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Issue 26, 2010
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Trap states and carrier dynamics of TiO2 studied by photoluminescence spectroscopy under weak excitation condition

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Abstract

Anatase and rutile TiO2 were investigated with photoluminescence techniques under the weak excitation condition, where trap states play a vital role in carrier dynamics. The visible emission of anatase and near-infrared (NIR) emission of rutile both exhibit extremely long lifetimes up to milliseconds. The decay processes can be well described by the power-law decay which corresponds to the trapping–detrapping effect. These results indicate that the luminescence processes in both anatase and rutile TiO2 have a close relationship with trap states. The visible emission band was assigned to the donor–acceptor recombination. Oxygen vacancies and hydroxyl groups mainly serve as the donor and acceptor sites, respectively. The NIR luminescence is originated from the recombination of trapped electrons with free holes, while the trapped electrons were formed through two paths, direct trapping or trap-to-trap hopping. The trap states in anatase and rutile TiO2 may largely influence the photocatalysis process of TiO2 and determine the photocatalytic activity under stationary illumination.

Graphical abstract: Trap states and carrier dynamics of TiO2 studied by photoluminescence spectroscopy under weak excitation condition

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Publication details

The article was received on 01 Dec 2009, accepted on 18 Mar 2010 and first published on 13 May 2010


Article type: Paper
DOI: 10.1039/B925277K
Citation: Phys. Chem. Chem. Phys., 2010,12, 7083-7090
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    Trap states and carrier dynamics of TiO2 studied by photoluminescence spectroscopy under weak excitation condition

    X. Wang, Z. Feng, J. Shi, G. Jia, S. Shen, J. Zhou and C. Li, Phys. Chem. Chem. Phys., 2010, 12, 7083
    DOI: 10.1039/B925277K

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