State-Specific (Linear-Response)-Polarizable Continuum Models/Time-Dependent Density Functional Theory Study on the Absorption and Emission Spectra of an Organic Fluorescent Emitter

3-(dicyanomethylene)-5,5-dimethyl-1-(3-[9-(2-ethyl-hexyl)-carbazol]-vinyl) cyclohexene (DCDHCC) is one of a series of organic dyes with good emission performance in photoelectric devices. The absorption and emission spectra of DCDHCC were computed using PBE0O, BMK, and M06 hybrids in the frame of time-dependent density functional theory (TDDFT) in combination with polarizable continuum models (PCMs). Linear-response (LR) and state-specific (SS) PCM approaches were used as well as 6-31G(d) and 6-31+G(d,p) basis sets. The absorption and emission spectra were calculated in benzene, tetrahydrofuran, and acetone and compared with experimental observations. On the one hand, choice of hybrids was found to have a greater effect on the absorption spectra than the basis sets or the solvent model and BMK was established to be a suitable functional for the calculation of the absorption spectra of DCDHCC, on the other hand, the basis set used had a significant impact on the geometries of the excited states and thus the emission spectra, and the 6-31+G(d,p) basis set was necessary for the optimization of the excited states. It is envisaged that our calculations may be of assistance in the design of analogous emitters.