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

We report the effect of inorganic nanolayers on electron injection in the polymer light-emitting diodes (PLEDs) in which a hole is the major charge carrier. The inorganic nanolayers with different 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 efficiency, which is significantly higher than that of one without an insulating layer. The enhancement may result from the lowering of the effective barrier height for electron injection while increasing electron-tunneling probability, which improve the balanced injection of hole and electrons.