Enhancement of the Thermoelectric Properties of Cu1.98Se by Na Doping

Cu 1.98− x Na x Se nanopowders were synthesized using a hydrothermal method and hot-pressed into bulk pellets to assess the effects of Na doping on the thermoelectric properties of Cu 1.98 Se. The original layered microstructure was maintained at low doping levels, although nanopores, together with point defects, appeared to decrease the thermal conductivity. The thermoelectric properties of the material were improved by Na doping, resulting in a maximum ZT value of 1.32 for Cu 1.94 Na 0.04 Se at 973 K. The experimental data indicate that an optimal level of Na doping effectively improves the thermoelectric performance of non-stoichiometric Cu 1.98 Se.