Enhanced thermal stability and power factor in layered Bi 2 Se 0.5 Te 2.5 Thin films across a broad temperature range

Bi 2 Te 3 -based n -type thin films with high thermoelectric performances are typically synthesised through the formation of dense structures, a process conventionally conducted at high temperatures. However, this method compromises thermal stability. In this study, structural design and multiple-step annealing were employed to enhance the thermal stability of high-performance Bi 2 Se 0.5 Te 2.5 thin films. Post-annealing, the disparity in the values of the Seebeck coefficient over the entire test temperature range, was reduced to 20 mu V K - 1 , which is approximately 32 % compared to pre-annealing measurements. The layered Bi 2 Se 0.5 Te 2.5 thin film demonstrated an elevated power factor (28 x 10 -4 W m - 1 K - 2 ), which was maintained across a broad temperature spectrum. This multiple-step annealing approach not only refines the structural integrity by extending the atomic diffusion duration but also mitigates defects and augments compositional uniformity at reduced temperatures. Consequently, layered Bi 2 Se 0.5 Te 2.5 films emerge as promising candidates for thermoelectric materials, offering enhanced long-term stability for diverse applications, including electric and hybrid electric vehicles, and portable electronic devices.