Experimental observation on the mixing systems and ways to significantly enhance the conductivity of PEDOT-sulfonated poly(imide) aqueous dispersion

Abstract

Conductive poly(3,4-ethylenedioxythiophene):sulfonated polyimide (PEDOT:SPI) films were successfully developed by decreasing the particle size along with the addition of anionic surfactant leading to potential applications in electronic devices. By varying the mixing system (magnetic bar at 1000rpm, mechanical at 1000rpm and mechanical at 4000rpm), we observed significant conductivity and thermal stability enhancement of the obtained PEDOT-SPI films by using designed stir shaft with high-speed mechanical mixing systems allowing for smaller particle sizes of PEDOT:SPI about 43nm averaging. In addition, the further conductivity enhancement and thermal stability of PEDOT:SPI was achieved by adding various amounts of anionic surfactant into the aqueous polymer suspension because of the resulting conformational changes. The highest conductivity, 9.5Scm−1, was achieved at 1wt% SDS in PEDOT:SPI (6FDA) film which increased by a factor of 5 from the PEDOT:SPI without addition of SDS. Moreover, using a high-speed mechanical mixing system and addition of anionic surfactant also improved the thermal stability of conductive films, which was verified by TGA analysis. Due to the combination of using high-speed mechanical mixing and adding of anionic surfactant, superior dispersion stability, high conductivity and good thermal stability PEDOT:SPI films were achieved.