Off-Center Distortions and Resonant Levels: A Pathway to Enhance Power Generation and Thermoelectric Cooling in PbSe Crystals

The scarcity of tellurium (Te) poses significant challenges to the widespread application of Bi2Te3-based thermoelectric systems. In this work, we investigated the potential of Te-free PbSe for thermoelectric applications by optimizing carrier mobility through crystal growth and a two-step strategy of light alloying and doping. First, Cd alloying was employed to reduce the lattice thermal conductivity (κlat) of n-type PbSe through the off-center effect while preserving carrier mobility. Subsequent In doping enhanced the effective mass via the resonant level formation, achieving a high weighted mobility-to-κlat ratio (μW/κlat∼338.4) and a large power factor of 36.7 μW cm-1 K-2 at 300 K in the Pb0.9972Se-0.008Cd-0.0008In crystal. Due to the reduced lattice thermal conductivity and largely promoted μW/κlat value, the optimized Pb0.9972Se-0.008Cd-0.0008In crystal exhibited a large ZT value of ∼0.5 at 300 K, a maximum ZT value of ∼1.3 at 673 K, and an average ZT value of ∼1.1 (300-773 K). Additionally, a thermoelectric generator based on the Pb0.9972Se-0.008Cd-0.0008In crystal achieves a power generation efficiency of 6.3%, while a 7-pair module (n-type Pb0.9972Se-0.008Cd-0.0008In crystal and p-type commercial Bi0.4Sb1.6Te3 material) demonstrated a maximum cooling temperature difference (ΔT) of 51.2 K (Th = 353 K). This work establishes PbSe as a cost-effective, high-performance thermoelectric material for thermoelectric cooling and power generation.