Indium-free transparent organic light emitting diodes with Al doped ZnO electrodes grown by atomic layer and pulsed laser deposition

We present highly efficient transparent organic light emitting diodes (OLEDs) with Al doped ZnO (AZO) electrodes prepared by atomic layer deposition and pulsed laser deposition (PLD). The power and current efficiencies exceed 27 lm/W and 44 cd/A at a brightness level of 100 cd/m2, respectively. At the same time, the transmissivity of the devices is above 73% in the visible part of the spectrum. Owing to an efficient WO3 buffer layer and an optimized PLD process for the deposition of the top AZO electrode, the OLEDs show leakage current densities as low as 3×10−5 mA/cm2 at a reverse bias of 6 V. Therefore, our study paves the way for indium-free, see-through OLED displays.