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.