Transparent Organic Light Emitting Diodes Using a Multilayer Oxide as a Composite Cathode

Transparent organic light emitting diodes are developed by using a multilayer oxide as a composite cathode.The device structure is ITO/ MoO3(10 nm)/NPB(60 nm)/Alq3(65 nm)/Al(1 nm)/MoO3(1 nm)/Al(X nm) /MoO3(30 nm).The composite cathode is MoO3/Al/MoO3(MAM).A thin Al layer(1 nm) was introduced as an interlayer between the Alq3 electron transport layer and the MAM electrode.On the one hand,the thin Al layer improves the interface flatness between electrode and organic layers,while improving the conductivity of the electrode.On the other hand,electron injection was greatly improved by forming an Ohmic contact between the electron transport layer and a thin Al layer.Then the OLEDs optimum performance is obtained by changing the thickness of Al in MAM.With the Al thickness of 18 nm,the highest brightness 2 297cd/cm2 is obtained.