An sp2-Carbon-Linked Pyrene-Based Covalent Organic Framework with Extended π-Conjugation for White LEDs

Conventional rare earth-based down-conversion luminescent materials face some challenges including supply constraints, high price, and environmental concerns. Herein, a two-dimensional pyrene-based covalent organic framework (Py-COF) achieves a photoluminescence quantum yield of 27.5%, owing to sp2-C linkages, extended π-conjugation, and donor–acceptor bipolar units. Moreover, it exhibits high thermal stability with a decomposition temperature of 570 °C. A series of white LEDs can be fabricated by combining yellow-emitting Py-COF with 460 nm GaN-based exciting chips. The results demonstrate the effectiveness of the above strategies in enhancing luminescent properties of COFs and highlight their potential as rare earth-free down-conversion materials in LEDs.