Electronic and optical properties of families of polycyclic aromatic hydrocarbons: A systematic (time-dependent) density functional theory study
Abstract
Homologous classes of polycyclic aromatic hydrocarbons (PAHs) in their crystalline state are among the most promising materials for organic opto-electronics. Following previous works on oligoacenes we present a systematic comparative study of the electronic, optical, and transport properties of oligoacenes, phenacenes, circumacenes, and oligorylenes. Using density functional theory (DFT) and time-dependent DFT we computed: (i) electron affinities and first ionization energies; (ii) quasiparticle correction to the highest occupied molecular orbital (HOMO)-lowest unoccupied molecular orbital (LUMO) gap; (iii) molecular reorganization energies and (iv) electronic absorption spectra of neutral and ±1 charged systems. The excitonic effects are estimated by comparing the optical gap and the quasiparticle corrected HOMO-LUMO energy gap. For each molecular property computed, general trends as a function of molecular size and charge state are discussed. Overall, we find that circumacenes have the best transport properties, displaying a steeper decrease of the molecular reorganization energy at increasing sizes, while oligorylenes are much more efficient in absorbing low-energy photons in comparison to the other classes.
- Publication:
-
Chemical Physics
- Pub Date:
- June 2011
- DOI:
- 10.1016/j.chemphys.2011.04.013
- arXiv:
- arXiv:1104.2978
- Bibcode:
- 2011CP....384...19M
- Keywords:
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- Condensed Matter - Materials Science
- E-Print:
- 26 pages, 9 figures, 4 tables, accepted for pubblication in Chemical Physics (14/04/2011)