Electrochemical co-deposition of sol–gel/carbon nanotube composite thin films for antireflection and non-linear optics

Abstract

Sol–gel/carbon nanotube (CNT) nano-composite films were electrochemically deposited by applying a negative potential to a conducting substrate, i.e. indium tin oxide (ITO) and an Ag grid printed on polyethylene terephthalate (PET). The deposition is driven by the local pH rise on the cathode that catalyzes the formation of sol–gel films. The latter serve as a binder and trap for CNTs. The deposition can be well manipulated by the deposition potential and time, and the film can be selectively electrodeposited on the conductive parts of Ag grids printed on PET from an optimized dispersion. The thickness, transmittance, morphology and hydrophilicity of the films are characterized by profilometry, spectrophotometry, scanning electron microscopy (SEM) and water contact angle, respectively. It is further revealed that the electrodeposited sol–gel/CNT composite films have non-linear optical properties and exhibit pronounced antireflective performance (specular reflection < 0.5%) over a visible to long-wave IR range, allowing their potential application as optical materials.