Influence of the Halogenated Substituent on Charge Transfer Mobility of Aniline Tetramer and Derivatives: Remarkable Anisotropic Mobilities

Abstract

The halogen-substituted derivatives and the parent aniline tetramer as organic semiconductors have been theoretically investigated with a focus on the electronic properties and charge transport properties through density functional theory and Marcus–Hush theory methods. The study on the transport properties of holes and electrons can obtain insight into the effect of halogenation substitution on injection of charge carriers and transport character. The equilibrium geometries, reorganization energies, frontier molecular orbitals, intermolecular electronic couplings, electrostatic potential isosurfaces, and angular resolution anisotropic mobilities were calculated. The calculated results revealed that perfluorination and perchlorination can induce stronger structure relaxation and effectively lower the highest occupied molecular orbital and lowest unoccupied molecular orbital levels. The angle dependence mobilities of the three crystals show remarkable anisotropic character. The carrier mobility curves for both electron and hole transport of the parent aniline tetramer and halogen-substituted derivatives all show a remarkable anisotropic feature. Furthermore, the ANIH and ANICl crystals show higher electron-transfer mobilities than hole-transfer mobilities and, hence, perform better as an n-type organic semiconductor. The ANIH crystal possesses a low reorganization energy combined with a high electronic coupling and electron-transfer mobility, which indicates that the ANIH crystal might be a more ideal candidate as an n-type organic semiconductor material.