Charge transport properties for carbazolyl groups pendant poly(glutamate)

Abstract

Carbazolyl groups pendant poly(glutamate) (PCLG) was prepared to analyze its charge-transport properties by employing mobility measurements and thermally-stimulated current (TSC) measurements. The mobility induced TSC (MITSC) model proposed by I.Chen was employed to evaluate the experimental TSC spectra with mobility results. Simulated MITSC spectra showed good agreement in its peak temperature with experimental TSC spectra for PCLG. This suggests that the carrier transport followed the trap-limited mechanism estimated by the mobility results. Further, the peaks in experimental TSC spectra appeared over the same temperature range as that in thermally-stimulated polarization current (TSPC) spectra. Since the TSPC spectra were found to be correlated with the dielectric tan δ spectra for PCLG, the peaks in TSPC spectra are attributed to the side-chain relaxation for PCLG. Therefore, the similarity between TSPC and TSC spectra indicates that the charge-transport mechanism for PCLG was considerably affected by side-chain relaxation for PCLG, which would vary the energy state of trap sites and effectively reduces the energy for the release of the carriers trapped on the illuminated surface. © 1999 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 37: 61–69, 1999