Dynamic Polar Hydrogen\nBonds and Photoconductivity\nof an Alkylamide-Substituted Carbazole Derivative

Carbazole derivatives have long been known to exhibit\nexcellent\nphotoconductivity. Molecular arrangement control using intermolecular\nhydrogen bonds is an effective method for controlling carrier transport\nproperties. In this work, we synthesized <i>N</i>,<i>N</i>′-ditetradecyl-9-methyl-3,6-carbazoledicarboxamide\n(<b>C14CBC</b>) by introducing two tetradecylamide (−CONHC<sub>14</sub>H<sub>29</sub>) chains into the 3,6-position of 9-methyl-carbazole\nand considered electronic structure, phase transition behavior, molecular\nassembly structure, dielectric property, and photoconductivity of <b>C14CBC</b>. <b>C14CBC</b> forms a 1D π-stacking column\nstructure by intermolecular amide hydrogen bonding. <b>C14CBC</b> shows a solid–solid phase transition at 346 K and a melting\npoint at 458 K. The temperature- and frequency-dependent dielectric\nconstants show a response due to the dynamics of polar amide units\nabove 400 K. The conductivity of the S1 and S2 phases is governed\nby the trap level and the HOMO–LUMO band gap. In the dynamic\nhigh temperature solid phase, the activation energy decreased upon\nphotoirradiation.