Influence of chemical modification (bromination) on structure and charge transport in poly(N-vinylcarbazole)

Bromine has been randomly substituted in the 3 or 6 position of the pendant carbazole group of poly(N-vinylcarbazole) using N-bromosuccinimide in chlorobenzene solution. X-ray diffraction indicated that this substitution interferes with the interchain interactions in the amorphous polymer eliminating the unusual degree of chain parallelism and destroying the ability to crystallize. Charge carrier photogeneration and mobility measurements show that holes are still the majority carrier in the bromine-substituted polymer but both generation and mobility are substantially reduced compared to the unsubstituted polymer. It has not been possible to separate the influence of pendant group electronic structure from that of bulk chain conformation in this modification of the polymer photoconductive properties.