基于新型电荷生成层的P-i-N结构白色有机叠层电致发光器件

采用2,9-Dimethyl-4,7-diphenyl-1,10-phenanthroline(BCP): 5 wt.% cesium carbonate(Cs₂CO₃)和N, N'-Bis(naphthalen-1-yl)-N,N'-bis(phenyl)-benzidine(NPB): 20 wt.% molybdenum oxide(MoO₃)分别作为器件的电子注入层和空穴注入层,研究了N型和P-i-N结构有机电致发光器件的载流子传输特性.载流子传输层中BCP: Cs₂CO₃和NPB:MoO₃的引入有效增强了载流子注入能力,从而降低了器件的驱动电压.基于新型电荷生成层BCP: 5 wt.% Cs₂CO₃/ NPB: 20 wt.% MoO₃制备了色稳定、高效率P-i-N结构有机叠层器件.与单元器件相比,引入新电荷生成层有机叠层器件的最大电流效率增大了2.5倍,表明该电荷生成层可以有效地将电子和空穴分别注入到相邻发光单元中.采用该电荷生成层制备了P-i-N结构白色有机叠层器件,器件的上下发光单元分别为橙光和蓝光发射.当发光亮度从500增加到5 000 cd/m²时,器件的色坐标稳定在(0.33, 0.29)附近,接近白光等能点.利用单色发光单元堆叠制备白色有机叠层器件的方法为实现色稳定、高效率的白色有机电致发光器件提供了一种有效的途径.

Highly Efficient Tandem P-i-N White Organic Light Emitting Diode Based on a New Charge General Layer

Organic light emitting diodes(OLEDs) were fabricated using 5 wt.% cesium carbonate(Cs₂CO₃) doped 2,9-Dimethyl-4,7-diphenyl-1,10-phenanthroline(BCP) as eletron-injection layer and 20 wt.% molybdenum oxide(MoO₃) doped N, N'-Bis(naphthalen-1-yl)-N,N'-bis(phenyl)-benzidine(NPB) as hole-injection layer, respectively, and the carrier transfer characteristics were examined. The lowered driving voltage suggests BCP: Cs₂CO₃ and NPB: MoO₃ efficiently enhance carrier injection in OLEDs. Color-stable and efficient tandem P-i-N white organic light emitting diode(WOLED) with a new charge generation layer, which consists of BCP: 5 wt.% Cs₂CO₃/NPB: 20 wt.% MoO₃, has been fabricated. The maximum current efficiency of the two-unit tandem P-i-N orange device is enhanced by 2.5 factors with respect to the one-unit device. Such a connecting structure permits efficient opposite hole and electron injection into two adjacent emitting units and gives tandem devices superior electrical and optical performances. The tandem P-i-N WOLED with the charge generation layer, in which the individual orange phosphorescent and blue fluorescent were used as emissive units, exhibits excellent color stability and higher efeciency. The Commission Internationale de l'Eclairage (CIE) chromaticity coordinates almost focus exactly on (0.33, 0.29) between 500 cd/m² and 5 000 cd/m², which closes to the point of equal energy (0.33,0.33). The results may prove the method to be effective to enhance the current efficiency and color-stable of WOLED.