Converting heat into electrical energy: a giant leap for oxides

Interface_SGAn Italian-Swiss study just published in ‘Nature Communications’ reveals how some artificial materials composed of different oxides are able to convert heat into electricity with unprecedented efficiency. This work uncovered by researchers from the Universities of Genoa and Geneva, in collaboration with the Italian National Centre for Research (Cnr) opens the door to the use of large-scale thermoelectricity.

This international study reveals that some artificial oxides can display a thermoelectric efficiency never observed before. Although the thermoelectric effect, i.e. the ability to convert heat into electrical energy, can be observed in virtually all materials, its efficiency is relatively low and today only 10% of the energy lost in heat can be recovered. The study shows that in developing the properties of materials at the nanoscale, record values of thermoelectricity at low temperature can be obtained.

Until today the scarcity of materials with high energy conversion efficiency has limited their use in specific sectors (such as space probes or some small fridges used in wine cellars). In the future, the fact of having a new class of high-performance and economical materials could significantly expand their use to industry, for example by improving the performances of computer processors or car engines.

This research reveals the great potential of oxides, because besides sustaining very high temperatures and being non-toxic, they can have a high coefficient of energy conversion. “The measurements at low temperature on the interface between two insulating oxides LaAlO3 and SrTiO3 unveil giant thermoelectricity values,” says Jean-Marc Triscone, Professor at the Department of Quantum Matter Physics, University of Geneva, whose group is known for its work on the interface between these oxides. Denver Li, Stefano Gariglio and Alexandre Fête were heavily involved in this research.

This study coordinated by Daniele Marré (University of Genoa Cnr) has had a major impact on the understanding of the physical properties of these materials. Surprisingly, the researchers could observe the presence of trapped electrons, these electronic states having long been sought after in these artificial systems by other techniques without success. These innovative results found interpretation in the theoretical model developed by the team of Alessio Filippetti at Cnr, Cagliari.

The challenge in the future will be to optimize the properties of these materials in order to produce artificial structures displaying high thermoelectric coefficients at room temperature or, possibly, at high temperature.

Cnr press release (in italian)

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