Real-time measurements of interfacial charge transfer rates at silicon/liquid junctions
- Creators
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Forbes, Malcolm D. E.
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Lewis, Nathan S.
Abstract
The rates of interfacial charge transfer from photogenerated carriers in semiconductor electrodes to solution donors and acceptors are fundamentally important in the area of semiconductor electrochemistry. However, to date there have been no real-time measurements of the charge-transfer rates between semiconductors and outer sphere redox couples. Previous steady-state current-voltage experiments have led to the suggestion that such rates might be extremely fast (>10¹¹ s⁻¹), because evidence has been obtained for interfacial charge transfer events competing with thermalization of the photoexcited carriers (i.e. "hot carrier injection processes"). Additionally, luminescence decay measurements on CdS surfaces in contact with strongly adsorbing, inner sphere redox reagents such as 1.0 M KOH/l.O M S²⁻ have indicated high surface recombination velocities (> 10⁵ cm/s) and have yielded photoexcited carrier lifetimes of less than 100 ps. In contrast, simple theoretical estimates of the interfacial charge transfer rate constants for outer sphere redox systems can be used to predict carrier lifetimes between 10⁻⁶ and 10⁻³ s under common experimental conditions. To address these issues, we report herein the first real-time kinetic rate measurements from carriers in a semiconductor to outer sphere redox donors and acceptors in the liquid phase.
Additional Information
© 1990 American Chemical Society. We thank B. J. Tufts for running the XPS experiments, P. G. Santangelo and A. Kumar for experimental assistance, and E. Yablonovitch, T. Gmitter, M. Kunst, J. Warman, and H. Tributsch for helpful discussions regarding the experimental setup. We are also grateful to R. Swanson and R. Sinton of Stanford University for providing the Si samples. M.D.E.F. is grateful for financial support from the National Science Foundation through its Postdoctoral Fellowship Program in Chemistry. This work was supported by Grant No. CHE-8814263 from the National Science Foundation.Additional details
- Eprint ID
- 120999
- Resolver ID
- CaltechAUTHORS:20230419-898249000.7
- NSF Postdoctoral Fellowship
- NSF
- CHE-8814263
- Created
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2023-04-25Created from EPrint's datestamp field
- Updated
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2023-04-25Created from EPrint's last_modified field
- Other Numbering System Name
- Caltech Division of Chemistry and Chemical Engineering
- Other Numbering System Identifier
- 8097