A systematic study on synthesis parameters and thermoelectric properties of tellurium nanowire bundles

The controlled growth of tellurium (Te) nanocrystals is vital for making Te-based nanomaterials with finely tuned morphology and thermoelectric properties. Herein, to reveal the controlling parameters and their roles behind the synthesis of Te nanowire bundles (NBs), they were systematically investigated. The unveiled growth mechanism of Te-NBs is a “solid-solution-solid” transformation process from amorphous Te (a-Te) spheres to trigonal Te (t-Te) NBs. Accordingly, Te-NBs with different sizes and crystallinity have been successfully prepared by simply adjusting the reaction temperature and initial solution pH to regulate the generating rate of Te atoms and the dissolution rate of a-Te spheres. Well-ordered Te-NBs with a large width and high crystallinity can be synthesized at an optimized reaction temperature of 90 °C and an initial solution pH value of 10. The relationship between the thermoelectric properties of the Te-NB thin film (Te-NBs-TF) and the width and crystallinity of the NBs exposes that a large width and high crystallinity lead to a high thermoelectric performance of Te-NBs-TFs, and the optimized results can reach a power factor of 35.2 μW m−1 K−2 at room temperature. This work provides crucial information for the controllable synthesis of Te-NBs and a facile preparation avenue of Te-based thermoelectric films, which paves the way for future industrial applications of high-performance thermoelectric devices.