Substitution of Ethynyl-Thiophene Chromophores on Ruthenium Sensitizers: Influence on Thermal and Photovoltaic Performance of Dye-Sensitized Solar Cells

Abstract

A new high molar extinction coefficient ruthenium(II) bipyridyl complex, “Ru(2,2-bipyridine-4,4′-dicarboxylic acid)(4,4′-bis((3-hexylthiophen-2-yl)ethynyl)-2,2′-bipyridine)(NCS)2 (N(C4H9)4), MC101” was synthesized and fully characterized by 1H-NMR, ESI-MASS, FT-IR, UV-Vis., and fluorescence spectroscopes. The dye showed relatively high molar extinction coefficient of 25.0 × 103 M-1 cm-1 at λ maximum of 544 nm, while the reference C101 has shown 15.8 × 103 M-1cm-1 at λ maximum 528 nm. The monochromatic incident photon-to-collected electron conversion efficiency of 44.1% was obtained for MC101 over the entire visible range, while the C101 sensitized solar cell fabricated and evaluated under identical conditions exhibited 40.1%. The DSSCs fabricated with 0.54 cm2 active area TiO2 electrodes and high efficient electrolyte (E01), from the sensitizers MC101 and C101 exhibited energy conversion efficiencies of 3.25% (short-circuit current density (JSC) = 7.32 mA/cm2, VOC = 610 mV, ff = 0.725) and 2.94% (JSC = 6.60 mA/cm2; VOC = 630 mV; ff = 0.709), respectively, under air mass of 1.5 sunlight.