Substitution effects of Ru–terpyridyl complexes on photovoltaic and carrier transport properties in dye-sensitized solar cells

Abstract

Four Ru–4,4′-dicarboxylterpyridyl (dctpy) complexes, substituted with different types of functional groups (H, F, Me, and MeO), were synthesized for dye-sensitized solar cell (DSC) applications, and the influences of the substituents on the dye-adsorption, spectral, electronic, and photovoltaic properties of the Ru–dctpy dyes were observed. UV-vis spectra of the four dyes in MeOH did not exhibit any significant differences as the substituent was changed. However, the UV spectra of dye-sensitized TiO₂ films showed differences in absorbance intensities, reflecting the dye-loading amount on the TiO₂ surface (Me > H > MeO > F). The photovoltaic properties of the DSCs, based on the four Ru dyes, were changed by the effects of the substituents. The Ru–Me dye exhibited the best conversion efficiency, 7.94%, with the best electron injection efficiency (τ_e). The Ru–F dye, in contrast, exhibited the worst efficiency, 6.29%, due to a short τ_e and rapid charge recombination.