Aluminum-Doped Zinc Oxide Anode for Organic Light Emitting Diodes Grown by Pulsed Laser Deposition Using Plasma-Enhanced Oxygen Radicals

We report aluminum-doped zinc oxide (AZO) anode for the organic light emitting diodes (OLEDs) grown by oxygen plasma-enhanced pulsed laser deposition (PE-PLD). AZO film with growth temperature of 400 °C and O₂ gas flow rate of 3.5 sccm showed the transmittance of 95% in the visible (400 nm∼700 nm) wavelength region, the sheet resistance of 14.9 Ω/cm², and the very smooth surface root mean square (rms) roughness of 0.46 nm. Indium tin oxide (ITO) film was compared to the AZO films and OLEDs was fabricated using the ITO film and the AZO films as anode, respectively. The luminous efficiency (cd/A) of the OLEDs including the ITO anode was 1.92 cd/A, meanwhile, 2.37 cd/A of the luminous efficiency was achieved by the OLEDs including the AZO anode with growth temperature of 400 °C and O₂ gas flow rate of 3.5 sccm, albeit the surface work function of the AZO anode (= 4.67 eV) is lower than that of the ITO anode (= 4.92 eV).