Seven 3-(3'-pyridyl)-6-aryl-1,2,4-triazolo[3,4-b]-1,3,4-thiadiazole derivatives have been studied at the B3LYP/6-31G* level of density functional theory (DFT). All the compounds have planar structure, and adiabatic and vertical electron affinities, intramolecular reorganization energies and absolute hardness have been obtained. The results on the basis of the theoretical calculations indicate that the HOMO and LUMO energies of the substituted molecules can be tuned by changing the substituents. These changes lead to energy shifts in the order of 0.346～1.10 eV. The intramolecular reorganization energies confirm that 3-(4'-cyanogen-3'-pyridyl)-6-aryl-1,2,4-triazolo[3,4-b]-1,3,4-thiadiazole is a good candidate for electron transport materials. By having simple substituents at proper positions one can control the reorganization energy, which in turn indicates that electron transport properties can be tuned. The data of absolute hardness agree that compound E and G are difficult to transport electron. The absorption spectra of compounds A, B and C are obtained by using TD-DFT, and the difference of maximum absorption peaks are from 3 to 10 nm compared with the experimental data.

Key words: electron transporting material, reorganization energy, thiadiazole derivative, density functional theory