多層結構之高效率藍光及白光共軛高分子發光二極體設計

Design of highly efficient blue and white multilayer polymer-based light-emitting diode

賴煥中(Huan-Chung Lai)

指導教授 ： 洪勝富 ； 孟心飛

國立清華大學/電機資訊學院/電子工程研究所/碩士(2006年)

摘要

利用溶液製程製作共軛高分子發光二極體可大幅降低成本與簡化製程，但是其效率仍遠低於小分子發光二極體。高效率的瓶頸可能在於製作多層結構時產生的互溶問題，目前文獻上有數種方法可避免，但是都有明顯的缺點。
本論文研究目標是製作出高效率的藍光及白光共軛高分子發光二極體。此研究建立在之前學長研究的緩衝層技術的基礎上，逐步引入電洞阻擋層(電子傳輸層)、電子阻擋層(電洞傳輸層)，發展雙層結構、三層結構並且經由確認膜厚與觀察元件表現來推測多層結構的可行性，進一步證明此緩衝層技術可廣泛運用至各類型高分子結構上。
本論文研究結果裡，共軛高分子藍光發光二極體的外部量子效率達到接近理論極限的4.2%，電流效益達7.3cd/A，是目前單一激發態的藍光高分子發光二極體的最高效益。在此基礎上發展白光發光二極體，外部量子效益達到2.4%。

關鍵字

共軛高分子 ； 發光二極體 ； 多層結構 ； 高效率 ； 高亮度 ； 藍光 ； 白光

並列摘要

Although solution-processible polymer-based light-emitting diode (PLED) is structurally simple and cost-effective, its efficiency is still far below small molecular light-emitting diode (OLED). The bottleneck to high efficiency is that solution processing itself causes intermixing between spin-coated polymer layers. Various techniques were developed to avoid intermixing and allowed for the fabrication of multilayered polymer structure.
My research goal is to study how to design highly efficient blue and white PLEDs. My research is based on buffer layer technique previously developed in our Lab. We test the integrality of multilayer structure by checking the total film thickness and observing the performance of devices. We found that this buffer layer technique could be a general and reliable method to fabricate multilayer PLED. Then we introduce hole blocking-layer (electron- transporting layer), electron-blocking layer (hole-transporting layer) into double-layer and triple-layer structures.
With our optimization by adding an electron-blocking layer, the external quantum efficiency (EQE) of blue PLED can be increased from 1.5% to 4.2% (from 2.7cd/A to 7.3cd/A) which is closed to the theoretical limit. The EQE of white PLED based on this highly efficient blue PLED reaches 2.4%, and the luminance is over 20000cd/m2.

並列關鍵字

PLED ； multilayer ； high efficiency ； high luminance ； blue ； white

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