Acrylate Optically Clear Adhesives with Excellent Oxygen Barrier for Organic Light-Emitting Devices

Abstract

The organic light-emitting devices (OLEDs) sealed by optically clear adhesives (OCAs) always face the risk of luminescence loss due to the formation of dark spots caused by the oxygen attack, for which the poor oxygen barrier property of the OCAs is responsible. To address this issue, a new type of acrylate-based OCAs matrix was initially synthesized; then the modified boron nitride (mBN) was integrated to create a physical “passive” barrier, and hydroxyl-terminated polybutadiene (HTPB) as an efficient chemical “active” oxygen scavenger was also introduced to prepare acrylate-based OCAs with superior oxygen barrier property. The oxygen permeability coefficient is as low as 4.76 cc·mil·m^–2·day^–1·0.1 MPa^–1, which is 35.61 times lower than that of the unmodified acrylate matrix, due to the synergistic barrier effect of mBN and HTPB. Even after 6 months, the OCAs still maintain a good oxygen barrier performance, with an oxygen permeability coefficient of 103.43 cc·mil·m^–2·day^–1·0.1 MPa^–1. The OCAs also exhibit excellent water barrier performance (11.26 g·mil·m^–2·day^–1), high light transmittance (>87%), strong peeling force (13.5 N/25 mm), and a remarkable strain recovery ratio (73%). When testing the luminous performance of OLEDs at room temperature, the working time of OLEDs sealed by our OCAs corresponding to a 5% decrease in relative luminous efficiency is extended by 10 h, compared to that of OLEDs sealed by commercial adhesives. Furthermore, when the OLEDs are stored at 85 °C for 7 days, the OLEDs sealed by our OCAs still exhibit luminous performance comparable to that of ones by commercial adhesives. Thus, this work presents a novel approach to prepare OCAs with outstanding comprehensive performance, especially the excellent oxygen barrier property, showing the significant potential for OLEDs sealing.