Enhancing thermoelectric properties of Bi2Te3 film via CuI doping: Sputtering and solid iodination methods verified by ab initio calculation

Abstract

We have introduced an innovative method for preparing CuI-doped Bi2Te3 films for the first time, which was also validated through ab initio calculations. The chemical reaction between the Cu-Bi2Te3 film and iodine was conducted using the solid iodination method at room temperature. The results from X-ray diffraction and energy-dispersive spectrometry suggest that the sputtering process, followed by the solid iodination method, holds promise for synthesizing CuI-doped Bi2Te3 films. Additionally, appropriately doping Bi2Te3 with CuI enhances the (00l) crystal orientation, increases carrier concentration and mobility, resulting in improved electrical conductivity. Furthermore, our calculation results align with our experimental findings. An excess of substitutional CuI dopant tends to generate secondary phases, leading to alterations in the intrinsic conductivity and a reduction in the thermoelectric properties of Bi2Te3. Leveraging the enhanced electrical transport properties achieved through CuI doping, the maximum power factor of the (CuI)0.2Bi2Te2.9 film reaches approximately 2.40 × 10−3 W/mK2 at 423 K, representing a 66 % enhancement compared to that of the Bi2Te2.9 film, which has a power factor of 1.44 × 10−3 W/mK2.