Studies on carrier confinement for polymer electroluminescent devices with multilayer structure

Recently, high luminance and high efficiency were realized in organic thin-film electroluminescence devices with multilayer structure, which include an emitting layer, a hole transporting layer, and an electron transporting layer. Generally these carrier transporting layers have the properties of inhibiting different type carriers such as transporting hole while inhibition electrons, by which the carrier are confinement in emitting layer. In this letter, we report some properties of hole blocking layers which were realized in a double layer structure with ITO/emitting layer/hole blocking layer/Al. In this structure, the emitting layer was 1,1,4,4,-tetraphenyl-1,3-butadiene(TPB) doped poly(N-vinylcarbazole) (PVK), which has large hole mobility, and hole blocking layer was PBD.