The thermoelectric performance in transition metal-doped PbS influenced by formation enthalpy

Abstract

Transition metals have excellent valence electrical properties and unique electronic state distribution and are regarded as potential materials for improving thermoelectric performance. However, the impact of transition metals on thermoelectric materials is restricted to the solid solution limit and doping efficiency, reinforcing the shortcomings in systematic research. Here, thermoelectric properties of transition metal (Ti, V, Cr, Zr, Nb, Mo)-doped PbS are compared and analyzed systematically based on the formation enthalpy. The DFT calculation indicates that the doping (except Zr) leads to the bandgap expansion and the density of states distortion near the Fermi level, while the localization property of the latter results in an invalid resonance level. The formation enthalpy dominates the carrier concentration due to the opposite trend of carrier concentration and formation enthalpy. The formation enthalpy of Zr, Ti, and Nb doping is more negative than others, leading to the more significant optimization of carrier concentration. The Moss–Burstein effect promotes the bandgap expansion, leading to weaker bipolar effects for Zr, Ti, and Nb doping. Eventually, the thermoelectric performance for Ti, Zr, and Nb doping is superior to others at high temperature. The Hume-Rothery rule of the formation enthalpy supplementation is more suitable for the doping and alloying in thermoelectricity. Thermodynamic stability analysis based on the formation enthalpy contribute the PbS-based thermoelectric devices evaluation. The present finding demonstrates the significant effect of formation enthalpy on the thermoelectric properties of PbS and provides a useful avenue for the doping modification and thermodynamic stability analysis of other thermoelectric alloy materials.