High Molar Extinction Coefficient Heteroleptic Ruthenium Complexes for Thin Film Dye-Sensitized Solar Cells

来自 ACS

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摘要：

Two novel heteroleptic sensitizers,Ru((4,4-dicarboxylic acid-2,2'-bipyridine)(4,4'-bis(p-hexyloxy-styryl)-2,2-bipyridine)(NCS)_2 and Ru((4,4-dicarboxylic acid-2,2'-bipyridine)(4,4'-bis(p-methoxystyryl)-2,2'-bipyridine) (NCS)_2,coded as K-19 and K-73,respectively,have been synthesized and characterized by ~1H NMR,FTIR,UV-vis absorption,and emission spectroscopy and excited-state lifetime and spectroelec-trochemical measurements.The introduction of the alkoxystyryl group extends the conjugation of the bipyridine donor ligand increasing markedly their molar extinction coefficient and solar light harvesting capacity.The dynamics of photoinduced charge separation following electronic excitation of the K-19 dye was scrutinized by time-resolved laser spectroscopy.The electron transfer from K-19 to the conduction band of TiO_2 is completed within 20 fs while charge recombination has a half-life time of 800 mus.The high extinction coefficients of these sensitizers enable realization of a new generation of a thin film dye sensitized solar cell (DSC) yielding high conversion efficiency at full sunlight even with viscous electrolytes based on ionic liquids or nonvolatile solvents.An unprecedented yield of over 9% was obtained under standard reporting conditions (simulated global air mass 1.5 sunlight at 1000 W/m~2 intensity) when the K-73 sensitizer was combined with a nonvolatile "robust" electrolyte.The K-19 dye gave a conversion yield of 7.1% when used in conjunction with the binary ionic liquid electrolyte.These devices exhibit excellent stability under light soaking at 60 deg C.The effect of the mesoscopic TiO_2 film thickness on photovoltaic performance has been analyzed by electrochemical impedance spectroscopy (EIS).

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关键词：

Tio2 Films High-Efficiency Recombination Conversion Impedance Electrolyte Performance Electricity Sunlight Design