Effect of polymer-insulating nanolayers on electron injection in polymer light-emitting diodes

We report the effect of polymer-insulating nanolayers on electron injection in the polymer light-emitting diodes (PLEDs) in which a hole is the major charge carrier. Several different polymer nanolayers with varying dielectric constants were placed between the emitting layer and the aluminum cathode, and their influence on the device performance was investigated. The device with a nanolayer of lower dielectric constant demonstrated higher luminescence quantum efficiency. In particular, when a similar to10-nm-thick polystyrene layer was employed, the device gave approximately two orders of magnitude higher external quantum efficiency than that of the one without an insulating nanolayer. (C) 2004 American Institute of Physics.