Enhanced thermoelectric performance in CuAgSe/Cu2Se composite by cold sintering mediated nanoengineering

Cu₂Se based thermoelectric materials have remarkable thermoelectric properties especially at high temperature, but the inferior low/medium temperature performance and energy consuming processing prevent the industrial application. In this study, CuAgSe/Cu₂Se composites were prepared by cold sintering process using vitamin C as transient liquid, which not only reduces the sintering temperature to 350 °C, but also achieve superior thermoelectric performance compared with the material prepared by spark plasma sintering. The preserved CuAgSe nanoplates greatly suppress the thermal conductivity of composite, while improves the Seebeck coefficient via energy screening effect due to the heterojunctions at interfaces. In addition, the CSP induced dislocations and internal strains also effectively scatter the phonon transport, As a result, a ZT value of about 1.5 at 700 K and a high average ZT value of 0.94 from 400 K to 700 K are obtained, which demonstrates the great potential of CSP for applications in thermoelectric composites.