title: Effect of five-membered ring and heteroatom substitution on charge transport properties of perylene discotic derivatives: A theoretical approach.
abstract: Density functional theory calculations were carried out to investigate the evolvement of charge transport properties of a set of new discotic systems as a function of ring and heteroatom (B, Si, S, and Se) substitution on the basic structure of perylene. The replacement of six-membered rings by five-membered rings in the reference compound has shown a prominent effect on the electron reorganization energy that decreases ∼0.2 eV from perylene to the new carbon five-membered ring derivative. Heteroatom substitution with boron also revealed to lower the LUMO energy level and increase the electron affinity, therefore lowering the electron injection barrier compared to perylene. Since the rate of the charge transfer between two molecules in columnar discotic systems is strongly dependent on the orientation of the stacked cores, the total energy and transfer integral of a dimer as a disc is rotated with respect to the other along the stacking axis have been predicted. Aimed at obtaining a more realistic approach to the bulk structure, the molecular geometry of clusters made up of five discs was fully optimized, and charge transfer rate and mobilities were estimated for charge transport along a one dimensional pathway. Heteroatom substitution with selenium yields electron transfer integral values ∼0.3 eV with a relative disc orientation of 25°, which is the preferred angle according to the dimer energy profile. All the results indicate that the tetraselenium-substituted derivative, not synthetized so far, could be a promising candidate among those studied in this work for the fabrication of n-type semiconductors based on columnar discotic liquid crystals materials.
authors: Departamento de Química Física y Analítica, Universidad de Jaén, Campus Las Lagunillas, E23071 Jaén, Spain.
authors: Amparo
authors: A
authors: Navarro
authors: Departamento de Química Física y Analítica, Universidad de Jaén, Campus Las Lagunillas, E23071 Jaén, Spain.
authors: M Paz
authors: MP
authors: Fernández-Liencres
authors: Departamento de Química Física y Analítica, Universidad de Jaén, Campus Las Lagunillas, E23071 Jaén, Spain.
authors: Tomás
authors: T
authors: Peña-Ruiz
authors: Instituto de Energía Solar and Departamento TFB, E.T.S.I. Telecomunicación, Universidad Politécnica de Madrid, Ciudad Universitaria, Madrid 28040, Spain.
authors: Gregorio
authors: G
authors: García
authors: Departamento de Química Física y Analítica, Universidad de Jaén, Campus Las Lagunillas, E23071 Jaén, Spain.
authors: José M
authors: JM
authors: Granadino-Roldán
authors: Departamento de Química Física y Analítica, Universidad de Jaén, Campus Las Lagunillas, E23071 Jaén, Spain.
authors: Manuel
authors: M
authors: Fernández-Gómez