Ultralong room-temperature phosphorescence of crystalline organic luminogens: excitation-dependence, chirality, and host-guest doping.

Crystalline room temperature phosphorescence (RTP) materials combined with chirality and excitation-dependent properties hold significant application value and play a crucial role in elucidating intrinsic RTP mechanisms. Here, four guests and a host material named APET-H, APET-F, APET-Cl, APET-Br, and BCN were designed and synthesized in turn, with non-conjugated structures features and multiple electron rich functional groups. The guest materials showed different chirality features and high-contrast RTP in crystalline state, with optical rotation of -15.8° to 2°, RTP lifetimes of 69-256 ms, and afterglow lifetimes of 0.3-3 s. More importantly, APET-F and APET-Cl presented excitation dependent RTP in crystalline state and concentration dependent fluorescence emission in solution. By host-guest doping, RTP and afterglow lifetimes were significantly promoted, with RTP lifetimes of 342-399 ms and afterglow lifetimes of 4-6 s. More importantly, the doping systems showed similar fluorescence and RTP emission maxima, but with different RTP lifetimes. Thereby, the advanced-level anti-counterfeiting pattern and information encryption could be achieved by choosing the above crystals and doping systems. Finally, the underlying luminescent mechanisms were discussed in detail based on crystal analysis and theoretical calculations.