Computational design of benzo [1,2-b:4,5-b′] dithiophene based thermally activated delayed fluorescent materials

•A reverse intersystem crossing from higher triplet to singlet excited states is proposed.•The calculated emission wavelengths of these investigated molecules may exhibit long wavelength emission characters.•The charge transfer properties of these design molecules are calculated using density functional theory.

A series of benzo [1,2-b:4,5-b′]dithiophene based thermally activated delayed fluorescent molecules have been designed and investigated using density functional theory and time-dependent density functional theory. The theoretical calculations showed that the designed 4, 8-positions of benzo [1,2-b:4,5-b′]dithiophene substituted molecules exhibited a mixed states, which comprised a large proportion of charge transfer components and a small part of locally excited components. The calculated emission wavelengths of the investigated molecules may exhibit long wavelength emission characters. For the designed 4, 8-positions substituted molecule with two [1,2,5]thiadiazolo[3,4-c]pyridine-7-carbonitrile electron-accepting units, which exhibited zero singlet-triplet energy gap, the predicted hole and electron mobilities are 3.43 cm2 v−1 s−1 and 0.18 cm2 v−1 s−1, respectively. Our study may provide new ideas for the design of highly efficient thermally activated delayed fluorescent candidates by realizing the full potential of both singlet and triplet excitons.

Graphical abstractComputational design of benzo [1,2-b:4,5-b′]dithiophene based thermally activated delayed fluorescent molecules by realizing the full potential of both singlet and triplet excitons.Figure optionsDownload full-size imageDownload as PowerPoint slide