近年來由於液晶顯示器（LCD）與太陽能電池（Solar cell）的發展，透明導電膜的運用也愈趨成長，為了降低成本與減少氧化銦錫（ITO）使用量，必須開發一些具透明且有導電性的非銦材料，氧化鋅摻雜鋁（AZO）就是其中之ㄧ。本研究的目的為製作氧化鋅摻雜鋁透明導電膜，因此必須先找到配製鍍膜液的條件。 先前本實驗室發展出用氯化鋅（ZnCl2）和氫氧化鈉（NaOH）在乙二醇（EG）溶劑中進行酸鹼中和，再加熱縮合後得到粒徑約 5~6nm，泛藍光且透明度高的氧化鋅奈米結晶。但是其缺點為會有大量的副產物NaCl 鹽類存在難以去除且 ZnO固含量低約 4wt%。 相較於許多文獻都是經過多次鍍膜程序，我們想要ㄧ次就製作出數百奈米的厚度，所以必須將鍍膜液中 ZnO 濃度提高到 50wt%以上，並且將鹽類去除。 經由實驗發現利用 PGME當cosolvent可以讓己烷（hexane）與 EG互溶，並降低介電常數藉以將氧化鋅凝絮，等己烷溶劑揮發後即可得到高濃度的透明氧化鋅溶膠，並且去除了大部分的鹽類，由 TGA 測量結果得知此時 ZnO 含量約 64wt%。接著利用甲醇配置成濃度約 30wt%的鍍膜液，使用浸漬塗佈法（dip-coating）拉升一次，在空氣中加熱到 400℃將有機物去除，即可得到穿透度>90%的氧化鋅薄膜，由 SEM 觀察得知厚度約 300nm。 氧化鋅鍍膜程序確定後，接著進行氧化鋅摻雜鋁透明導電膜的研究，在合成源頭之氯化鋅中加入摻雜不同比例的鋁，依照前述鍍膜的程序製作出 AZO透明導電薄膜。除了?雜的量以外，不同氣氛、不同溫度下進行?燒，都會影響膜的導電性質，因此必需嘗試不同實驗條件，藉以獲得最低的電阻值與最高透明度的導電膜。本研究最後獲得電阻率大約0.02Ωcm，厚度約 300nm，片電阻約691Ω/□的AZO透明導電薄膜。 Significant progress has been made in transparent conductive oxide (TCO) films, largely motivated by the emergence of LCD and solar cell industries. In the search for a cheaper and indium-free materials to replace the traditional ITO, aluminum-doped zinc oxide (AZO) has been the leading candidate. Therefore, the objective of this research is to identify experimentally the controlling factors that ultimately govern the transparency and electrical conductivity of AZO film. ZnO nanoparticles of size 5~6 nm have been successfully synthesized previously in our Lab by titrating zinc chloride with sodium hydroxide in ethylene glycol solution, followed by low temperature aging. However, such method has two serious drawbacks – the production of unwanted sodium chloride byproduct, and a low concentration (4 wt%). This would require multiple coatings and sintering needed to achieve the desired thickness. To achieve the desired AZO film thickness with a single coating, the concentration of ZnO solution must be about 50 wt%. At the same time the NaCl byproduct must be remove. Using PGME as a co-solvent to dissolve hexane in EG, ZnO nanoparticles were precipitaled while redisperse after evaporation of hexane. TGA analysis showed an increased in weight percent (64 wt%). After dilution with methanol to 30 wt%, the as-prepared film with one dip-coating cycle was sintered in air at 400oC. The resulting film showed a transparency of higher than 90% and a thickness of 300 nm as measured by SEM. Subsequent study involved the dopping of aluminum and sintering conditions on the electrical conductivity and transparency of AZO films. Variables sadas sintering atomsphere and temperature were also tested to study their respective impacts.
