Pressure-induced improvement of Seebeck coefficient and thermoelectric efficiency of CoSb3

• We design an A novel high pressure Seebeck coefficient measurement method for bulk-skutterudite CoSb3.
• High pressure Seebeck coefficient and electrical resistivity measurement of CoSb3 were conducted in the pressure range of 0–25 GPa.
• The thermoelectric efficiency (α) of CoSb3 was tremendously improved under high pressure.
• The employed high-pressure cell with DAC is a model of a simple and effective TE device.

A novel high pressure Seebeck coefficient (S) measurement method has been used for bulk-skutterudite CoSb3. The Seebeck coefficient and electrical resistivity (ρ) of CoSb3 were measured in the pressure range of 0–25 GPa. The Seebeck coefficient of CoSb3 increases very fast with the increase of the pressure and reaches a maximum value of 375 μV/K. A considerable pressure induced improvement of the thermoelectric efficiency (α) is found at about 10 GPa. A direct band gap change to indirect band gap with increasing pressure was found for CoSb3 and both S and ρ abruptly rise due to the opening of the energy gap. These results indicate that the thermoelectric properties of CoSb3 could be effectively improved under certain pressures.