在1987年Dr. Tang的研究小組成功地製作出兩層的有機發光二極體，有機發光二極體便開始吸引研究工作者的目光，新世代的平面顯示器－有機電激發光顯示器(Organic Light Emitting Device, OLED)因而崛起。有機電激發光顯示器和小尺寸的LCD產品比起有其先天的優勢，而其優點有具自發光性、低耗電量、無廣視角的限制、高亮度、低生產成本、高對比度、重量輕、響應速度快、可全彩化、動態影像顯示等…是一項極富市場潛力的新產品，可應用於手機、個人數位助理機、數位照相機及筆記型電腦的螢幕，因此，有機電激發光二極體在未來次世代的平面顯示器上扮演者舉足輕重的角色。
在各種色光中以白光最為重要，就目前照明設備而言，白光可取代現今所使用的日光燈管，亦可用來當做液晶顯示器的背光源並應用在全彩化的技術上，因此，白光有機電激發光二極體對整個顯示器的發展或光電科技產業極為重要。一般來說，白光有機電激發光二極體可分為單層結構及多層結構。單層結構的白光在元件製作上雖然簡單，但其元件的發光效率始終沒有辦法突破，因此，本實驗之目的即在製作高效率、高亮度的白光有機電激發光二極體，藉以改善單層白光有機電激發光二極體在效率上的問題。
本實驗中所研製的白光結構為ITO/NPB/DPVBi/CDBP:Ir(btp)2acac/Alq3/BCP/CsF/Al。所有的有機材料成長在覆有ITO的玻璃基板上，NPB在此當作電動傳輸層、DPVBi為藍色發光層、CDBP為主材料摻雜Ir(btp)2acac作為紅光的發光層、Alq3作為綠光的發光材料、BCP為電洞阻擋層及Al金屬當作陰極。此處，CsF為幫助電子注入的緩衝層(Buffer layer)。本實驗之重點在於找到Ir(btp)2acac摻雜在CDBP的最佳濃度，並找出三層發光層的最佳厚度，進而探討其多層白光OLED的光電特性。Ir(btp)2acac所摻雜的濃度會影響其能量轉移的效果，而各發光層之間的厚度會影響其電子與電洞再結合的區域，因此，藉由控制Ir(btp)2acac摻雜的濃度比例及各發光層的厚度來得到多層的白光OLED。從實驗的結果可以得知，Ir(btp)2acac摻雜的比例為2.5%時，可藉由完全的能量轉移得到紅光的貢獻，再搭配藍光發光層DPVBi 200Å及綠光發光層Alq3 250Å。最後，我們可以得到白光有機電激發光元件並利用I-V、J-L、EL及PL等特性曲線分析探討多層白光的光電特性，並建立其發光機制。
在此白光有機電激發光元件的研究下，我們可得到最佳的元件結構為ITO/NPB(200Å)/DPVBi(200Å)/CDBP: 2.5% Ir(btp)2acac(100Å)/Alq3(250Å)/BCP(50Å)/CsF/Al，在最佳的元件結構下，可得白光的CIE座標為(0.35, 0.33)，當電流密度為416 mA/cm2時，可得到白光最佳的輝度為7005 cd/m2。

Since 1987 Tang and VanSlyke successfully studied a two-layer heterostructure device configuration, organic light-emitting diode (OLED) has attracted much attention. The flat-panel display OLED of new generation was discovered. Orange light-emitting device has many innate advantages than small size LCD, such as self emitting, low consumed power, wide view angle, high brightness, low cost, high contrast, fast response, high brightness, wide view angle, and supports in full color application, etc. Because of these advantages, organic light-emitting device is to be a product that owns the market potential in next generation.
Among many colors of light source, white light is the most important of them because it can not only replace the modern fluorescent tube but also be backlight for liquid crystal displays and apply to full color technology. Hence, white organic light-emitting diode plays an important role in optoelectronics technology and the field of display. Generally, the structure of white organic light-emitting device can be divided into two kinds. One is the structure of single layer, and the other is the structure of multilayer. Manufacturing the white organic light-emitting device of single layer is easy, the efficiency of this device don’t still be improved. Therefore, the purpose of this experiment is to fabricate a white organic light-emitting device with high efficiency and high luminescence, so as to improve the efficient problem of white organic light-emitting device with single layer.
In this experiment, the structure of white organic light-emitting device was ITO/ NPB/ DPVBi/ CDBP: Ir(btp)2acac/ Alq3/ BCP/ CsF/ Al. All of the organic materials were deposited at ITO substrate. NPB was used as hole-transporting layer, DPVBi was used as blue emitting layer, Ir(btp)2acac was the red fluorescence dye and doped in CDBP. CDBP doped with Ir(btp)2acac that was used as red emitting layer, BCP was used as hole-blocking layer, Alq3 was used as green emitting layer and electron-transporting layer and Al was used as cathode. Here, CsF was used as buffer layer to help electrons inject. The purpose in this experiment is finding the optimum doped rate for CDBP and Ir(btp)2acac in coevaporation and the optimum thickness of three emitting layers. At the same time, we will analyze the optoelectronic characteristics of multilayer white organic light-emitting device. The deposition rate of Ir(btp)2acac in coevaporation would affect the efficiency of energy transfer and thickness of three emitting layers would affect the location of recombination. Therefore, by controlling the deposition rate and thickness of three emitting layers could obtain the multilayer white organic light-emitting device in this experiment. From the experimental results, we could obtain the contribution of red light by complete energy transfer from CDBP to Ir(btp)2acac when the deposition rate in coevaporation was 1: 2.5. At the same time, the optimum thickness of DPVBi and Alq3 was 200Å and 250Å, respectively. Finally, we could obtain the optimum white organic light-emitting device and utilize the characteristic curves of I-V、L-V、EL and PL analyzing the optoelectronic characteristics of white organic light-emitting device.
In this study of white organic light-emitting device, we could obtain the optimum structure was ITO/ NPB (200Å)/ DPVBi (200Å)/ CDBP:2.5% Ir(btp)2acac (100Å)/ Alq3 (250Å)/ BCP (50Å)/ CsF/ Al. At this optimum structure, we obtained the best white CIE coordinate was on (0.35, 0.33). When the voltage was at 15 V, the highest luminance of white organic light-emitting device was 7005 cd/m2.

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