Materials that can convert heat into electricity or vice versa are called thermoelectric materials (TE materials). When direct current is passed through a TE material, either absorption or dissipation of heat occurs at the two ends of a material by Peltier effect so that this phenomenon can be applied to cooling or heating. Cooling the surrounding area of the one end of a TE material is specifically called Peltier cooling. In contrast, when the temperature difference is applied to the two ends of a material, electromotive force (thermoelectric power) is generated by Seebeck effect and electric power can be extracted by flowing the current to the external circuit. This is called thermoelectric power generation.

Thermoelectric devices or modules for cooling or power generation are all energy converters (transducers), and their performance, namely thermoelectric energy conversion efficiency, depends largely on that of TE materials. Dimensionless figure of merit, ZT, is usually used to evaluate the performance of a TE material, and search for high ZT materials has been an enthusiastic topic in the past 30 years.

Global issues of environmental disruption were recognized in the thermoelectric community and triggered searching for new TE materials in the mid‐1980s. Vining's prediction that there is no limit for ZT value (1992), Dresselhaus's proposal of low‐dimensional nanostructure (1993), and Slack's concept of “phonon glass‐electron crystal” (PGEC; 1995) were the major supporters for the following materials exploration research. Low‐dimensional nanostructure concept led to the research of superlattice materials/devices and further developed to the “bulk nanostructuring” concept, which has greatly increased the ZT value. The “PGEC” concept has given rise to many new materials such as skutterudite and its related compounds and clathrates with network structure. Various other proposals of novel concepts, discovery of new physical phenomena, and development of low‐cost chemical processes all enhanced TE materials research worldwide, resulting in improving the thermoelectric performance of inorganic materials reaching ZT > 2 at mid to high temperatures. On the other hand, organic and hybrid TE materials research has been widely conducted in the past 10 years aiming at its application to flexible energy harvesting that is required in the future IoT society.

Based on such a background, this book was timely written by three distinguished materials scientists. It contains fundamentals and applications of TE materials and devices, and their near‐future perspectives are introduced and discussed.

The book consists of 11 chapters. Chapter 1 describes the fundamentals of electronic transport, Chapter 2 describes the controlling phonon transport in nano bulk solids, and Chapter 3 describes the nonoxide materials such as Bi2Te3‐based materials, skutterudite‐based materials, Si–Ge alloys, and other alloy materials. In Chapters 4–8, synthetic processes, structures, and properties of representative TE materials are presented. In Chapter 4, ZnO and In₂O₃; in Chapter 5, perovskite type oxides; in Chapter 6, oxide cobaltates; and in Chapter 7, complex oxides are employed and fully described. Chapter 8 describes the novel TE materials and nanocomposites, followed by nanostructure design and organic–inorganic nanocomposites. Chapter 9 provides the detailed description of synthesis and processing of oxide TE materials. Chapter 10, modeling and optimizing of thermoelectric devices. Finally, in Chapter 11, photovoltaic–thermoelectric integration devices for the future applications are introduced.

This is a well‐organized guide book for graduate students. I would strongly suggest professors and teachers in physics, chemistry, or materials science to adopt it as a textbook or a reference book for their teaching classes. It is also helpful for researchers who are getting involved in TE research and development.