Delocalization of exciton and electron wavefunction in non-fullerene acceptor molecules enables efficient organic solar cells

Guichuan Zhang, Xian Kai Chen, Jingyang Xiao, Philip C.Y. Chow, Minrun Ren, Grit Kupgan, Xuechen Jiao, Christopher C.S. Chan, Xiaoyan Du, Ruoxi Xia, Ziming Chen, Jun Yuan, Yunqiang Zhang, Shoufeng Zhang, Yidan Liu, Yingping Zou, He Yan, Kam Sing Wong, Veaceslav Coropceanu, Ning LiChristoph J. Brabec, Jean Luc Bredas, Hin Lap Yip, Yong Cao

Research output: Contribution to journalArticlepeer-review

31 Citations (Scopus)

Abstract

A major challenge for organic solar cell (OSC) research is how to minimize the tradeoff between voltage loss and charge generation. In early 2019, we reported a non-fullerene acceptor (named Y6) that can simultaneously achieve high external quantum efficiency and low voltage loss for OSC. Here, we use a combination of experimental and theoretical modeling to reveal the structure-property-performance relationships of this state-of-the-art OSC system. We find that the distinctive π–π molecular packing of Y6 not only exists in molecular single crystals but also in thin films. Importantly, such molecular packing leads to (i) the formation of delocalized and emissive excitons that enable small non-radiative voltage loss, and (ii) delocalization of electron wavefunctions at donor/acceptor interfaces that significantly reduces the Coulomb attraction between interfacial electron-hole pairs. These properties are critical in enabling highly efficient charge generation in OSC systems with negligible donor-acceptor energy offset.

Original languageEnglish
Article number3943
JournalNature communications
Volume11
Issue number1
DOIs
Publication statusPublished - Dec 1 2020
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Chemistry(all)
  • Biochemistry, Genetics and Molecular Biology(all)
  • Physics and Astronomy(all)

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