Fluorescence properties of organic dyes: quantum chemical studies on the green/blue neutral and protonated DMA-DPH emitters in polymer matrices

Abstract

The absorption and fluorescence spectra of the green emitter DMA-DPH {1-[4-(dimethylamino)phenyl]-6-phenylhexa-1,3,5-triene} and its protonated blue-emitter form have been studied theoretically through time-dependent density functional theory (TD-DFT) and resolution-of-identity 2nd order perturbative coupled cluster (RI-CC2) calculations with basis sets up to augmented triple-ζ quality, in the gas phase and in solvents of different polarity. These systems dispersed in a polymer matrix are of interest for applications in organic light emitting diode devices (OLEDs). Calculations show that the observed absorption and emission spectra correspond to transitions between the S₀ and S₁ states, in both systems. The nature and characteristics of these transitions are discussed. Excellent agreement with experimental data is obtained, both for absorption and emission, provided that the state-specific polarized continuum model (SS-PCM) method is employed for the inclusion of the solvent.