  Solid-state thermoelectric devices are currently used in applications ranging
from thermocouple sensors to power generators in satellites, to portable
air-conditioners and refrigerators. With the ever-rising demand throughout the
world for energy consumption and CO2 reduction, thermoelectric energy
conversion has been receiving intensified attention as a potential candidate
for waste-heat harvesting as well as for power generation from renewable
sources. Efficient thermoelectric energy conversion critically depends on the
performance of thermoelectric materials and devices. In this review, we discuss
heat transfer in thermoelectric materials and devices, especially phonon
engineering to reduce the lattice thermal conductivity of thermoelectric
materials, which requires a fundamental understanding of nanoscale heat
conduction physics.
