RADIATION-INDUCED CONDUCTIVITY IN POLY(METHYLPHENYLSILYLENE) AND POLY(DI-N-HEXYLSILYLENE) STUDIED BY TIME-RESOLVED MICROWAVE CONDUCTIVITY

The transient conductivity change resulting on nanosecond pulsed irradiation of poly-(methylphenylsilylene) (PMPS) and poly(di-n-hexylsilylene) (PDHS) has been studied using the time-resolved microwave conductivity (TRMC) technique from nanoseconds to milliseconds after the pulse. The transients show a dispersive decay. In PMEPS, where the hole is the major charge carrier, the mobility at room temperature appears to decrease with time from an initial value of at least 3 x 10(-8) m2/V-s on a nanosecond time scale to a value 1 order of magnitude less at milliseconds. In PDHS the initial radiation-induced conductivity per unit dose is 2 orders of magnitude larger than for PMPS at room temperature and corresponds to a charge carrier mobility of at least 1 x 10(-5) M2/V.s. The end-of-pulse conductivity decreases by a factor of 20 at the solid-to-mesophase transition.