Transport properties and enhanced thermoelectric performance of aluminum doped Cu3SbSe4

Abstract

The electrical transport and thermoelectric properties of Cu₃Sb_1−xAl_xSe₄ (x = 0, 0.01, 0.02 and 0.03) compounds are investigated in the temperature range of 300–600 K. The results indicate that with increasing Al content from x = 0 to x = 0.03, hole concentration increases monotonically from 8.04 × 10¹⁷ to 1.19 × 10¹⁹ cm⁻³ due to the substitution of Al³⁺ for Sb⁵⁺, thus leading to a large decrease in the electrical resistivity of Cu₃Sb_1−xAl_xSe₄. Meanwhile, the increase in hole concentration leads to a transition from a non-degenerate (x = 0) to a partial degenerate (x = 0.01, 0.02) and then to a degenerate state (x = 0.03). The power factor (PF) of all the Al-doped Cu₃Sb_1−xAl_xSe₄ samples is remarkably improved due to the optimization of hole concentration. Lattice thermal conductivity κ_L of the heavily doped sample (x = 0.03) is reduced. As a result, a large thermoelectric figure of merit ZT = 0.58 is obtained for Cu₃Sb_0.97Al_0.03Se₄ at 600 K, which is around 1.9 times as large as that of the un-doped Cu₃SbSe₄.