Decoupling energy pathway and reshaping spectrum of dual-mode organic afterglow with programmable crystalline...

Organic afterglow materials exhibiting both thermally activated delayed fluorescence (TADF) and room-temperature phosphorescence (RTP) hold great promise for advanced photonic applications. However, precise control over their emission properties remains challenging due to the intrinsically overlapped spectra and coupled energy dynamics of TADF and RTP, as well as the difficulty in dynamically tuning these properties post-synthesis. While photonic crystals provide a powerful platform for manipulating light-matter interactions, their use in directing the energy pathways of TADF/RTP dual-mode organic afterglow remains largely unexplored. Herein, we report a strategy to decouple and synergistically regulate the dual-mode organic afterglow using crystalline colloidal arrays (CCAs) with two mechanisms: First, radiative energy transfer and resonant absorption by far-field coupling within the CCAs to promote the re-absorption of the TADF component, thereby suppressing the TADF channel and selectively enhancing the RTP component. Second, the photonic bandgap of the CCA system acts as a spectrally selective filter to tune the afterglow spectrum. This work establishes a versatile platform for the post-synthetic, multidimensional tailoring of dual-mode organic persistent luminescence and opens new avenues for designing programmable afterglow devices for encryption, sensing and display technologies.