Grafting
nanotechnology on thermoelectric materials leads to significant
advances in their performance. Creation of structural defects including
nano-inclusion and interfaces via nanostructuring
achieves higher thermoelectric efficiencies. However, it is still
challenging to optimize the nanostructure via conventional
fabrication techniques. The thermal instability of nanostructures
remains an issue in the reproducibility of fabrication processes and
long-term stability during operation. This work presents a versatile
strategy to create numerous interfaces in a thermoelectric material via an atomic-layer deposition (ALD) technique. An extremely
thin ZnO layer was conformally formed via ALD over
the Bi0.4Sb1.6Te3 powders, and numerous
heterogeneous interfaces were generated from the formation of Bi0.4Sb1.6Te3–ZnO core–shell
structures even after high-temperature sintering. The incorporation
of ALD-grown ZnO into the Bi0.4Sb1.6Te3 matrix blocks phonon propagation and also provides tunability in
electronic carrier density via impurity doping at
the heterogeneous grain boundaries. The exquisite control in the ALD
cycles provides a high thermoelectric performance of zT = 1.50 ± 0.15 (at 329–360 K). Specifically, ALD is an
industry compatible technique that allows uniform and conformal coating
over large quantities of powders. The study is promising in terms
of the mass production of nanostructured thermoelectric materials
with considerable improvements in performance via an industry compatible and reproducible route.
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