We report a panchromatic cyclometalated Ru(II) complex, denoted as O18, which shows intense metal-to-ligand charge transfer transitions in the visible to near-IR region with the absorption tail extending to 800 nm. The panchromatic spectra response and enhanced molar extinction coefficient (ε = 1.9 ×104 M−1 cm−1 at 593 nm in solution) of O18 are attributed to the stabilization of the lowest unoccupied molecular orbital and the increased absorption cross section via rationally extending the π-conjugated system of 2,2′-bipyridyl (bpy) ligands. As a result, NiO solar cells sensitized with O18 show short-circuit currents up to 3.43 mA cm−2 and efficiencies up to 0.104% under simulated 1 Sun condition, which are the best among all cyclometalated-Ru(II)-sensitized p-type dyesensitized solar cells. Femtosecond transient absorption spectroscopy reveals decreased geminate recombination across the O18−NiO interface by 1 order of magnitude compared to our previous report.

Molecular orbital engineering of a panchromatic cyclometalated RuII dye for p-type dye sensitized solar cells

251st National Meeting (2016)

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