Trifluoromethylation Enables a 3D Interpenetrated Low-Band-Gap Acceptor for Efficient Organic Solar Cells

By Hanjian Lai, Qiaoqiao Zhao, Ziyi Chen, Huirong Chen, Pengjie Chao, Yulin Zhu, Yongwen Lang, Nannan Zhen, Daize Mo, Yuanzhu Zhang and 1 more. 2020

193 citations recorded by the source corpus.

Summary Trifluoromethylation has been used for nonfullerene acceptors, resulting in an ultra-narrow band-gap molecule named BTIC-CF3-γ. Compared to its fluorinated and chlorinated analogs, BTIC-CF3-γ possesses the most red-shifted absorptions. The single-crystal structure of BTIC-CF3-γ reveals that the cooperated π-π interactions from H aggregations of central fused cores and J aggregations of end groups lead to a three-dimensional (3D) interpenetrating network, which provides more electron-hopping junctions between different acceptor molecules. After blending with PBDB-TF, a champion power conversion efficiency (PCE) of 15.59% is realized, which is the highest value in reported ultra-narrow band-gap acceptors. Notably, a PCE of 16.50% is also achieved in BTIC-CF3-γ-based ternary devices due to their red-shifted absorptions. Overall, our results provide a visualized understanding of molecule packings of this family of acceptors and also demonstrate that trifluoromethylation is a useful strategy to design highly efficient ultra-low band-gap acceptors for the next nonfullerene solar devices.

Subfields: Electrical and Electronic Engineering, Polymers and Plastics

View Paper: https://www.semanticscholar.org/paper/9a29fd913f09eede0cf14e0880ba1baba91fadd8