NiO İNCE FİLM BAZLI ELEKTROKROMiK KAPLAMA/CiHAZ TASARIMI, HAZIRLANMASI VE KARAKTERiZASYONU
Özet
Electrochromism is the fundamental mechanism by which the optical properties of the material change in a reversible manner with the electrical voltage applied on the electrochromic material. Color, optical transmittance, reflectance, and absorbance of the electrochromic material change. Variation in optical properties emerge visually as color change.
Electrochromic (EC) coatings / devices such as screen, glass, and mirror, which have basic usage areas, have just started to be seen in our daily lives. Particularly in today's world, where efficient use of existing energy sources is a major concern, smart glasses come to the forefront for effective use of the solar radiation, in other words, to ensure energy saving.
Problems related with the stability and lifetime of the electrochromic devices currently in use speed up the research in this area. Non-homogeneous coloration/bleaching on large surfaces requires further research. Adjustment of the user-controlled switching period is also another problem. Although the coloration mechanism of the metal oxide electrochromic materials has been studied since the 1980s has still not been fully understood. In particular, the coloration / bleaching processes of NiO thin films which are one of the most studied anodic electrochromic materials, need to be optimized depend on the film deposition and post-deposition parameters.
In this study, the optimization of the deposition parameters of the NiO thin films deposited by RF magnetron sputtering was done. Optical, electrochromic and structural properties of NiO thin films were investigated in detail. Effects of deposition parameters such as working pressure, RF power, substrate temperature, argon gas pressure and partial pressure of oxygen and hydrogen in argon were studied. Influence of different electrolyte solutions, solution molarity, scanning rate, and number of cycles on the electrochromic properties of these films was investigated. XPS and XRD measurements were performed for the colored and bleached state of the NiO thin films exhibited large optical modulation and high coloration to understand the coloration and bleaching processes in the films.
Then, custom design electrochromic devices (ECD) with different configurations were fabricated using the NiO film as an anodic layer developed on this study. The ECDs were fabricated in a laminated and an all-solid state structures. All thin films employed in the ECDs were also deposited using RF magnetron sputtering technique. ITO and WO3 thin films were used as transparent conductive layer and cathodic layer, respectively in the devices.
The wet and dry lithiation processes were studied in detail with the aim of fabricating ECDs for the commercial applications in this study. Propionic acid, potassium chlorate, lithium perchlorate solutions dissolved in propylene carbonate were selected as ion-conducting layer for the laminated ECDs. For the all-solid-state devices, oxide thin films such as ZrO2, Ta2O5 and LiNbO3 were used as ion-conducting layer. The electrochromic performance of these devices were investigated.
