掺杂型红色有机电致发光显示器件

全色显示是有机电致发光显示(OLED)器件发展的目标,而高性能红色发光器件一直是制约全彩色OLED器件实用化的瓶颈,也是目前有机电致发光显示研究的热点。制作了掺杂DCJTB和不同浓度的rubrene两种荧光染料的红色有机电致发光显示器件,以NPB和Alq₃分别作为空穴传输层和电子传输层,发现器件性能与只掺杂DCJTB的器件相比有明显提高,发光效率提高到2～3倍。通过Frster理论和能带理论分析了器件的能量转移机理,研究发现Frster能量转移不是掺杂器件能量转移的主要形式,载流子俘获机制才是器件效率提高的主要原因;rubrene的引入使得能量能够更有效地从Alq₃转移到DCJTB,从而显著地提高了器件的发光效率和性能。

Red Doped Organic Light-emitting Diodes

Full color display is the goal of organic light-emitting diode (OLED),but the making of stable red devices is the great barrier in the mass production of OLED,and is also the most interesting field nowadays.In order to use organic light-emitting diodes in display,it is very important to obtain red emitting light.There are two methods for getting it:doping high fluorescent dyes in host materials or using metal complexes.Phosphorescent dyes have been efficiently used so far.Now some red organic light-emitting diodes have been realized by doping the dye rubrene with different dopant concentrations in light-emitting layers.We demonstrate red organic light-emitting diodes with the electroluminescent layers consisting of tris (8-hydroxyquinoline) aluminum (Alq₃) doped with the dye DCJTBand rubrene,which the emission efficiency depends on the concentrations of DCJTBand rubrene.The typical cell structure is as follows:ITO/CuPc/NPB/Alq₃:rubrene:DCJTB/Alq₃/LiF/Al],where N,N’-bis-(1-napthyl)-N,N’-diphenyl-1,1’-biphenyl-4,4’-diamine (NPB) and Alq₃ are used respectively as the hole transporting layer and electron transporting layer.It is found that the luminence efficiency of the devices in which DCJTBand rubrene were properly doped is twice to three times that of those doped only with DCJTB.The emission of guest in doped organic light emitting diodes may result from either energy transfer from host,carrier trapping or both mechanisms.In order to understand the energy transport mechanism between host and guest materials,we use the Frster theory and energy band to explain it,and found that the main energy mechanism of dopant emission in the doped red OLEDis not the Frster energy transfer,but the sequential carrier trapping,and that rubrene can assist the energy transfer from Alq₃ to DCJT Bmore efficiently,which greatly improved the luminence efficiency and performances of devices.