Effects of linking units on fused-ring electron acceptor dimers
2020
Cai, Guilong | Xiao, Yiqun | Li, Mengyang | Rech, Jeromy James | Wang, Jiayu | Liu, Kuan | Lu, Xinhui | Tang, Zheng | Lian, Jiarong | Zeng, Pengju | Wang, Yiping | You, Wei | Zhan, Xiaowei
Three fused-ring electron acceptors (SIDIC, DIDIC and TIDIC) were designed and synthesized using single bond, vinylene and acetylene units linked indaceno[3,2-b]dithiophene dimers as electron-rich cores and 3-(1,1-dicyanomethylene)-5,6-difluoro-1-indanone as electron-deficient termini. These molecules exhibit strong absorption from 550 to 900 nm with large attenuation coefficients of 1.8–2.0 × 10⁵ M⁻¹ cm⁻¹ and high electron mobilities of 2.2–4.9 × 10⁻³ cm² V⁻¹ s⁻¹. In combination with wide-bandgap polymer FTAZ as a donor, organic solar cells exhibit efficiencies of 9.3–13.1%. Effects of the linking units on optical, electronic, morphologic, and photovoltaic properties were revealed. Relative to SIDIC, vinylene-bridged DIDIC shows red-shifted absorption, while acetylene-bridged TIDIC shows blue-shifted absorption. Compared with SIDIC and DIDIC, TIDIC has a lower HOMO, higher electron mobility, and higher device efficiency.
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