An over 16% efficiency organic solar cell enabled by a low-cost pyrazine-based polymer donor

Abstract

Developing organic photoactive materials with simple chemical structures is a promising strategy to solve the critical cost issue of organic solar cells (OSCs). Here, two pyrazine-based polymer donors with completely non-fused conjugated backbones, named PPz and PPz-T, are designed, synthesized and characterized for application in OSCs. The materials-only costs (MOCs) of both polymers are much lower than those of the current high-performance polymer donors. The temperature-dependent hole mobilities and optical absorption measurements reveal that PPz-T shows lower energy disorder and stronger pre-aggregation behavior than PPz. Moreover, more efficient exciton dissociation between PPz-T and BTP-eC9 occurs because of the matched highest occupied molecular orbital (HOMO) level. Finally, the optimal PPz-T:BTP-eC9-based device delivers a high power conversion efficiency (PCE) of 16.16%, which is one of the highest PCEs achieved in OSCs based on low-cost polymer donors. This work demonstrates that desirable PCE approaching state-of-the-art values can be achieved using newly designed low-cost polymers.