented. Then, the influence of strain on perovskite films and solar cells is also explored in this review. We outline strain characterization techniques from micro- and macro-scale perspectives. Furthermore, various representative strain-regulation strategies are summarized. Finally, we highlight key directions that have been overlooked in strain-related research on PSCs. We hope that this review will encourage researchers to gain a deeper understanding of strain in PSCs. It may inspire more in-depth research into the internal physical and chemical mechanisms. We also aim to promote the development of strain-evolution characterization techniques and emphasize the necessity of strengthening and refining theoretical models for practical application scenarios.