Fast Regeneration of CdSe Quantum Dots by Ru Dye in Sensitized TiO2 Electrodes

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• 作者：Ivn Mora-Ser ; Vlassis Likodimos ; Sixto Gimnez ; Eugenia Martnez-Ferrero ; Josep Albero ; Emilio Palomares ; Athanassios G. Kontos ; Polycarpos Falaras ; Juan Bisquert
• 刊名：Journal of Physical Chemistry C
• 出版年：2010
• 出版时间：April 15, 2010
• 年：2010
• 卷：114
• 期：14
• 页码：6755-6761
• 全文大小：332K
• 年卷期：v.114,no.14(April 15, 2010)
• ISSN：1932-7455

文摘

Interacting properties of colloidal CdSe quantum dots (QDs) and polypyridyl ruthenium dyes employed as cosensitizers of mesoporous TiO₂ electrodes as well as the effect of QDs coating and anchoring mode (direct and linker adsorption) have been investigated by photoluminesce (PL), Raman, and transient absorption (TAS) spectroscopies. Direct adsorption of QDs on TiO₂ leads to a more efficient PL quenching compared to that of QDs attached by means of a molecular linker (cysteine). This fact suggests higher electron injection for the former anchoring mode. Coating of ZnS on CdSe QDs sensitized TiO₂ electrodes passivates the QDs surface states and partially releases quantum confinement effects, as is observed in colloidal core−shell nanoparticles. Subsequent cosensitization with a ruthenium molecular dye dramatically quenches the PL of the QDs/TiO₂ electrodes, even in the presence of ZnS coating, indicating the presence of strong photoinduced charge transfer between the CdSe QDs and the dye molecules. This is firmly supported by TAS spectroscopy on the interfacial recombination kinetics that points to the fast hole transfer from the photoexcited QDs to the dye. The regenerating action of molecular dyes for QD sensitizers can have important implications in the development of efficient photovoltaic devices based on the synergistic action of dye-QD-TiO₂ heterostructures.