Room-Temperature Phosphorescent Materials Based on β-Diketone Derivatives Exhibiting Excitation- & Concentration-Dependent Characteristics

Room-temperature phosphorescence (RTP) materials have attracted extensive attention owing to their potential applications in chemical sensing, optoelectronic devices, bioimaging, and information encryption. However, developing RTP materials with dynamically tunable emission colors that respond to multiple external stimuli remains a significant challenge. In this work, BA@TTA composites were constructed by doping 2-thenoyltrifluoroacetone (TTA) guest molecules into a boric acid (BA) host matrix, exhibiting efficient room-temperature afterglow. Upon changing the excitation wavelength from 254 nm to 365 nm, the afterglow emission color can be tuned from blue to yellow, indicating prominent excitation-wavelength-dependent luminescence behavior. Moreover, with increasing TTA content, the yellow afterglow under 365 nm excitation is gradually enhanced, whereas the blue afterglow component under 254 nm excitation remains nearly unchanged. This excitation- & concentration-dependent color-tunable phosphorescence of BA@TTA originates from the coexistence of isolated and aggregated TTA species, in which efficient intermolecular energy transfer and aggregation-induced electronic interactions reduce the excited-state energy gap, enhance spin-orbit coupling, and accelerate intersystem crossing, thereby enabling color-tunable room-temperature phosphorescence. This universal mechanism is extended to other β-diketone derivatives for high-security multi-level information encryption.