The next generation of thermoelectric materials

From the mid-1950s to the present the major design concepts for bulk thermoelectrics were those used by A.V. Ioffe. These were to select semiconducting compounds of heavy elements from the lower part of the periodic table and then to reduce the lattice thermal conductivity by forming mixed crystals. This approach led to the thermoelectrics based on Bi, PbTe and Bi₂Te₃. In this study we report on ongoing research of a new type of semiconducting material system with an open crystal lattice structure. The concept of a “phonon glass and an electron crystal” (PGEC) is at the heart of this investigation. Such materials possess electronic properties normally associated with good semiconductor single crystals and thermal conductivity normally associated with amorphous materials. The introduction of this concept to thermoelectrics is one of the most significant innovations in thermoelectrics in the last 30 years. We will report on transport properties measurements on some of these new materials, some of which possess ZT values higher than any new materials presently under investigation