有機發光二極體在近幾年內逐漸在顯示器市場上的受到重視，因為它有許多的優點，如: 高亮度、自發光、低功率損耗、較廣的視角、製程簡單及低成本，。而在有機發光二極體中，高亮度及發光純度的藍光及綠光有機發光二極體已經被發展出來了，但是紅光的特性仍是不足以與藍光及綠光比較，所以改善紅光有機發光二極體的特性，對於在顯示器上的發展是很重要的。
在我們的實驗中，所使用的紅色螢光材料是DCJTB，我們將它以共蒸著的方式摻雜在發光層中，使元件發出紅色光，在摻雜的時候， DCJTB濃度的控制對所做出來的元件特性的影響是很大的。首先我們將DCJTB摻雜在Alq3中靠近跟NBP的介面處，但是這樣做出來的元件特性仍然是不理想的，最大輝度只有227 cd/m2。於是我們將整層Alq3都摻雜DCJTB，這樣做的目的是讓更多的複合中心產生，提高發光效率。如我們預期的，在這種結構中，元件特性有效的改善許多，它的最大輝度可以到達1063 cd/m2，而在20mA的時候，輝度是116 cd/m2，這都比之前的結構高出許多。這個結果也証明了，在發光層中因摻雜的增日，而增加了載子復合的機會，使得發光的效率提高了。另外，我們也試著將DCJTB摻雜在NPB中，來觀察跟摻雜在Alq3中的差異之處。結果，摻雜在NPB中會產生兩個缺點，一是反向飽和電流太大，崩潰電壓特性不好；二是在EL頻譜中會出現另一個峰值，這會降低光的純度。所以NPB並不適合當做母體材料。
最後，我們在Alq3跟陰極中間加入LiF這一層，這將會加強電子的注入，在我們的實驗結果中，最適合的LiF厚度是9Å，而DCJTB的濃度是3%，在這樣的結構中，元件的最大亮度可以提高到1085 cd/m2，而在20mA的時候 可以達到287 cd/m2。

Organic light-emitting devices (OLEDs) have been attracting attention for application in flat-panel displays due to their high brightness, bright self-emission, low power consumption, capability of emitting a wide range of colors and ease of processing. In OLEDs, green and blue OLEDs with high efficiency, good color characteristics, and long lifetimes have been reported, however, the performance of red OLEDs is still not satisfactory. It is important to improve the performance of red OLEDs.
In the experiment, DEJTB is used as the red fluorescence materials, which is doped in the emission layer to emit red light. The concentration of DCJTB is important for device performance. First, we doped DCJTB closed the interface of NPB and Alq3, but the device performance is still bad, the maximum luminescence is only 277 cd/m2. Then, we doped DCJTB in full Alq3 layer. In this structure, the device performance can be effectively improved; the maximum luminescence was increased to 1063 cd/m2, this result proved that, when the fluorescence dyes were doped in emission layer, it would augment the recombination center in the device so that the probability of carrier recombination was enhanced, and the luminescence is 116 cd/m2 at 20mA. In addition, we try to dope fluorescence dyes in NPB layer to observe the different between doping in Alq3 and doping in NPB. But the structure has two main disadvantages: (1) low breakdown voltage, (2) shoulder peak; as a result, NPB is incongruent to be used as a host material.
Finally, a thin LiF is inserted between Alq3 and Al to enhance the electrons injection; the optimum thickness of LiF is about 9Å. The maximum luminescence achieved 1085 cd/m2 , and the luminescence is 287 cd/m2 at 20 mA. From the results of our experiment, the best concentration of DCJTB is 3%, and the optimum thickness of LiF is 9Å.

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