The Effect of Star-Shaped Oligothiophenes with a Carbazole Core on Their Structural and Optical Properties

A comparative analysis of the structure and properties of donor–acceptor star-shaped compounds based on oligothiophene with electron-withdrawing dicyanovinyl groups and a different electron-donating branching center—planar 9-phenyl-9H-carbazole and propeller-shaped triphenylamine—has been carried out. It is shown that the absorption maxima in the spectra of 9-phenyl-9H-carbazole derivatives shift to shorter wavelengths, the HOMO energy decreases, and the LUMO energy increases. Moreover, in contrast to propeller-shaped triphenylamine-based compounds, which do not form ordered states, the T-shaped branched molecules based on carbazole form highly ordered crystal structures with different symmetry.