中间层对白色全磷光有机电致发光器件性能的影响

Effect of Interlayer on Phosphorescent White Organic Light-emitting Diodes

制备了基于蓝色磷光材料bis[3,5-difluoro-2-(2-pridyl)phenyl-(2-earboxypyribyl)iridumⅢ](FIrpic)、红色磷光材料bis(2-methyldibenzo[f,h]quinoxaline)(acetylacetonate)iridium(Ⅲ)(Ir(MDQ)2acac)的双波段白光有机电致发光器件。蓝色磷光材料FIrpic被掺杂在一种宽带隙的主体材料1,3-bis(triphenylsilyl)benzene(UGH3)之中,红色磷光材料Ir(MDQ)2acac被掺杂在主体材料4,4',4″-tris(carbazol-9-yl)triphenylamine(TCTA)之中,并在两发光层之间加入一种宽带隙的空穴传输材料1,3-bis(carbazol-9-yl)benzene(mCP)作为中间层。制备的器件结构为ITO/NPB(40 nm)/TCTA∶Ir(MDQ)2acac 7%(10 nm)/mCP(x nm)/UGH3∶Firpic 8%(30 nm)/BPhen(30 nm)/LIF(0.8 nm)/AL(200 nm)。实验结果表明,中间层的加入促进了发光层中电子和空穴的平衡并抑制了发光层之间的能量转移。加入适当厚度的中间层之后,器件的性能得到了明显的提升,相比于无中间层器件,最高电流效率由3.4 cd/A提高到13.2 cd/A。

Phosphorescent white organic light-emitting diodes with double light-emitting layers were fabricated based on phosphorescent blue emittor bis[3,5-difluoro-2-(2-pridyl) phenyl-(2-earboxy-pyribyl)iridumⅢ] (FIrpic) and red emittor bis(2-methyldibenzo[f,h]quinoxaline)(acetylaceto-nate) iridium(Ⅲ)(Ir(MDQ)2acac). FIrpic was doped in an ultra wide band-gap host 1,3-bis(tri-phenylsilyl)benzene (UGH3), and Ir(MDQ)2acac was doped in the host 4,4’,4'-tris(carbazol-9-yl)triphenylamine(TCTA). A hole transporting wide-band-gap material 1,3-bis(carbazol-9-yl)ben-zene (mCP) was introduced between the emitting layers. The device structure was ITO/NPB(40 nm)/TCTA:Ir(MDQ)2acac 7%(10 nm)/mCP(x nm)/UGH3: Firpic 8%(30 nm)/BPhen(30 nm)/LiF(0. 8 nm)/Al(200 nm). The results show that the interlayer plays an important role of balancing charge carriers, and blocking energy transfer between the emitting layers. With an appro-priate thickness of the interlayer, the device performances can be significantly enhanced. Compared with the device without interlayer, the maximum current efficiency can be enhanced from 3. 4 cd/A to 13. 2 cd/A.