Enhancing the Performance of a Fused-Ring Electron Acceptor by Unidirectional Extension

• Published in: Journal of the American Chemical Society 2019-12, Vol.141 (48), p.19023-19031
• Main Authors: Jia, Boyu, Wang, Jing, Wu, Yao, Zhang, Mingyu, Jiang, Yufeng, Tang, Zheng, Russell, Thomas P, Zhan, Xiaowei
• Format: Article
• Language: English
• Subjects: INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
• ISSN: 0002-7863; 1520-5126
• DOI: 10.1021/jacs.9b08988

The unidirectional extension of a smaller fused-ring system into a larger one in a single direction will increase the conjugation length, allowing a fine-tuning of electronic properties. Here, we designed and synthesized a unidirectionally extended fused-8-ring-based nonfullerene acceptor, AOIC, and a bidirectionally extended fused-11-ring electron acceptor, IUIC2, and compared these with the parent fused-5-ring electron acceptor, F5IC. They share the same electron-accepting groups and alkylphenyl side chains but have different fused-ring electron-donating units. Core extension from 5 to 11 rings up-shifts the energy levels, red shifts the absorption spectra, and reduces bandgaps. The unidirectionally extended AOIC has the highest mobility (2.1 × 10–3 cm2 V–1 s–1) relative to the parent F5IC (1.0 × 10–3 cm2 V–1 s–1) and the bidirectionally extended IUIC2 (4.7 × 10–4 cm2 V–1 s–1). Upon blending with the donor PTB7-Th, AOIC-based organic photovoltaic cells show an efficiency of 13.7%, much better than that of F5IC-based cells (5.61%) and IUIC2-based cells (4.48%).