Improvement of thermoelectric properties for silicene by the hydrogenation effect

Abstract

In the present work, the thermoelectric performances of pure silicene and hydrogenated silicene are investigated by first-principles calculations based on the semiclassical Boltzmann transport theory. Hydrogenation provides an effective way to modulate the band structures of silicenes, which leads to discrepant electric and thermal transport properties. It is found that hydrogenation combining the doping and temperature effects changes the band structures, lowers the electrical conductivity and thermal conductivity, and enlarges the absolute values of the Seebeck coefficient of silicenes. The end product is the presence of a high thermoelectric figure of merit (ZT) of hydrogenated silicene, which is as high as 2.2 along the y-direction at 800 K and an n-type doping concentration of 1 × 1020 cm−3. The study demonstrates that the hydrogenation combining the doping and temperature effects can be used to improve the thermoelectric performance of materials to achieve excellent thermoelectric conversion.