Exciton-like trap states limit electron mobility in TiO2 nanotubes

Christiaan Richter; Charles A. Schmuttenmaer

doi:10.1038/nnano.2010.196

Exciton-like trap states limit electron mobility in TiO₂ nanotubes

Christiaan Richter
, Charles A. Schmuttenmaer

Faculty of Industrial Engineering, Mechanical Engineering and Computer Science

University of Iceland

Research output: Contribution to journal › Article › peer-review

Abstract

Nanoparticle films have become a promising low-cost, high-surface-area electrode material for solar cells and solar fuel production. Compared to sintered nanoparticle films, oriented polycrystalline titania nanotubes offer the advantage of directed electron transport, and are expected to have higher electron mobility. However, macroscopic measurements have revealed their electron mobility to be as low as that of nanoparticle films. Here, we show, through time-resolved terahertz spectroscopy, that low mobility in polycrystalline TiO₂ nanotubes is not due to scattering from grain boundaries or disorder-induced localization as in other nanomaterials, but instead results from a single sharp resonance arising from exciton-like trap states. If the number of these states can be lowered, this could lead to improved electron transport in titania nanotubes and significantly better solar cell performance.

Original language	English
Pages (from-to)	769-772
Number of pages	4
Journal	Nature Nanotechnology
Volume	5
Issue number	11
DOIs	https://doi.org/10.1038/nnano.2010.196
Publication status	Published - Nov 2010

Bibliographical note

Funding Information: The authors acknowledge support from the Chemical Sciences, Geosciences and Biosciences Division, Office of Basic Energy Sciences, Office of Science, US Department of Energy (DE-FG02-07ER15909) for partial support of this work.

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10.1038/nnano.2010.196

Cite this

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title = "Exciton-like trap states limit electron mobility in TiO2 nanotubes",

abstract = "Nanoparticle films have become a promising low-cost, high-surface-area electrode material for solar cells and solar fuel production. Compared to sintered nanoparticle films, oriented polycrystalline titania nanotubes offer the advantage of directed electron transport, and are expected to have higher electron mobility. However, macroscopic measurements have revealed their electron mobility to be as low as that of nanoparticle films. Here, we show, through time-resolved terahertz spectroscopy, that low mobility in polycrystalline TiO2 nanotubes is not due to scattering from grain boundaries or disorder-induced localization as in other nanomaterials, but instead results from a single sharp resonance arising from exciton-like trap states. If the number of these states can be lowered, this could lead to improved electron transport in titania nanotubes and significantly better solar cell performance.",

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AB - Nanoparticle films have become a promising low-cost, high-surface-area electrode material for solar cells and solar fuel production. Compared to sintered nanoparticle films, oriented polycrystalline titania nanotubes offer the advantage of directed electron transport, and are expected to have higher electron mobility. However, macroscopic measurements have revealed their electron mobility to be as low as that of nanoparticle films. Here, we show, through time-resolved terahertz spectroscopy, that low mobility in polycrystalline TiO2 nanotubes is not due to scattering from grain boundaries or disorder-induced localization as in other nanomaterials, but instead results from a single sharp resonance arising from exciton-like trap states. If the number of these states can be lowered, this could lead to improved electron transport in titania nanotubes and significantly better solar cell performance.

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