Efficient and Stable Flexible Organic Solar Cells via the Enhanced Optical-Thermal Radiative Transfer

Heating is a knotty factor contributing to device degradation of flexible organic solar cells (FOSCs), and thermal regulation plays a crucial role in the realization of long operational lifetime. Herein, a passive cooling strategy for stable FOSCs is proposed by boosting the optical-thermal radiative transfer to reduce the insufficient thermal dissipation and the elevated temperature caused by irradiation-induced heating, while retaining their flexibility and portability. A spectrally selective coupling structure consisting of subwavelength hemisphere pattern and distributed Bragg reflector is integrated into FOSCs to collectively enhance out-coupling of infrared radiation and limit near-infrared absorption-induced heat generation, leading to a reduced heat power intensity of 292.5 W cm(-2) and the decreased working temperature by 9.6 degrees C under outdoor sunlight irradiation. The D18:Y6:PC71BM-based FOSCs achieve a power conversion efficiency of over 17% with a prolonged T-80 lifetime as long as one year under real outdoor working conditions. These results represent a new opportunity for enhancing the operational stability of FOSCs.