Boosting the Performance of WO3/n‐Si Heterostructures for Photoelectrochemical Water Splitting: from the Role of Si to Interface Engineering

TitleBoosting the Performance of WO3/n‐Si Heterostructures for Photoelectrochemical Water Splitting: from the Role of Si to Interface Engineering
Publication TypeJournal Article
Year of Publication2019
AuthorsY. Zhao, G. Brocks, J.W Genuit, R. Lavrijsen, M.A Verheijen, A. Bieberle
JournalAdvanced Energy Materials
Volume9
Issue26
Pagination1900940
Date Published07/2019
Abstract

Metal oxide/Si heterostructures make up an exciting design route to high‐performance electrodes for photoelectrochemical (PEC) water splitting. By monochromatic light sources, contributions of the individual layers in WO3/n‐Si heterostructures are untangled. It shows that band bending near the WO3/n‐Si interface is instrumental in charge separation and transport, and in generating a photovoltage that drives the PEC process. A thin metal layer inserted at the WO3/n‐Si interface helps in establishing the relation among the band bending depth, the photovoltage, and the PEC activity. This discovery breaks with the dominant Z‐scheme design idea, which focuses on increasing the conductivity of an interface layer to facilitate charge transport, but ignores the potential profile around the interface. Based on the analysis, a high‐work‐function metal is predicted to provide the best interface layer in WO3/n‐Si heterojunctions. Indeed, the fabricated WO3/Pt/n‐Si photoelectrodes exhibit a 2 times higher photocurrent density at 1.23 V versus reversible hydrogen electrode (RHE) and a 10 times enhancement at 1.6 V versus RHE compared to WO3/n‐Si. Here, it is essential that the native SiO2 layer at the interface between Si and the metal is kept in order to prevent Fermi level pinning in the Schottky contact between the Si and the metal.

DOI10.1002/aenm.201900940
Division

MaSF

Department

EMI

PID

76e19c2d21db601884bc97f37dd5c914

Alternate TitleAdv. Energy Mater.

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