Enhanced Ultra‐Long Room Temperature Phosphorescence by Intermolecular Donor–Acceptor Interaction in Polymer Network

Abstract Ultra‐long room temperature phosphorescence (URTP) is an attractive phenomenon in organic photonics. However, most of the reported strategies for enhancing URTP require complicated synthesis processes. Herein, a novel strategy is reported, two birds with one stone, for enhancing URTP by doping the ground‐state intermolecular donor–acceptor complexes into a dense polymer network: i) The dense network ensures the formation of intermolecular donor–acceptor complexes, which provide a smaller singlet‐triplet energy difference (ΔEST) and more intersystem crossing (ISC) channels than the individual donor or acceptor molecules; ii) The dense network adequately suppresses the non‐radiative relaxation caused by molecular vibrations and oxygen quenching. The URTP intensities of the intermolecular donor–acceptor complexes doped film are 20 times higher than that of the film only doped with acceptor molecules, and the phosphorescence lifetime is up to 200 ms. The theoretical calculation reveals the electronic interaction between donor and acceptor and the increased ISC channel, which elucidates the photophysical mechanism of the strategy and confirms its rationality. An advanced encryption application is developed based on enhanced URTP films. This work opens a new direction for URTP materials through the intermolecular donor–acceptor interaction.