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Investigation of (Leaky) ALD TiO2 Protection Layers for Water-Splitting Photoelectrodes


Moehl, Thomas; Suh, Jihye; Sévery, Laurent; Wick-Joliat, René; Tilley, S David (2017). Investigation of (Leaky) ALD TiO2 Protection Layers for Water-Splitting Photoelectrodes. ACS applied materials & interfaces, 9(50):43614-43622.

Abstract

Protective overlayers for light absorbers in photoelectrochemical water-splitting devices have gained considerable attention in recent years. They stabilize light absorbers which would normally be prone to chemical side reactions leading to degradation of the absorber. Atomic layer deposition (ALD) enables conformal and reproducible ultrathin protective layer growth even on highly structured substrates. One of the most widely investigated protective layers is amorphous TiO2, deposited by ALD at a relatively low temperature (120–150 °C). We have deposited protective layers from tetrakis(dimethylamido)titanium(IV) at two different temperatures and investigated their chemical composition as well as optical and electrochemical properties. Our main findings reveal a change in the flat band potential with thickness, reaching a stable value of about −50 to −100 mV versus reversible hydrogen electrode for films >30 nm, with doping densities of ∼1020 cm3. Practical thicknesses to achieve pinhole-free films are evaluated and discussed.

Abstract

Protective overlayers for light absorbers in photoelectrochemical water-splitting devices have gained considerable attention in recent years. They stabilize light absorbers which would normally be prone to chemical side reactions leading to degradation of the absorber. Atomic layer deposition (ALD) enables conformal and reproducible ultrathin protective layer growth even on highly structured substrates. One of the most widely investigated protective layers is amorphous TiO2, deposited by ALD at a relatively low temperature (120–150 °C). We have deposited protective layers from tetrakis(dimethylamido)titanium(IV) at two different temperatures and investigated their chemical composition as well as optical and electrochemical properties. Our main findings reveal a change in the flat band potential with thickness, reaching a stable value of about −50 to −100 mV versus reversible hydrogen electrode for films >30 nm, with doping densities of ∼1020 cm3. Practical thicknesses to achieve pinhole-free films are evaluated and discussed.

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Additional indexing

Item Type:Journal Article, refereed, original work
Communities & Collections:07 Faculty of Science > Department of Chemistry
08 University Research Priority Programs > Solar Light to Chemical Energy Conversion
Dewey Decimal Classification:540 Chemistry
Language:English
Date:2017
Deposited On:08 Feb 2018 11:19
Last Modified:19 Feb 2018 10:53
Publisher:American Chemical Society (ACS)
ISSN:1944-8244
OA Status:Closed
Publisher DOI:https://doi.org/10.1021/acsami.7b12564

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