六角形集光結構及微透鏡應用於微型發光二極體高正向輝度及抗反射之研究

Abstract

在面板產業中，微型發光二極體（micro-LED、μLED）具有相當大的發展前景。LED結合LCD與OLED的優點，同時具有自發光、低延遲、高亮度、壽命長等優點，也同時可以達到高發光效率。隨著技術進步，LED逐漸微型化，在量產上的問題除了巨量轉移的良率和LED尺寸縮減上出現的側壁缺陷效應導致LED發光效率低落外，LED尺寸縮減同時也會使晶粒開始出現向下及側向出光，而這些非正向的出光在LED封裝後經過封裝層之間的界面及封裝層與空氣間的界面時，容易出現全反射及較大角度的折射，因而降低正向出光。 本篇論文目的是為降低micro-LED面板的環境光反射，同時降低此面板之正向輝度損耗。本設計在考慮製程可行性、且無需進行對組的情況下設計了兩層集光結構。第一次集光結構可依靠非等向性蝕刻及旋轉塗佈製作，而二次集光結構為微透鏡，可以更進一步匯聚光線，並可依靠等向性蝕刻製作。本設計利用光學模擬軟體LightTools®建立模型並以蒙地卡羅法進行光線追跡，從模擬結果可以發現此設計有達到降低環境光反射及降低正向輝度損耗之目的。 經過調整模型中各項參數，模型之總環境光反射最低可達4.80%，損耗最低至14.52%。

Micro light-emitting diodes (micro-LEDs, μLEDs) have a promising future in the panel industry, combining the advantages of LCDs and OLEDs with the advantages of self-luminescence, short response time, high brightness, and long service life, as well as high luminous efficiency. As technology advances, LEDs are gradually miniaturized, and the challenges in mass production is to maintain a certain yield in mass transfer, and the low LED luminous efficiency causing by the sidewall defects effect on the single LED die while LED size reduce. After the LED is packed, these non-positive light outputs pass via the interfaces between the packaging layers and between the packaging layers and the air, are susceptible to total reflection and large angle refraction, which reduces the forward brightness. The purpose of this paper is to reduce the ambient light reflection from micro-LED panels and to reduce the forward brightness loss of these panels. This design is a two-layer light-collecting structure with process feasibility and no need for alignment. The design relies on non-isotropic etching and spin coating for the first light collection structure to achieve light convergence, while the second collection structure is a micro-lens with isotropic etching for further light convergence. The design is modeled by LightTools® software and ray tracing performed by the Monte Carlo method. The simulation results show that the design can reduce the reflection of ambient light and the loss of forward brightness. After adjusting the parameters in the model, the total ambient light reflection is as low as 4.80% and the loss is as low as 14.52%.