The enhancement of light extraction efficiency of electroluminescent device by optical structure
|關鍵字:||extraction;efficiency;LED;OLED;photonic crystal;microlens array;出光效率;光子晶體;微透境陣列|
|摘要:||近年來，由於有機發光二極體(OLED)及發光二極體(LED)等電致發光件(Electroluminescence devices)大量應用於LCD等顯示器或照明設備上，有輕薄，可撓式(flexible)等優點，。然而，其較低的出光效率仍是一個極需解決的問題。當光源從主動層(active layer)發出，大部分的光會侷限(trapped)在高折射率層中，導致出光效率低。且在基版(substrate)與空氣的介面上由於全反射的影響，部分的光會被反射回來，此亦為造成出光效率低的原因之一。為提升電致發光元
Electroluminescent devices such as OLEDs and LEDs applied on flat panel display (ex. LCD) or lighting devices have the features of light weight and flexible. However, the low light extraction efficiency is one of the critical issues needed to be solved. When the light emitted from the active region, large portion of the light will be trapped inside the high-index layers which results in low extraction efficiency. Moreover, due to the total internal reflection effect at the interface between substrate and air, part of the light will be further reflected. As a consequence, only small portion of the emitted light will extract into the air. In order to enhance the light extraction efficiency of such electroluminescent devices, a two-dimensional photonic crystal structure and a microlens arrays are applied onto OLED and LED, respectively. An estimation of such nano and micro scale optical structures applied on lectroluminescent devices is made to see how the efficiency can be increased. According to our simulation result, 117% and 135% of enhancements in PC-OLED and microlens array based LED is obtained.
|Appears in Collections:||Thesis|
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