A study on characterization of nano-porous NiO thin film to improve electrical and optical properties for application to automotive glass

• Published in: Thin solid films 2017-11, Vol.641, p.28-33
• Main Authors: Lee, Won Chang, Choi, Eun Chang, Boo, Jin-Hyo, Hong, Byungyou
• Format: Article
• Language: English
• Subjects: Block copolymer; Electrochromic film; Nanoporous films; Nickel oxide; Sol-gel deposition
• ISSN: 0040-6090; 1879-2731
• DOI: 10.1016/j.tsf.2017.02.049

Nano-porous nickel oxide (NiO) film is coated on the indium tin oxide glass using nickel acetate solution containing block copolymer as the surfactant by the sol-gel method with a spin coating technique. The block copolymer assists the porosity of NiO thin film, which improves the ion intercalation and deintercalation. The electrochromic properties of NiO thin films with different thickness are investigated in an aqueous alkaline electrolyte (0.1M KOH) by means of cyclic voltammetry, chronoamperometry and transmittance measurements. The nano-porous structure of NiO thin film gives good reaction kinetics with high diffusion coefficient of 1.79×10−9cm2s−1. In the case of NiO thin film with thickness of 170nm, the electrochromic properties are observed with the coloration efficiency of 129.73cm2C−1, coloration/bleaching time of 7.95/3.33s and transmittance modulation of 28% at a wavelength of 550nm. The thinner NiO film is, the better diffusion coefficient and coloring change time are. However, the transmittance modulation and coloration efficiency of the device are better as NiO film is thicker. Therefore, it is important to optimize the electrochromic device parameters depending on application area because they are trade-off relation. •Porous NiO film can be made using block copolymer as surfactant.•Thinner porous NiO film demonstrates the better diffusion coefficient.•Transmittance modulation and switching time are related to porous NiO film thickness.