COMPARISON OF ELECTROLUMINESCENCE AND PHOTOLUMINESCENCE EFFICIENCIES OF ORGANIC ELECTROLUMINESCENT DEVICES HAVING A BILAYER STRUCTURE

The recombination processes of electrons and holes injected into the t ris(8-hydroxyquinolino)aluminum (ALQ) layer of organic electroluminesc ent (EL) devices having the ALQ/diamine biller structure were studied. From the comparison of the EL and PL (photoluminescence) emissions, t he quantum efficiency of EL under the normal operational conditions wa s estimated to be about 0.12 times that of FL. Experimental results su ggested the occurrence of nonemissive electron-hole recombination proc esses at the ALQ/diamine interface.