Hole Transfer Originating from Weakly Bound Exciton Dissociation in Acceptor-Donor-Acceptor Nonfullerene Organic Solar Cells

  • Meng Si Niu
  • , Kang Wei Wang
  • , Xiao Yu Yang
  • , Peng Qing Bi
  • , Kang Ning Zhang
  • , Xian Jin Feng
  • , Fei Chen
  • , Wei Qin
  • , Jian Long Xia
  • , Xiao Tao Hao

Research output: Journal PublicationArticlepeer-review

50 Citations (Scopus)

Abstract

The underlying hole-transfer mechanism in high-efficiency OSC bulk heterojunctions based on acceptor-donor-acceptor (A-D-A) nonfullerene acceptors (NFAs) remains unclear. Herein, we study the hole-transfer process between copolymer donor J91 and five A-D-A NFAs with different highest occupied molecular orbital energy offsets (Î"EH) (0.05-0.42 eV) via ultrafast optical spectroscopies. Transient absorption spectra reveal a rapid hole-transfer rate with small Î"EH, suggesting that a large energy offset is not required to overcome the exciton binding energy. Capacitance-frequency spectra and time-resolved photoluminescence spectra confirm the delocalization of an A-D-A-structured acceptor exciton with weak binding energy. Relative to the hole-transfer rate, hole-transfer efficiency is the key factor affecting device performance. We propose that holes primarily stem from weakly bound acceptor exciton dissociation, revealing a new insight into the hole-transfer process in A-D-A NFA-based OSCs.

Original languageEnglish
Pages (from-to)7100-7106
Number of pages7
JournalJournal of Physical Chemistry Letters
Volume10
Issue number22
DOIs
Publication statusPublished - 21 Nov 2019

ASJC Scopus subject areas

  • General Materials Science
  • Physical and Theoretical Chemistry

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