Time-resolved exciton diffusion measurements of fluorescence coupled with a TiO2 quencher, in poly(3-hexylthiophene) (P3HT), was described. Ellipsometry was performed on P3HT films over a range of thicknesses and the data used to construct a uniaxial model from which the absorption as a function of film thickness was calculated. The PL decays show that, over all four thicknesses there is a clear trend with the P3HT on TiO2 decaying faster than its fused silica counterparts. Ultrafast electron transfer to TiO2 is demonstrated from MEH-PPV and a thiophene oligomer, supporting the use of an infinite quencher in the proposed model. Internal conversion to the lowest state is found to be the dominant relaxation pathway of the higher energy exciton in a polythiophene derivative.