Electronic and optical properties of functionalized polyaromatic hydrocarbons: a computational investigation on perfluorinated circumacenes

We report a systematic computational investigation on the electronic and optical properties of some representive polyaromatic hydrocarbons of interest for solid-state applications. We focus in particular on the five first members of the circumacenes family (i.e., coronene, ovalene, circumanthracene, circumtetracene, and circumpentacene). 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 exchange-correlation functional B3LYP. We quantified the effect of the complete substitution of peripheral hydrogen atoms with fluorine atoms for a series of key molecular properties relevant for molecular electronics and photonics: electron affinities, ionization energies, quasi-particle energy-gaps, optical absorption spectra, and exciton binding energies. We discuss the possible implications of the general trends observed with respect to both fundamental research and opto-electronic applications.