Journal of Physical Chemistry B 2011-10-27

Spectroscopy and single-molecule emission of a fluorene-terthiophene oligomer.

G E Khalil, A M Adawi, B Robinson, A J Cadby, W C Tsoi, J-S Kim, A Charas, J Morgado, D G Lidzey

Index: J. Phys. Chem. B 115(42) , 12028-35, (2011)

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Abstract

We study the thiophene-based oligomer poly[2,7-(9,9-bis(2'-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 0-0 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.