Abstract: Organic electroluminescent (EL) devices with a bilayer structure (ITO/LBfilm/PBD/Al) were fabricated with an Langmuir Blodgett (LB) film of amphiphilic complex bis[ Nhexadecyl 8-hydroxy-2-quinoline carboxamide] lanthanum[La(HQ)₂Cl] as the emitting material. Excellent performance of the ELdevices originates from the insertion of an electron transport layer between the electrode and the emitting layer. Greenish yellow ELemission with a luminance of about 1219cd/m² was observed with a low voltage drive(7.5 V). The number of the layers of LBfilms and the deposited surface pressure have a strong influence on the I-Vcharacteristics, ELintensity, as well as break down voltage of the ELdevices. When the LBfilms were prepared at the surface pressure of 25 mN/m, the current density crossing this kind of diodes had stronger nonlinear I-Vcharacteristics and the organic ELdevice had a higher ELintensity than another device prepared at lower surface pressure(5 and 15 mN/m). At a lower surface pressure, there may be some point defects or pinholes in the LBfilm, in which the high tunnel current would increase exponentially with the field, leading to an increase in the current density crossing the ELdevice and a decrease in the recombination probability of electrons and holes at a higher voltage.

Key words: Electroluminescent device, Langmuir Blodgett film, Bilayer devices