Despite strong recent advances in the activities of conjugated polymer photocatalysts for hydrogen production from water, few studies have attempted to deconvolute the many interlinking factors that affect photocatalytic performance. In this thesis, I study two series of solution processable polymer photocatalysts to determine structure-function-performance relationships. In both cases, the photocatalytic performance depends strongly on the inclusion of more polar groups, such as dibenzo[b,d]thiophene sulfone backbone units or oligo(ethylene glycol) side chains. I use optical, spectroscopic, and structural characterisation techniques to understand the different catalytic activities of these systems.
I find that polar groups improve the wettability of the material with water in all cases, and this improved wettability translates into improved hydrogen evolution performance. In all cases, hydrogen evolution rates are correlated with the number of electrons that are available to do proton reduction on the micro- to millisecond timescale. However, backbone and side chain modifications affect photocatalytic performance in different ways: the inclusion of dibenzo[b,d]thiophene sulfone backbone units improves both the thermodynamic driving force for hole transfer to the sacrificial electron donor and the kinetics of electron transfer to the metal co-catalyst; the inclusion of oligo(ethylene glycol) side chains heightens the degree of polymer swelling, extending the electron polaron lifetime by reducing charge recombination.