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Spectroscopy and Single-Molecule Emission of a Fluorene-Terthiophene Oligomer

Khalil, G. K. ; Adawi, A. M. A. ; Robinson, B. ; Cadby, A. J. C. ; Tsoi, W. C. T. ; Kim, J-S. ; Charas, A. ; Morgado, J. ; Lidzey, D. L.

Journal of Physical Chemistry B Vol. 115, Nº 42, pp. 12028 - 12035, October, 2011.

ISSN (print): 1520-5207
ISSN (online): 1520-6106

Journal Impact Factor: 4,189 (in 2008)

Digital Object Identifier: 10.1021/jp206368g

Abstract
We study the thiophene-based oligomer poly-
[2,7-(9,9-bis(20-ethylhexyl)fluorene)-alt-2,5-terthiophene] (PF3T)
in solution and when dispersed at low concentration into a
polynorbornene matrix. We find that at high concentration in
solution the 00 electronic transition observed in fluorescence
is suppressed, a result indicative of the formation of weakly
coupled H-aggregates. At low concentration in a polymer matrix,
emission from both single molecules and molecular aggregates is
observed. We find that the fluorescence spectra of most PF3T
emitters are composed of a number of relatively narrow emission
features, indicating that the emission usually occurs from multiple chromophores. A small number of PF3T molecules are however
characterized by single chromophore emission, spectral blinking, and narrowed emission peaks.