Enhancing Thermoelectric Performance of n-Type SnSe Polycrystals through Rare-Earth Element Doping and Vacancy Compensation

SnSe has attracted considerable interest in thermoelectric research owing to its intrinsically low lattice thermal conductivity and distinctive electronic band structure. However, the development of n-type SnSe remains constrained by the low efficiency of electron doping. In this work, a synergistic strategy involving rare-earth element doping and vacancy compensation is employed to enhance the thermoelectric performance of n-type SnSe polycrystals. Rare-earth elements (La, Ce, Nd, and Pr) are systematically investigated as electron dopants. The results indicate that Pr exhibits the highest doping efficiency in SnSe. In addition, excess Pb is introduced to compensate for intrinsic Sn vacancies, mitigating the vacancy-induced scattering of charge carriers and thereby synergistically optimizing both carrier concentration and carrier mobility. As a result of the significantly enhanced electrical conductivity, the optimized sample Sn_0.95Pr_0.05Pb_0.15Se achieves a maximum ZT value of 1.2 at 773 K. This work presents an effective approach for enhancing the thermoelectric performance of n-type SnSe.