一种具有稳定发射光谱的高效率白色有机电致发光器件

Efficient White Electroluminescent Device with Stable Emission Spectrum

报道一种具有稳定发射光谱的新型白色有机电致发光器件.选择DCJTB作为红光染料将其掺入空穴传输材料NPB中作为空穴传输层和第一发光层,提供蓝光和红光;选择AlQ作为电子注入敏化剂,将其掺入NPB中作为第二发光层,提供蓝光和绿光.DCJTB和AlQ的掺杂浓度分别被优化为0.4%和1.4%,第二发光层的厚度被优化为3 nm.最终,得到了纯白色发射的有机电致发光器件;该器件启亮电压仅3.1 V,最大亮度高达32749 cd/m2,器件的最大电流效率为8.67 cd/A,器件的最大功率效率为8.78 lm/W.而且,空穴型主体材料的选择导致该器件的色稳定性非常理想.随着电流密度的提高,该器件的色坐标始终稳定在(0.343,0.342)到(0.328,0.336)的范围内.

In this work,we report a novel white organic light-emitting device（WOLED） with stable emission spectrum.Red emitter 4-（dicyanomethylene）-2-tert-butyl-6-（1,1,7,7-tetramethyljulolidyl-9-enyl）-4H-pyran（DCJTB） was selected and doped into N,N’-diphenyl-N,N’-bis（1-naphthyl）-1,1’-diphenyl-4,4’-diamine（NPB） layer as hole transport layer and the first light-emitting layer（EML1）,which provides blue and red emissions.The widely used green material tris（8-hydroxyquinoline） aluminum（AlQ） was selected as sensitizer of electron injection and doped into NPB layer as the second light-emitting layer（EML2）,which provides blue and green emissions.The doping concentrations of DCJTB and AlQ were optimized to be 0.4% and 0.14%,respectively,while the thickness of EML2 was optimized to be 3 nm.Finally,we obtained the pure white organic light-emitting device,which possesses 3.1 V turn-on voltage,32749 cd/m2 maximum brightness,8.67 cd/A maximum current efficiency,and 8.78 lm/W maximum power efficiency.More importantly,the use of hole-type host material help to confine the recombination zone of holes and electrons,thus improving the stability of electroluminescent spectrum.With increasing current density,the Commission Internationale de l’Eclairage（CIE） coordinates of this device change from（0.343,0.342） to（0.328,0.336）.