Thermally stimulated current studies of charge transport in polysilanes

Abstract

We show the applicability of thermally stimulated current (TSC) spectroscopy, a well established method of trap spectroscopy, for studying hopping transport in polysilanes. The 'traps' are the hopping centers and are highly concentrated compared to dilute traps arising from defects and impurities. Activation energies ranged from 0.3 eV at 5×104 V/cm to 0.2 eV at 3×105 v/cm for poly(phenylmethylsilane), in agreement with time of flight spectroscopy. The hopping transport peak in TSC is distinguished from trapping states which may be present in the sample. When traps were deliberately formed at the surface by UV irradiation, a second peak was observed, corresponding to an activation energy of 0.5 ev.