Nanostructured SnSe: hydrothermal synthesis and disorder-induced enhancement of thermoelectric properties at medium temperatures

Nanostructured SnSe was fabricated using hydrothermal methods followed by sintering in an evacuated-and-encapsulated ampoule. The effects of reaction temperature (150-170 degrees C), duration (6-12 h) and sintering temperature (450-580 degrees C) on the electronic transport are investigated. It is found that both the electrical conductivity and thermopower of hydrothermally synthesized and nanostructured SnSe increase with temperature and follow the variable range hopping process. As a result, disorder-induced improvement of electronic transport combined with low thermal conductivity on the pressed sample face perpendicular to the pressed direction leads to zT = 0.54 at 550 K for the sample sintered at 500 degrees C, demonstrating a significant improvement of zT value in the intermediate temperature range for the SnSe system.