Thermoelectric Transport Properties of Pb(Bi1-xSnx)2Te4 (0≤x≤1) compounds

Abstract

In this study, the effect of Sb incorporation on the thermoelectric transport properties of tetradymite-type Pb(Bi2-xSbx)Te4 (0≤x≤1) compounds is presented. PbBi2Te4 (x = 0) possesses a high electron concentration of ~1.6×10²⁰/cm³ at room temperature and exhibits n-type degenerate semiconductor behavior, in which electrical conductivity decreases and negative Seebeck coefficient increases almost linearly with increasing temperature. For x = 0.5, the electron concentration decreased to ~5.5×10¹⁹/cm³ and n-type semiconductor characteristics was observed. When the Sb content increased to x = 1, the majority charge carrier was found to be hole (p ~ 3.3×10¹⁹/cm³), thus a change in polarity from n-type to p-type semiconductor was observed. It was suggested that the change in polarity with Sb incorporation observed in this study is due to the formation of a p-type antisite defect, which is formed because the electronegativity of Sb is closer to that of Te than that of Bi. Due to the decrease in charge concentration with the increase in Sb content, it was possible to increase the power factor near room temperature for x = 0.5. However, the overall output factor decreased with increasing x. These results are expected to be helpful in efforts to improve the thermoelectric properties of tetradymite-type homologous compounds through antisite defect control.