The Renaissance of Oligothiophene-Based Donor-Acceptor Polymers in Organic Solar Cells

作者：Yin, Bingyan; Chen, Zhili; Pang, Shuting^*; Yuan, Xiyue; Liu, Zhitian^*; Duan, Chunhui^*; Huang, Fei; Cao, Yong

来源：Advanced Energy Materials, 2022, 12(15): 2104050.

DOI：10.1002/aenm.202104050

• donor-acceptor polymers
• oligothiophene
• organic solar cells
• polymer donors
• simple structures

The power conversion efficiencies (PCEs) of organic solar cells (OSCs) have increased rapidly owing to the development of non-fullerene acceptors (NFAs). However, the development of polymer donors lags behind significantly. Currently, the polymer donors are dominated by a handful of thiophene-substituted benzo[1,2-b:4,5-b']dithiophene (BDTT) polymers, which suffer from lengthy synthesis and high production cost. Compared with BDTT-based polymers, oligothiophene-based donor-acceptor polymers feature much easier synthesis, which were the prevailing polymer donors in fullerene-based OSCs, but almost disappeared in non-fullerene OSCs. Herein, two oligothiophene-based donor-acceptor polymers (PTTz-3HD and PTTz-4HD) are reported to re-evaluate this kind of polymer in non-fullerene OSCs. Benefiting from the exquisite alkyl chain design, the polymer PTTz-3HD exhibits more planar conformation, stronger aggregation, and higher crystallinity, which in turn contributes to the formation of an optimal active layer morphology when blended with NFA. As a result, a PCE of 16.1% and 16.7% is achieved by PTTz-3HD in binary and ternary OSCs, respectively. Of particular note, the product of short-circuit current density and fill factor of PTTz-3HD is fully comparable to those of BDTT-based polymers. These results suggest the renaissance of oligothiophene-based donor-acceptor polymers in OSCs and demonstrate a promising avenue to access high-efficiency OSCs from low-cost materials.

• 单位
  武汉工程大学