Charge separation, band-bending, and recombination in WO3 photoanodes
File(s)
Accepted version
Author(s)
Type
Journal Article
Abstract
In metal oxide-based photoelectrochemical devices, the spatial separation of photogenerated electrons and holes is typically attributed to band-bending at the oxide/electrolyte interface. However, direct evidence of such band-bending impacting upon charge carrier lifetimes has been very limited to date. Herein we use ultrafast spectroscopy to track the rapid relaxation of holes in the space-charge layer and their recombination with trapped electrons in WO3 photoanodes. We observe that applied bias can significantly increase carrier lifetimes on all time scales from picoseconds to seconds and attribute this to enhanced band-bending correlated with changes in oxygen vacancy state occupancy. We show that analogous enhancements in carrier lifetimes can be obtained by changes in electrolyte composition, even in the absence of applied bias, highlighting routes to improve photoconversion yields/performance, through changes in band-bending. This study thus demonstrates the direct connection between carrier lifetime enhancement, increased band-bending, and oxygen vacancy defect state occupancy.
Date Issued
2019-09-19
Date Acceptance
2019-08-16
Citation
Journal of Physical Chemistry Letters, 2019, 10 (18), pp.5395-5401
ISSN
1948-7185
Publisher
American Chemical Society
Start Page
5395
End Page
5401
Journal / Book Title
Journal of Physical Chemistry Letters
Volume
10
Issue
18
Copyright Statement
© 2019 American Chemical Society
Sponsor
The Royal Society
The Royal Society
Identifier
https://www.ncbi.nlm.nih.gov/pubmed/31416313
Grant Number
RSG\R1\180434
UF130178
Subjects
Science & Technology
Physical Sciences
Technology
Chemistry, Physical
Nanoscience & Nanotechnology
Materials Science, Multidisciplinary
Physics, Atomic, Molecular & Chemical
Chemistry
Science & Technology - Other Topics
Materials Science
Physics
WATER OXIDATION
TUNGSTEN-OXIDE
OXYGEN EVOLUTION
THIN-FILMS
MECHANISTIC ASPECTS
OPTICAL-PROPERTIES
DYNAMICS
ELECTRODES
KINETICS
HOLES
03 Chemical Sciences
02 Physical Sciences
Publication Status
Published
Coverage Spatial
United States
Date Publish Online
2019-08-16