Effect of parylene layer on the performance of OLED

Abstract

An organic light-emitting device structure with a thin parylene layer deposited by low-temperature chemical vapour deposition at the anode-organic interface was fabricated. Such a structure gives higher luminescence efficiency when operated at the same current density compared to one without the parylene layer. In addition, the devices with a thin parylene layer also show a smaller number and smaller size dark non-emissive areas, slower growth rate of the dark areas and a longer device lifetime. The modified surface of the indium tin oxide (ITO) shows an increased work function compared to that of the ITO surface alone and a reduced surface roughness, which contributes to the device performance improvement. The parylene layer is a conformal coating on the ITO surface, which could significantly stabilise the interface leading to a more uniform current density. It also provides a good barrier for blocking oxygen and moisture diffusion and hence reducing dark spot occurrence.