Evaluation of the stability of different encapsulated blue OLEDs

Abstract

Organic light emitting diodes (OLEDs) are nowadays the most attractive technology for displays and lighting applications. However, their short lifetime remains the most important limit for their broad commercialization. In particular, blue OLEDs generally present the worst stability respect to the other colors. While the extrinsic degradation can be easily controlled by proper encapsulation, understanding the origins of the intrinsic degradation remains a challenge: up to now, the proposed mechanisms have not considered possible phenomena that can occur during OFF-time periods. In this study, intrinsic degradation phenomena have been studied through shelf life experiments performed at different storage conditions on two types of blue OLEDs. Experiments revealed that physical aging occurs for both types of devices, leading to irreversible time-dependent luminance loss.