抄録
Charge carrier transport in amorphous photoconductive polymers was studied by choosing poly-N-vinylcarbazole as a typical photoconductive polymer. In the first part of this report, the physical meaning of Gill's empirical equation, which was widely accepted to describe the drift mobility in many amorphous organic photoconductors, was interpreted from the viewpoint of molecular dynamics. It was shown that the critical temperature To in Gill's equation has a close connection with the glass transition temperature Tg and that the drift mobility μo represents the drift mobility in the supercooled liquid state at temperature To. Charge carrier transport phenomena were discussed in relation to the structural carrier trap. Secondly, the upper limit of the drift mobility, i. e., trap-free drift mobility, in amorphous organic materials was estimated to be of the order of l×l0-3 cm2/sec·V, which is about 104 times larger than the overall drift mobility, by introducing a thermal equilibrium between free and trapped carriers. Thirdly, it was found that the drift mobility of PVCz was increased by adding some kind of pyrazoline derivative. The enhancement of the drift mobility in a PVCz-pyrazoline derivative binary system was reasonably interpreted in terms of a new idea of two-step detrapping mechanism from the deep trap level to the conduction state via an intermediate trap level provided by the dopant.
