PBD在稀土配合物与PVK混合体系电致发光中的作用

研究了PBD以较低浓度与铽配合物Tb(m-MBA)₃phen]₂·2H₂O、PVK共掺杂体系的电致发光，制作了两类电致发光器件：ITO/PVK:Tb complex/PBD/LiF/Al，ITO/PVK：Tb complex:PBD/PBD/LiF/Al。在共掺杂的发光层中铽配合物的电致发光来源于两个途径，一个是由PVK到铽配合物的能量传递，另一个是电子和空穴在铽配合物上直接复合发光。改变PBD在发光层中的掺杂比例，制得一系列器件，通过对其光谱和亮度的研究，发现PBD在较低浓度掺杂时器件的稳定性和亮度随掺杂浓度的增加而降低。通过分析认为PBD的加入对给体(PVK)到受体(Tb complex)的能量传递效率影响较小，主要是由于PBD的加入使得电子和空穴在PVK链间的跳跃受到限制，使在由PVK、铽配合物和PBD三者掺杂组成的发光层中，注入的电子和空穴不能有效地在铽配合物上复合，这样就会减少激子在铽配合物上直接复合的概率，而造成器件的亮度和效率降低。

Effects of PBD on the Electroluminescence (EL) of Tb Complex Doped PVK System

Electroluminescent (EL) properties of the terbium complex Tb(m-MBA)₃phen]₂·2H₂O doped PVK system were investigated. Two kinds of devices with the structures of ITO/PVK:Tb complex/PBD/LiF/Al and ITO/PVK:Tb complex:PBD/PBD/LiF/Al were fabricated. PBD emission appears in the EL spectra of ITO/PVK:Tb complex/PBD/LiF/Al in comparison with ITO/PVK:Tb complex:PBD/PBD/LiF/Al. The reason is that PBD acts as a hole blocking material in the emitting layer (PVK: Tb complex: PBD) and thus the combination of excitons mostly occur within this layer. The energy of terbium complex emission comes from two different ways, namely energy transfer and direct combination of carriers. By altering the doping weight ratio of PBD, a set of devices were fabricated with the configuration of ITO/PVK:Tb complex:PBD/PBD/LiF/Al. Both the efficiency and brightness of these devices decrease with the rising of the PBD doping weight ratios. The efficiency of the carriers trapping may decrease with the rising of PBD doping ratios, for PBD may block the hoping of hole or electron between the PVK chains, causing a decrease in the brightness and efficiency. The PBD doping ratios have little effect on the efficiency of Frester energy transfer based on our synthesis.