skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: 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 Laboratory (PNNL), Richland, WA (US), Environmental Molecular Sciences Laboratory (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:
Journal Article: 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. 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, and Chambers, Scott A. Mon . "Visible light carrier generation in co-doped epitaxial titanate films". United States. doi: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}
}

Journal Article:
Free Publicly Available Full Text
Publisher's Version of Record

Citation Metrics:
Cited by: 6 works
Citation information provided by
Web of Science

Save / Share:

Works referenced in this record:

Enhanced Photoelectrochemical Activity in All-Oxide Heterojunction Devices Based on Correlated “Metallic” Oxides
journal, September 2013

  • Apgar, Brent A.; Lee, Sungki; Schroeder, Lauren E.
  • Advanced Materials, Vol. 25, Issue 43, p. 6201-6206
  • DOI: 10.1002/adma.201303144

Epitaxial SrTiO3 films with electron mobilities exceeding 30,000 cm2 V-1 s-1
journal, April 2010

  • Son, Junwoo; Moetakef, Pouya; Jalan, Bharat
  • Nature Materials, Vol. 9, Issue 6, p. 482-484
  • DOI: 10.1038/nmat2750

Perovskite oxides for visible-light-absorbing ferroelectric and photovoltaic materials
journal, November 2013

  • Grinberg, Ilya; West, D. Vincent; Torres, Maria
  • Nature, Vol. 503, Issue 7477, p. 509-512
  • DOI: 10.1038/nature12622

Enhancement of Ferroelectricity in Strained BaTiO3 Thin Films
journal, November 2004