熱處理效應對溶膠凝膠法製備之氧化鎢薄膜電致色變特性分析

Effect of thermal annealing and Characterization of electrochromic WO3 film synthesized by sol-gel method

游毓珈(Yu-Chia Yu)

指導教授 ： 程金保

國立臺灣師範大學/科技學院/工業教育學系/碩士(2008年)

摘要

本研究分別以金屬烷氧化合物(M-OR)及金屬離子(MZ+)為主製作氧化鎢薄膜鍍液。以FTIR鑑定前驅粉體之成分，以及使用TGA與DSC檢測前驅粉體之熱穩定性。前驅溶液以異丙醇為溶劑，檸檬酸為蟄和配位基（chelating ligand），使用旋塗方式將氧化鎢薄膜塗佈於ITO玻璃基板上，並比較氧化鎢薄膜未退火狀態及350 ℃溫度於不同退火條件（大氣退火、真空退火與氧氣氛退火）之電致色變性質分析。本研究中使用AFM、SEM與XRD觀察鍍膜表面形貌與微結構，並以LiClO4/PC為電解質，對元件施加± 2.0 V電壓後觀察薄膜在UV/VIS/NIR光譜 (190 – 2600 nm)實驗中著-去色穿透率變化與電化學性質。
由SEM觀察薄膜表面形貌發現氧化鎢薄膜表面皆具有微小裂縫與微孔現象，有利電致色變過程電子與離子的進出。由光譜圖可發現，氧化鎢薄膜在紫外光波段穿透率幾乎為零，於近紅外光譜區段具有一定的阻隔能力，穿透率約在10％以下。實驗結果以迴流方式去除過氧化氫之金屬烷氧化合物前驅粉體，製備之氧化鎢鍍膜，並於氧氣氛退火之試片具有最佳電致色變性質。此外，在可見光波長範圍氧氣氛退火之薄膜具有較高的穿透率，而經由真空退火的薄膜穿透率較低。最後，氧化鎢薄膜之能隙在經過大氣及真空退火之後，著色態能隙與未退火薄膜能隙比較有下降的現象。

關鍵字

氧化鎢 ； 溶膠凝膠法 ； 電致色變

並列摘要

The sol-gel technique has been employed for synthesizing three precursor materials for the deposition of tungsten oxide based electrochromic films, including M-OR and MZ+. The characteristics of these precursor materials have been tested by FTIR、TGA and DSC. The precursor based solid materials were dissolved in isopropyl alcohol individually and citric acid was used as organic chelating agent to get the coating gel. Then the sol-gel process is used to prepare the tungsten oxide thin film on indium tin oxide conductive glass (ITO glass) by the way of spin coating. The annealing treatment is conducted at 350℃ under the open air, vacuum, and oxygen environment, respectively, in order to understand the influence of different heat treatment environment on the electrochromic property of tungsten oxide film. The atomic force microscope (AFM) and scanning electron microscope (SEM) were used to observe the surface morphology and it is found that there are some small cracks and micropores on the surface of tungsten oxide film, which are favorable for the access of electrons and ions during the electrochromic process.
The experimental results indicate that the solution was refluxed at 55 ℃ for 24 hours to decompose excess hydrogen peroxide can make the thin films with better electrochromic property. The spectrogram shows that the ultraviolet (UV) transmittance of colored tungsten oxide film is nearly zero, and there is a certain isolating ability under near infrared (NIR) spectrum region, the transmittance is below about 10%. The thin films annealed at oxygen environment show higher transmittance modulation between colored and bleached state under visible light (VIS) spectrum region, but the films annealed at vacuum environment have lower transmittance modulation. Finally, the band gap of colored state of the tungsten oxide films annealed under open air and vacuum environment is lower than the band gap of as-deposited film.

並列關鍵字

tungsten oxide ； sol-gel method ； electrochromic property

參考文獻

5. P.H. Lissberger, J.M. Pearson, The performance and structural properties of multiplayer optical filters, Thin Solid Films, 34 (1976) pp. 349 – 355.

6. C.G. Granqvist, Handbook of Inorganic Electrochromic Material, Elsevier, Amsterdam, 1995.

7. E.S. Lee, D.L. DiBartolomeo, S.E. Selkowitz, Daylighting control performance of a thin-film ceramic electrochromic window: Field study results, Energy and Buildings, 38 (2006) pp. 30 – 44.

8. Nilgun Ozer, Carl M. Lampert, Electrochromic characterization of sol-gel deposited coatings, Solar Energy Materials & Solar Cells, 54 (1998) pp. 147 – 156.

9. J. livage, D. Ganguli, Sol-gel electrochromic coatings and devices: A review, Solar Energy Materials & Solar Cell, 68 (2001) pp. 365 – 381.