Theoretical study on the electron transport properties of chlorinated pentacene derivatives

The effects of chlorination on the geometries, electronic structures and transport properties for some chlorinated pentacene derivatives (nCl-PENT-n) have been theoretically investigated by using density functional theory calculations and Marcus-Hush theory. Compared with PF-PENT, introducing chlorine atoms into pentacene, remarkably decreases the frontier molecular orbital energies while scarcely increases the internal reorganization energy, therefore improves their air-stability and ability of electron injection. Based on the experimental crystal parameters, the predicted hole and electron mobility (μh = 0.46 cm2 V−1 s−1, μe = 0.61 cm2 V−1 s−1) values for 6,13-dichloropentacene (DCP) crystal indicate that DCP crystal may be a promising candidate as ambipolar OFET materials. After the present work the results indicate that 4Cl-PENT-1 should be good n-channel material (μe = 2.74 cm2 V−1 s−1). In addition, the angular dependent simulation for electron mobility shows that the electron transport is remarkably anisotropic in the studied molecular crystals and the maximum μe appears along the crystal axis direction since molecules along this direction exhibit the close face-to-face stacking arrangement with short interplanar distances (∼3.7–5.3 Å), which induces large electronic couplings.