Dye Dependent Regeneration Dynamics in Dye Sensitized Nanocrystalline Solar Cells: Evidence for the Formation of a Ruthenium Bipyridyl Cation/Iodide Intermediate

作者：John Noel Clifford, Emilio Jose Palomares, Mohammad Khaja Nazeeruddin, Michaël Grätzel, James Robert Durrant · 发表于：The Journal of Physical Chemistry C · 年份：2007 · DOI：10.1021/jp067458t · 被引用次数：273 · 研究领域：TiO2 Photocatalysis and Solar Cells、Advanced Photocatalysis Techniques、Electrochemical Analysis and Applications

We report a transient absorption study of the kinetics of re-reduction of ruthenium bipyridyl dye cations adsorbed to nanocrystalline TiO 2 films by iodide ions, employing a series of Ru II (dcbpy) 2 X dyes, where dcpby = 4,4‘-dicarboxy-2,2‘-bipyridyl and X = (NCS) 2, (CN) 2, DTC (diethyldithiocarbamate), and Cl 2 . The data indicate that this re-reduction (or ‘regeneration') reaction proceeds via a transient (dye + −iodide) intermediate complex formed by reaction of photogenerated dye cations with one iodide ion. The subsequent reaction of this complex with a second iodide ion, forming I 2 -, is shown to be the kinetically and thermodynamically limiting step in the overall regeneration reaction. The implications of this reaction scheme for the function of dye sensitized photoelectrochemical cells are discussed, considering in particular the high photovoltaic efficiencies obtained for such devices employing such ruthenium bipyridyl senstiser dyes in combination with iodide/tri-iodide based redox electrolytes.