Improvement in color properties of copper mesh electrodes via electrophoretic coating with nano-structured carbon materials

Abstract

In this study, the effects of coating with nano-structured carbon materials, such as carbon nanotube (CNT) and graphene, on the characteristics of transparent conductive electrodes based on copper (Cu) meshes, particularly on the visibility related to their color properties, were examined. The electrical sheet resistance of the Cu meshes remained almost unchanged regardless of the coating with CNT and graphene. Through the electrophoretic deposition method, the CNT and graphene layers were selectively used to coat only the regions where Cu mesh patterns had been formed, which helped minimize the transmittance loss caused by the coating with CNT and graphene. The reflectance of the Cu mesh was substantially reduced by the coating with CNT and graphene, meaning that the CNT or graphene coating layer played the role of suppressing the visible light reflected from the Cu mesh. In addition, the reflectance reduction effect was greater when the Cu mesh was coated with CNT rather than with graphene, which was attributed to the difference in particle size between the CNT suspension and the graphene suspension. Furthermore, the chromatic parameters (e.g., redness, yellowness) of the Cu meshes approached almost zero as the thickness of the CNT or graphene coating layer increased, meaning that the Cu meshes became nearly colorless, while the primitive Cu mesh was tinged with a red-orange color. The experiment results presented in this study verified that the combined technology with CNT and graphene coating contributed to the amelioration of the poor visibility caused by the high reflectance and color-tinted nature of the conventional Cu mesh.