Visible light carrier generation in co-doped epitaxial titanate films
Abstract
Perovskite titanates such as SrTiO3 (STO) exhibit a wide range of important functional properties, including high electron mobility, ferroelectricity—which may be valuable in photovoltaic applications—and excellent photocatalytic performance. The wide optical band gap of titanates limits their use in these applications, however, making them ill-suited for integration into solar energy harvesting technologies. Our recent work has shown that by doping STO with equal concentrations of La and Cr we can enhance visible light absorption in epitaxial thin films while avoiding any compensating defects. In this work, we explore the optical properties of photoexcited carriers in these films. Using spectroscopic ellipsometry, we show that the Cr3+ dopants, which produce electronic states immediately above the top of the O 2p valence band in STO reduce the direct band gap of the material from 3.75 eV to between 2.4 and 2.7 eV depending on doping levels. Transient reflectance measurements confirm that optically generated carriers have a recombination lifetime comparable to that of STO and are in agreement with the observations from ellipsometry. Finally, through photoelectrochemical yield measurements, we show that these co-doped films exhibit enhanced visible light photocatalysis when compared to pure STO.
- Authors:
- Publication Date:
- Research Org.:
- Pacific Northwest National Lab. (PNNL), Richland, WA (United States). Environmental Molecular Sciences Lab. (EMSL)
- Sponsoring Org.:
- USDOE
- OSTI Identifier:
- 1184281
- Alternate Identifier(s):
- OSTI ID: 1226716
- Report Number(s):
- PNNL-SA-107663
48341
- Grant/Contract Number:
- AC05-76RL01830; BES DMSE 10122
- Resource Type:
- Accepted Manuscript
- Journal Name:
- Applied Physics Letters, 109(9):Article No. 092901
- Additional Journal Information:
- Journal Name: Applied Physics Letters, 109(9):Article No. 092901
- Country of Publication:
- United States
- Language:
- English
- Subject:
- Environmental Molecular Sciences Laboratory
Citation Formats
Comes, Ryan B., Smolin, Sergey Y., Kaspar, Tiffany C., Gao, Ran, Apgar, Brent A., Martin, Lane W., Bowden, Mark E., Baxter, Jason, and Chambers, Scott A. Visible light carrier generation in co-doped epitaxial titanate films. United States: N. p., 2015.
Web. doi:10.1063/1.4913930.
Comes, Ryan B., Smolin, Sergey Y., Kaspar, Tiffany C., Gao, Ran, Apgar, Brent A., Martin, Lane W., Bowden, Mark E., Baxter, Jason, & Chambers, Scott A. Visible light carrier generation in co-doped epitaxial titanate films. United States. https://doi.org/10.1063/1.4913930
Comes, Ryan B., Smolin, Sergey Y., Kaspar, Tiffany C., Gao, Ran, Apgar, Brent A., Martin, Lane W., Bowden, Mark E., Baxter, Jason, and Chambers, Scott A. Mon .
"Visible light carrier generation in co-doped epitaxial titanate films". United States. https://doi.org/10.1063/1.4913930. https://www.osti.gov/servlets/purl/1184281.
@article{osti_1184281,
title = {Visible light carrier generation in co-doped epitaxial titanate films},
author = {Comes, Ryan B. and Smolin, Sergey Y. and Kaspar, Tiffany C. and Gao, Ran and Apgar, Brent A. and Martin, Lane W. and Bowden, Mark E. and Baxter, Jason and Chambers, Scott A.},
abstractNote = {Perovskite titanates such as SrTiO3 (STO) exhibit a wide range of important functional properties, including high electron mobility, ferroelectricity—which may be valuable in photovoltaic applications—and excellent photocatalytic performance. The wide optical band gap of titanates limits their use in these applications, however, making them ill-suited for integration into solar energy harvesting technologies. Our recent work has shown that by doping STO with equal concentrations of La and Cr we can enhance visible light absorption in epitaxial thin films while avoiding any compensating defects. In this work, we explore the optical properties of photoexcited carriers in these films. Using spectroscopic ellipsometry, we show that the Cr3+ dopants, which produce electronic states immediately above the top of the O 2p valence band in STO reduce the direct band gap of the material from 3.75 eV to between 2.4 and 2.7 eV depending on doping levels. Transient reflectance measurements confirm that optically generated carriers have a recombination lifetime comparable to that of STO and are in agreement with the observations from ellipsometry. Finally, through photoelectrochemical yield measurements, we show that these co-doped films exhibit enhanced visible light photocatalysis when compared to pure STO.},
doi = {10.1063/1.4913930},
journal = {Applied Physics Letters, 109(9):Article No. 092901},
number = ,
volume = ,
place = {United States},
year = {Mon Mar 02 00:00:00 EST 2015},
month = {Mon Mar 02 00:00:00 EST 2015}
}
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Works referencing / citing this record:
Tuning the optical and thermoelectric properties of SrTi 0.8−x Sn 0.2 Fe x O 3
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