有機發光元件膜層厚度與微金字塔陣列膜搭配之出光效率最佳化整體設計

Abstract

為了應用有機發光元件於固態照明用途，我們優化發光場型與微金字塔陣列膜。我們藉由電磁理論計算有機發光元件發光層的發光場型，再貼附微金字塔透鏡陣列，用光線追跡的方法探討膜層厚度所造成之發光場型和微金字塔底角關係。並進一步使用高折射率基板及截頭微金字塔陣列提升發光功率及正向亮度。由光線追跡方法得知，發光層Alq3厚度越高，場型半高全寬越大，利用微金字塔陣列提升的功率比和亮度比越高。且當場型半高全寬和基板折射率越大，我們必須使用大底角的微金字塔增進正向亮度。一般而言，微金字塔底角60度有較高的功率比，底角45度則有較高的亮度比。在基板折射率1.72，Alq3厚度90 nm時，有機發光元件貼附微金字塔陣列有最佳的耦合效率56%。 截頭微金字塔可更進一步增進有機發光元件的功率和正向亮度。在全佈滿的情況下，半高微金字塔陣列有最佳的功率增益效果，而高於四分之三原本高度的截頭微金字塔可用作提升有機發光元件的正向亮度。

We optimize the source apodization of organic light-emitting devices (OLEDs) with micro-pyramid array films for solid state lighting. To discover the relationship between the source apodization and the base angle of micro-pyramid array films, we calculate the organic emitter apodization with different thicknesses of Alq3 layer from electromagnetic theory, and simulate micro-pyramid array films are attached on top of OLEDs by using ray-tracing method. Moreover, we use the high-refractive-index substrate and truncated micro-pyramid array in order to enhance the luminous power and normal-direction luminous intensity. In general, when the base angle equals to 60 degree, the luminous power ratio is the highest; when the base angle equals to 45 degree, the luminance ratio is the highest. When Alq3 layer is thicker, the angular FWHM is larger, and the luminous power and luminance ratio is higher. Besides, when the angular FWHM is large and the refractive index of substrate is high, we must use micro-pyramids of large base angle to enhance more normal-direction luminous intensity. The best coupling efficiency 56% is that OLEDs with the micro-pyramid array for Alq3 thickness of 90 nm when the refractive index of substrate is 1.72. Truncated micro-pyramid array films further enhance the luminous power and luminous intensity of OLEDs. When the fill factor equals to 1.0, the half-height micro-pyramid array has the best luminous power enhancement; besides, we use the truncated micro-pyramid array with the height which is higher than three quarters of full-height in order to enhance the luminous intensity.