Optimizing textured structure of polycrystalline SnSe thermoelectric material by solvent-regulated cold sintering

Tin selenide (SnSe) has emerged as a promising thermoelectric material with potential applications in waste heat harvesting. However, optimal performance is typically achieved in single crystals of SnSe, whose fabrication and long-term reliability under operating conditions remain challenging. Polycrystalline ceramic materials are preferred and are generally processed by spark plasma sintering (SPS), which involves high temperatures, costly equipment and intensive energy consumption. In this work, we propose a liquid-phase-assisted cold sintering process as an energy-efficient and scalable alternative to SPS that also promotes the anisotropic alignment of grains in polycrystalline SnSe. The use of a water-ethanol transient liquid phase significantly reduces interfacial friction between SnSe nanosheets, resulting in dense ceramics in which a high degree of favorable crystallite orientation is preserved. The resulting samples exhibit power factors of up to 4.6 μ W cm −1 K −2 at 773 K for the most textured sample, which is comparable or even superior in terms of in-plane electrical performance to those processed by SPS, demonstrating the suitability of cold sintering for high-performance SnSe thermoelectric materials.