Temperature Dependence of Magnetophotoconductance in One-Dimensional Molecular Assembly of Hexabenzocoronene

Temperature dependencies of transient photocharge and magnetophotoconductance effect of columnar self-assemblies of the hexabenzocoronene derivative (HBC-C14), which is a prospective one-dimensional photoconductor, presented different thermal activation processes for carrier generation and transportation, respectively. Thermal equilibrium between the low-lying short distance and high-lying long-distance geminate electron-hole (e-h) pairs is the origin for activation in carrier generation. The energy difference between these e-h pairs is estimated to be 7 meV, which was mainly due to the Coulomb interaction. On the other hand, the carrier transport with thermal activation was understood by the multiple trapping model. Carrier detrapping from localized states located in the band gap causes the thermal activation in the carrier transport. The shallow energy depth at the density peak of the localized state from the mobility edge (10 ± 3 meV) is a unique nature of HBC-C14 self-assemblies. A very narrow Gaussian distribution for density of the localized states was also clarified.