Reduced Nonradiative Recombination Energy Loss Enabled Efficient Polymer Solar Cells via Tuning Alkyl Chain Positions on Pendent Benzene Units of Polymers

Xiaoman Bi, Ziang Wu, Tao Zhang, Cunbin An, Ye Xu, Kangqiao Ma, Sunsun Li, Shaoqing Zhang, Huifeng Yao, Bowei Xu, Han Young Woo, Shaokui Cao, Jianhui Hou

Research output: Contribution to journalArticlepeer-review

3 Citations (Scopus)

Abstract

Nonradiative recombination energy loss (Î"E3) plays a key role in enhancing device efficiencies for polymer solar cells (PSCs). Until now, there is no clear resolution for reducing Î"E3 via molecular design. Herein, we report two conjugated polymers, PBDB-P-p and PBDB-P-m, which are integrated from benzo[1,2-b:4,5-b′]dithiophene with alkylthio chain substituted at para-or meta-position on pendent benzene and benzo[1,2-c:4,5-c′]dithiophene-4,8-dione. Both the polymers have different temperature-dependent aggregation properties but similar molecular energy levels. When BO-4Cl was used as an acceptor to fabricate PSCs, the device of PBDB-P-p:BO-4Cl displayed a maximal power conversion efficiency (PCE) of 13.83%, while the best device of PBDB-P-m:BO-4Cl exhibited a higher PCE of 14.12%. The close JSCs and fill factors in both PSCs are attributed to their formation of effective nanoscale phase separation as confirmed by atomic force microscopy measurements. We find that the PBDB-P-m-based device has 1 order of magnitude higher electroluminescence quantum efficiency (EQEEL) than in the PBDB-P-p-based one, which could arise from the relatively weak aggregation in the PBDB-P-m-based film. Thus, the PBDB-P-m-based device has a remarkably enhanced VOC of 0.86 V in contrast to 0.80 V in the PBDB-P-p-based device. This study offers a feasible structural optimization way on the alkylthio side chain substitute position on the conjugated polymer to enhance VOC by reducing nonradiative recombination energy loss in the resulting PSCs.

Original languageEnglish
Pages (from-to)24184-24191
Number of pages8
JournalACS Applied Materials and Interfaces
Volume12
Issue number21
DOIs
Publication statusPublished - 2020 May 27

Keywords

  • alkylthio-substituted position
  • nonradiative recombination energy loss
  • open-circuit voltage
  • polymer donor
  • polymer solar cells

ASJC Scopus subject areas

  • Materials Science(all)

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