Author's note: In entering the field of thermoelectric (TE) technology in 1987, one of the things that troubled me, was the lack of comprehensive literature covering the fine details of theory. Certainly, there were pivotal works that offered valuable perspectives, but something was lacking. For all their merits, they simply did not develop an intuitive understanding of how the mechanics of semiconductors made it all possible. TE elements were largely treated as black boxes, relying upon course & imprecise descriptions, simplifications, and averages. You could see the inputs and outputs, but not the proverbial gears turning. This was an explicable plateau, of course-so many of the building blocks were assembled in an age of paper, pencils, and slide rules. Refinements in TE theory would require easy access to high-speed computers for exploring interdependencies-and this technology would not arrive until much of the foundation had calcified.

Thus in 2011, when I contemplated a book about the basics of thermoelectric science, I wanted to go behind the curtain. Given my experience in computer modeling of TE material performance, I suspected that I could shed a lot of light on key concepts. In truth, I was only at the threshold of a journey that would take me to many different vantage points over an eight-year period. I kept being pulled deeper and deeper into the matrix of conceptual development.

In the end, I was able to further break down many constructs of TE functionality. This was particularly true in coming to terms with temperature dependencies of material properties. Rather than ignoring these complexities as though they were of minor consequence, I faced them head on. This meant further developing computer models. It became abundantly clear that temperature dependency was not only very important, but vital to understanding the underlying mathematics and seeing how thermoelectric systems reach states of equilibrium. Many of the intricacies of TE science become especially tangible when examined through a lens of thermal interaction. Elusive constructs like Thomson Effect become much more clearly delineated.

Tackling this array of interrelationships, I tried earnestly to make explanations as accessible as possible, supporting the prose with ample illustrations, graphs, and tables. That said, I cannot pretend that this is an easy walk through the forest. I wish it had been possible to make everything wondrously entertaining from beginning to end, but alas. Technical writing all-too-frequently rests upon abstractions and attention to minutiae. You can't just pound a concept home ad nauseum. Instead, after you come at it from every conceivable angle, you must ask your readers to take deliberate time and care in moving through the more demanding passages. There is no denying that this requires significant work and active thinking. Particular points are hard-fought and it is essential for readers to let the logic slowly "soak in"-re-reading key paragraphs, examining the related graphs and tables in detail, and pondering the implications fully. In short, study is essential. What is happening to energy levels as those charge carriers move through the materials? What makes them demand or jettison energy and how does that effect the thermal and electrical operations? With suitable effort, readers can see the intricacies and understand so much more about the processes and principles which inform a modern theoretical foundation.

While this book presents significant challenges to readers, they can at least benefit from my dedication to providing explanations which weren't even in the mist when I came into the field. I have strived with diligence to place critical concepts well within the reach of those who want to master them. This book is the guide and roadmap to a vast web of thermoelectric fundamentals. It just requires your commitment to complete the journey.