Fluorinated End Group Enables High-Performance All-Polymer Solar Cells with Near-Infrared Absorption and Enhanced Device Efficiency over 14%

作者：Yu, Han; Qi, Zhenyu; Yu, Jianwei; Xiao, Yiqun; Sun, Rui; Luo, Zhenghui^*; Cheung, Andy Man Hong; Zhang, Jianquan; Sun, Huiliang; Zhou, Wentao; Chen, Shangshang; Guo, Xugang; Lu, Xinhui^*; Gao, Feng^*; Min, Jie^*; Yan, He^*

来源：Advanced Energy Materials, 2021, 11(4): 2003171.

DOI：10.1002/aenm.202003171

• all&#8208
• polymer solar cells
• fluorinated end groups
• polymer acceptors
• polymers
• solar cells

Fluorination of end groups has been a great success in developing efficient small molecule acceptors. However, this strategy has not been applied to the development of polymer acceptors. Here, a dihalogenated end group modified by fluorine and bromine atoms simultaneously, namely IC-FBr, is first developed, then employed to construct a new polymer acceptor (named PYF-T) for all-polymer solar cells (all-PSCs). In comparison with its non-fluorinated counterpart (PY-T), PYF-T exhibits stronger and red-shifted absorption spectra, stronger molecular packing and higher electron mobility. Meanwhile, the fluorination on the end groups down-shifts the energy levels of PYF-T, which matches better with the donor polymer PM6, leading to efficient charge transfer and small voltage loss. As a result, an all-PSC based on PM6:PYF-T yields a higher power conversion efficiency (PCE) of 14.1% than that of PM6:PY-T (11.1%), which is among the highest values for all-PSCs reported to date. This work demonstrates the effectiveness of fluorination of end-groups in designing high-performance polymer acceptors, which paves the way toward developing more efficient and stable all-PSCs.

• 单位
  武汉大学