Enhanced Thermoelectric Performance of Cu3SbSe4 Doped with Alkali-Ion (Na and K)

The thermoelectric properties of alkali-ion-doped compounds Cu 3 Sb 1− x M x Se 4 (M = Na and K) prepared by mechanical alloying and spark plasma sintering compaction, are investigated systematically between 300 K and 673 K. The increase in the hole carrier concentration causes a reduction in the electrical resistivity in the whole temperature range and a rise in the power factor at elevated temperature for alkali-ion-doped compounds as compared to pristine Cu 3 SbSe 4 . For example, the maximum power factors for Cu 3 Sb 1− x Na x Se 4 ( x = 0.02 and 0.03) and Cu 3 Sb 0.99 K 0.01 Se 4 at 673 K are all increased by around 1.6 times compared to the un-doped sample. As a result, the peak ZT value reaches 0.52 and 0.71 at 673 K for Cu 3 Sb 1− x Na x Se 4 ( x = 0.02 and 0.03) and Cu 3 Sb 0.99 K 0.01 Se 4 , which is 27% and 73% larger than that (0.41) of the un-doped sample, respectively. In this work, K-doping is more effective in improving thermoelectric performance of Cu 3 SbSe 4 , due to its larger ionic radius, which can bring more lattice distortions and point defects to scatter phonons than Na-doping. Graphic Abstract