Scientists decode why lead selenide outperforms rival materials for heat-to-power conversion
Researchers have identified why PbSe converts heat to electricity more efficiently than chemically similar competitors—a discovery that could accelerate development of thermoelectric devices for waste-heat recovery in industrial and automotive applications. The finding, based on quantum simulations, reveals unusual atomic vibrations that suppress heat flow, a property that manufacturers can now target when engineering next-generation energy materials.
Originaltitel: Intrinsic localized mode and low thermal conductivity of PbSe
<p>Lead chalcogenides such as PbS, PbSe, and PbTe are of interest for their exceptional thermoelectric properties and strongly anharmonic lattice dynamics. Although PbTe has received the most attention, PbSe has a lower thermal conductivity and a nonlinear temperature dependence of thermal resistivity despite being stiffer, trends that prior first-principles calculations have not fully reproduced. Here, we use ab initio calculations that explicitly account for strong anharmonicity and a computationally efficient stochastic phase-space sampling scheme to identify the origin of this low thermal conductivity as an anomalously large anharmonic interaction, exceeding in strength that in PbTe, between the transverse optic and longitudinal acoustic branches. The strong anharmonicity is reflected in the striking observation of an intrinsic localized mode that forms in the acoustic frequencies. Our work shows the deep insights into thermal phonons that can be obtained from ab initio calculations that do not rely on perturbations from the ground-state phonon dispersion.</p>