Fabrication of Bismuth-Antimony-Telluride Alloy/Poly(3,4-ethylenedioxythiophene) Hybrid Films for Thermoelectric Applications at Room Temperature by a Simple Electrochemical Process

In this study, we synthesized flexible bismuth-antimony-telluride (Bi0.5Sb1.5Te3 (BST))/poly(3,4-ethylenedioxythiophene) (PEDOT) composite films using a simple two-step electrochemical deposition process. After electrochemically polymerizing ethylenedioxythiophene (EDOT) first on the gold-coated polyethylene terephthalate (PET), BST was deposited using the PEDOT layer as a working electrode. The effect of electrochemical potential on the morphology and crystal structure of the electrochemically deposited BST alloy was investigated through scanning electron microscopy and X-ray diffraction. The results show that a cauliflower-like morphology appears with a preferential orientation along the (110) direction of Bi0.5Sb1.5Te3 within the proper potential range. We also optimized the deposition time to achieve higher thermoelectric performance on the BST/PEDOT composite film. The optimal BST/PEDOT film produced by electrochemical deposition of BST for 80 min showed superior performance compared to other previously reported organic/inorganic composite materials. The maximum power factor was about 427 mu W m-1 K-2 at an electrical conductivity of 167 S cm-1 and a Seebeck coefficient of 160 mu V K-1. This process can be readily applied to practical fabrication of efficient thermoelectric materials.