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

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

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).

Citation

Huo, M.-M., Hu, R., Yan, W., Wang, Y.-T., Chee, K., Wang, Y., & Zhang, J.-P. (2017). Acceptor side-chain effects on the excited state dynamics of two-dimensional-like conjugated copolymers in solution. Molecules, 22(9), Article 1398. https://doi.org/10.3390/molecules22091398

• Journal Article Type: Article
• Acceptance Date: Aug 18, 2017
• Publication Date: Aug 25, 2017
• Deposit Date: Feb 7, 2018
• Publicly Available Date: Feb 7, 2018
• Journal: Molecules
• Electronic ISSN: 1420-3049
• Publisher: MDPI
• Peer Reviewed: Peer Reviewed
• Volume: 22
• Issue: 9
• Article Number: 1398
• DOI: https://doi.org/10.3390/molecules22091398
• Keywords: two-dimensional like conjugated copolymers; acceptor side-chain; transient absorption spectrum; intramolecular charge-transfer characters; excited state dynamics
• Public URL: https://nottingham-repository.worktribe.com/output/879282
• Publisher URL: http://www.mdpi.com/1420-3049/22/9/1398
• Contract Date: Feb 7, 2018