Double-layer electroluminescent devices with Langmuir–Blodgett films of amphiphilic 8-hydroxyquinoline lanthanum as emitter

A double-layer organic thin film electroluminescent (EL) device has been prepared by using the LB film technique. Its basic structure consists of a hole-transport layer of material, poly (N-vinylcarbazole) (PVK) and an electron-transport layer of material, the Langmuir–Blodgett films of bis [N-hexadecyl-8-hydroxy-2-quinolinecarboxamide] lanthanum (LaL2Cl). Comparing with the luminance of the single-layer EL device (ITO/LB film/Al), the double-layer EL device (ITO/PVK/LB film/Al) has a higher luminance (873 cd m−2) and operates at a lower driving voltage (8 V). The deposited surface pressure of the LB film had strong influence on the EL intensity of the devices. The luminancent mechanism of the EL devices was discussed.