Polymeric solar cells are a promising alternative for producing clean and renewable energy due to the possibility of fabricating them onto large areas of lightweight, flexible substrates by solution processing at low cost. In this context, oligothiophenes and polythiophenes are attracting increasing interest because they offer a range of promising properties. The conductivity of the materials is increased by doping with an electron acceptor (iodine is commonly used) and this results in major changes in the infrared and Raman spectra, that “blur” the spectra because the electronic structure has been drastically modified. Inelastic neutron scattering (INS) spectra are unaffected by such changes and would allow the underlying dynamics to be observed.