Effects of the Introduced Single-Wall Carbon Nanotubes on the Performance of Blue Phosphorescence Organic Light-Emitting Diodes

Abstract

In this paper, the effects of single-walled carbon nanotubes (SWCNTs) on the performance of blue phosphorescence organic light-emitting diodes (OLEDs) are investigated by altering the place of SWCNTs in prepared devices. Three kinds of OLEDs in which SWCNTs are spin-coated between the organic layer and the cathode or doped into the organic emitting layer or into the hole-injection layer are prepared. It is found that the SWCNTs doped into the hole-injection layer can enhance the current efficiency because the SWCNTs can reduce hole transport ability and balance two kinds of carriers. Even though SWCNTs doped into the organic emitting layer can improve the transport characteristics of polymer, excess holes lead to an imbalance of holes and electrons in the organic layer, and a lower current efficiency is obtained. SWCNTs located between the organic layer and the cathode can enhance the electron injection from the cathode to the organic layer, and the luminance and current efficiency characteristics are effectively improved.