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13 October 2008


InP boosts thermo-photovoltaic efficiency record to 12%

A three-year collaborative research project, funded partially by the UK's Technology Strategy Board and the Engineering and Physical Sciences Research Council (EPSRC), has delivered first-generation thermo-photovoltaic (TPV) cells with energy conversion efficiencies of up to 12% (compared to 9% for existing, commercially available devices).

The consortium partners in the project are CIP Technologies (CIP) of Martlesham Heath, Ipswich (which manufactures photonic hybrid integrated circuits and indium phosphide-based optoelectronic chips, devices, arrays and modules for the communications and defence markets), III-V substrate maker Wafer Technology Ltd of Milton Keynes (a member of the IQE plc group of companies), and the University of Oxford’s Physics Department. On the TPV project, CIP is responsible for epitaxial growth and the fabrication of both devices and fully packaged TPV modules, Wafer Technology has developed a new range of low-cost InP substrates, and Oxford performs cell design and device testing.

TPVs are similar to solar cells, but operate at infrared rather than visible wavelengths, generating electricity directly from heat. Applications include waste heat recovery from industrial plant such as blast furnaces, combined heat and power (CHP) generation and domestic boilers, as well as silent mobile power generation.

Rather than the more traditional gallium antimonide (GaSb), the new, record single-junction TPV cells are based on indium phosphide (InP), which offers higher efficiency, low-cost growth, and fabrication using industry-standard processes, combined with the potential to fabricate more highly integrated and complex cells.

“CIP’s expertise in InP growth and fabrication continues to demonstrate successful application to new markets and products, and builds on its III-V solar cell expertise to continue to address areas of environmental importance,” says TPV project manager Dr David Rogers.

The consortium is now working on a second-generation cell design with a more complex, multi-layer construction that should improve infrared capture further and boost efficiency beyond 15% (widening the range of viable applications for the technology).

“The advanced technology that has emerged from this project complements solar photovoltaic cells, and significant efficiency gains from the second-generation product are expected,” says CIP’s commercial & contracts manager, Andrew Bridges. “CIP is leading the commercial exploitation and volume manufacture of this technology and is actively seeking partners and end users to develop its full market potential,” he adds.

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