運用微共振腔原理之有機發光元件的光學設計

Optical Design of Organic Light-Emitting Devices Based on Microcavity Effect

翁知楷(Jhih-Kai Wong)

指導教授 ： 林晃巖

國立臺灣大學/電機資訊學院/光電工程學研究所/碩士(2012年)

https://doi.org/10.6342/NTU.2012.01773

摘要

有機發光元件由於具備自發光、輕薄、可撓式、全彩化、省電、可視角廣、反應時間快速及製程簡單等優點。可望在次世代主流顯示器佔有一席之地。但由於有機發光元件其物理尺度在一、二百奈米之內，在可見光波段範圍會受到其薄膜結構干涉光學影響，於此我們導入微共振腔效應以分析有機發光元件。並探討在微共振腔效應中廣視角干涉與多波干涉對元件發光的影響。
本篇論文使用一光學模型模擬元件在不同薄膜結構下，計算在不同視角，發光頻譜與出光強度變化。並搭配前面敘述微共振腔理論設計出最佳化有機發光元件。在設計最佳化過程中，首先考慮廣視角干涉優化決定發光區位置後，利用多波干涉決定在微共振腔中總光學厚度，設計出理想的有機發光元件。更進一步探討下發光有機元件陽極結合分佈式布拉格反射鏡設計，藉由提升微共振腔效應，可提升光強度及降低發光頻譜的半高頻寬。之後探討上發光型有機發光元件在陰極上覆蓋一層介電材料之影響，可發現陰極相位移及反射率改變造成發光強度及頻譜變化。因此藉由調控電子傳輸層厚度維持微共振腔之共振波長不變，當調控陽極比陰極多約36~39%反射率時，其對應共振波長會有最佳的正向光強度。最後結合上發光共同結構，設計出僅調變電子傳輸層厚度來達到高亮度與色彩涵蓋區域廣之紅綠藍三色有機發光元件。

關鍵字

有機發光元件 ； 微共振腔 ； 光學模擬

並列摘要

There are many advantages on the organic light-emitting device (OLED), such as, self-emission, slimmer shape, flexibility, larger color gamut, low power consumption, wide viewing angle, faster response time and lower cost. The OLED will play an important role among the next generation of mainstream displays. However, the physical scale of the OLED is about one or two hundred nanometers. The stack of organic films causes the optical interference effect in the visible region. So we introduce the microcavity effect to analyze the structure of OLEDs. About the microcavity effect, the two main mechanisms are wide-angle and multi-beam interference. And we discuss both mechanisms which influence the emission spectrum and intensity distribution of the OLEDs.
In this thesis, we demonstrate an optical model to simulate the emission spectrum, intensity distribution and other optical characteristics of the OLEDs by varying their thin-film structure and viewing angle. Next, we combine the microcavity theory to design and optimize the OLEDs. In a design process, we first consider the wide-angle interference to design the emission zone to optimize the OLEDs. Then we use the multi-beam interference to calculate the total optical thickness in the microcavity in order to design optimized device. Furthermore, we discuss the design which combines the bottom-emitting OLEDs and distributed Bragg reflector. It can improve 64% intensity and narrow the full-width half maximum of the emission spectrum from 52 nm to 33 nm. As well, we design the capping layer on the cathode of the top-emission OLEDs and discuss the influence on it. We find that the variation of the phase shift and reflectivity of the cathode will change the emission spectrum and the intensity. Therefore, we modulate the thickness of the electric transport layer to maintain the resonant wavelength of the cavity. When the reflectivity of the anode is higher 36~39% than that of the cathode, the optimum emission at the normal direction can be obtained. Eventually, we use this structure to design the common structure for red, green and blue emission. For the purpose, we modulate the thickness of the electric transport layer to achieve a RGB OLEDs of high intensity and wide color gamut.

並列關鍵字

OLED ； microcavity ； optical simulation

參考文獻

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