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Synergetic alkoxy side-chain and chlorine-contained end group strategy toward high performance ultra-narrow bandgap small molecule acceptors
  • +6
  • Yingping Zou,
  • Qingya Wei,
  • Songting Liang,
  • Beibei Qiu,
  • Wei Liu,
  • Xiang Xu,
  • Yuang Fu,
  • Xinhui Lu,
  • Jun Yuan
Yingping Zou
Central South University

Corresponding Author:yingpingzou@csu.edu.cn

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Qingya Wei
Central South University
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Songting Liang
Central South University
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Beibei Qiu
Zhejiang Normal University
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Wei Liu
Central South University
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Xiang Xu
Central South University
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Yuang Fu
The Chinese University of Hong Kong
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Xinhui Lu
The Chinese University of Hong Kong
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Jun Yuan
Central South University
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Abstract

Ultra-narrow bandgap (ultra-NBG) small molecule acceptors (SMAs) show great potential in organic solar cells (OSCs) due to the extend-ed near-infrared (NIR) absorption. In this work, a synergetic alkoxy side-chain and chlorine-contained end group strategy is employed to achieve A-DA’D-A type ultra-NBG SMAs by introducing alkoxy chains with oxygen atom at the second position into the thiophene β posi-tion as well as replacing the F atoms with Cl atoms in the end group. As a result, the heptacyclic BZO-4F shows a redshifted absorption onset (960 nm) than Y11 (932 nm) without oxygen atoms in the side chains. Then, the fluorinated end groups are substituted with the chlorinated ones to synthesize BZO-4Cl. The absorption onset of BZO-4Cl is further redshifted to 990 nm, corresponding to an optical ultra-NBG of 1.25 eV. When blending with the polymer donor PBDB-T, the binary devices based on PBDB-T: BZO-4F and PBDB-T: BZO-4Cl delivers power conversion efficiencies (PCEs) over 12%. Furthermore, ternary devices with the addition of BZ4F-O-1 into PBDB-T: BZO-4Cl system achieve the optimal PCE of 15.51%. This work proposes a synergetic alkoxy side-chain and chlorine-contained end group strategy to achieve A-DA’D-A type ultra-NBG SMAs, which is important for future molecular design.
09 Apr 2023Reviewer(s) Assigned
09 May 2023Review(s) Completed, Editorial Evaluation Pending
13 May 2023Editorial Decision: Revise Minor
02 Jun 20231st Revision Received
02 Jun 2023Submission Checks Completed
02 Jun 2023Assigned to Editor
02 Jun 2023Review(s) Completed, Editorial Evaluation Pending
06 Jun 2023Editorial Decision: Accept