20.2% record efficiency! Single knot OPV!

• Organic photovoltaics (OPVs ) face a trade-off between efficient charge transport and suppressed nonradiative recombination due to brightness quenching caused by aggregation of organic semiconductors. In order to solve this huge challenge, researcher Li Wei of Wuhan University of Technology and others designed a π-extended non-fullerene acceptor (NFA) B6Cl with large gaps in the honeycomb network and introduced it into the photovoltaic system.

  
  

  The study found that the presence of a small amount (i.e., 0.5 or 1 wt%) of B6Cl can compress the molecular packing of the host acceptor L8-BO, resulting in the π-π stacking distance shortening from 3.59 to 3.50 Å, which helps to improve charge transport and ordering Alkyl chain stacking suppresses nonradiative energy loss due to suppression of CC and CH bond vibrations, which is verified by high-energy X-ray scattering measurements.

  This morphological change ultimately leads to the simultaneous improvement of JSC, FF and VOC of OPV. As a result, the maximum PCE of PM6:L8-BO and D18:L8-BO increased from 19.1% and 19.3% to 19.8% and 20.2%, respectively, which is one of the highest values ​​of single-junction OPV. The effect of B6Cl in improving OPV properties was further demonstrated in a series of polymers: NFA OPV.

  
  
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• Yuandong Sun, Liang Wang, Chuanhang Guo, Jinyi Xiao, Chenhao Liu, Chen Chen, Weiyi Xia, Zirui Gan, Jingchao Cheng, Jinpeng Zhou, Zhenghong Chen, Jing Zhou, Dan Liu, Tao Wang, and Wei Li*, π-Extended Nonfullerene Acceptor for Compressed Molecular Packing in Organic Solar Cells To Achieve over 20% Efficiency, J. Am. Chem. Soc. 2024

  
  

  https://doi.org/10.1021/jacs.4c01503