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Stable and tunable phosphonic acid dipole layer for band edge engineering of photoelectrochemical and photovoltaic heterojunction devices


Wick-Joliat, René; Musso, Tiziana; Prabhakar, Rajiv Ramanujam; Löckinger, Johannes; Siol, Sebastian; Cui, Wei; Sévery, Laurent; Moehl, Thomas; Suh, Jihye; Hutter, Jürg; Iannuzzi, Marcella; Tilley, S David (2019). Stable and tunable phosphonic acid dipole layer for band edge engineering of photoelectrochemical and photovoltaic heterojunction devices. Energy & Environmental Science, 12(6):1901-1909.

Abstract

A key challenge for photoelectrochemical water splitting is that high performance semiconductors are not stable in aqueous electrolytes, necessitating corrosion protection layers such as TiO2. In the best case, the protection layer would also serve as the heterojunction partner, minimizing complexity and thereby cost. However, the bands of most high performance semiconductors are poorly aligned with TiO2, limiting the photovoltage. Here, we describe a method to overcome this limitation through the placement of a tunable dipole layer at the interface of the p- and n-type materials, shifting the relative band positions to enable an increased photovoltage. The introduction of a phosphonic acid (PA, H3PO3) layer increases the photovoltage of TiO2-protected Si, Sb2Se3, and Cu2O photocathodes. The dipole effect scales with PA surface coverage, and gives even larger shifts when multilayers are employed. By varying the thickness from submonolayer to multilayer (up to 2 nm), we are able to tune the photovoltage of p-Si/TiO2 over a range of 400 mV.

Abstract

A key challenge for photoelectrochemical water splitting is that high performance semiconductors are not stable in aqueous electrolytes, necessitating corrosion protection layers such as TiO2. In the best case, the protection layer would also serve as the heterojunction partner, minimizing complexity and thereby cost. However, the bands of most high performance semiconductors are poorly aligned with TiO2, limiting the photovoltage. Here, we describe a method to overcome this limitation through the placement of a tunable dipole layer at the interface of the p- and n-type materials, shifting the relative band positions to enable an increased photovoltage. The introduction of a phosphonic acid (PA, H3PO3) layer increases the photovoltage of TiO2-protected Si, Sb2Se3, and Cu2O photocathodes. The dipole effect scales with PA surface coverage, and gives even larger shifts when multilayers are employed. By varying the thickness from submonolayer to multilayer (up to 2 nm), we are able to tune the photovoltage of p-Si/TiO2 over a range of 400 mV.

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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 > Environmental Chemistry
Physical Sciences > Renewable Energy, Sustainability and the Environment
Physical Sciences > Nuclear Energy and Engineering
Physical Sciences > Pollution
Uncontrolled Keywords:Renewable Energy, Sustainability and the Environment, Nuclear Energy and Engineering, Pollution, Environmental Chemistry
Language:English
Date:1 January 2019
Deposited On:07 Feb 2020 15:58
Last Modified:29 Jul 2020 14:08
Publisher:Royal Society of Chemistry
ISSN:1754-5706
OA Status:Hybrid
Publisher DOI:https://doi.org/10.1039/c9ee00748b
Project Information:
  • : FunderSNSF
  • : Grant IDPYAPP2_160586
  • : Project TitleSolar Water Splitting: Photovoltage, Surface Dipole, and Catalysis Strategies
  • : FunderCOST Action MP1407 (e-MINDS)
  • : Grant IDIZCNZ0-174856 C16.0075
  • : Project Title

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