電場輔助水熱法氧化鋅奈米線成長之研究

本研究主要目的為探討藉由外加電場輔助水熱法成長氧化鋅奈米線並研究其特性與作為染料敏化太陽能電池之光電極的影響。水熱法其優點是在於低溫、低成本製程。首先以射頻磁控濺鍍機在矽基板上沉積氧化鋅薄膜為晶種層，水熱法實驗中以硝酸亞鉛六水化合物 (Zn(NO3)．6H2O) 和六亞甲基四銨 ((CH2)6N4 ) 為主要反應物，電場輔助藉由施加不同電場方向與強度，來影響氧化鋅奈米線之成長。利用場發射電子顯微鏡(FE-SEM)觀察表面形貌發現當電場垂直入射與出射基板面時，氧化鋅奈米線會呈現不同的成長速率；而X光繞射(XRD)下顯示出外加電場不會影響氧化鋅奈米線C軸取向之特性；光致螢光光譜(PL)在線徑長度較短時，有較少之光學缺陷；XPS顯示出當出射電場強度增加，使得氧缺陷相對的減少。並將其應用於染料敏化太陽能電池上，當電場強度193.4 kV/m出射透明導電玻璃基板面成長氧化鋅奈米線時，有最佳光電轉換效率η＝0.3％，並經由交流阻抗(EIS)證實，其電解質與光電極間的阻抗為最小，導致光電流最大，提升了光電轉換效率。

關鍵字

氧化鋅；水熱法；電場；染料敏化太陽能電池

並列摘要

The important aim of this paper is to study of ZnO nanowires grown by electric field assisted hydrothermal growth process. The properties of zinc oxide nanowires were analyzied and application of a photoanode in dye-sensitized solar cell was discussed. Hydrothermal method is the low temperature, low-cost process for fabrication of the single crystal nanostructure. The ZnO film on Si substrate was deposited by RF-sputter as a seed layer. Used Zn(NO3)•6H2O and (CH2)6N4 as reactants in the hydrothermal method. We applied the electric field with different direction and strength for influenced the growth of ZnO nanowires. We found that the growth rates were different while the electric field direction was different determined by FE-SEM. XRD diffraction patterns show that the external electric field will not affect the ZnO nanowires characteristics of C-axis orientation. PL spectral show the amount of optical defect in ZnO nanowires is decrease as its length is shorter. The XPS shows strength of electric field exit was increased, the oxygen defect of surface was reduced. And ZnO nanowires applied in dye-sensitized solar cell, the best conversion efficiency, η = 0.3 %, in this study was obtained when the electric field of 193.4 kV/m out from the transparent conductive oxide glass substrate employed. By EIS confirmed that the impedance between the electrolyte and ZnO nanowire arrays was minimized and result in obtained the maximum of photocurrent to enhance the photoelectric conversion efficiency.