absorption and phosphorescent mechanism of three Au（III） complexes, Au（2,5-F2C6H3-C^CAC）（C = C-C6H4N（C6Hs）2 [Au25FPh], Au（3,5-F2C6Ha-CACAC）（C=C-C6H4N（C6Hs）2 [Au35FPh], and Au（3,5-F2C6H3-CAC^C）（C=C-C6H4N（1H- indole）2 [Au35FID], are calculated and compared using density functional theory （DFT） and time-dependent DFT （TDDFT）. The calculated results reveal that enlarging the center CACAC ligand will result in the enhanced LMCT participation. This theoretical contribution allows design of new Au（III） complexes with higher phosphorescence efficiency.
A series of dye molecules was designed theoretically.Particularly,azoles and their derivatives were chosen as the modifying groups linking to ancillary ligands of [Ru（dcbpyH2）2（NCS）2]（N3,dcbpy=4,4＇-dicarboxy2,2＇-bipyridine;NCS=thiocyanato）.Density functional theory（DFT） based approaches were applied to exploring the electronic structures and properties of all these systems.The dye molecule with 1,2,4-triazole groups which exhibits a very high intensity of absorption in visible region,was obtained.Time-dependent DFT（TD-DFT） results indicate that the ancillary ligand dominates the molecular orbital（MO） energy levels and masters the absorption transition nature to a certain extent.The deprotonation of anchoring ligand not only affects the frontier MO energy levels but also controls the energy gaps of the highest occupied MO（HOMO） to the lowest unoccupied MO（LUMO） and LUMO to LUMO＋1 orbital.If the gap between LUMO-LUMO＋1 is small enough,the higher efficiency of dye-sensitized solar cell（DSSC） should be expected.
