新穎有機發光元件之電磁模擬與元件研製

Electromagnetic Simulation and Fabrication of Novel Organic Light-Emitting Devices

林俊良(Chun-Liang Lin)

指導教授 ： 吳忠幟

國立臺灣大學/電機資訊學院/光電工程學研究所/博士(2006年)

https://doi.org/10.6342/NTU.2006.10174

摘要

由於有機發光二極體元件可以做為高效率、大面積及全彩的顯示器應用，近年來受到廣泛的研究及討論。在有機發光二極體元件中，許多元件結構的光學效應會很嚴重影響元件的效能。在這論文中，我們用古典電磁學去模擬及分析典型有機發光二極體、上發射型有機發光二極體及光學微共振腔有機發光二極體的發光特性。
上發射型有機發光二極體應用於主動矩陣有機發光二極體顯示器有很多技術上的長處。然而，上發射型有機發光二極體固有的強光學共振腔效應將會複雜化元件效率及其他視角特性的優化條件。在這博士論文中，我們提出一個上發射型有機發光二極體做為顯示器應用時，優化其視角特性的方法論。這分析跟方法論的有效性也經由實驗結果驗證了。
接下來，我們有系統地分析利用兩金屬電極形成光學微共振腔的有機發光二極體的光學特性。分析的結果顯示，若要從光學微共振腔元件得到比傳統元件較高的發光效率，需要有高反射的背反射鏡面以及低吸收、高反射的出口鏡面。同時，也利用嚴謹的電磁學模型，分析研究共振波長對於光學微共振腔發光特性的影響。
由於一般來說有機材料的低傳導特性及低載子傳輸能力，有機發光二極體的優化條件，都是將發光位置設計在反射金屬電極的第一個反節點位置附近。在這論文中，利用有包含傳導摻雜的元件結構，我們在理論上以及實驗上研究相對於金屬電極的發光位置對於發光特性的影響。分析結果顯示，若將發光位置放在接近第二個反節點附近，將可以得到1.2倍的整體出光量的增加，以及1.6倍的正向發光效率的增加。取決與細部條件，第二個反節點的元件也許有如強光學微共振腔中經常觀察到的更指向性的發光，但是沒有嚴重地隨視角變化的顏色飄移的問題。

關鍵字

有機發光二極體 ； 微共振腔 ； 模擬

並列摘要

Organic light-emitting devices (OLEDs) have been the subjects of intense investigation in recent years due to their applications in efficient, large-area and full-color displays. In OLEDs, the optical effects of various device structures are critical to device performances. In this thesis, we use the classical electromagnetic theory to model and analyze the emitting characteristic of typical OLEDs, top-emitting OLEDs, and microcavity OLEDs.
Top-emitting organic light-emitting devices (OLEDs) have a few technical merits for active-matrix OLED displays. Generally stronger microcavity effects inherent with top-emitting OLEDs however complicate optimization of device efficiency and other viewing characteristics, such as colors and viewing-angle characteristics. In this thesis, a general methodology for optimizing viewing characteristics of top-emitting OLEDs for display applications is suggested. The effectiveness of the analysis and the methodology is confirmed by experimental results.
Next, optical characteristics of microcavity organic light-emitting devices (OLEDs) having two metal mirrors are systematically examined. Analyses show that a high-reflection back mirror and a low-loss high-reflection exit mirror are essential for such microcavity devices to obtain luminance enhancement relative to conventional noncavity devices. The effects of resonant wavelengths on performances of microcavity organic light-emitting devices by using the rigorous classical electromagnetic model are also examined.
Due to generally low conductivity and low carrier mobilities of organic materials, organic light-emitting devices (OLEDs) are typically optimized for light outcoupling by locating emitters around the first antinode of the metal electrode. In this thesis, by utilizing device structures containing conductive doping, we investigate theoretically and experimentally the influences of the location of emitters relative to the metal electrode on OLED emission, and show that substantial enhancement in light outcoupling (1.2 times) or forward luminance (1.6 times) could be obtained by placing emitters around the second antinode instead of the first antinode. Depending on the detailed condition, the second-antinode device may also give more directed emission as often observed in strong-micrcavity devices yet without suffering color shift with viewing angles.

並列關鍵字

OLED ； microcavity ； simulation

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