Insight into Electron-Donating Ancillary Ligands in Ruthenium Terpyridyl Complexes Configuration on Performances of Dye-Sensitized Solar Cells

Three heteroleptic ruthenium terpyridyl complexes, RC-T51, RC-T52, and RC-T53, with efficient electron-donating ancillary ligands were molecularly designed, synthesized and applied as sensitizers for dye-sensitized solar cell. With the replacement of labile isothiocyanates (NCS) ligand by electron-donating ancillary ligands, all the RC dyes exhibited superior optical properties and suitable electrochemical characteristics. The lowest excited-state decay dynamic analysis for RC dyes were carried out by time-resolved photoluminescence measurements. Among the RC dyes, the solar cell sensitized by RC-T53 achieved the best short-circuit current density of 14.20 mA cm^-2 and power conversion efficiency of 6.17%. Compared with N749, DFT calculations, and transient absorbance decay kinetics rationalized the relatively inferior performances of RC dyes which were ascribed to the improper delocalization of the HOMO energy level and the inefficient dye generation process. Substituting the labile NCS ligand by electron-donating ancillary ligand bearing bidentate structure, the devices based on RC dyes exhibited excellent stability in the accelerated tests (60°C for 1000 h) in combination with low volatility electrolyte. (Figure Presented).