尖端有機發光元件結構之研究

Abstract

在本篇論文中，我們研究了混合層結構發光二極體對操作時間的影響，我們利用插入一層紅色薄膜染料去觀察元件頻譜的變化，發現混合層元件衰減的程度，跟載子複合多寡的位置是有很大的相關性的。經由光激發光來探討元件材料的衰減，發現載子複合最多的區域，材料也被破壞的最多。我們認為，焦耳熱影響混合層結構元件非均勻的衰減相關。 此外，我們使用一個新合成材料來當作電子傳輸層，並將元件跟一般傳統元件比較，驅動電壓在25mA/cm2時有著2.2伏特的降低。我們也使用電洞傳輸層及電子傳輸層作為紅色磷光發光層之主體材料，並達到 14.3cd/A 之電流效率及 2.5V 驅動電壓之降低。

In this thesis, we study the degradation phenomena in a mixed-host (MH) organic light-emitting device (OLED) by using ultra-thin probe method. We observed spectral shift and then stable during the aging process, which results from materials decay. Non-uniform materials degradation with time at different positions of the MH emitting layer (EML) is observed by using photoluminescence measurement to define the intrinsic decay of materials. The decay rate exhibits similar trends to the recombination distribution in the MH-EML, which means degradation is a heat-assisted process. Besides, we used a novel material, 1,1'-bis(2-phenyl-1,3,4-oxadiazol-5-yl) ferrocene (Fe-OXD), as electron transport layer (ETL) material which reduces the turn-on voltage by 2.2V at the current density 25mA/cm2 as compared to the conventional OLED. ETL and hole-transport layer materials are used as the host of the EML in a red phosphorescent, which shows a high efficiency of 14.3cd/A and a 2.5V lower driving voltage at 14mA/cm2.