In Silico Exploration for Maximal Charge Transport in Organized Tetrabenzoacenes through Pitch and Roll Displacements

Abstract

A series of π-conjugated tetrabenzoacenes (TBA), including nitrogen (un)doped derivatives are computationally evaluated to comprehend the correlation between intrinsic structural arrangements and charge transport characteristics. The central charge transport parameters such as reorganization energy and electronic coupling are individually tuned through peri-substitutions, core-substitutions and/or π-extension in TBA derivatives. Based on reorganization energies, nitrogen doping impeded the electron transport in TBA analogs owing to significant structural changes associated with the reduction process. Our approach employing mapping of dimeric arrangements of TBA, modulated via long (pitch) and short (roll) axes displacements of the molecular entities, versus charge transfer coupling disclosed potential charge transport regions in addition to the ideal cofacial modes. Charge transport characteristics of molecular packing arrangements of TBA mimicking the different orientations of graphene bilayers were analyzed, providing insights into the possible material applicability of TBA derivatives. The transition from completely aligned graphitic AA packing sequence to slip-stacked AB and AA’ stacking domains revealed a dent in the charge transport map owing to node-antinode interaction of the frontier molecular orbitals. TBA analogs encompassing expanded π-system materialized highly displaced dimeric orientation from AB type packing to occupy a hierarchy favoring high charge transfer coupling than the AB type. Thus, realizing stable interchromophoric arrangements of small organic molecules through chemical or physical techniques to control their charge transporting efficiencies is an indispensable step towards the generation of better organic electronic devices.