Structural, electronic, and optical properties of some new dithienosilole derivatives

Structural, electronic, and optical properties of a series of organic semiconductors based on dithienosilole (DTS) and its derivatives were theoretically studied using density functional theory (DFT) and time-dependent-DFT (TD-DFT) methods. Our calculated results suggest that two phenyl groups substituted at silicon atom, as well as functional groups at 1,1′-positions, are an efficient way to induce substantial changes in the optical and electronic properties of DTS compounds. By substituting the functional groups at 1,1′-positions of DTS dimeric compound, we successfully make changes in the charge transport rate of the designed compounds, especially a remarkable reduction in hole reorganization energies. Introduction of pyridyl groups is efficient to lower the LUMO level, and optical band gap energies, to increase the charge and the balance transport rate between hole and electron for producing the ambipolar transport materials promising for use not only in the OLED but also in DSSC devices. Graphical abstract