A comparative study of the effects of terminal aromatic moieties in spirobifluorene core-based diketopyrrolopyrrole non-fullerene acceptors

• Published in: New journal of chemistry 2018, Vol.42 (14), p.11854-11861
• Main Authors: Chen, Zhi-Cai, Xie, Yuan, Yu, Yuan-Yuan, Wu, Hong-Bin, Wan, Jun-Hua
• Format: Article
• Language: English
• Subjects: Benzothiophene; Charge transfer; Conjugation; Energy conversion efficiency; Heterojunctions; Molecular chains; Organic chemistry; Photovoltaic cells; Quantum efficiency; Solar cells
• ISSN: 1144-0546; 1369-9261
• DOI: 10.1039/C8NJ01549J

This work focuses on the development of diketopyrrolopyrrole (DPP)-based small molecular nonfullerene acceptors to pair traditional and low-cost poly(3-hexylthiophene) (P3HT) in bulk heterojunction (BHJ) organic solar cells. Different end capped groups, 1,2,3-trifluorobenzene and fused-ring moieties (benzo[ b ]thiophene and benzo[ b ]furan), were separately introduced into promising DPP-based nonfullerenes SF-DPP-EH, and three new spiro-DPPs SF-(DPP3F)4 , SF-(DPPBT)4 and SF-(DPPBF)4 ) were obtained. These terminal groups largely extend the conjugation in SF-DPP-EH with an obvious red-shifted absorption (25–43 nm). Of the three new spiro-DPPs, SF-(DPP3F)4 showed the best solubility in common solvents and gave a power conversion efficiency of 1.67% when blended with P3HT. The charge-transfer state ( E CT ) at the donor–acceptor interface was directly probed through measuring the subbandgap external quantum efficiency (EQE) to estimate the energy loss in spiro-DPP based devices.