Regio‐Regular Polymer Acceptors Enabled by Determined Fluorination on End Groups for All‐Polymer Solar Cells with 15.2 % Efficiency. Issue 18 (17th March 2021)

• Record Type: Journal Article
• Authors: Yu, Han; Pan, Mingao; Sun, Rui; Agunawela, Indunil; Zhang, Jianquan; Li, Yuhao; Qi, Zhenyu; Han, Han; Zou, Xinhui; Zhou, Wentao; Chen, Shangshang; Lai, Joshua Yuk Lin; Luo, Siwei; Luo, Zhenghui; Zhao, Dahui; Lu, Xinhui; Ade, Harald; Huang, Fei; Min, Jie; Yan, He
• Is Part Of: Angewandte Chemie international edition. Volume 60:Issue 18(2021)
• Page Start: 10137
• Page End: 10146
• Publication Date: 2021-03-17
• Subjects: all-polymer solar cells -- fluorinated end group -- isomeric effect -- organic solar cells -- polymer acceptors; Chemistry -- Periodicals; 540
• DOI: 10.1002/anie.202016284
• Languages: English
• ISSNs: 1433-7851

Abstract

Abstract: Polymerization sites of small molecule acceptors (SMAs) play vital roles in determining device performance of all‐polymer solar cells (all‐PSCs). Different from our recent work about fluoro‐ and bromo‐ co‐modified end group of IC‐FBr (a mixture of IC‐FBr1 and IC‐FBr2), in this paper, we synthesized and purified two regiospecific fluoro‐ and bromo‐ substituted end groups (IC‐FBr‐ o & IC‐FBr‐ m ), which were then employed to construct two regio‐regular polymer acceptors named PYF‐T‐ o and PYF‐T‐ m, respectively . In comparison with its isomeric counterparts named PYF‐T‐ m with different conjugated coupling sites, PYF‐T‐ o exhibits stronger and bathochromic absorption to achieve better photon harvesting. Meanwhile, PYF‐T‐ o adopts more ordered inter‐chain packing and suitable phase separation after blending with the donor polymer PM6, which resulted in suppressed charge recombination and efficient charge transport. Strikingly, we observed a dramatic performance difference between the two isomeric polymer acceptors PYF‐T‐ o and PYF‐T‐ m . While devices based on PM6:PYF‐T‐ o can yield power conversion efficiency (PCE) of 15.2 %, devices based on PM6:PYF‐T‐ m only show poor efficiencies of 1.4 %. This work demonstrates the success of configuration‐unique fluorinated end groups in designing high‐performance regular polymer acceptors, which provides guidelines towards developing all‐PSCs with better efficiencies. Abstract : A regio‐regular polymer acceptor PYF‐T‐ o with highly conjugated polymerization sites is synthesized, exhibiting red‐shifted absorption and ordered inter‐chain packing compared to its isomeric counterparts (PYF‐T and PYF‐T‐ m ). When employed in all‐polymer solar cells, the PYF‐T‐ o ‐based devices yield a higher efficiency of 15.2 %.