Facile chemical synthesis and enhanced thermoelectric properties of Ag doped SnSe nanocrystals

A two-step, surfactant-free solution growth process was utilized to synthesize p-type Ag doped SnSe nanocrystals in gram quantities. The formation mechanism of SnSe nanocrystals was studied by high resolution transmission electron microscopy, and it was shown that the main surface and edge facets are {100} and {011} respectively. A clear phase transition near 800 K was discovered in the temperature dependence of thermal conductivity. The thermoelectric properties of SnSe pellets prepared by spark plasma sintering exhibit a significant increase of zTmax (0.8 at 850 K) in the 3% Ag doped SnSe. The zTmax value is about 40% higher than that of the pristine SnSe. The consequence is mainly attributed to the enhancement of carrier concentration and power factor by Ag doping. Our results demonstrate that this facile chemical method is amenable to fabricate high quality SnSe nanocrystals and might also be applied to other anisotropic crystalline materials.