磷光客体三重态能级对基于PVK主体的电致发光器件的影响

将磷光客体掺入PVK:PBD主体材料中是获得高效率磷光电致发光器件 (PhPLED)的有效途径.然而,分别掺杂Ir(pppy)₃、Ir(F-pppy)₃和Ir(F₂-pppy)₃三种磷光客体的PhPLED器件性能件却显著不同.我们分别模拟主-客体间能量转移和客体直接捕获电子空穴对两种机制,研究了三种客体材料的磷光发射及其衰减过程.研究表明:平衡的载流子注入和客体高效率的载流子捕获是实现Ir-配合物掺杂的PhPLED器件性能优良的主要机制,PVK较低的三重态能级使其无法成为蓝光磷光电致发光器件的主体,在PVK中掺入PBD的方法,则进一步降低了主体材料的三重态能级,这是蓝光磷光电致发光器件运行效率较低的主要原因.本文的研究结果可为高分子磷光电致发光器件的制备技术和新型磷光主体的设计提供参考.

Effects of Triplet Energy Levels of Phosphorescent Guests on Luminescent Efficiency of PVK Based Polymeric Light-Emitting Diodes

Doping phosphorescent guests to PVK and PBD matrix is an effective method to achieve high-efficiency phosphorescent polymeric light-emitting diodes(PhPLED).However,by doping Ir(pppy)3,Ir(F-pppy)3 and Ir(F2-pppy)3 to the PVK and PBD matrix,great difference of the device properties have been observed.In order to investigate the reasons for these phenomena,we use steady-and time-resolved-spectroscopy to study the effect of energy transfer from host to guest and direct electron and hole trapping mechanisms on the light-emitting properties of the active layers.The experimental results show that the balanced carrier injection and high efficient charge trapping are important mechanisms for obtaining high-efficiency PhPLEDs with PVK as the host.PVK does not fit blue PhPLED preparation because of its lower triplet energy level.Doping PBD to PVK host will further decrease the triplet energy level of the host.Our work provides important photophysical basis for the design of the phosphorescent hosts and the PhPLED device.