Thermal Stability of Organic Solar Cells: From Material Design to Interface Engineering

Organic solar cells (OSCs) have emerged as a promising next‐generation photovoltaic technology owing to their unique advantages, including flexibility, light weight, and solution processability. Although the power conversion efficiency (PCE) of single‐junction devices has exceeded 21%, insufficient thermal stability remains a major bottleneck to commercialization. This review systematically summarizes three major mechanisms responsible for thermally induced degradation in photovoltaic devices: insufficient intrinsic thermal stability of the constituent materials, thermally induced morphological evolution of the active layer, and interfacial aging. On this basis, representative advances in improving thermal stability are reviewed from three perspectives: intrinsic material design, morphology‐locking strategies, and interface engineering. Finally, the challenges associated with simultaneously optimizing efficiency and thermal stability are discussed, highlighting the importance of coordinated design across the entire device architecture for advancing organic photovoltaics toward practical applications.