Passivation of organic light-emitting diodes with aluminum oxide thin films grown by plasma-enhanced atomic layer deposition

The passivation of organic light-emitting diodes (OLEDs) with Al2O3 films containing small amounts of N (Al2O3:N) was investigated by plasma-enhanced atomic layer deposition using a direct rf plasma with a short pulse time. Luminance—voltage and current density—voltage curves of an OLED passivated with a 300nm Al2O3:N film at 60°C remained unchanged compared to those of nonpassivated OLED and 96% of the initial luminance were maintained even after operating for 850h at 14mA∕cm2. The lifetime of an OLED with an 80°C Al2O3:N film was 650h, 6.2 times longer than that of a nonpassivated sample, although the luminance—voltage characteristics of the OLED were altered to a considerable extent.