Tetrafluoroquinoxaline based polymers for non-fullerene polymer solar cells with efficiency over 9

• Published in: Nano energy 2016-12, Vol.30, p.312-320
• Main Authors: Yuan, Jun, Qiu, Lixia, Zhang, Zhi-Guo, Li, Yongfang, Chen, Yiwang, Zou, Yingping
• Format: Article
• Language: English
• Subjects: Light harvesting; Non-fullerene polymer solar cells; Non-fullerene small molecule; Photovoltaic properties; Tetrafluoroquinoxaline
• ISSN: 2211-2855
• DOI: 10.1016/j.nanoen.2016.10.008

In order to increase the power conversion efficiency (PCE) of non -fullerene polymer solar cells (PSCs), the absorption spectra of donor and acceptor should be complementary for efficient light harvesting. Here, we designed and synthesized two types of medium bandgap polymers in which two dimension-conjugated benzodithiophene (BDT) (BDTT and BDTPS) was used as the electron donating units and tetrafluoroquinoxaline (ffQx) was used as electron accepting unit, namely PffQx-T and PffQx-PS, for the application as donor in the PSCs with a popular non-fullerene small molecule ITIC as acceptor. Their optical, electrochemical and photovoltaic properties were well investigated. Under AM 1.5G, 100mW/cm−2, all the PSCs with the ffQx-based polymers as donor exhibited PCEs over 8% (8.47% for PffQx-T and 9.12% for PffQx-PS). To the best of our knowledge, the PCE of 9.12% is the highest value for BDT-Qx fullerene-free PSCs to date, which is even higher than that of fullerene-based devices. Using tetrafluoroquinoxaline based polymers as electron donor in non-fullerene polymer solar cells, a power conversion efficiency of 9.12% with a high Voc of 0.97V was obtained. [Display omitted] •Two types of tetrafluoroquinoxaline (ffQx) polymers- PffQx-T and PffQx-PS, were synthesized.•Variation of side chains has minimal effect on LUMO level, but moderate impact on HOMO level.•PSCs based on PffQx-PS/ITIC exhibits a high PCE of 9.12% with a high Voc of 0.97 V.