Active-Transition-Metal Tellurides: Through Crystal Structures to Physical Properties

Materials showing thermoelectric properties known as thermoelectrics can reversibly convert a temperature gradient into electricity. Since the vast majority of energy we use comes from thermal processes or creates thermal energy as waste energy, the search for materials able to efficiently convert thermal energy is of extreme importance. The discovery of a new, highly efficient thermoelectric material is complicated due to the special requirements imposed on the combination of electrical and thermal transport properties. Metal chalcogenides (MCs) have attracted significant attention as high performance thermoelectric materials. Their subgroup, active-transition-metal chalcogenides, shows structural and compositional diversity, including a wide occurrence of low-dimensional structural motifs, which opens up a fruitful area for explorations. This area has been preliminarily explored from both structural and functional viewpoints revealing very promising directions and unique compounds. Nevertheless, systematic investigations on transport properties are still missing. Available data suggests the presence of low bandgap semiconductors satisfying at least one of the conditions for a good thermoelectric, whereas the potential for structural and electronic variation in the form of active metal doping and substitution leaves a decent chance to uncover a candidate with acceptably low thermal conductivity and subsequently high thermoelectric performance.