| AVS 62nd International Symposium & Exhibition | |
| Electronic Materials and Processing | Tuesday Sessions |
| Session EM-TuP |
| Session: | Electronic Materials and Processing Poster Session |
| Presenter: | WonChang Lee, Sungkyunkwan University, Republic of Korea |
| Authors: | W.C. Lee, Sungkyunkwan University, Republic of Korea J.U. Wie, Sungkyunkwan University, Republic of Korea E.C. Choi, Sungkyunkwan University, Republic of Korea B.Y. Hong, Sungkyunkwan University, Republic of Korea |
| Correspondent: | Click to Email |
Electrochromic materials are able to change the optical properties persistently and reversibly by an external voltage. Applications of electrochromic materials include rearview mirrors, smart windows, display panels, etc. A large number of transition metal oxides such as the well-known tungsten trioxide (WO3) cathodic material, which reversibly switches from transparent to blue upon lithium or proton insertion.
In contrast, nickel oxide (NiO) is an anodically coloring material but despite promising features such as high coloration efficiency, good optical memory and cost effectiveness. NiO is often used as a secondary electrochromic material to complement cathodically coloring WO3 in prototype electrochromic devises. Because NiO have for a long time attracted attention as counter electrode regarding their brownish color in the oxidized state that, together with the blue color of the reduced WO3, yields a neutral gray color device in the colored state. The electrochromism in NiO films is rather complicated although it is generally accepted that the reversible transition between colored and bleached states is related to redox process between the NiOOH and NiO. Moreover, owing to their rapid degradation on cycling, difficulties in using nickel oxide films have been encountered. However, the problems of NiO thin films that limit their commercialization and poor durability are still debated. When NiO film is formed as porous structure, the surface area to the volume ratio is large and the same probably lead to an increase in the ion intercalation and deintercalation. The large-area surface of the porous film structure can be helpful for the augmenting the optical modulation.
In our study, the porous NiO thin film was deposited using sol gel-method and dip-coating technique on the Indium Tin Oxide (ITO) glass. The NiO thin film was formed by annealing process at different temperatures after the dip-coating technique. Studies on the effect of annealing temperature to improve the crystallinity and the electrochromic properties of the NiO thin films have been carried out. So, we confirmed that the electrochromic efficiency was improved by optimizing of the annealing condition.