Controllable multicolor emission from initially non-emissive organic molecules by pressure engineering.

Developing smart luminescent materials with off-on switchable responsiveness, which enables dark-to-bright state transitions in response to external stimuli, has garnered great interest across various domains. However, most of the reported systems with only monochromatic switching have limited their expansion toward advanced applications. Herein, a pressure-treated strategy is introduced to initially non-emissive isonicotinic acid (INA), achieving controllable switching from the dark state to high-quality multicolor emissions (i.e., blue, white, and yellow light). Experimental and theoretical analyses reveal that pressure-treated engineering can effectively modulate the intermolecular charge transfer strength within and between layers, enabling controlled emission color switching. Notably, the bright white light with CIE coordinates (0.31, 0.37) and the yellow light with CIE coordinates (0.42, 0.45) are retained under ambient conditions. The findings not only impart new vitality to nonemissive organic small molecules but also offer a new perspective for designing smart luminescent materials with multicolor and controllable properties.