Search Menu
Photonics Media Photonics Buyers' Guide Photonics EDU Photonics Spectra BioPhotonics EuroPhotonics Industrial Photonics Photonics Showcase Photonics ProdSpec Photonics Handbook
More News
Email Facebook Twitter Google+ LinkedIn Comments

Thermophotovoltaics: A hot topic in the UK

Photonics Spectra
Aug 2009
Both efficiency and bandgap engineering provide electricity via heat waste recovery.

Jörg Schwartz, European Correspondent,

Two British consortia have received funding from the country’s Technology Strategy Board for the development of thermophotovoltaic (TPV) technology. One project, now finished, set a record for energy conversion efficiency; the other, focusing on a different material platform, has just begun.

Thermophotovoltaic systems consist of solar cells that bring their own sun – where the “sun,” or emitter, usually is radiating in the infrared spectral range, and the actual cells converting the photons into electrons are different from standard solar cells, which are tailored for high efficiency in the visible.

In their classical configuration, TPV systems comprise an emitter – such as a burner – a semiconductor-based converter cell, and filters and reflectors to direct and select the radiation to be converted. This makes them quiet and self-contained – yet nonrenewable – electricity sources with few or no moving parts. Consequently, applications such as remote site and portable electricity generation have been among the most obvious targets for TPVs, not only for off-grid power generators but also to feed battlefield electronics.

Recently, however, their potential use for the recovery of waste heat from industrial plants such as blast furnaces has come into play. Here the emitter and its temperature radiation profile are a given and can no longer be tailored to match the converter cell; thus, engineering the cell’s bandgap is even more important, so that the absorption properties of the cell match the emitter’s IR radiation spectrum.

Cells converting infrared radiation into electricity are key parts of thermophotovoltaic systems. This cell was made using InP, which is well-known because of its widespread use in photonic applications such as integrated optics.

“TPV technology has a lot of potential but is still in its early stages, and one of the main areas for improvement is the conversion efficiency,” said Dr. David Rogers, TPV project manager at the Centre for Integrated Photonics (CIP) Ltd. In his project, which was funded by the Engineering and Physical Sciences Research Council, CIP and its partners, Oxford University and Wafer Technology Ltd., demonstrated a record conversion efficiency of up to 12 per cent from devices with a single p-n junction, based on indium phosphide (InP) materials. This compares with 9 per cent from existing commercially available cells.

Fabrication and growth of InP, including compound InGaAs crystals, is a known technology, making for efficient production and the opportunity to apply some tricks to optimize the bandgap.

In the second consortium, research continues in another more traditional material platform, gallium antimonide (GaSb), which has a bandgap of 0.72 eV – similar to InGaAs – and which has been widely used in TPV research and engineering. This project aims to use alloys such as InAsSb or InGaSbN and to lattice-match them to GaSb substrates, further reducing the bandgap and improving the absorption characteristics at long wavelengths.

“In contrast to InP, the materials are less well understood,” said Dr. Mark Furlong, director of Wafer Technology. “But if this is changed, the benefit can be substantial.” The expectation is that the new cells will more effectively generate electricity from waste heat sources, such as glass melting furnaces, for which temperatures below 1000 °C are particularly relevant.

Partners in the second project include defence company QinetiQ Ltd., Lancaster University and, again, Wafer Technology, which, obviously, has more than one iron in the fire.

defenseenergyEuroPhotonicsEuroPhotonics News & FeaturesFiltersindustrialopticssolar cellsThermophotovoltaic systemsTPV systemsWafers

Terms & Conditions Privacy Policy About Us Contact Us
back to top
Facebook Twitter Instagram LinkedIn YouTube RSS
©2018 Photonics Media, 100 West St., Pittsfield, MA, 01201 USA,

Photonics Media, Laurin Publishing
x Subscribe to Photonics Spectra magazine - FREE!
We use cookies to improve user experience and analyze our website traffic as stated in our Privacy Policy. By using this website, you agree to the use of cookies unless you have disabled them.