Hierarchical Morphology Stability under Multiple Stresses in Organic Solar Cells

Improving device stability is an imperative area of realizing commercial utilization for organic solar cells (OSCs). Morphology evolutions of solution-processable active layers have proved to be responsible for ubiquitous device degradation due to their profound impacts on charge generation, transport, and extraction. This Perspective aims to understand and promote device stability in terms of morphology control and evolution from the subnanoscale to hundreds of nanometers. We start with analyzing the role of molecular packing and aggregation within domains on device stability and then focus on the structure of phase separation stemming from donor-rich and acceptor-rich domains. Potential mechanisms of morphology evolution within the individual length scale and some related reinforcing strategies when suffering from heating, irradiation, and mechanical stress are discussed. Finally, we summarize and propose major limitations and future directions for further promoting research on device stability in OSCs.