Stability of organic solar cells (OSCs)

After more than two decades of development, the power conversion efficiencies (PCEs) of organic solar cells (OSCs) have been greatly improved, and the PCEs of the state-of-the-art OSCs based on the bulk heterojunction (BHJ) concept have now surpassed 10% in single layer devices. In addition to the power conversion efficiency, the OSCs should achieve acceptable stability and operation lifetime under solar irradiation in ambient to fulfill their applications in industry. This chapter summarizes the OSC performance degradation mechanisms and pathways, and affords useful strategies to improve the OSC stabilities. The strategies for stability improvement are summarized as followings: (a) developing organic semiconductors with improved photo-stability; (b) stabilizing the optimal blend film morphology; (c) using more stable metal electrodes, which can be accomplished by employing inverted device structures; (d) minimizing the degradation of interfacial layers. Under the guides of these strategies, many protocols have been developed in the community, recently. In combination with device encapsulation, organic solar cells with further improved device stability under operation condition will be achieved in the near future.