Carrier Transport and Viscosity of Discotic Liquid Crystalline Photoconductor Hexaoctyloxytriphenylene

摘要

In this study, the carrier transport and viscosity of 2,3,6,7,10,11 -hexaoctyloxytriphenylene (C8OTP) have been studied by a time-of-flight method and a rotation viscometer. One-anion and two-cation transport was observed in the isotropic liquid phase, whereas the ambipolar electronic and one-anion transport was observed in the columnar mesophase. The activation energies for the ionic conductions in the isotropic liquid phase and columnar mesophase were 0.3 and 0.3 eV, respectively. The viscosity of C8OTP was investigated in the isotropic liquid phase and the activation energy was 0.4 eV. The Stokes radii of ionic carriers were experimentally estimated using Walden's rule. The Stokes radii for one anion and two cations were approximated to be 1, 2, and 8 A, respectively. The Stokes radius of 8 A for the larger cation represented the molecular size of C8OTP itself, assuming that C8OTP is a flat spheroid.