Enhanced thermoelectric performance of n-type (PbSe)n(Sb2Te3) pseudo-binary via Zn filling and Ag2Se compositing

• We constructed a pseudo-binary PbSe-Sb 2 Se 3 with intrinsically low lattice thermal conductivity. • We revealed the distinct features and microstructural origin of Sb-doping (at Pb site) and Sb 2 Se 3 alloying in PbSe. • We realized synergetic enhancement of thermoelectric power factor and reduction of lattice thermal conductivity. Lead selenide (PbSe) is considered to be decent candidate replacing lead telluride (PbTe) as intermediate temperature (600–900 K) thermoelectric application due to its lower intrinsic lattice thermal conductivity, higher thermal stability, and larger abundance of Se than Te. To improve the thermoelectric performance of n-type PbSe, we constructed an n-type PbSe-Sb 2 Se 3 pseudo-binary via alloying Sb 2 Se 3 into PbSe matrix to obtain a reduced lattice thermal conductivity at a broad temperature range. Next, we introduced extra Zn into matrix to optimize the electron concentration. Last, we further added excess Ag 2 Se to modulate the lattice thermal conductivity at temperature< 523 K. Eventually, we obtained an ultralow lattice thermal conductivity of ~ 0.40 W m −1 K −1 and a large peak ZT of ~ 1.36 at 773 K in the composition of (PbSe) 40 (Sb 2 Se 3 )Zn 0.1 (Ag 2 Se) 0.75 ; meanwhile, the average ZT between 323 and 773 K is as high as ~ 0.78, revealing a significant improvement over pristine PbSe.