Cu-Se Bond Network and Thermoelectric Compounds with Complex Diamondlike Structure

The ternary diamond-like compound Cu2SnSe3 was studied, which displays the primary bond network in the material in real space. Although the compositions or structures of the compounds among copper-containing diamond like family, especially for the multication contained systems, are very complicated, the underlying relationship of structure/function was observed to be similar. The partial carrier density distribution in CZTS also shows a similar Cu-Se charge accumulation, whereas Zn and Sn atoms have little contribution to the partial charge density close to valence band maximum but donate electrons to the whole system. The electrical conductivity is greatly enhanced after In/Sn substitution, changing from 12600 S m-1 to 93200 S m-1 at room temperature, which results in the improvement of power factor within the whole temperature range. The matrix and the doped compounds exhibit extremely low thermal conductivity, especially at high temperature, as well as tunable electrical property.