The history of thermoelectricity is largely intertwined with the most significant advances of thermodynamics and condensed-matter physics over the last two centuries. The discovery of the thermoelectric effects (Seebeck, Peltier and Thomson) played a key role in the birth of irreversible thermodynamics, largely acting as a workbench of models and theories —including the experimental validation of the Onsager-Casimir relations. Thermoelectricity has further promoted advances in solid-state physics and chemistry, inspiring research on the relationships between thermal conductivity and crystal structure of materials over the first half of the XX century —which further extended to defect engineering in real crystals. In more recent times, research on thermoelectric materials has promoted and motivated a major research endeavor to clarify factors affecting thermal conductivity in nanostructures, in a more general effort to apply nanotechnology to enhance the performance of thermoelectric materials to be exploited in thermoelectric generators and coolers.
Thermoelectricity is today among the most exciting fields of research for a materials physicist. The challenge of devising materials with exceptional properties (low thermal conductivity, high electrical conductivity, and a large Seebeck coefficient) has triggered a global, interdisciplinary endeavor to exploit scientific creativity. The need for sustainable energy has added a technological momentum. Still, thermoelectricity remains a substantial branch of thermodynamics, and the modes of operation of a thermoelectric system still call for sophisticated theoretical analyses, which have inspired novel developments of irreversible thermodynamics, from the analysis of the efficiency at a finite rate to recent studies on phonon hydrodynamics.
The 207 Course of the International School of Physics “Enrico Fermi” dedicated to Advances in Thermoelectricity: Foundational Issues, Materials, and Nanotechnology encompassed the full complexity of modern thermoelectricity. Its organization aimed at exposing students to all most cogent themes relevant to current research in the field. Twelve lecturers participated in the course, and we gratefully thank both those who provided contributed written papers that are published in this volume and those who just provided their lectures.
Classes began with three series of lectures on the fundamentals of thermodynamics, solid-state physics, and statistical mechanics applied to thermoelectricity —delivered by D. Narducci (“Thermodynamics and thermoelectricity”), G. J. Snyder (“Transport property analysis method for thermoelectric materials: Materials quality factor and the effective mass model”), and R. Rurali (“A primer on phonon transport”). Applications of such concepts to materials were then the subject of the lectures given by M. Martin-Gonzalez (“Past and present of metal chalcogenides, oxides, Heusler compounds and Zintl phases as thermoelectrics: A brief summary”) and K. Koumoto (“Low-dimensional inorganic/organic hybrid thermoelectrics”). Furthermore, Y. Grin and H. Sirringhaus delivered lectures on silicon and silicides and on charge and heat transport in organics. Additional insights into applications of nanoscience to thermoelectricity were provided by G. Benenti (“Theoretical approaches for nanoscale thermoelectric phenomena”), and N. Neophytou (“Electronic transport simulations in complex band structure thermoelectric materials”) while J. P. Heremans contributed highlights on spin thermoelectrics and related topics (“Thermal spin transport and spin in thermoelectrics”). The driving force from advanced technology was covered by the lectures delivered by C. Fanciulli (“Thermoelectric harvesting: Basics on design optimization and applications”) and B. Lorenzi (“Heat conversion in solar thermoelectric harvesters” and “Heat conversion in hybrid solar thermoelectric harvesters”).
The course gathered 51 students from 24 countries and was organized to foster informal and continual interactions among students and lecturers. The lively, participative spirit of the course was one of its major successes. This was also the result of the exceptional organizational framework provided by the Varenna secretary. We wish also to gratefully acknowledge the sponsorships we received from ISC s.r.l., the Italian Thermoelectric Society, Elsevier, and the University of Milano-Bicocca, which enabled the partial or full waiving of registrations fees for students coming from less-developed countries and which concurred to support travel expenses of some of the lecturers coming from non-European countries. Last but not least, we gratefully acknowledge the Italian Physical Society that provided us with the opportunity of organizing this course in the prestigious framework of the “E. Fermi” School of Physics.
Dario Narducci, G. Jeffrey Snyder and Carlo Fanciulli