Tunable Emission Properties of Indolizine-Based Aggregation-Induced Emission Luminogens for White-Light Emission.

Unlike conventional fluorophores experiencing aggregation-caused quenching (ACQ) in the solid state, aggregation-induced emission (AIE) luminogens (AIEgens) exhibit enhanced fluorescence upon aggregation. This property renders AIEgens promising for various technological applications. However, developing red-emitting AIEgens with high fluorescence efficiency remains challenging due to structural constraints. Compact red-light-emitting AIEgens hold great potential, as their small, simple fluorescent frameworks enable facile modification and precise color tuning. This study presents a novel compact indolizine-based AIE system with solid-state emission tunable from cyan (496 nm) to deep red (669 nm), with an average molecular weight (MW) of 312.8 g/mol. The deep-red-emitting derivative is uncommon among short-conjugation, low-molecular-weight (∼280 g/mol) systems and demonstrates exceptional photophysical characteristics. Through carbonyl functional groups, we modulated molecular packing, resulting in distinct optical properties and emission tunability in solid and aggregated states. Structural investigations using single-crystal X-ray diffraction (SCXRD) and computational modeling revealed that molecular packing and intermolecular interactions significantly influence emission behavior. Integration of these AIEgens into blue-light-emitting diode chips facilitated white-light production with CIE coordinates (0.360, 0.362) and a color temperature of 4533 K. These findings underscore the potential of indolizine-based AIEgens for next-generation emissive materials, providing insights for their rational design and broader technological applications.