Polysiloxanes With Pendant Carbazole Groups. Preparation and Photoconductivity

Abstract

The synthesis and the photoconductive properties of four novel polysiloxanes are reported. In the polymers 3a-d carbazole groups are attached to the polysiloxane backbone with flexible spacers of various length. The polymers were prepared from the carbazole derivatives 1a-d and poly(hydrogenmethylsiloxane) 2 in a polymer analogous reaction; they were charaterized by DSC and various spectroscopic methods.

Time-of-flight measurements show that polysiloxane 3a has an effective charge carrier mobility of 9.8 × 10^-7 cm²/Vs which is roughly the same as has been found for the well known polymeric photoconductor poly(N-vinylcarbazole) (PVK). The absolute values of the transient photocurrent are somewhat smaller for polymer 3a. This is a consequence of the different charge carrier quantum yield in the two materials. Polymer 3a and PVK were also investigated by the xerographic discharge method, which yields similar values of the dark decay and the photo decay of both polymers.