Abstract: Bismuth telluride-based materials have been extensively studied due to their outstanding thermoelectric performance at room temperature. However, bismuth telluride is inherently brittle. Consequently, the development of flexible bismuth telluride-based materials with high thermoelectric performance remains a significant challenge in thermoelectric research. In this study, the non(00l) layered flexible p-type thermoelectric thin films was fabricated by depositing Cu_0.005Bi_0.5Sb_1.495Te₃ onto polyimide (PI) substrates using magnetron sputtering technology, with a systematic investigation of the effect of sputtering pressure on thermoelectric properties. The results show that at 0.7 Pa sputtering pressure, the mobility is enhanced due to the large grain size and high crystallinity, while the carrier concentration is optimized to 5.78×10¹⁹ cm^-3, and the room-temperature power factor (PF) reaches 1660 μW·m^-1·K^-2. In addition, the film exhibits excellent mechanical flexibility, showing less than 10% variation in resistivity at a bending radius of 5 mm and less than 5% variation in Seebeck coefficient after 600 cycles of bending. Furthermore, a flexible thermoelectric device comprising four p-type thermoelectric legs (5 mm×25 mm×767 nm) was designed and fabricated based on this film. The device demonstrates promising performance, generating an output voltage of 18.5 mV, with a power density reaching 44.80 μW·cm^-2 under a temperature difference of 30 K. The touch-sensitive linguistic output design of the device demonstrates promising potential for language assistance applications. This work provides valuable insights for the magnetron sputtering preparation of high-performance flexible bismuth telluride-based thermoelectric materials and the optimization of their properties.

Key words: Cu_0.005Bi_0.5Sb_1.495Te₃, magnetron sputtering, thin film, flexible thermoelectric device