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Operando Analysis of Semiconductor Junctions in Multi‐Layered Photocathodes for Solar Water Splitting by Impedance Spectroscopy


Yang, Wooseok; Moehl, Thomas; Service, Erin; Tilley, David (2021). Operando Analysis of Semiconductor Junctions in Multi‐Layered Photocathodes for Solar Water Splitting by Impedance Spectroscopy. Advanced Energy Materials:Epub ahead of print.

Abstract

Although electrochemical impedance spectroscopy (EIS) is a powerful technique for investigating optoelectronic devices, realistic equivalent circuit (EC) models suitable for multi‐layered water splitting electrodes have rarely been reported due to their complex nature. In the present study, the utility of the EIS method for investigating multi‐layered photocathodes for photoelectrochemical water splitting is demonstrated. By analyzing the EIS data of TiO2‐coated Sb2Se3 photocathodes, one is able to obtain information about the constituent semiconductors and interfaces such as recombination processes, carrier lifetimes, doping densities, and flat band potentials under operando conditions. The charge transfer time to the electrolyte is also extracted from the EIS data and confirmed by transient photocurrent decay measurements. In addition, the method is successfully applied to other photocathodes with different classes of light absorber, such as metal oxides (Cu2O) and crystalline Si, to compare the device characteristics under real operational conditions. It is shown that the lifetime of photo‐generated carriers in the Si photocathode is much higher than those of the Sb2Se3 and Cu2O photocathodes. It is believed that the EIS analysis method presented in this study will become a powerful routine characterization technique for discovering the limiting factors in a wide range of photo‐electrosynthetic as well as photovoltaic devices.

Abstract

Although electrochemical impedance spectroscopy (EIS) is a powerful technique for investigating optoelectronic devices, realistic equivalent circuit (EC) models suitable for multi‐layered water splitting electrodes have rarely been reported due to their complex nature. In the present study, the utility of the EIS method for investigating multi‐layered photocathodes for photoelectrochemical water splitting is demonstrated. By analyzing the EIS data of TiO2‐coated Sb2Se3 photocathodes, one is able to obtain information about the constituent semiconductors and interfaces such as recombination processes, carrier lifetimes, doping densities, and flat band potentials under operando conditions. The charge transfer time to the electrolyte is also extracted from the EIS data and confirmed by transient photocurrent decay measurements. In addition, the method is successfully applied to other photocathodes with different classes of light absorber, such as metal oxides (Cu2O) and crystalline Si, to compare the device characteristics under real operational conditions. It is shown that the lifetime of photo‐generated carriers in the Si photocathode is much higher than those of the Sb2Se3 and Cu2O photocathodes. It is believed that the EIS analysis method presented in this study will become a powerful routine characterization technique for discovering the limiting factors in a wide range of photo‐electrosynthetic as well as photovoltaic devices.

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Additional indexing

Item Type:Journal Article, refereed, original work
Communities & Collections:07 Faculty of Science > Department of Chemistry
08 Research Priority Programs > Solar Light to Chemical Energy Conversion
Dewey Decimal Classification:540 Chemistry
Scopus Subject Areas:Physical Sciences > Renewable Energy, Sustainability and the Environment
Physical Sciences > General Materials Science
Uncontrolled Keywords:Renewable Energy, Sustainability and the Environment, General Materials Science
Language:English
Date:18 January 2021
Deposited On:03 Feb 2021 15:30
Last Modified:04 Feb 2021 21:01
Publisher:Wiley-VCH Verlag
ISSN:1614-6832
OA Status:Closed
Publisher DOI:https://doi.org/10.1002/aenm.202003569
Project Information:
  • : FunderSNSF
  • : Grant ID200020_184737
  • : Project TitlePhotoelectrochemical Synthesis of Hydrogen and Value-Added Chemicals for a Sustainable Chemical Industry

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