High-performance as-cast non-fullerene polymer solar cells from benzo[1,2-:4,5-′]difuran polymer a rational copolymer design

• Published in: Journal of materials chemistry. C, Materials for optical and electronic devices Materials for optical and electronic devices, 2021-10, Vol.9 (39), p.13617-13624
• Main Authors: He, Enfang, Zheng, Zhi, Lu, Yi, Guo, Fengyun, Gao, Shiyong, Mola, Genene Tessema, Zhao, Liancheng, Zhang, Yong
• Format: Article
• ISSN: 2050-7526; 2050-7534
• DOI: 10.1039/d1tc03966k

In this study, we synthesized a novel benzo[1,2- b :4,5- b ′]difuran (BDF) copolymer (F13-R) by introducing ester-substituted thiophene into the PDiFPBDF-TBz (F13) backbone aiming to finely tune the molecular stacking and aggregation for non-fullerene as-cast polymer solar cell (PSC) applications. Compared with F13, F13-R displayed a slight blue-shifted absorption, a deeper highest occupied molecular orbital (HOMO) energy level of −5.60 eV, and improved intermolecular stacking. In PSCs, it is found that the as-cast F13-R : IT-4F device, which does not need any solvent additive and thermal/solvent annealing, could achieve a power conversion efficiency (PCE) of 12.2% with an open-circuit voltage ( V oc ) of 0.904 V, a short-circuit current density ( J sc ) of 17.61 mA cm −2 and a fill factor (FF) of 76.60%. The as-cast F13-R : IT-4F device is the first PSC fabricated from low-cost BDF polymers, and its performance is among the best performances in as-cast PSCs. These results demonstrate that fine-tuning the BDF polymer structure via a copolymer design could be an efficient strategy to develop low-cost and high-performance as-cast PSCs. In this study, we introduced an ester-substituted thiophene into the benzo[1,2- b :4,5- b ′]difuran (BDF)-based polymer (PDiFPBDF-TBz, F13) backbone to synthesize a novel polymer donor (F13-R) to develop the highly-efficient as-cast PSCs.