The performance of thermoelectric materials is mainly governed by the materials’ electrical and thermal conductivity properties and a number of new materials and structures have been exploited in order to optimize the energy conversion efficiency. Especially, nanostructure engineering via dopants, precipitates or phase/twin/grain boundaries is found to be effective in increasing the conversion efficiency by reducing the thermal conductivity. However, a direct correlation of these nanostructures to the material’s property is yet to be elucidated. Nowadays, with the rapid development of aberration-corrected transmission electron microscopy (TEM), the resolution of electron microscopes takes a leap forward to sub-angstrom and sub-eV, which allows a direct access to a material’s structure and chemical composition at an atomic scale.

 The presentation will start with a brief and realistic coverage of the emerging and maturing themes in the context of energy sources, efficiency, charge storage and distribution. It will illustrate GeTe as one example of emerging excitements in nanostructured materials and systems for thermoelectric materials. It will highlight the role of advanced and classical electron microscopy in unravelling the hierarchical architecture of the constituents and their intimate interplay in governing key phenomena in thermoelectric materials.