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Charge Transfer in Single Chains of a Donor-Acceptor Conjugated Tri-Block Copolymer.


Type

Article

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Authors

Hooley, Emma N 
Jones, David J 
Greenham, Neil C 
Ghiggino, Kenneth P 
Bell, Toby DM 

Abstract

The photophysics of a conjugated triblock copolymer comprising poly(9,9-dioctylfluorene-co-bis-N,N'-(4-methylphenyl)-bis-N,N'-phenyl-1,4-phenylenediamine) (PFM) electron donor and poly(4-(9,9-dioctyl-9H-fluoren-2-yl)benzo[c][1,2,5]-thiadiazole) (F8BT) electron acceptor blocks has been studied in solution, in films, and as single chains. While an additional long-wavelength emission apparent in neat films of the copolymer is attributed to interchain exciplex formation, no such long-wavelength emission is apparent in solution or from single molecules. However, in these cases, time-resolved fluorescence measurements indicate the presence of a delayed fluorescence. The kinetics of the delayed emission can be interpreted in terms of an equilibrium between a locally excited and a charge-transfer state at the interface of the copolymer block components. Rate constants and thermodynamic quantities associated with these processes have been evaluated. The single-molecule results allow the assignment of an intramolecular charge-transfer state in an isolated conjugated block copolymer chain.

Description

Keywords

Conjugated polymer, block copolymer, single molecule fluorescence, charge transfer, delayed fluorescence, exciplex

Journal Title

J Phys Chem B

Conference Name

Journal ISSN

1520-6106
1520-5207

Volume Title

119

Publisher

American Chemical Society (ACS)
Sponsorship
We thank the Australian Research Council (ARC) for financial support of this research through grants DP0986166, LE100100131 and LE110100161. ENH acknowledges an Australian Postgraduate Award. We acknowledge Sam Ashworth for technical assistance with data collection. NCG is grateful to the School of Chemistry, The University of Melbourne for a Wilsmore Fellowship, and to Queen’s College, Melbourne for a Sugden Fellowship.