制备了结构为ITO/MoO3(30 nm)/NPB(40 nm)/TCTA(10 nm)/CBP∶R-4B(8%)(30 nm)/电子传输层(40 nm)/LiF(1 nm)/Al(150 nm)的器件, 其中R-4B为红色磷光染料, 电子传输层分别采用Alq3、Bphen∶Alq3(x%)和Bphen, 对3种不同电子传输层器件的发光性能进行了研究。结果表明: Bphen∶Alq3(x%)作为电子传输层的器件与Alq3或Bphen作为电子传输层的器件相比, 亮度提高了约3.5倍, 电流效率提高了1.1～2.5倍, 效率滚降变得平缓。采用Bphen∶Alq3作为电子传输层, 不仅减小了电子在LUMO能级传输时的跳跃传输距离, 而且在一定程度上抑制了Bphen的结晶, 使器件的电子传输能力和效率滚降性能得到改善。

Red phosphorescent organic light emitting diodes were fabricated using R-4B phosphorescent dye. The device structure was ITO/MoO3 (30 nm)/NPB(40 nm)/TCTA (10 nm) /CBP∶R-4B(8%) (30 nm)/electron transport layer (40 nm)/LiF(1 nm)/Al(150 nm) . The electron transport layers were Alq3, Bphen∶Alq3 (x%) and Bphen, respectively. The electroluminescent properties were studied by using different electron transport layers. The results show that the brightness and the current efficiency of the device using Bphen∶Alq3 (x%) as electron transport layer is 3.5 times and 1.1－2.5 times respectively stronger than that of using Alq3 or Bphen as electron transport layer. Meanwhile, the efficiency roll-off of device became smooth. Using Bphen∶Alq3 as electron transport layer can not only reduce the hopping distance when electrons transmit between LUMO levels, but also restrain the crystallization of Bphen, and as a result, the electron conductivity and efficiency roll-off of the device are improved.