Use of a flexible thermoelectric source is a feasible approach to realizing self-powered wearable electronics and the Internet of Things. Inorganic thin films are promising candidates for fabricating flexible power supply, but obtaining high-thermoelectric-performance thin films remains a big challenge. In the present work, a p -type Bi x Sb 2− x Te 3 thin film is designed with a high figure of merit of 1.11 at 393 K and exceptional flexibility (less than 5% increase in resistance after 1000 cycles of bending at a radius of ∼5 mm). The favorable comprehensive performance of the Bi x Sb 2− x Te 3 flexible thin film is due to its excellent crystallinity, optimized carrier concentration, and low elastic modulus, which have been verified by experiments and theoretical calculations. Further, a flexible device is fabricated using the prepared p -type Bi x Sb 2− x Te 3 and n -type Ag 2 Se thin films. Consequently, an outstanding power density of ∼1028 μW cm −2 is achieved at a temperature difference of 25 K. This work extends a novel concept to the fabrication of high-performance flexible thin films and devices for wearable energy harvesting.
Shengqiang Cui,Chao Wang,Min Hao,Xudong Huang,Chunhui Wang,Xinxin Wang,Yajing Wang
Bismuth telluride-based alloys are widely used as commercial thermoelectric materials around room temperature. In this study, Bi 0.46 Sb 1.54 Te 3 alloys were synthesized using a solid-state reaction method with precise control of the Bi/Sb stoichiometric ratio. Increasing Bi content enhanced the bond polarity, raising the formation energy of antisite defects, and reducing carrier concentration. The carrier concentration decreased from 5 . 7 × 1 0 19 cm −3 to 4 . 2 × 1 0 19 cm −3 . Additionally, SEM observations identified a significant presence of precipitates, while TEM analysis revealed nano-sized secondary phases within the matrix. Due to the scattering of phonons by precipitates on the grain surfaces and nano-sized secondary phases, the lattice thermal conductivity near room temperature was significantly reduced to 0.29 W/m K. The optimized composition achieved a peak ZT of 1.59 at 350 K and an average ZT (ZT ave ) of 1.46 between 300–500 K. This work demonstrates that controlling the Bi/Sb ratio is an effective strategy to improve the thermoelectric performance of (Bi,Sb) 2 Te 3 alloys.
For Bi x Sb 2− x Te 3 (BST) in thermoelectric field, the element ratio is easily influenced by the chemical environment, deviating from the stoichiometric ratio and giving rise to various intrinsic defects. In P-type polycrystalline BST, Sb Te and Bi Te are the primary forms of defects. Defect engineering is a crucial strategy for optimizing the electrical transport performance of Bi 2 Te 3 -based materials, but achieving synchronous improvement of thermal performance is challenging. In this study, mesoporous SiO 2 is utilized to successfully mitigate the adverse impacts of vacancy defects, resulting in an enhancement of the electrical transport performance and a pronounced reduction in thermal conductivity. Crystal and the microstructure of the continuous modulation contribute to the effective phonon–electronic decoupling. Ultimately, the peak zT of Bi 0.4 Sb 1.6 Te 3 /0.8 wt% SiO 2 (with a pore size of 4 nm) nanocomposites reaches as high as 1.5 at 348 K, and a thermoelectric conversion efficiency of 6.6% is achieved at Δ T = 222.7 K. These results present exciting possibilities for the realization of defect regulation in porous materials and hold reference significance for other material systems.
危险品化学品经营许可证（带存储）