Hole Transport in Hydrazone-Doped Polymer Films

Hole drift mobilities were measured in hydrazone-doped polycarbonate films under various concentrations, temperatures and electric fields. Hydrazone molecules used were 9-ethylcarbazole-3-carbaldehyde diphenylhydrazone (CTM1), 9-ethylcarbazole-3-carbaldehyde methylphenylhydrazone (CTM2), and 1-pyrenecarbaldehyde diphenylhydrazone (CTM3). Charge transport in the films obeyed the nonadiabatic small-polaron hopping formalism with almost the same activation energies at concentrations investigated. CTM2 exhibited a different concentration dependency and relatively small mobility especially at high concentrations. Analysis by disorder formalism indicated that the energetic disorder parameter (σ) is almost the same and the non-energetic disorder parameter (Σ) is different. We found some correlations between the mobilities of the CTMs and molecular overlap and orientation in the single crystalline state of CTMs.