有機發光元件光學特性之研究

Abstract

在有機發光元件中，有一大部分的光，被波導在玻璃基板、有 機層或透明電極中，而無法輻射至空氣中，而為人眼所見。因此，如 何增進有機發光元件發光效率為一重要之研究課題。在本論文中，我 們探討了實驗上在下發光元件貼附不同微透鏡膜以增進發光效率，此 外亦建立一套理論模型，以探討在上發光元件上加上介電層及保護層 對發光效率的影響。 貼附了具有高透鏡覆蓋率、小透鏡直徑和高透鏡高徑比之微透 鏡膜的下發光元件，具有較佳的發光效率。我們展示了正向發光效率 增進42.5%，發光功率效率增進45%的結果。因微透鏡膜產生的影像 模糊被定量分析，且發現其與發光效率有正相關。我們示範了一種微 透鏡膜在主動矩陣有機發光顯示器上有超過20% 增進的發光效率， 且具有可接受的模糊寬度45 μm。 上發光元件比下發光元件效率高的原因在於少了被浪費在玻璃 中的波導模態。我們首先驗證了模擬程式的正確性和提供了設計法 則。結論為上發光元件有：(1)總共振腔的光學厚度是目標波長的一 半、(2)發光偶極到反射陽極的光學距離是目標波長的四分之一和(3) 陽極比陰極多約16%的反射率會有最佳的目標波長強度。

Due to the waveguiding effect of the glass substrate, organic layers and/or transparent electrode, only portion of light escape outside the atmosphere and be detected by the human eyes. Hence, the efficiency improvement is considered as an important issue for an organic light-emitting device (OLED). In this thesis, we investigate the luminous enhancement effect of different microlens array films (MAFs) attachment to a bottom emission OLED (BOLED) experimentally. Besides, we also establish a theoretical program to simulate the optical characteristics of a top-emission OLED (TOLED) with dielectric and passivation layers. MAF-BOLED with higher coverage ratio, smaller base area and higher height ratio exhibits higher luminous efficiency. The normal direction luminous efficiency of 42.5% enhancement and luminous power efficiency improvement of 45% are shown. The image blur phenomenon due to MAFs attachment is quantitatively defined and it is found to be positively related to luminous enhancement ratio. We demonstrated a MAF, which has acceptable blur-width of 45 μm and more than 20% white light efficiency enhancement on an active-matrix OLED (AM-OLED). In our TOLED simulation, we validated the correctness of the program and the design rules are given. We conclude that TOLED devices, which have: (1) total optical cavity thickness of half the desired wavelength, (2) the optical distance between dipole and the reflective anode of quarter of the desired wavelength, and (3) the anode reflectivity larger than that of cathode by around 16%, have optimized peak intensity in desired wavelength.