Tuning terminal aromatics of electron acceptors to achieve high-efficiency organic solar cells

• Published in: Journal of materials chemistry. A, Materials for energy and sustainability Vol. 7; no. 48; pp. 27632 - 27639
• Main Authors: Qin, Ran, Wang, Di, Zhou, Guanqing, Yu, Zhi-Peng, Li, Shuixing, Li, Yuhao, Liu, Zhi-Xi, Zhu, Haiming, Shi, Minmin, Lu, Xinhui, Li, Chang-Zhi, Chen, Hongzheng
• Format: Journal Article
• Language: English
• Published: Cambridge Royal Society of Chemistry 2019
• Subjects: Aromatic compounds; Bromine; Chemical synthesis; Conjugation; Electrons; Energy conversion efficiency; Excitons; Mixtures; moieties; Organic chemistry; Photovoltaic cells; Polymers; Solar cells; solar energy; Structural design; Structural engineering; thiophene
• ISSN: 2050-7488; 2050-7496; 2050-7496
• DOI: 10.1039/c9ta11285e

Herein, two new electron acceptors, BTTPC and BTTPC-Br, are developed through extending the conjugation of terminal electron accepting moieties with thiophene and bromine units. Such a structural design effectively improves the hole transfer of exciton dynamics in blends, revealing that BTTPC-Br and BTTPC based blends, in the presence of a smaller energetic offset as a driving force, exhibit faster hole transfer from acceptors to the polymeric donor interface, 4 times (BTTPC-Br) and 1.5 times (BTTPC) faster than 0.44 picoseconds of unmodified Y5. As a result, organic solar cells (OSCs) based on the BTTPC-Br acceptor, outperforming those of BTTPC:PBDB-T and Y5:PBDB-T, reach a power conversion efficiency of 15.22%, which is so far one of the highest among the single junction OSCs made with PBDB-T polymer donor. The structural tuning of non-fullerene acceptors with extended terminal aromatics enables faster hole transfer from the acceptor to the donor at smaller energy offsets, thereby achieving high efficiency in organic solar cells.