Intramolecular-Catalyzed Vitrimers with White-Light Emission for Light-Emitting Diode Encapsulation

Currently available encapsulating materials for white light-emitting diodes (WLEDs) have certain limitations, such as the toxicity of phosphors and the non-recyclable nature of the encapsulating materials. In this study, relatively promising encapsulating materials with two significant advantages are developed. First, the chips can be directly encapsulated without phosphors using luminescent encapsulating materials. Second, the encapsulating materials can be reprocessed for recycling via intramolecular catalysis. To this end, blue-light-emitting vitrimers (BEVs) are prepared by the reaction of epoxy resin with amines and are found to exhibit strong blue emission and fast stress relaxation via internal catalysis. To obtain white-light emission, a well-designed yellow component, perylenetetracarboxylic dianhydride, is grafted into the BEVs to generate white-light-emitting vitrimers (WEVs). A rare synergy of blue- and yellow-light emission affords white-light emission. When the WEV is used as an encapsulating adhesive for 365 nm LED chips without inorganic phosphors, stable white light with CIE coordinates (0.30, 0.32) is successfully achieved, indicating a promising future for WLED encapsulation.