Thermoelectric properties of n-type transition metal-doped PbSe

Thermoelectric properties of transition metal (Ti, V, Cr, Zr, Nb, Mo, Hf, Ta, or W)-doped PbSe were studied. Peak ZT∼1.1, ∼1.15, and ∼1.2 at about 873 K has been achieved in Ti_0.015Pb_0.985Se, Zr_0.005Pb_0.995Se, and Nb_0.01Pb_0.99Se, respectively, with increased room temperature Hall carrier concentration to ∼10¹⁹–10²⁰ cm⁻³. However, the lower temperature ZT (<600 K) is not favorable compared with other transition metal (V, Cr, Mo, or W)-doped PbSe with lower doping concentration. Higher room temperature ZT contributes to the higher average ZT despite lower peak ZT. First-principles calculation found resonant states created in n-type PbSe doped by Ti, V, Zr, Nb, Mo, Hf, Ta, or W similar to Cr-doped PbSe, while Pisarenko plots show absence of resonant states due to the deep residence of the states and the limited doping concentration confirmed by the calculations.