Thermoelectric phonon stop band materials

Using an analogy with photon band gap materials, we introduce a concept of the phonon stop-band materials for thermoelectric applications. We show that acoustic phonon propagation can be inhibited along certain directions in quantum dot superlattices with appropriately chosen parameters. It is also demonstrated that for realistic quantum dot parameters (dot size is few nanometers) it is possible to achieve a stop band in the phonon energy range that affects the value of the thermal conductivity tensor. The latter opens up a novel way for thermal conductivity reduction and thus, for increasing the thermoelectric figure of merit.