Critical Roles of Polymers in the Development of Flexible Perovskite Solar Cells

Flexible perovskite solar cells (FPSCs) are promising candidates due to their lightweight, bendable form factor and potential for integration into wearable and portable electronics. However, their commercialization is still hindered by both intrinsic and extrinsic instabilities, as well as performance losses under external stress. Polymers have proven to be key enablers in addressing these challenges by promoting crystal growth, improving interfacial contact, and reinforcing device structure. This review highlights polymer design strategies that enhance mechanical flexibility, environmental stability, defect passivation, and perovskite film crystallinity. State-of-the-art solutions and benchmark approaches are summarized to showcase recent progress in achieving high power conversion efficiency (PCE) retention over extended bending cycles. Finally, future research directions in polymer selection and design are discussed, with particular emphasis on the emerging role of machine learning for polymer optimization. Hence, this review emphasizes the critical role of polymers in advancing the development of FPSCs.