Non-fullerene acceptors for organic solar cells

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Abstract

Non-fullerene acceptors (NFAs) are currently a major focus of research in the development of bulk-heterojunction organic solar cells (OSCs). In contrast to the widely used fullerene acceptors (FAs), the optical properties and electronic energy levels of NFAs can be readily tuned. NFA-based OSCs can also achieve greater thermal stability and photochemical stability, as well as longer device lifetimes, than their FA-based counterparts. Historically, the performance of NFA OSCs has lagged behind that of fullerene devices. However, recent developments have led to a rapid increase in power conversion efficiencies for NFA OSCs, with values now exceeding 13%, demonstrating the viability of using NFAs to replace FAs in next-generation high-performance OSCs. This Review discusses the important work that has led to this remarkable progress, focusing on the two most promising NFA classes to date: rylene diimide-based materials and materials based on fused aromatic cores with strong electron-accepting end groups. The key structure–property relationships, donor–acceptor matching criteria and aspects of device physics are discussed. Finally, we consider the remaining challenges and promising future directions for the NFA OSCs field.

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Figure 1: The structure and working mechanism of a bulk-heterojunction organic solar cell.
Figure 2: Representative polymeric electron donors (d1–d11, d21).
Figure 3: Representative polymeric electron donors (d12–d20, d22–d28).
Figure 4: Rylene diimide-based small-molecule electron acceptors.
Figure 5: Rylene diimide-based polymeric electron acceptors.
Figure 6: Fused-ring electron acceptors (a42–a63).
Figure 7: Fused-ring electron acceptors (a64–a76).

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Acknowledgements

X.Z. acknowledges support from the National Natural Science Foundation of China (Grant Nos 21734001 and 51761165023). S.B. and S.R.M. acknowledge support from the US Department of the Navy, Office of Naval Research (Grant No. N00014-14-1-0580 (CAOP MURI)). Z.W. acknowledges support from the National Natural Science Foundation of China (Grant No. 21734009). H.Y. acknowledges support from the National Basic Research Program of China (Grant Nos 2013CB834701 and 2014CB643501) and the Hong Kong Innovation and Technology Commission (Grant Nos ITC-CNERC14SC01 and ITS/083/15). A.K.-Y.J. acknowledges support from the US Office of Naval Research (Grant No. N00014-17-1-2201) and the Asian Office of Aerospace R&D (Grant No. FA2386-15-1-4106).

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C.Y., S.B., Z.W., H.Y. and X.Z. researched data for the article. All authors contributed to the writing and editing of the article before submission.

Correspondence to Xiaowei Zhan.

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