Theoretical insights into Sb2Te3/Te van der Waals heterostructures for achieving very high figure of merit and conversion efficiency

Thermoelectric technology offers a promising solution for sustainable energy conversion, but maximizing efficiency and figure of merit (ZT) remains a significant challenge. This work explores the novel structural, electronic, and thermoelectric properties of Sb₂Te₃/Te van der Waals heterostructures (vdWHs) through first-principles computation and Boltzmann transport theory. Our study reveals that the Sb₂Te₃/Te vdWHs exhibit very low lattice thermal conductivity (0.28 $W{m}^{-1}{K}^{-1}$) and high Seebeck coefficient (811 $\mu V{K}^{-1})$, driven by energy-filtering effects across the interface and a band gap of 0.47 eV. Notably, the calculated ZT reaches a record-high value of 8.83 at 400 K, substantially surpassing previous benchmarks for similar materials. Unlike prior studies, we extend our investigation by tuning the dimensions to 2 × 2 × 1 and 3 × 3 × 1 supercells and exploring tri-layer Te/Sb₂Te₃/Te vdWHs. Our results show that the ZT of the 2 × 2 × 1 supercell reaches an even higher value of 9.14, further exceeding the performance of the unit cell. Additionally, the heterostructures demonstrate a remarkable thermoelectric conversion efficiency (η) of 32.25 % and thermionic refrigeration efficiency surpassing 51.9 % of Carnot efficiency at 400 K, highlighting their potential for high-performance cooling applications. These findings significantly advance the integration of high-efficiency heat-to-electricity conversion and cooling within a single material system, setting a new benchmark for thermoelectric performance and establishing Sb₂Te₃/Te vdWHs as a leading candidate for next-generation thermoelectric and electronic technologies.