Optimizing the thermoelectric performance of n-type PbSe through dynamic doping driven by entropy engineering

Abstract

As an ideal candidate for PbTe, which maintains excellent performance at mid-temperature, PbSe holds great application potential. In this work, based on an optimized dynamic doping material system, a series of entropy-enhanced n-type lead chalcogenides Pb_1−ySn_ySe_1−xTe_xS_x-2at%Cu (x = 0 and y = 0; x = 0.1 and y = 0; x = 0.25 and y = 0; x = 0.25 and y = 0.125) are synthesized. The thermoelectric properties of PbSe are modulated by gradually increasing its configurational entropy through alloying with Te/S/Sn. Research results show that the increase in configurational entropy improves the crystal symmetry of PbSe and significantly increases the Seebeck coefficient while maintaining good electrical properties. The dense dislocations and nanoscale to submicron-scale incoherent precipitates generated lead to the localization of phonons, increase anharmonicity, and reduce the lattice thermal conductivity at room temperature to 0.73 W m⁻¹ K⁻¹. The total thermal conductivity drops significantly by 69.8%. Consequently, the thermoelectric properties of Pb_0.875Sn_0.125Se_0.5Te_0.25S_0.25−2at%Cu are remarkably improved, with a maximum dimensionless merit ZT_max of ∼1.46 at 623 K and an average dimensionless merit ZT_ave of ∼1.15 at 300–700 K. In addition, the room-temperature dimensionless merit ZT_RT ∼0.64 is the highest reported for n-type PbSe. This optimization strategy of dynamic doping combined with entropy engineering to regulate electron and phonon transport demonstrates a feasible means to improve thermoelectric performance.