氧化鋅薄膜調制液晶預傾角之研究

Abstract

本論文旨在研究氧化鋅薄膜對液晶配向之特性，經由改變氧化鋅薄膜的濕潤性來控制液晶分子的預傾角。氧化鋅薄膜是藉由溶膠–凝膠法成長於ITO玻璃基板上，我們發現透過控制氧化鋅薄膜鍛燒溫度的高低或紫外光曝光時間可以改變氧化鋅薄膜之親疏水性。薄膜表面濕潤性主要是受到薄膜表面形貌和化學組成所影響。藉由掃描式電子顯微鏡、原子力顯微鏡、螢光光譜和化學分析電子能譜儀的觀察發現，鍛燒溫度的高低影響了氧化鋅薄膜表面結構和化學組成，然而紫外光曝光僅改變氧化鋅薄膜的化學組成。氧化鋅薄膜在鍛燒溫度從190 °C增加到250 °C或紫外光曝光時間從0分鐘增加到14分鐘時，水的接觸角約從100°降低到60°。我們的實驗數據顯示當氧化鋅薄膜之水的接觸角降低時，液晶配向從垂直配向漸變成水平配向。

In this work, we find that the pretilt angle of LC molecules aligned on the ZnO film depends on the surface wettability. We demonstrate that the surface wettability of ZnO films fabricated by sol-gel process can be modified by the annealing temperature or UV illumination. The wettability of ZnO films depends on morphologies and chemical compositions. The observations of the scanning electron microscope (SEM), atomic force microscope (AFM), photoluminescence (PL) and electron spectroscopy for chemical analysis (ESCA) of ZnO films have shown that the annealing temperature can modify both the morphologies and chemical compositions of ZnO films; on the other hand, the UV illumination only modifies the chemical compositions of ZnO films. The surface wettability of ZnO films can be controlled from approximately 100° to 60° as the annealing temperature increases from 190 to 250 °C or the UV illumination time increases from 0 to 14 minutes. Our experimental results show that the pretilt angles of LCs on ZnO films can be successfully adjusted over a wide range from 0.5° to 89.5° as the contact angle of water on the ZnO films changes from 60° to 100°.