Some poly (3,4-disubstituted)thiophenes bearing both cyano and alkoxy or thioalkoxy groups have been synthesized
by direct (hetero)arylation polymerization (DHAP) of 2-iodo-3,4-disubstituted thiophenes. The electron
donor and acceptor properties of substituents in positions 3 and 4 allow to adjust the HOMO and LUMO levels.
On the other hand, in order to avoid the polymer solubility problems, long branched or unbranched alkyl chains
have also been introduced. Thus polymers with alkoxy groups have led to complete absorption in the wavelength
range of the visible spectrum whereas in the presence of thioalkoxy groups, the absorption of the visible
spectrum is only partial. Theoretical calculations have shown that sulphur creates torsions leading to a nonplanar
polymer chain.