CHARGE-CARRIER TRANSPORT IN POLY(NORMAL-PROPYLMETHYLSILANE) OVER A WIDE TEMPERATURE-RANGE ENCOMPASSING THE GLASS-TRANSITION AND THE MELTING-POINT

The hole drift mobility of poly(n-propylmethylsilane) showing thermochromism has been measured over a wide temperature range encompassing its glass transition temperature Tg and its melting point Tm. The drift mobility obeys Gill’s empirical expression for the field and temperature dependences below Tg. It levels oil near 10-4cm2 V-1S-1 with the disappearance of the field dependency above Tg, and gradually decreased just below Tm, where distinct thermochromism due to the change of the effective a conjugation length in the Si backbone chain was observed. Above Tm, the mobility increases again in the molten state. The lowering of the drift mobility due to the shortening of the σ conjugation length was also observed in rapidly quenched samples which exhibited a mobility about one order of magnitude lower, strongly indicating that the effective a conjugation length in the Si backbone chain determines the charge-carrier transport properties in organopolysilanes. © 1990 Taylor & Francis Ltd.