Research Progress in Degradation Mechanism of Organic Solar Cells

During the last several years, with the emergence of non-fullerene Y-series star molecular acceptors, the power conversion efficiency of single-junction organic solar cells has exceeded 19%. However, the relatively poor stability of the devices under different operating conditions seriously restricts its commercialization. Therefore, more and more researches are focused on the causes of devices degradation of organic solar cells and how to improve the stability of organic solar cells (OSCs). OSCs have complex active layer materials and different device structure. It is still not clear about the performance and decay process of organic solar cells. Most of the previous reviews on OSC stability are based on external factors such as moisture, oxygen, light and heat, and lack of explanation of device degradation process. In this review, the literatures of OSCs device degradation in recent years are reviewed and several factors that cause performance degradation in OSCs devices are summarized. Firstly, the device performance attenuation caused by the change of active layer, the photooxidation reaction caused by chemical molecule changes, photochemical reaction, and device aging process, and the morphological changes in active layers caused by photothermal stresses and their effects on device performance are reviewed. Then, the influence of the changes at the interface and transporting layer degradation is introduced. Finally, the multi-directional strategies for improving the stability of OSCs are stated and how to improve the stability of organic solar cells is suggested.