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<p>Multithiophene-based fused-ring electron acceptors (MFREAs) have demonstrated remarkable performance not only in organic solar cells, but also in other optoelectronic devices owing to their extended near-infrared absorption. However, an insufficient electrostatic potential (ESP) difference with the donor results in a weak intermolecular electric field (IEF), which leads to low exciton dissociation efficiency. In addition, the narrow bandgap causes substantial energy loss (<i>E</i><sub>loss</sub>), thereby restricting the open-circuit voltage. To address these problems, we developed two novel MFREAs, 6TFIC-C11-4F and 6TFIC-C11-4Cl, which were developed from the typical molecule 6TIC-4F <i>via</i> central-core side-chain fluorination and terminal chlorination. Although core fluorination slightly attenuated the intramolecular charge transfer (ICT) effect, this strategy significantly increased the overall average ESP value, strengthening the donor-acceptor IEF, thereby facilitating exciton dissociation. Terminal chlorination enhanced the ICT effect, resulting in a red-shifted absorption spectrum and stronger IEF. Notably, 6TFIC-C11-4F exhibited increased intermolecular interactions and reduced <i>π</i>-<i>π</i> stacking distances, leading to better charge transport. As a result, the PM6:6TFIC-C11-4F device achieved a decent power conversion efficiency of 13.32%, significantly outperforming the PM6:6TIC-4F device (10.52%). In addition, the PM6:6TF-IC-C11-4Cl device demonstrated reduced <i>E</i><sub>loss</sub> and a higher short-circuit current density, validating the potential of central-core side-chain fluorination and terminal chlorination in designing high-performance MFREAs.</p>

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Modulating Molecular Electrostatic Potential Unlocks Efficient Exciton Dissociation in A-D-A-type Narrow Bandgap Acceptors-based Organic Solar Cells

  • 期刊论文

  • 发表日期：

    2026年6月22日

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  • Jin Li,
  • Ping Jiang,
  • Hao-Jia Ding,
  • Ming-Tao Liu,
  • Yue Zhen,
  • Dan Liu,
  • Jia-Nan Fang,
  • Pei-Pei Zhu,
  • Shen-Bo Zhu,
  • Hua-Wei Hu,
  • Xun-Fan Liao,
  • Yi-Wang Chen

摘要

Multithiophene-based fused-ring electron acceptors (MFREAs) have demonstrated remarkable performance not only in organic solar cells, but also in other optoelectronic devices owing to their extended near-infrared absorption. However, an insufficient electrostatic potential (ESP) difference with the donor results in a weak intermolecular electric field (IEF), which leads to low exciton dissociation efficiency. In addition, the narrow bandgap causes substantial energy loss (Eloss), thereby restricting the open-circuit voltage. To address these problems, we developed two novel MFREAs, 6TFIC-C11-4F and 6TFIC-C11-4Cl, which were developed from the typical molecule 6TIC-4F via central-core side-chain fluorination and terminal chlorination. Although core fluorination slightly attenuated the intramolecular charge transfer (ICT) effect, this strategy significantly increased the overall average ESP value, strengthening the donor-acceptor IEF, thereby facilitating exciton dissociation. Terminal chlorination enhanced the ICT effect, resulting in a red-shifted absorption spectrum and stronger IEF. Notably, 6TFIC-C11-4F exhibited increased intermolecular interactions and reduced π-π stacking distances, leading to better charge transport. As a result, the PM6:6TFIC-C11-4F device achieved a decent power conversion efficiency of 13.32%, significantly outperforming the PM6:6TIC-4F device (10.52%). In addition, the PM6:6TF-IC-C11-4Cl device demonstrated reduced Eloss and a higher short-circuit current density, validating the potential of central-core side-chain fluorination and terminal chlorination in designing high-performance MFREAs.