Enhanced electrical and mechanical properties of Bi₂Te₃-based thermoelectric thick films enabled by a practical dynamic regulation strategy

The application of high-density and high-performance micro thermoelectric devices is still in its infancy, mainly restricted by the low performance of Bi₂Te₃-based thick film as well as the limited device integration. In this study, we proposed a dynamic regulation strategy to simultaneously strengthen the thermoelectric and mechanical properties for n-type Bi₂Te₃-based thick films. The effects of growth temperature and time on thermoelectric properties have been firstly explored. As the thermoelectric properties exhibit consistent degradation with increasing thickness at static growth temperature, an effective rising temperature method is introduced to dynamically regulate the nucleation rate and growing diffusion ability. Thus, the grain refinement with compact texture structure leads to a relatively large carrier mobility (77.1 cm²·V⁻¹·s⁻¹) and appropriate concentration (5.25 × 10¹⁹ cm⁻³) as well as further 12% improvement of power factor with an average value up to 12.0 μW·cm⁻¹·K⁻² over a wide temperature ranging from 313 K to 453 K. Furthermore, significant enhancement of mechanical property is also achieved with high elastic modules (56.03 GPa), hardness (0.63 GPa) and large energy dissipation capacity to prevent micro-cracks. This study provides a practical solution with dynamic temperature control to fabricate high-performance Bi₂Te₃ thick films with enhanced mechanical property and processing feasibility for micro thermoelectric devices.