Organic full-color narrowband afterglow

Abstract

Developing a facile and universally applicable strategy to achieve organic full-color narrowband afterglow (OFNA) is highly desirable, as it meets the strategic demands for low-cost and high-color-purity displays in flexible electronics. Here, OFNA is achieved through a general protocol involving the mixing, melting, and cooling of panchromatic boron-nitrogen-containing multiple resonance thermally activated delayed fluorescence (MR-TADF) emitters with a host matrix, tri(2-methylphenyl)phosphine oxide (TTPO), followed by photoactivation. The emission peaks of OFNA range from 468 to 669 nm, with full-width at half-maximum values of ≤0.21 eV and Commission Internationale de L'Eclairage coordinates ranging from (0.142, 0.190) to (0.733, 0.267). Molecular dynamics simulations demonstrate that the glassy morphology formed by TTPO after heating-annealing can provide a rigid microenvironment for fluorophores, which can effectively confine the molecular vibrations and stabilize their conformations. When the blended films are photoactivated, the triplet excitons can slowly repopulate to the singlet state and release afterglow. Finally, representative MR emitters are utilized to develop high-color-purity flexible organic afterglow fibers, optical waveguide fibers, and data encryption applications.