Effects of substitution and functionalization on the electronic, optical, and transport properties of polycyclic aromatic hydrocarbons

CARDIA, ROBERTO;MALLOCI, GIULIANO;CAPPELLINI, GIANCARLO

2015-01-01

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Abstract

The electronic and optical properties of some represenative molecules belonging to the PAHs family of interest for solid state applications have been studied within a (TD)DFT scheme. We focus in particular on Pentacene, Pyrene and two Dibenzochrysenes (angular and compact).For the isolated gas-phase molecules we performed all-electrons Density Functional Theory (DFT) and Time Dependent DFT (TDDFT) calculations with a localized Gaussian basis-set and the hybrid B3LYP exchange-correlation functional [1],[2]. Electron affinities, ionization energies, fundamental energy-gaps, optical absorption spectra, exciton binding energies, and reorganization energies for holes and electrons have been calculated and compared with the available experimental/theoretical data for the pure molecules and for the corresponding substituted ones. The substitutions under study comprehend perhalogenation as other possibilities (e.g. TIPS group or sulfur substitution) which have all an experimental counterpart. Possible consequences of our findings on the above mentioned electronic and optical properties with respect to applications and fundamental research will be discussed.