Structural and spectroscopic characteristics of polycyclic fluorophores relevant to organic light-emitting diodes

Seminaphtho[a]-fluorone (SNAFR-1) and 7,8,10-triphenylfluoranthene (TPF), recently synthesized polycyclic fluorophores, are used in organic light-emitting diodes (OLEDs) as novel emitting layers. The electronic structures and spectroscopic properties of SNAFR-1 and TPF in the gas phase have been studied by the DFT/TDDFT methods using hybrid functionals, B3LYP and PBE0, and the 6-31G(d) basis set. The lowest singlet electronic transitions (S0 → S1) in SNAFR-1 and TPF are delocalized over the whole molecules. On the basis of the CIS-optimized structure of the excited states, TD-PBE0 calculations predict emission wavelength of 572 nm for SNAFR-1, and of 475 nm for TPF, which are comparable, respectively, to 560 and 468 nm observed experimentally for photoluminescence.