Controllable Multicolor Luminescence in Homophthalic Anhydride via Pressure Treatment Engineering

The co-multiplexing of polychromatic emission and stimuli-responsive features within luminescent materials offers unique opportunities for the design of advanced smart materials. However, realizing tunable multicolor emission in single-component materials remains a formidable challenge, particularly when aiming for reproducible and structurally consistent performance. Here, we realized adjustable multicolor emission ranging from blue to cool white and finally warm white light in homophthalic anhydride (HA) crystals through pressure treatment engineering. Detailed structural analyses and theoretical calculations reveal that pressure treatment engineering shortens intermolecular nonbonded interaction distances, enhances orbital coupling, and induces the formation of long-range coupled molecular orbitals. This effect not only enables dimer-based charge transfer (CT) transitions but also modulates the oscillator strengths of multiple CT states, thereby enabling precise control over the photoluminescence (PL) color of HA crystals. This work not only highlights the potential of commercial HA crystals as stimuli-responsive multicolor emitters but also provides new insights for designing smart luminescent materials with multicolor and controllable properties.