Medium band-gap non-fullerene acceptors based on a benzothiophene donor moiety enabling high-performance indoor organic photovoltaics

作者：Li, Xiaojun; Luo, Siwei; Sun, Huiliang^*; Sung, Herman Ho-Yung; Yu, Han; Liu, Tao; Xiao, Yiqun; Bai, Fujin; Pan, Mingao; Lu, Xinhui; Williams, Ian Duncan; Guo, Xugang; Li, Yongfang; Yan, He^*

来源：Energy & Environmental Science, 2021, 14(8): 4555-4563.

DOI：10.1039/d1ee00687h

• POLYMER
• CELLS
• EFFICIENCIES

Organic photovoltaics (OPVs) are one of the most promising technologies to power indoor electronic devices. However, the limited types and design strategies of medium band-gap acceptor materials hinder the development of indoor OPVs. Currently, the state-of-the-art non-fullerene acceptors (NFAs) are Y6 and its derivatives, which are based on an A-DA ' D-A structure. In this paper, we report the modification of the Y6 structure by replacing Y6's D unit (thieno[3,2-b]thiophene) with benzothiophene, and synthesize two novel NFAs (LBT-DF and LBT-SCl) for indoor applications. The use of the benzothiophene unit reduces the intermolecular charge transfer effect, thus blue-shifting the absorption spectra and up-shifting the LUMO energy levels of the NFAs. As a result, LBT-SCl achieves a higher V-oc and thus PCE (up to 25.1%) than Y6 (22.2%) under indoor conditions. Interestingly, these two NFAs exhibit a non-planar aromatic structure, which is rarely observed in the published NFAs, because a better coplanar molecular configuration is usually considered as the critical factor in realizing high PCE. Different from the above mentioned molecular design concept, we find that non-planar structure acceptors also have great potential in OPVs. Our work provides an effective OPV material design guideline for developing high-performance indoor OPVs and also opens a new direction for the design of NFAs.

• 单位
  广州大学; 中国科学院