制备了结构为ITO/NPB/CBP:TBPe:rubrene/BAlq:Ir(piq)2(acac)/BAlq/Alq3/Mg:Ag的白色磷光有机电致发光器件.利用两种不同的主体材料,即用双载流子传输型主体材料CBP掺杂荧光染料TBPe及rubrene作为蓝光和橙黄光发光层;用电子传输型主体材料BAlq掺杂磷光染料Ir(piq)2(acac)作为红色发光层.以上双发光层夹于空穴传输层NPB与具有电子传输性的阻挡层BALq之间.讨论了如何控制染料的掺杂浓度,来得到高亮度的纯白光发射,以及如何利用各主体间的异质结,来平衡载流子在各发光层的分布,从而使白光器件获得较高的色稳定性.制备的纯白光器件在4.2V电压下启亮,在8.5V下获得的最大外量子效率为1.5%,13V下获得的色标标为(0.334,0.339),在17V下的发光亮度为15000cd/m^2.当驱动电压从10V升高到15V时,器件色坐标由(0.368,0.389)改变为(0.314,0.327).由于该白光器件拥有较高的色纯度和较好的色稳定性,其更加适合作为液晶显示的背光源或与彩色滤色膜匹配进而获得全色显示.
A novel phosphorescent white organic light-emitting device (WOLED) with configuration of ITO/NPB/CBP: TBPe : rubrene/ BAlq- It(piq) 2 (acac) / BAlq/Alq3/Mg: Ag was fabricated successfully, where the phosphorescent dye It(piq) 2 (acac) was doped into BAlq (electron transport material) as the red emitting layer, and fluorescent dye TBPe and together with rubrene was doped into CBP (ambipolar conductivity material) as the blue and orange emitting layer, respectively. The emitting layers were sandwiched between the undoped NPB and BALq layers. We also discussed how to achieve the bright pure white light with high stability through optimizing the doping concentration of each dopant and employing the balanced charges distribution for the introduction of the heterojunctions between the different hosts in detail. This device turns on at the driving voltage of 4.2 V. It presents a maximum external quantum efficiency and brightness of 1.5% and 15000 cd/m^2, respectively. The Commission Internationale de l'Eclairage (CIE) coordinates varies from (0.368, 0.389) at 10 V to (0.314, 0.327) at 15 V, and the best point is located at (0.334, 0.339) at 13 V. With the good EL performance, this kind of WOLED are particular suited for working as the backlight in LCD in combination with color filters to achieve the full color display.