Enhanced Thermoelectric Performance of BST/WSe₂ Heterostructures Through Defect-Driven Microstructural Modifications

This study presents the fabrication of BST/WSe₂ heterostructured films using dual-beam pulsed laser deposition to enhance thermoelectric performance. Periodic incorporation of WSe₂ into the BST matrix induces vertical perturbations that generate structural imperfections, such as staggered stacking, ripplocations, swapped bilayers, interlayer distortions, edge dislocations, and isolated W atoms, which collectively enhance phonon scattering and modulate charge transport. Additionally, the ambipolar nature of WSe₂ facilitates the tuning of carrier concentration and energy filtering, thereby contributing to improved thermoelectric efficiency. These effects are more pronounced in films deposited at 573 and 673 K, where excessive defect scattering suppresses carrier mobility, lowering electrical conductivity and power factor. In contrast, films grown at 623 and 723 K achieve a better balance, where moderate defect scattering and thermal excitation help offset mobility losses. Notably, the 623 K sample achieves a power factor of ≈60.72 µW cm^-1 K^-2 at 447 K, exceeding previous reports. These findings underscore the potential of defect and interface engineering, when coupled with ambipolar semiconductor WSe₂, for advancing the design of scalable, high-performance thermoelectric materials.