Investigation and field effect tuning of thermoelectric properties of SnSe2 flakes

The platform of Van der Waals dichalcogenides (VdWDs) includes a large number of compositions and phases. Among these, some VdWDs may possess remarkable thermoelectric properties. In this work we carry out experimental measurements of electric and thermoelectric properties of bulk-like flakes for selected promising compositions, namely semiconducting 2H-MoTe2, MoS2, WSe2, and SnSe2, as well as metallic 1T’-MoTe2 and WTe2. The most promising composition for thermoelectric applications turns out to be SnSe2. For this compound, we calculate electronic properties within the density functional theory, and transport properties within the Boltzmann transport formalism and constant relaxation time approximation, accounting for doping and scattering rates. The comparison of experimental results with theoretical calculations for SnSe2 shows fair agreement and indicates that the dominant carrier scattering mechanisms are by polar optical phonons at room temperature and by ionized impurities below 50 K.