Photogeneration and dynamics of charge carriers in the conjugated polymer poly(3-hexylthiophene)

The conjugated polymer poly(3-hexylthiophene) is a promising candidate for applications in organic thin-film electronic and optoelectronic devices. This dissertation addresses fundamental issues regarding the photogeneration and recombination dynamics of charge carriers in this polymer. Measurements were carried out using an electrodeless, low-field microwave detection technique. With this technique, the intrinsic charge-carrier photogeneration and charge-transport properties of the material can be studied, in the absence of effects arising from electrode contacts and high electric fields, commonly present in conventional DC conductivity studies. The following issues are investigated: The quantum yield and wavelength dependence of photoelectron emission from the polymer surface. The wavelength dependence and activation energy of the quantum yield of charge carrier photogeneration within thin layers. The role of molecular order in the photogeneration of charge carriers. The effect of exciton annihilation on the photoconductance. The recombination dynamics of photogenerated charge carriers. The GHz charge carrier mobility and its activation energy. A generalized version of the stretched-exponential (Kohlrausch) decay law is derived, which provides an analytical description of the diffusive recombination of charge carriers