ORACLE

The Challenges in thermoelectric (TE) materials concern mainly the replacement of expensive and toxic bismuth telluride-based TE devices with cheaper, environmentally benign and more efficient materials. Applications at ambient temperature, such as building-integrated renewable energy systems, have not yet reached commercialisation, mainly due to their high cost/power ratio.

The Goal of the proposed project is to discover novel inorganic and organic-inorganic clathrate compounds with high efficiency as TE materials. The exploratory synthesis will include high-temperature fusion, reactive precursors, ball milling and organic-salt flux techniques. The materials will be characterised via crystallographic and spectroscopic techniques and their structure-property relations will be extensively studied. The optimum chemical composition and nanostructure morphology of the n- and p-type clathrates will be determined along with the electrical and mechanical characteristics of the corresponding TE modules. The best performing modules will be subsequently used for applications of energy recovery from wasted heat.

The Innovation of the project is that: a) organic anions and cations will be incorporated for the first time into clathrate frameworks made of silicon, germanium and tin atoms to produce less toxic and more efficient materials for TE applications than the current state of the art, b) first-principle calculations, combined with machine-learning techniques and Hirshfeld surface analysis on the structural models will study the host-guest interactions and predict the physical properties of the compounds.

The Impact is to offer a new, broad class of semiconducting clathrates that can be used in TE devices with a cost/power ratio below €0.5/Watt and high potential for industrial exploitation. In addition, the exploration of these organic-inorganic compounds will expand the existing databases of traditional inclusion compounds, such as zeolites and metal-organic frameworks.