Preparation And Thermoelectric Properties Of PEDOT/SWCNT/BC Flexible Films

Conductive polymer/carbon nanotube composite thermoelectric materials have become the research hotspot of organic thermoelectric materials due to the excellent thermoelectric performance and high flexibility.However,there are still some problems,such as the introduction of carbon nanotubes(CNTs)increase the thermal conductivity,the mechanical properties of composites are low.In response to these problems,we select bacterial cellulose as a matrix to prepare SWCNT/BC composite materials with porous structures,PEDOT/SWCNT/BC and PEDOT@BC/SWCNT composite films,and the SWCNT contents,composite method,porous structure on the thermoelectric properties of the composites were investigated.Firstly,SWCNT/BC composites with different porosities are prepared by three methods:freeze-drying,freeze-drying and cold-pressing post-treatment,and vacuum suction filtration.The result show that the moderate porosity can effectively reduce the thermal conductivity and control the electrical conductivity without a significant decrease,so that the composite thermoelectric materials have best thermoelectric properties.Secondly,using PEDOT in-situ polymerization method,PEDOT is coated on the surface of BC nanofibers and SWCNT bundles to form a complete conductive network,which significantly improved the electrical conductivity,and in-situ polymerization also allowed PEDOT to be uniformly compounded.PEDOT/SWCNT/BC composites have low thermal conductivity and stable Seebeck coefficients that do not change with SWCNT content.The ZT value of the PEDOT/SWCNT/BC composite with 32%SWCNT content is 0.028.And the composite film has good flexibility and mechanical properties.Finally,we change the composite method of PEDOT and SWCNT,PEDOT is coated on BC nanofibers and the PEDOT@BC composite with SWCNT to obtain PEDOT@BC/SWCNT composite materials.The electrical conductivity and Seebeck coefficient increases with the increase of SWCNT content,and PEDOT@BC/SWCNT composite have a low thermal conductivity.The maximum ZT is 0.13 at 70%SWCNT,and the performance of the films do not decrease during the 200-time bending test,and it have good flexibility.