有機光電元件內的微共振腔效應及表面電漿子之研究

Investigation of Microcavity Effects and Surface Plasmon Polaritons in Organic Electro-Optical Devices

田堃正(Kun-Cheng Tien)

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(2010年)

https://doi.org/10.6342/NTU.2010.00148

摘要

在本論文中，首先是對非等向性及等向性發光材料所組成的有機發光元件結構建構光學模型並模擬其發光特性。並製作了分別具有非等向性及等向性光學特性的發光元件，量測發光頻譜，並與理論計算的結果相比較，發現相當吻合，因而確定該模型的有效性。
接下來我們分析了堆疊串接式白光有機發光元件(紅光+綠光+藍光堆疊串接式、雙色光+單色光堆疊串接式以及白光+白光堆疊串接式)的發光特性，結果發現雙色光+單色光堆疊串接式結構有著較好的色彩穩定度。
此外，我們針對不同氧化銦錫厚度的弱微共振腔有機發光元件結構進行理論計算及實驗研究，發現改變氧化銦錫厚度會使得元件效率有顯著的變化(1.34倍量子效率、1.44倍電流效率以及1.51倍功率效率之變化)。
另外，我們在厚度減薄的金屬電極上製作適當的吸光/再放光層，能夠將部分侷限在有機發光元件內的表面電漿子，藉由能量轉移機制而再放光。這種方法可用於實現具有光色可調性的雙面異色有機發光元件。
緊接著，我們對於金屬奈米顆粒的光學特性，以及它們和表面電漿子與強微共振腔結構之間的交互作用進行了研究。發現其反射頻譜在其共振頻率處會有明顯的峰值，而其頻率可藉由改變共振腔長度來調變。最後，我們針對強微共振腔結構與強吸光材料之間的交互作用進行討論，發現了類似上述的選擇性反射現象，未來有可能應用在反射式顯示器上。

關鍵字

有機發光元件 ； 堆疊串接式 ； 微共振腔 ； 表面電漿子 ； 侷域表面電漿子 ； 選擇性反射

並列摘要

In this dissertation, first the optical modeling and emission characteristics of OLEDs with anisotropic and isotropic emitting materials were discussed. Devices with anisotropic and isotropic emitting materials were fabricated and measured for comparison with simulation results. Experimental results match calculated results fairly well, therefore confirming the validity of the model.
Then the emission characteristics of tandem white OLEDs (R+G+B tandem, 2-color+1-color tandem, and white+white tandem) were analyzed. It was found that 2-color + 1-color tandem structure gives lower color shift than the other two types.
The weak-microcavity device structures with varied ITO thicknesses were investigated theoretically and experimentally. The efficiency characteristics of these devices showed significant variations (1.34 times in quantum efficiencies, 1.44 times in cd/A efficiencies and 1.51 times in lm/W efficiencies) in varying ITO thickness.
Furthermore, we recycled a portion of surface plasmon polaritons (SPPs) in OLEDs by capping the thinned metal electrode with an appropriate absorbing/re-emission medium, inducing SPP-mediated energy transfer and re-emission. Such an approach may be used for implementing double-emitting OLEDs with different emission colors on two sides and with a broad color tuning capability.
Next, the optical properties of metal nanoparticles and their interaction with SPPs and strong-microcavity structures were investigated. It was found that the reflectance spectra show obvious peaks around the resonance frequencies and they can be tuned by changing the cavity length. Finally, interaction between strong-microcavity structures and the strongly absorptive capping was discussed. Selective reflection phenomena were observed, which have the potential for use in reflective displays.

並列關鍵字

organic light-emitting devices ； tandem ； microcavity ； surface plasmon polaritons ； localized surface plasmon ； selective reflection

參考文獻

[69] S.A. Maier, Plasmonics: Fundamentals and Applications, Springer-Verlag (2007).

[5] S.A. Maier, Plasmonics: Fundamentals and Applications, Springer-Verlag (2007).

[2] S.A. Maier, Plasmonics: Fundamentals and Applications, Springer-Verlag (2007).

[7] S.A. Maier, Plasmonics: Fundamentals and Applications, Springer-Verlag (2007).

[1] M. Pope, H. Kallmann, and P. Magnante, Electroluminescence in organic crystals, J. Chem. Phys. 38 (1963) 2042-2043.