OLED (有機發光二極體) 是新一代平面顯示器技術，與LED元件一樣，是利用兩個導體電極之間插入多層有機材料製作而成，其與液晶顯示器（LCD）不同之處在於OLED螢幕可以製作得非常薄，且具有寬視角，並可用於可撓曲式透明顯示器等特殊應用。此外，OLED還具有低驅動電壓、快速響應以及低成本的優點。鑒於此，近年來， OLED特性的鑽研改善和機制研究，使我們更加深入的瞭解這塊領域。本研究目的在於使用熱蒸鍍的技術將OLED元件中沉積金屬氧化物薄膜作為無機緩衝層，並研究NiO摻雜K2CO3緩衝層如何改進整體元件之效率。此外，本論文將會使用導納頻譜技術來評估OLED元件之相關特性，以增加研究論述之可靠度。
首先，利用各種不同濃度和厚度的摻雜金屬氧化物，用以形成超薄緩衝層熱蒸鍍於ITO基板上，並利用紫外光臭氧進行表面處理後，藉此使用不同測量方法來探討其對於元件載子注入特性的影響。其中，以X射線和紫外線光電子光譜儀來測定其表面能量化來研究其分子束縛能量，及其接面特性和功函數。再者，利用接觸角量測表面薄膜，計算其表面能和表面極性，而原子力顯示器則是測量表面粗糙程度。最後，利用導納頻譜分析量測出電容及電導。由以上的量測之相關結果，搭配元件的驅動電壓降低、亮度和電流效率增加，可以得知加入一層金屬氧化物摻雜鹼金屬在ITO與電洞傳輸層可以大幅提升元件之綜合表現。
再來，我們利用緩衝層的最佳參數製作於熱活化性廷遲螢光 (TADF) OLED。本研究的目的為，利用金屬氧化物之電洞注入層於不同屬性的發光層做更進一步的探討，並為各種情況提供最佳化的設計。由於發光層的屬性不同，其中一種為單一發光層, 另一種為主客體發光層，因此本文將探討並研究其緩衝層對不同OLED 造成的影響和機制。
接著，為了觀察元件表現和可靠性，本文將研究電荷轉移的機制，以闡明兩種不同的OLED元件，並以亮度 - 電流 - 電壓、導納頻譜之電容-電壓測試、以及二次離子質譜儀測試來進行此特性之探討。此外，測量的目的為進行快速測試，可用於預測不同元間的長期性能，並觀察離子在有機材料中遷移的現象。

OLED (Organic-Light Emitting Diode) is a semiconductor technology just like an LED (Light Emitting Diode) component, made by inserting multiple sheets of organic thin film between two conductors. Unlike liquid-crystal displays (LCDs), OLED screens can be made very thin, have wide viewing angles, and can be used on bending transparent displays. In addition, OLEDs have other advantages such as low-voltage operation, fast response, and low cost. As a result, research on the OLED’s performance improvement and operating mechanism are thoroughly discussed in recent years. In this study, we use thermal evaporation method to deposit metal oxide films as inorganic buffer layer in OLEDs devices, and investigate how the K2CO3-doped NiO buffer layers improve device performance. We also use Admittance Spectroscopy technique for the investigation of reliability evaluation for OLED display.
First, we used various concentrations and thickness of alkali metal-doped metal oxide anode buffer layers on the ITO substrates. The anode substrates were then subjected to UV-O3 surface treatment. We studied the effect and mechanism on the improved hole injection properties of OLEDs with different measurement methods. X-ray Photoelectron Spectroscopy and Ultraviolet Photoelectron Spectrometer were used to measure molecules’ binding energy and work function. Contact angle measurement was used to measure surface energy and polarity. Atomic Force Microscope was applied to measure the surface roughness. Admittance Spectroscopy was utilized to measure the capacitance and conductance, which can be used to obtain the sheet resistance. With above measurement methods, adding with improved turn on voltage, luminance and current efficiency results, we can conclude that alkali metal-doped metal oxide anode buffer layers insertion between ITO and hole transporting layer may significantly improve performance of OLED devices.
Next, we applied the optimal parameters of anode buffer layers on different emission layer properties. The objective of this work is to examine different emitting attribute OLED devices using metal oxide hole injection layer and to provide optimum design for each case. We studied different affect and mechanism on emission layers as different emission mechanism could produce various phenomenon.
Finally, the investigation of charge transfer mechanism of OLEDs is crucial to determine performance and reliability. To determine these characteristics, two different OLED devices were elucidated to test on cell level and characterized by luminance-current-voltage (L-I-V), capacitance-voltage (C-V), and Secondary-ion Mass Spectrometry (SIMS) measurement. Additionally, the purpose of these measurements was also to perform accelerated test, which can be utilized to predict devices’ long term performance, and perform observation on the migration phenomenon of ions in organic materials.

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