An in-depth analysis of the vibronic absorption spectra for the recently synthesized blue-fluorescent OLED emitters bis[(1,2)(5,6)]indoloanthracene and biscarbazolo[3,4-a:3′,4′-h]anthracene has been carried out computationally at the density functional theory level within the Franck-Condon approximation. These molecules are characterized by extended and rich electronic absorption spectra with most absorption bands being of vibronic origin. The first excited singlet state of bis[(1,2)(5,6)]indoloanthracene compound demonstrates a clear observable double-peak vibronic progression for two different active modes in the absorption spectrum, while the S2 state is vibronically inactive. In contrast, for the larger biscarbazolo[3,4-a:3′,4′-h]anthracene compound the S0 → S2 transition demonstrates well-resolved intense vibronic bands which overlap the less intense progressions of few modes in the S0 → S1 transition. We have also found, that even the higher-lying and very intense S0 → S4 and S0 → S5 transitions for bis[(1,2)(5,6)]indoloanthracene and biscarbazolo[3,4-a:3′,4′-h]anthracene, respectively, are characterized by clear vibronic progressions in excellent agreement with experimental spectra.
- Franck-Condon approximation
- Vibronic spectra
ASJC Scopus subject areas
- Physics and Astronomy(all)
- Physical and Theoretical Chemistry