Enhancing the thermoelectric performance of SnSe1-xTex nanoplates through band engineering

We developed a facile microwave-assisted solvothermal method to produce large-scale SnSe1_xTex nanoplates with tens of microns in length and several hundred nanometers in thickness. Enhancements in both peak figure-of-merit (1.1) at 800 K and average figure-of-merit (0.56) from 300 to 800 K were achieved in the p-type SnSe0.9Te0.1 pellet. In addition to the decreased thermal conductivity, the enhancement in figure-of-merit was mainly due to the increase in the power-factor over the midtemperature range. The enhanced power-factor is caused by the high preferential orientation, large carrier concentration, and the band convergence of multiplevalences. The as-synthesized twodimensional SnSe1_xTex structures with a large size ratio between the lateral and axial directions secure high preferential orientation in the correspondingly sintered pellet, and the produced Sn vacancies increase the carrier concentration. Based on the optical properties and density functional calculations, we examined the band structure evolution of SnSe1_xTex with increasing Te ratio to confirm the band convergence. This study of alloying with Te provides an alternative approach to enhance the thermoelectric performance of SnSe