Highly efficient top emitting organic light-emitting diodes with organic outcoupling enhancement layers

We demonstrate high-efficiency top emitting organic light-emitting diodes employing silver (Ag) for both anode and cathode. Following the p - i - n doping and double emission layer concepts, the devices show a very high efficiency of 50 cd ∕ A at 1000 cd ∕ m 2 with a driving voltage of only 2.85 V . The efficiency can be further improved to 78 cd ∕ A by tuning the optical structure with an organic capping layer. A simple explanation based on the transmittance of the top contact cannot explain this efficiency enhancement. Instead, we theoretically show that this capping effect is dependent on the overall optical structure of the device.