The complexity of thermoelectric materials: why we need powerful and brilliant synchrotron radiation sources?

Tuning the transport properties between heat flux and electrical current may allow increasing the efficiency of thermoelectric materials, complex systems that hold great promises for energy harvesting and solid-state refrigeration. Actually, their atomic structure, charge distribution, and thermodynamic evolutions simultaneously contribute to determining the energy conversion efficiency between charge and heat. At present, the limited capability to simultaneously probe atomic structure, charge distribution states, and lattice or charge dynamics represents the real bottleneck toward a better understanding of the transport of electrons and phonons in these materials. A variety of techniques have been developed or are under development at synchrotron radiation facilities to make available powerful tools to all researchers to investigate these and other similar systems. We review here the main applications by emphasizing their advantage to investigate thermoelectric materials. We will also update the status and the opportunities available at the synchrotron radiation facilities all around the world. Finally, we will provide perspectives of these extraordinary sources for the thermoelectric materials community.