Acceptor side-chain effects on the excited state dynamics of two-dimensional-like conjugated copolymers in solution

Ming-Ming Huo, Rong Hu, Wei Yan, Yi-Tong Wang, Kuan Chee, Yong Wang, Jian-Ping Zhang

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Abstract

Excited state dynamics of two-dimensional-like conjugated copolymers PFDCN and PFSDCN based on alternating fluorene and triphenylamine main chains and malononitrile pendant acceptor groups with thiophene as π-bridge, have been investigated by using transient absorption spectroscopy. There is an additional conjugated –C=C– bond in PFDCN, which distinguishes it from PFSDCN. The lowest energy absorption band of each copolymer absorption spectrum is attributed to the π−π* transition with intramolecular charge-transfer, which has a lower fluorescence contribution than those of higher energy absorption bands. The optical excitation of either PFDCN or PFSDCN solution generates polaron pairs that then self-localize and evolve to a bound singlet exciton within a few picoseconds. Due to the additional conjugated –C=C– bond in the acceptor side-chain, PFDCN has a stronger intramolecular charge-transfer characteristic compared with PFSDCN, therefore exhibiting a longer self-localization time (7 ps vs. 3 ps for PFSDCN) and a shorter fluorescence lifetime (1.48 ns vs. 1.60 ns for PFSDCN).
Original languageEnglish
Pages (from-to)1398/1-1398/14
JournalMolecules
Volume22
Issue number9
DOIs
Publication statusPublished - 25 Aug 2017

Keywords

  • acceptor side-chain
  • excited state dynamics
  • intramolecular charge-transfer characters
  • transient absorption spectrum
  • two-dimensional like conjugated copolymers

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