High thermoelectric performance of polycrystalline SnSe prepared by cold sintering

Low-cost preparation of thermoelectric materials is crucial for reducing energy consumption. In this study, we prepared the nanopolycrystalline SnSe ceramic by combining the hydrothermal and cold sintering process (CSP) at a relatively low temperature of 170 °C from 300 MPa to 510 MPa. XRD analyses indicated that a pronounced preferential orientation of the cold sintered SnSe along the (h00) directions. SEM observations showed that a well-crystallized layered structure was formed. All SnSe samples exhibit remarkably low thermal conductivity of 0.3 Wm −1 K −1  at 773 K. This low thermal conductivity can be attributed to the use of ethanol as a transient liquid phase and the application of high pressure, which promotes the rearrangement of nanopolycrystals and introduces high densities of dislocations and stacking faults in SnSe. A maximum ZT value of 1.35 at 773 K was achieved for the 405 MPa sintered sample. This study provides a cost-effective and efficient strategy for the preparation of polycrystalline SnSe thermoelectric material.