Effective mass regulating of α-PbSe under pressure

Abstract

High pressure is an effective means to optimize the thermoelectric (TE) performance by sharply improving the electrical properties of materials. Studying the carrier effective mass (m*) is a feasible way to uncover the basic reason for superior electrical properties under high pressure. However, it is still difficult to obtain the m* under pressure in experiments. Thus, in this work, the m* of α-PbSe (Fm3̄m) under high pressure is calculated by band dispersion relation based on the density functional theory. It is found that the high pressure decreases m* of α-PbSe, which is the cause for excellent electrical properties. Moreover, the isotropy of m* enhances with the increase in the pressure, which means the high pressure further optimizes the isotropy of the carrier migration in the structure. It is reveled that the higher the pressure, the more beneficial to improve the electrical properties of α-PbSe, thus optimizing the TE performance before the phase transition pressure (4.5 GPa). This work is of great significance for exploring the mechanism of in situ high-pressure TE properties in the future, as well as the prediction and selection of high-performance TE materials under high pressure.