Conjugated polymers have been extensively studied and are implemented in devices such as transistors and lightemitting
devices. We will present a solution-based study by linear and nonlinear optical characterization techniques in
which we study the behavior of different substituted poly(thiophene)s. A profound hyper-Rayleigh scattering study has
been performed in their neutral and oxidized oxidation state while continuously monitoring the transition.
A variety of pyridinium and benzothiazolium-substituted conjugated donor-π-acceptor dipoles are studied by hyper-
Rayleigh scattering (HRS) in solution. We have investigated their potential as strong electron acceptor moiety and a
complete series has been synthesized and characterized. An elongation of the conjugated π-system for each molecule is
made and characterized to see the influence of the elongation of the conjugated π-system. A leveling off of the
hyperpolarizability β is already observed after three subsequent double bonds.