SnSe nanoparticles with the ultra-low lattice thermal conductivity: synthesis and characterization

Tin selenide (SnSe) with an orthorhombic system has recently become a hot spot in the thermoelectric field owing to its low thermal conductivity and high melting point. In this work, P-type SnSe nanoparticles with a mean diameter ca.20–25 nm have been synthesized first by a facile liquid-phase method. Interestingly, the synthesized SnSe nanoparticles have transformed from an intrinsic P-type to an N-type semiconductor after being annealed due to the generation of SnSe₂ secondary phase. The SnSe samples have been characterized by XRD, SEM, XPS, TEM, laser flash, and BET, and the results show that the nanostructure and the presence of SnSe₂ secondary phase enhance phonon scattering effect leading to freshly formed N-type SnSe that has an ultra-low lattice thermal conductivity and a low total thermal conductivity (0.368 Wm⁻¹ K⁻¹, 0.393 Wm⁻¹ K⁻¹) at 723 K. Obviously, this work provides a new way to obtain an N-type SnSe nanomaterial with ultra-low lattice thermal conductivity.