Molecular tailoring of trifluoromethyl-substituted conjugated polymers for efficient organic solar cells

• Published in: Polymer chemistry Vol. 12; no. 22; pp. 3346 - 3351
• Main Authors: Zhang, Xueqiao, Yao, Chao, Zhao, Jiajun, Ali, Muhammad Umair, Li, Aiyuan, Shen, Clifton Kwang-Fu, Yan, Chaoyi, He, Yaowu, Miao, Jingsheng, Meng, Hong
• Format: Journal Article
• Language: English
• Published: Cambridge Royal Society of Chemistry 14.06.2021
• Subjects: Charge transport; Design optimization; Donors (electronic); Electromagnetic absorption; Energy conversion efficiency; Fluorination; Molecular orbitals; Morphology; Open circuit voltage; Optoelectronics; Photovoltaic cells; Polymer chemistry; Polymers; Solar cells; Substitutes
• ISSN: 1759-9954; 1759-9962
• DOI: 10.1039/d1py00177a

Fluorination of polymer donors is a widely adopted approach to make efficient organic solar cells (OSCs). Herein, four new polymer donors were synthesized by introducing a trifluoromethyl-ester group-substituted thiophene (TEST) unit with different ratios into a typical polymer donor PBDB-TF which resulted in downshifting the highest occupied molecular orbital (HOMO) energy-level to −5.8 eV, thereby improving the open-circuit voltage ( V oc ) of the corresponding OSCs from 0.86 to 0.96 V. Besides, trifluoromethylation improved the intermolecular aggregation, and consequently, PBDB-TF with a TEST unit content of 20% exhibited superior light absorption, effective charge transport, and favorable morphology, leading to the formation of efficient OSCs with a high V oc of 0.88 V, a large fill factor (FF) of 72.70% and a best power conversion efficiency (PCE) of 12.02%. This work suggests a promising method to design efficient photoactive materials with well-optimized optoelectronic characteristics for high-performance OSCs via facile introduction of an electron-withdrawing group into polymer backbones. This work reports a series of novel trifluoromethylated polymers as efficient donor materials for high-performance OSCs.