Engineering Pathways Toward Stable and Efficient Flexible Perovskite Solar Cells

Flexible perovskite solar cells (F-PSCs) have emerged as a forefront technology in next-generation photovoltaics, combining lightweight design, mechanical flexibility, and low-temperature solution processability. Over the past decade, their power conversion efficiency (PCE) has dramatically improved from 2.62% to beyond 26%. This review provides a comprehensive summary of these developments. We begin by analyzing the crystallization kinetics of perovskite thin films, focusing on both homogeneous and heterogeneous nucleation pathways as interpreted through the LaMer growth model. Subsequently, we discuss substrate engineering, emphasizing polymeric and novel flexible substrates that dictate film quality and mechanical reliability. Perovskite layer optimization strategies are then examined, including microstructure regulation, defect passivation, and stress-management approaches achieved via grain boundary modulation and multifunctional interfacial buffer layers. Furthermore, we highlight the emerging self-healing concept, which leverages both physical mechanisms and chemical strategies to enhance durability under repeated mechanical deformation. Finally, we evaluate recent progress in device integration and large-area scalable manufacturing, outlining key opportunities and remaining challenges for commercialization. By consolidating these insights, this review establishes a coherent framework for improving the structural resilience, operational stability, and scalability of F-PSCs, thereby advancing their transition toward practical, flexible, and wearable energy applications.