Yb基阴极高性能有机顶部发光器件

摘要

金属Yb兼具功函数低、透光度高和化学稳定性相对较高等优点,非常适合作为有机顶部发光器件（TEOLED）的透明阴极材料。计算表明：TEOLED阴极层中加入金属Yb可以有效地抑制器件工作过程中产生的表面等离子体激元振荡（SPs）,从而提高器件的相关性能。本文比较性地研究了两种阴极层不同（Yb/Yb：Au和Yb/Yb：Ag）、结构相同（ITO/NPB/Alq3/阴极）的TEOLED。结果表明,直接利用Yb：Au或Yb：Ag共沉积层作为透明阴极的TEOLED的透光度很高,但其电子注入能力较差、发光效率较低;而在Yb：Ag（或Yb：Au）共沉积层和Alq3层之间插入厚度适当的Yb层后,虽然透光度略有下降,但其发光效率得到了显著的提高。%The properties of rare earth element Yb, such as low work function, high optical transmittance and rel- ative chemical stability make this metal very suitable to be used as transparent cathode materials for top - emitting organic light emitting devices （TEOLEDs）. Our calculation also demonstrates that introducing this material into TEOLED will reduce the affect of the surface plasmons （SPs） during operation and hence improve the perform- ance of the device. In this paper, we have comparatively studied two types of Yb - based cathode, Yb/Yb ： Au and Yb/Yb ： Ag, for the TEOLEDs with a structure of ITO/NPB/Alq3/cathode. The Yb ： Au or Yb ： Ag co - va- porization layer deposited directly on the Alq3 as cathode exhibits very high transmittance but poor electron injec- tion. Inserting a thin Yb layer with suitable thickness between the Yb：Ag （or Yb：Au） and Alq3 layers will sig- nificandy improve the light emitting efficiency of the TEOLED, though slightly reduce the transmittance of the cathode.