Ultrasonic-assisted construction of SnTe/ZnO core-shell heterostructures with decoupled electrical and thermal...

SnTe has attracted significant attention as a nontoxic PbTe alternative. However, its intrinsically high hole concentration (∼ 10(Zhu et al., 2022²⁰⁾-10²¹ cm^-3) and large lattice thermal transport conductivity (∼ 3.0 W m^-1 K^-1) pose significant challenges to performance optimization. This study uses an ultrasonic-assisted method to coat ZnO nanocrystals onto Sn_0.94In_0.06Te microcrystals. This constructs core-shell heterostructures that decouple electrical and thermal transport. Doping with In and coating with ZnO lower the carrier concentration (n_H) of Sn_0.94In_0.06Te/3 wt% ZnO to ∼5.8 × 10²⁰ cm^-3. Energy barriers at SnTe/ZnO interfaces selectively filter carriers, enhancing the Seebeck coefficient to ∼146 μV K^-1 (873 K). Meanwhile, multi-scale phonon scattering reduces the lattice thermal conductivity (κ_L) to ∼0.78 W m^-1 K^-1 at 873 K. Sn_0.94In_0.06Te/3 wt% ZnO achieves a peak zT of ∼0.72 at 873 K, representing a 106 % enhancement over pure SnTe. This work establishes a synergistic mechanism involving band engineering, interfacial energy filtering, and hierarchical phonon scattering. This mechanism offers a novel approach for developing high-performance lead-free thermoelectric materials.