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

23 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

  • Materials Science (all)
  • Physical and Theoretical Chemistry

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