Producing low-cost metal-oxide thin films with high electronic quality for solar water splitting is not easy. Quality improvements of the upper metal oxide thin films need thermal processing at high temperatures to melt the underlying glass. A team at the HZB-Institute for Solar Fuels has found a way to heat the metal-oxide thin film without damaging it.
Solar energy can drive reactions at the surface of photoelectrodes. Semiconducting thin films on transparent glass are used to convert light into electricity. Water splitting, a thermodynamically uphill reaction that could offer an attractive pathway for the long-term capture and storage of solar energy, is the focus of most photoelectrochemical studies.
Metal-oxide thin film photoelectrodes are interesting for their diverse functions. They comprise abundant elements that could offer infinite tunability at low costs.
It was made from plasma.
Several teams are working at the HZB Institute for Solar Fuels. The usual way to make them is by using a laser to hit a target with a laser pulse and then depositing the material into a highly energetic plasma.
Quality needs heat.
The quality of the thin film needs to be improved. The metal-oxide thin-film is thermal processed. Reducing atomic defects concentration and improvements in the order of the metal-oxide thin films would require thermal processing temperatures between 850 and 1000 degrees Celsius, but the glass would melt already.
The thin film is hot.
Dr. Ronen Gottesman from the HZB Institute for Solar Fuels used high-powered lamps to flash-heat the metal-oxide thin film. It can be reached up to 850 degrees Celsius without melting the glass.
The heat efficiently reduces structural defects, trap states, grain boundaries, and phase impurities, which would become more challenging to mitigate with an increasing number of elements in the metal-oxides. New innovative synthesis approaches are needed. We have demonstrated this on photoelectrodes made of Ta 2 O 5, TiO 2, andWO 3, which we heated to 850 C without damaging the substrates.
It was a record performance for snWO 4.
The new method was successful with a material that is considered a good candidate for solar water splitting. Phase impurities are left behind by conventional furnace heating. A new record performance of 1mA/ cm 2 was set for this material, which was 25% higher than the previous record.
This is also interesting for the production of quantum dots, which are also temperature-sensitive.
The research was published in a journal.
More information: Ronen Gottesman et al, Shining a Hot Light on Emerging Photoabsorber Materials: The Power of Rapid Radiative Heating in Developing Oxide Thin-Film Photoelectrodes, ACS Energy Letters (2022). DOI: 10.1021/acsenergylett.1c02220 Citation: Solar hydrogen: Better photoelectrodes through flash heating (2022, April 4) retrieved 4 April 2022 from https://phys.org/news/2022-04-solar-hydrogen-photoelectrodes.html This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only.
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