Zhishan Bo and Cuihong Li from Beijing Normal University, as well as Yahui Liu and Yuqiang Liu from Qingdao University, purposefully designed and synthesized three non fused ring electron acceptors (NFREAs) using the concept of halogenation, namely 3TT-C2-F, 3TT-C2-Cl, and 3TT-C2. The introduction of F or/and Cl atoms into the molecular structure (3TT-C2-F and 3TT-C2-Cl) enhances π - π stacking, improves electron mobility, and regulates the nanofiber morphology of the blend film, thereby promoting exciton dissociation and charge transfer.
Especially, the blend film based on D18:3TT-C2-F exhibits high charge mobility, extended exciton diffusion distance, and well formed nanofiber network. These factors result in a power conversion efficiency (PCE) of 17.19% for the device, exceeding 3TT-C2-Cl (16.17%) and 3TT-C2 (15.42%). This represents the highest efficiency achieved by NFREA based devices to date. These results highlight the potential of halogenation in NFREA as a promising method for enhancing the performance of organic solar cells.
Li, D., Zhang, H., Cui, X., Chen, Y.-N., Wei, N., Ran, G., Lu, H., Chen, S., Zhang, W., Li, C., Liu, Y., Liu, Y., Bo, Z., Halogenated Nonfused Ring Electron Acceptor for Organic Solar Cells with a Record Efficiency of Over 17%. Adv. Mater. 2023, 2310362.
https://doi.org/10.1002/adma.202310362
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