Excited state properties of the p- and n-type semiconductors of thiazolothiazole derivative having thiophene and trifluormethylphenyl rings

Excited state properties of novel p- and n-type organic semiconductors with a thiazolothiazole unit are theoretically investigated with quantum chemical methods. The calculated absorption frequencies of them are consistent with the experimental data. The dihedral angles between the thiazolothiazole unit and the trifluoromethylphenyl (or thiophene) are examined from the optimized geometries at ground states. To study the influence of the individual units of the derivatives to the excited state properties of them, the energies and densities of frontier orbital HOMOs and LUMOs of the individual unit and the derivatives are investigated in the absorption processes. The excited properties of the two derivatives are studied with 2D and 3D real-space analysis methods, which are employed to study the electron–hole coherence and the excitation delocalization (with transition density matrix method), and charge and energy transfer (with transition and charge difference density method). The insights of the optical electron properties of the semiconductor in the absorption are revealed theoretically.