Effect of Hydrothermal Synthesis Temperature on the Microstructural and Thermoelectric Characteristics of Thermally Deposited Bi0.5Sb1.5Te3 Thin Films

Bismuth antimony telluride (Bi0.5Sb1.5Te3) is a ternary compound with good thermoelectric properties at near room temperature. In this research, Bi0.5Sb1.5Te3 powders were hydrothermally synthesized at different temperatures (100, 150, 190, and 230 degrees C) for 24 h. The deposition procedure of Bi0.5Sb1.5Te3 thin films was done by using thermal evaporation. The phases and microstructures of powders and thin films were investigated by x-ray diffraction and field emission scanning electron microscopy. Moreover, the size distribution of powders was investigated using a particle size analyzer. The phase and microstructural results of the different synthesized powders confirmed that the Bi0.5Sb1.5Te3 thin film prepared by powder synthesis at 150 degrees C for 24 h is the best choice for manufacturing with good thermoelectric properties because of its nano-sized grains and high purity. The results showed that the Bi0.5Sb1.5Te3 thin film fabricated by powders synthesized at 150 degrees C has a single rhombohedral phase with a good semiconductor performance. The results of thermoelectric tests confirmed that the Bi0.5Sb1.5Te3 thin film fabricated using a hydrothermal method and thermal evaporation deposition approach shows a high Seebeck coefficient (183.5 mu V/K) and low electronic thermal conductivity (1.32 x 10(-4) W/m k(-1)) at 298 K. Besides, the power factor values of 0.7, 2.59 and 2.9 mu W/cm K-2 were obtained at 298, 373 K and 473 K, respectively. [GRAPHICS] .