A gated strategy stabilizes room‐temperature phosphorescence

Abstract Room‐temperature phosphorescence (RTP) of purely organic materials is easily quenched with unexpected purposes because the excited triplet state is extremely susceptible to external stimuli. How to stabilize the RTP property of purely organic luminogens is still challenging and considered as the bottleneck in the further advancement of the bottom‐up approach. Here, we describe a gated strategy that can effectively harness RTP by employing complexation/dissociation with proton. Due to the order‐disorder transition orientation of intermolecular packing, the RTP of organic molecules 2,4,6‐tris(4′‐bromo‐[1,1′‐biphenyl]‐4‐yl)‐1,3,5‐triazine (Br‐TRZ) will easily vanish upon mechanical force. Impressively, by enhancing its intramolecular charge transfer effect, the protonated Br‐TRZ stubbornly possesses an obvious RTP under external grinding, whatever in the ordered or disordered intermolecular arrangement state. Consequently, the “ Lock” gate of RTP was achieved in the protonated Br‐TRZ molecule. Combined with theoretical calculation analysis, the enhanced charge transfer effect can narrow the singlet−triplet energy gap significantly, and stabilize the RTP property of triazine derivative sequentially. Furthermore, the locked RTP can be tuned via proton and counterions repeatedly and show excellent reversibility. This gated RTP concept provides an effective strategy for stabilizing the RTP emission of purely organic systems.