New thermophotovoltaic technology
A simple and economical method for the fabrication of cells, created by the Belgian company IMEC, will improve this technology, which converts radiation from non-solar heat sources into electricity
Imec, a Belgian company that specializes in research in the field of nanotechnology, announced an innovative way to reduce production costs of germanium-based thermophotovoltaic cells.
Although termophotovoltaic (TPV) technology was created at the MIT in Boston already in the 60s, it has moved forward only in the last few years, following innovations introduced for conventional photovoltaics.
Essentially, TPV cells work like ordinary solar cells, except that they convert radiation from heat sources with temperatures much lower than the Sun’s temperature. For example an incandescent high temperature corpus, like the hot-red wall of a domestic heating system, molten metal, specially designed burners and so on.
They are therefore ideally suited in an industrial context, for example to generate electricity from waste heat released during glass or steel production or in homes, added to domestic heating systems, to reduce heat loss and therefore increase the efficiency of these devices.
They also have better quantum efficiency, up to 100 times higher than radiation-based photovoltaic cells.
On the other hand they still have low electrical efficiency, higher costs and require further research in order to engineer the system.
They can be made of various materials, also combined: silicon, germanium, gallium compounds, antimony, indium and arsenic.
Thermophotovoltaic cells are fabricated by Imec on substrates of germanium, seen as an element with great potential for this type of system.
What is new about these cells is the processing method. Up to now cells were fabricated on epi-ready germanium substrates, a highly complex technique that formed the emitter by means of atomic stratification on a specific substrate that determined its structure. Under the new method, germanium substrates are formed by diffusion on a substrate of amorphous silicon: an apparently simple innovation which could nevertheless prove essential for the development of the TPV market. In fact, the reason why this technology has not been commercialized is that it involved high costs, due to the complexity of the systems.
(June 2010)
