Optical Transmittance Improvements of Al_2O_3/TiO_2 Multilayer OLED Encapsulation Films Processed by Atomic Layer Deposition

摘要

Encapsulation of organic light-emitting diodes (OLEDs) is the only way to prevent degradation due to the penetration of moisture and oxygen. However, the upper encapsulation layer, located in the path through which light from the OLED passes, adversely affects light transmission. In this study, we calculated the optical transmittance by using admittance trajectory simulation and compared the data with actual Al_2O_3/TiO_2 multilayer film processed by atomic layer deposition (ALD). By applying the simulated data on to actual encapsulation layer, we can observe the optical transmittance increase of up to 8% compared to the film of Al_2O_3/TiO_2/Al_2O_3 structure. Over 90% of optical transmittance was achieved for all the visible wavelength ranges while maintaining water vapor transmission rate (WVTR) of the processed multilayer thin film as low as of 5 × 10~(-5) g/m~2/day, which was measured using MOCON Aquatran 2.