表面多孔化Bi_(2)Te_(3)柔性薄膜的制备及热电性能研究

Preparation of Bi_(2)Te_(3) flexible film with porous surface and its thermoelectric properties

柔性热电器件能够满足复杂环境的热量收集和转化需求,是目前研究的重要方向之一。但受制于材料电/声输运性能的强关联作用,柔性热电器件的能量转化效率仍然较低。以聚酰亚胺为柔性衬底,采用磁控溅射的方式制备Bi_(2)Te_(3)柔性热电薄膜,并通过退火对薄膜表面进行改性。结果表明,高温退火能够诱导Bi_(2)Te_(3)薄膜表面产生多孔化结构,且孔隙密度和尺寸可通过退火工艺调控;多孔结构对薄膜的电/声输运性能具有协同优化作用,薄膜热导率较退火前降低约50%,Bi_(2)Te_(3)柔性薄膜的热电优值显著提升。

Flexible thermoelectric devices can meet the demand of heat collection and conversion in various environments.However,the energy conversion efficiency of flexible thermoelectric devices is still low,which is mainly due to the strong correlation between the electrical and acoustic transport properties of materials.In this paper,Bi_(2)Te_(3) flexible thermoelectric thin films are prepared by magnetron sputtering on the flexible polyimide substrate,and the surfaces of the thin films are modified by annealing.The results show that high temperature annealing can induce the porous structure on the surface of Bi_(2)Te_(3) film,and the density and size of pores can be controlled by annealing parameters.The electrical/acoustic transport properties of the thin films could be synergistic optimized by porous surface.The thermal conductivity of the thin films decreases by about 50%compared with that before annealing,and the ZT value of Bi_(2)Te_(3) flexible thin film is improved significantly.