High Molar Extinction Coefficient Ru(II)-Mixed Ligand Polypyridyl Complexes for Dye Sensitized Solar Cell Application

Two new ruthenium(II) mixed ligand terpyridine complexes, “Ru(Htcterpy)(NCS)(L1) (N(C4H9)4), mLBD1” and Ru(Htcterpy)(NCS)(L2)(N(C4H9)4), mLBD2 were synthesized and fully characterized by UV-Vis, emission, cyclic voltammogram, and other spectroscopic means, and the structures of the compounds are confirmed by 1H-NMR, ESI-MASS, and FT-IR spectroscopes. The influence of the substitution of L1 and L2 on solar-to-electrical energy conversion efficiency (η) of dye-sensitized solar cells (DSSCs) was evaluated relative to reference black dye. The dyes showed molar extinction coefficients of 17600 M−1 cm−1 for mLBD1 and 21300 M−1 cm−1 for mLBD2 both at λ maximum of 512 nm, while black dye has shown 8660 M−1 cm−1 at λ maximum of 615 nm. The monochromatic incident photon-to-collected electron conversion efficiencies of 60.71% and 75.89% were obtained for mLBD1 and mLBD2 dyes, respectively. The energy conversion efficiencies of mLBD1 and mLBD2 dyes are 3.15% (?SC=11.86 mA/cm2, ?OC=613 mV, ff=0.4337) and 3.36% (?SC=12.71 mA/cm2, ?OC=655 mV, ff=0.4042), respectively, measured at the AM1.5G conditions, the reference black dye-sensitized solar cell, fabricated and evaluated under identical conditions exhibited η-value of 2.69% (?SC=10.95 mA/cm2, ?OC=655 mV, ff=0.3750).