Strongly Coupled Ruthenium−Polypyridyl Complexes for Efficient Electron Injection in Dye-Sensitized Semiconductor Nanoparticles

• DOI: 10.1021/jp051285a
• Publication Date: 2005-08-11T06:54:36Z
• Authors: G. Ramakrishna; D. Amilan Jose; D. Krishna Kumar; Amitava Das; Dipak K. Palit; Hirendra N. Ghosh
• Keywords: 02 engineering and technology; 0210 nano-technology; 7. Clean energy

Dynamics of interfacial electron transfer (ET) in the ruthenium−polypyridyl complex [{bis(2,2'-bpy)-(4-[2-(4'-methyl-2,2'-bipyridinyl-4-yl)vinyl]benzene-1,2-diol)} ruthenium(II) hexafluorophosphate] (Ru-cat)-sensitized TiO2 nanoparticles has been investigated using femtosecond transient absorption spectroscopy detecting visible and near-infrared region. It observed that Ru-cat is coupled strongly with through its pendant catechol moiety. Electron injection confirmed by direct detection electrons conduction band, cation radical adsorbed dye, a bleach dye real time as monitored spectroscopy. A single-exponential pulse width limited (<100 fs) observed, origin it might have from nonthermalized excited states molecule. The result gave strong indication competes thermalization photoexcited due to large coupling elements for forward ET reaction. Back-ET dynamics determined monitoring decay kinetics injected also recovery dye. fit multiexponential function, where ∼30% are recombined constant <2 ps, again indicating charge recombination However, our results shown relatively long-lived separation Ru-cat/TiO2 system compared other organic dye-sensitized similar interactions.