Dynamic Polar Hydrogen Bonds and Photoconductivity of an Alkylamide-Substituted Carbazole Derivative

Abstract

Carbazole derivatives have long been known to exhibit excellent photoconductivity. Molecular arrangement control using intermolecular hydrogen bonds is an effective method for controlling carrier transport properties. In this work, we synthesized N,N′-ditetradecyl-9-methyl-3,6-carbazoledicarboxamide (C14CBC) by introducing two tetradecylamide (−CONHC₁₄H₂₉) chains into the 3,6-position of 9-methyl-carbazole and considered electronic structure, phase transition behavior, molecular assembly structure, dielectric property, and photoconductivity of C14CBC. C14CBC forms a 1D π-stacking column structure by intermolecular amide hydrogen bonding. C14CBC shows a solid–solid phase transition at 346 K and a melting point at 458 K. The temperature- and frequency-dependent dielectric constants show a response due to the dynamics of polar amide units above 400 K. The conductivity of the S1 and S2 phases is governed by the trap level and the HOMO–LUMO band gap. In the dynamic high temperature solid phase, the activation energy decreased upon photoirradiation.