Composite Encapsulation Films with Ultrahigh Barrier Performance for Improving the Reliability of Blue Organic Light‐Emitting Diodes

Abstract

AbstractThis work presents a facile method to fabricate composite encapsulation bilayer films with ultrahigh barrier performance for the blue organic light‐emitting diodes (OLEDs). The encapsulation film is composed of the SiNx and Al2O3 layers prepared via incorporation of plasma enhanced chemical vapor deposition (PECVD) and spatial atomic layer deposition (S‐ALD) methods. It is found that the hybrid bilayer films possess excellent barrier performance with water vapor transmission rate (WVTR) of ≈10−6 g m−2 day−1 and a long lag time. No black spots are found when applied to the blue OLEDs for more than 1000 h under the accelerated aging condition. The improved stability of the composite barrier originates from introduction of the nanoscale Al2O3 to SiNx layer, leading to the decrease of the stored strain energy. Besides, the Al2O3 layer could help decouple the pinholes on the SiNx surfaces, which blocks permeation of the moisture to degrade the OLEDs. The interface toughness between the OLED and barrier remains stable, which hinders the delamination of the SiNx layer in the severe environment completely.