Properties of CNTs coated by PEDOT:PSS films via spin-coating and electrophoretic deposition methods for flexible transparent electrodes

Hybrid-type transparent electrodes, which possess the characteristics desirable for flexible touch screen panels, were fabricated by coating PEDOT:PSS [poly (3, 4-ethylene-dioxythio-phene):poly (styrenesulfonate)] films on carbon nanotubes (CNTs) via either spin-coating or electrophoretic deposition (EPD). For all the samples including the CNTs and the hybrid electrodes (i.e., PEDOT:PSS-coated CNTs), surface morphologies and cross-sections, sheet resistances, and visible transmittances were characterized as functions of their preparation conditions. Also, to identify the flexible capabilities of the hybrid electrodes, the changes in their sheet resistances due to repetitive bending (up to 30,000 times) were measured and compared with the results measured for the CNTs. In the hybrid-type electrodes, the PEDOT:PSS particles filled up the voids between the tubes in the CNTs, thereby forming a conduction bridge for electron transfer and eventually decreasing the sheet resistance. Furthermore, the PEDOT:PSS layers induced physical gripping of the CNTs to enable them to adhere better to the underlying PET substrates, indicating that the hybrid electrodes were more desirable in flexibility than were the CNTs.