The photophysical properties are calculated for the dibenzothiophene sulfone substituted with various electron donor moieties:3,7-bis[N,N-di(4-tert-butylphenyl)amino]dibenzothiophene-S,S-dioxide (1L), 2,8-bis[N,N-di(4-tert-butylphenyl)amino]dibenzothiophene-S,S-dioxide (1A), and 2,8-bis[N,N-di(4 methoxyphenyl)amino]dibenzothiophene-S,S-dioxide (2A). It is shown that the linear arrangement of the electron donor substituents relative to the dibenzothiophene sulfone acceptor turns compound (1L) an efficient prompt fluorescent emitter, while the angular arrangement of the substituents decreases the efficiency of prompt fluorescence, but increases the efficiency of thermally activated delayed fluorescence (TADF). Replacing the auxiliary tert-butyl groups in the donor moieties by methoxy groups leads to an increase in k(ISC) and k(RISC). OLEDs are made with the studied compounds.