Spectroscopic investigations of copolymers incorporating various thiophene and phenylene monomers

Experimental and theoretical studies are combined in order to describe copolymers involving various thiophene and phenylene monomers (TBT). The copolymers structures are confirmed and their optical properties are examined. The incorporation of a block unit, such as biphenylene, bipyridine or anthracene into the full conjugated backbone has a significant effect not only on the structural and vibrational properties of the compound but also on its optical behavior, resulting in different electronic transitions and emission colors from blue to blue-greenish and green. Therefore, a better correlation between photoluminescence and Raman vibrational modes assigned to the phonon emission is established. Theoretical studies, based mainly on density functional theory (DFT) calculations, are performed to explain the effect of the block unit incorporation in the optical property modifications. As a result, the blue shift is related to a less planar structure of the copolymer. (c) 2006 Elsevier B.V. All rights reserved.