Realization of High Thermoelectric Performance in Polycrystalline Tin Selenide through Schottky Vacancies and Endotaxial Nanostructuring

Here, we report a remarkable high-average figure of merit (ZT) of 0.73 with the peak ZT of 1.9 in bulk polycrystalline tin selenide (SnSe), generating a high energy conversion efficiency of ∼12.5%. The remarkable high thermoelectric performance results from the enhanced electrical transport properties and reduced lattice thermal conductivity through Schottky vacancies and endotaxial nanostructuring. High angle annular dark field scanning transmission electron microscopy identified amounts of Schottky vacancies and endotaxial PbSe nanoprecipitates present in the SnSe matrix. Schottky vacancies and endotaxial PbSe nanostructures contribute to low lattice thermal conductivity by establishing strong phonon scattering centers. Consequently, an extreme low lattice thermal conductivity of 0.23 W m–1 K–1 was achieved at 873 K. Schottky vacancies lead to the increase in carrier concentration, contributing to the enhancement of electrical conductivity and power factor (PF). The maximum PF reached 7.5 μW cm–1 K–2 at 873 K. In addition to the high peak ZT, a high average ZT and outstanding thermoelectric conversion efficiency were realized, which ensured its huge potential in practical application. This work provides a new strategy for enhancing thermoelectric performance and designing prospective high-performance thermoelectric materials.