Improvement of electrode/organic layer interfaces by insertion of monolayerlike aluminum oxide film

We studied improvement of the electrode/organic interface in organic electroluminescent diodes which consist of 8-hydroxyquinoline aluminum (Alq3) and diamine derivative (TPD). An aluminum oxide (Al2O3) monolayer was inserted between TPD and the indium tin oxide (ITO) anode. An improvement of emission is observed in a diode with an Al2O3 layer between 0.5 and 1 nm thick inserted in the surface of the anode/organic layer. The mechanism of increase in emission efficiency is discussed.