有機發光二極體(OLED)作為新一代顯示器之技術之一，與液晶顯示器(LCD)相比OLED可以製作成很薄之螢幕，具有廣視角、可撓曲性、低驅動電壓等優勢，因此在近數十年來引起很大之關注，並大量投入鑽研機制之探討與效能之改善，使OLED相關產品之開發與量產能夠蓬勃發展。
本論文以提升OLED元件之載子注入與傳輸性質，進而改善元件效率與穩定性為研究動機，探討ZnO摻雜Nb2O5材料，利用熱蒸鍍技術將此金屬氧化物薄膜沉積於OLED元件上，分析此薄膜之特性與如何提升元件整體之性能。
本論文分為兩個部分，第一部分利用不同Nb2O5摻雜濃度和ZnO基厚度優化之金屬氧化物當作緩衝層，蒸鍍於ITO基板上再使用紫外光臭氧後處理，並利用各種量測方法探討其對於載子注入特性的影響。其中，以X射線與紫外光電子能譜儀測定薄膜之材料特性與功函數值，再利用接觸角量測計算出表面能與極性還有量測表面粗糙度，並利用單載子元件之電流密度數據計算載子遷移率。由量測結果得知，此金屬氧化物作為緩衝層可降低驅動電壓、提升亮度表現與發光效率，具較好的載子平衡效果，可大幅地增強元件整體效能。
第二部分嘗試將此材料應用於漸變式摻雜結構上，並將原本文獻之兩層摻雜改變為三層摻雜梯度，發現能夠提升元件載子之注入與發光效率，並透過紫外光電子能譜儀之測量結果畫出各層材料之間的能帶關係圖，發現漸變式摻雜層的HOMO位置會介於陽極功函數與傳輸層HOMO之間，可降低載子注入之能障，有效提升電洞之注入，並利用導納頻譜技術對元件之發光行為進行分析，可成功觀察載子之注入、傳輸、堆積、再結合等行為，呼應其光電物理特性之量測，以增加研究內容論述之可靠性。

In this thesis, we used metal oxide materials of Nb2O5-doped ZnO (NZO) by using thermal evaporation technology to deposit this film on organic light-emitting diodes (OLEDs) and analyzed it how to improve the overall performance of the device. We found out 1nm-NZO thin film with 1mole% was the best parameter in this study and the optimized device got highest current efficiency (5.26 cd/A) and maximum luminous (25370 cd/m2). In the second part, we tried to apply this material to a graded doping structure by thermal co-evaporating with organic layer and changed doping gradient. We found that the three-graded doping layer would move the HOMO energy level to the middle of the energy barrier between the anode and the organic layer so that the energy barrier of carrier injection can be reduced, thereby improving the efficiency of the device.

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