Application: Thermoelectrics

Green energy from wasted heat sounds like a free lunch, but thermoelectric materials do provide a promising vehicle. Dictated by the second thermodynamic law, a great amount of energy input is being (has to be) wasted in the form of heat. As global economic activities explode, thermal waste also spikes due to the sharp rise of energy expenses. Among all the others, thermoelectric materials convert heat directly and cleanly into electricity, without any moving parts and very high specific power (i.e., remarkable advantage in maintenance and scaling). However, due to tightly interrelated but competing requirements in material properties, the pursuit of high thermoelectric performance has proven strenuous for nearly 200 years. Nonetheless, the figure of merit experienced a sudden jump thanks to improvements in nanoscale fabrication and synthesis. We are currently studying phonon transport on two-dimensional superlattices using molecular dynamics, lattice dynamics, as well as density functional perturbation theory. Our primary concerns are two-fold: i) the anomalous transport physics, such as the dependence of thermal properties on structural dimensions; and ii) possible high-throughput designs for practical applications.