# Interface‐Engineered Bi0.5Sb1.5Te3/WSe2 Heterostructures for Enhanced Thermoelectric Performance

## TL;DR

This paper explores how engineering interfaces in BST/WSe2 heterostructures improves thermoelectric performance through structural and electronic effects.

## Contribution

The study demonstrates that interface engineering in BST/WSe2 heterostructures enhances thermoelectric performance via lattice strain and moiré patterns.

## Key findings

- BST/WSe2 heterostructures show high crystallinity and lattice compression with minor secondary phases.
- Interfacial strain and moiré patterns enhance Seebeck coefficients and power factors above 50 µW cm−1 K−2.
- Non-uniform WSe2 domains create p–n junction-like regions that reinforce energy filtering and carrier control.

## Abstract

BST/WSe2 heterostructures are deposited via pulsed laser deposition to examine the influence of interfacial structure and compositional heterogeneity on thermoelectric performance. X‐ray diffraction reveals high crystallinity with uniform lattice compression along both in‐plane and out‐of‐plane directions, accompanied by minor secondary phase inclusions. Cs‐STEM resolves well‐defined quintuple layers and compressed van der Waals gaps. At the same time, lattice strain is evident in structurally distorted regions, and moiré patterns arising from lattice mismatch are specifically observed within the mixed region adjacent to the BST interfaces. Temperature‐dependent transport measurements show enhanced electrical conductivity, with S3 reaching the highest values and S2 closely following, driven by thermally activated carrier generation. Positive Seebeck coefficients indicate p‐type transport, with S2 maintaining >430 µV K−1 from 310 to 440 K due to interfacial energy filtering. Non‐uniform WSe2 domains form internal p–n junction‐like regions that locally tune carrier concentration and reinforce energy filtering. Effective mass analysis suggests band flattening due to interfacial strain and moiré reconstruction, enabling high Seebeck coefficients and thermally stable power factor (>50 µW cm−1 K−2).

BST/WSe2 heterostructures grown by pulsed laser deposition exhibit semicoherent van der Waals interfaces, characterized by lattice strain, compressed gaps, and localized moiré patterns. These interfacial features modulate carrier generation and energy filtering, yielding high Seebeck coefficients and a consistently high power factor above 50 µW cm−
1 K−
2 across the measured temperature range, demonstrating an effective route to improved thin‐film thermoelectrics.