ELECTRONIC TRANSPORT IN AMORPHOUS-SILICON BACKBONE POLYMERS

Measurements of hole transport in polysilylenes have now been carried out over an extended range of temperature and field. This extended data facilitates detailed comparison to extensively characterized glassy carbon backbone polymers like poly(N-vinylcarbazole) (PVK). Hole transport data in polymethylphenylsilylene (PMPS) serves as a model and has been analyzed in both a modified Arrhenius framework and in terms of a picture of hopping in a Gaussian distribution of states broadened by disorder. The principal conclusion stressed here is that respective transport properties observed in PMPS and PVK are surprisingly similar despite the following key difference: hole or hole polaron transport in PVK does not involve states derived from the carbon backbone but rather direct hopping among pendant carbazole sidegroups which can be thought of as isolated small molecules (chromophores). On the other hand it si found that in polysilylenes room temperature drift mobilities remain about 10-4cm2/volt-sec even in aliphatic sidegroups containing species where there is negligible overlap of chromophore wave functions. The latter implies that in polysilylenes generally, transport states probably associated with the chain backbone still remain relatively localized. © 1987.