Synergistically optimizing carrier and phonon transport properties in n-type PbTe through I doping and SnSe alloying

Abstract

PbTe is a promising thermoelectric material, but the properties in n-type PbTe need further improvement to match its advanced p-type material. In this work, the thermoelectric performance in n-type PbTe is synergistically enhanced with iodine (I) doping and SnSe alloying. The experiments show that I element is a good donor dopant to tune the carrier density and SnSe alloying can effectively balance the triple-relations between carrier mobility, carrier effective mass, and lattice thermal conductivity. Thus, high carrier mobility of ∼755 cm2V−1s−1 results in an optimum power factor (PF) of ∼27.0 μWcm−1K−2 in PbTe–2%SnSe at 573 K. Microstructure observation reveals the dispersively embedded Sn-rich nanoprecipitates in PbTe–2%SnSe, which largely suppresses lattice thermal conductivity at room temperature, from ∼3.41 Wm−1K−1 in PbTe to ∼1.01 Wm−1K−1 in PbTe–2%SnSe. Combined the optimized PF and decreased thermal conductivity, the peak ZT value of ∼1.5 can be obtained at 773 K in PbTe–2%SnSe. The obtained high thermoelectric performance in our work is comparable with other advanced n-type PbTe thermoelectrics and has great application potential.