Surface modification of plastic substrates via corona-pretreatment and its effects on the properties of carbon nanotubes for use of flexible transparent electrodes

Abstract

In this study, the surface of polyethylene terephthalate (PET) substrates was modified via corona treatment before the deposition of carbon nanotubes (CNTs), and the effects of such surface modification on the properties of the CNTs for flexible transparent electrodes were investigated. The changes in the surface roughness, contact angle, and surface energy of the PET substrates due to the corona treatment were characterized in terms of the applied corona energies, PET feeding directions, and treatment times. The higher corona energies, the more frequent treatment times, and the bi-directional treatment produced the larger surface roughness of the PET substrates. The results of the contact angles and the surface energies indicated that the surfaces of the PET substrates became hydrophilic from hydrophobic after the corona treatment. The analysis using X-ray photoelectron spectroscopy confirmed that oxygen polar groups appeared when the PET substrates were corona-treated. In addition, the increase in the CNTs' sheet resistance values due to their repeated outer and inner bending (up to 16,000 times) was found to have been significantly alleviated when the CNTs were deposited on the corona-treated PET substrates. This confirmed that the adhesion of the CNTs was improved after the corona pretreatment of the PET substrates. (c) 2015 Elsevier B.V. All rights reserved.