Bphen掺杂Cs_2CO_3作为电子传输层对OLED器件性能的影响

为改善OLED器件的载子注入平衡,本文在其结构ITO/MoO3/NPB/Alq3/Cs2CO3/Al中,分别引入高电子迁移率材料Bphen及Bphen∶Cs2CO3作为电子传输层。通过改变Bphen的厚度以及Bphen中Cs2CO3的体积掺杂浓度,研究其对器件发光亮度、电流密度和效率等性能的影响。实验结果表明,采用Bphen或者Bphen∶Cs2CO3作为电子传输层,均能提高器件的电子注入能力,改善器件的性能。相比于未引入Bphen的器件,采用25nm的Bphen作为电子传输层,改善了器件的电子注入,使器件的最大电流效率提高112%;采用体积掺杂浓度为15%,厚度为5nm的Bphen∶Cs2CO3作为电子传输层,减小了电子注入势垒,使器件的最大电流效率提高27%,并且掺杂层厚度的改变对器件的电子注入影响很小。该方法可用于OLED器件的阴极修饰,对器件性能的提升将起到一定的促进作用。

Impact of Bphen doping Cs2CO3 as electron transport layer on the performance of OLEDs

In order to improve the balance of carrier injection, a high electron mobility material Bphen and Bphen:Cs₂CO₃ are introduced in OLED devices respectively based on the structure of ITO/MoO₃/NPB/Alq₃/Cs₂CO₃/Al. The experiments study the effect of Bphen and Bphen doping Cs₂CO₃ on the OLED devices of luminescence brightness, current density and efficiency by changing the thickness of Bphen and the volume concentration of Cs₂CO₃doped in Bphen. Experimental results show that Bphen or Bphen:Cs₂CO₃ used as electron transport layer both can improve electronic injection and the performance of devices. Compared with the devices without Bphen, adding 25 nm thickness Bphen as electron transport layer can improve the device of electron injection, which increase the maximum current efficiency by 112%.Adding 5 nm thickness Bphen:Cs₂CO₃(15% volume concentration doped) as electron transport layer can reduce the electron injection barrier, which increase the maximum current efficiency by 27%. However, changing the doping layer thickness has little impact on the device's electron injection. This method can be used in cathode decorate of OLED devices and play a certain role in promoting the devices' performance.