高效率双发光层结构白色荧光有机电致发光器件

High-efficiency White Fluorescent OLED with Double Emission Layers

通过将橙色荧光染料Rubrene和蓝色荧光染料BCzVBi分别掺入NPB和DPVBi中作为发光层,制备了结构为ITO/m-MTDATA(30nm)/NPB(20nm)/NPB∶0.5wt% Rubrene(10nm)/DPVBi∶5wt% BCzVBi(15nm)/Bphen(25nm)/LiF(0.6nm)/Al的双发光层结构白色有机荧光电致发光器件。器件发光主要是Rubrene直接俘获载流子和主体材料DPVBi到客体BCzVBi的能量传递两种发光机制竞争的结果。在低压下Rubrene俘获载流子发光占主导地位,导致器件的橙光相对较强,随电压升高主客体能量传递增强,使蓝光相对强度增强。器件最大电流效率为6.5cd/A,最大亮度为16 140cd/m2。亮度从1 000cd/m2增加到10 000cd/m2,器件的发光色坐标从(0.33,0.37)变化到(0.30,0.32),始终处于白光区。

By doping rubrene into NPB host as the orange emitting layer and BCzVBi into（DPVBi）host as the blue emitting layer,respectively,high efficiency white fluorescent organic light emitting diodes（WOLED）with double emission layers were fabricated with the structure of ITO/m-MTDATA（30nm）/NPB（20nm）/NPB∶0.5wt% Rubrene（10nm）/DPVBi∶5wt% Bphen（25nm）/LiF（0.6nm）/Al.The emitting performance can be attributed to the competition of the two mechanisms of the carrier trapping in the orange emitting layer and efficient frster energy transfer in the blue emitting layer.The former becomes a dominant emitting mechanism at low voltage,thus resulting in an enhanced orange emmission.With the applied voltage increasing,the blue emmission relative intensity enhance is due to the dominant later mechanism.The device achieves the maximum current efficiency and brightness of 6.5cd/A and 16 140cd/m^2,respectively.With the luminance increasing from 1 000cd/m^2 to 10 000cd/m^2,the CIE coordinates of the device is shifted from（0.33,0.37）at 7Vto（0.30,0.32）,which is close to white light equivalent energy point of（0.33,0.33）.