Efficient triplet energy transfer in a 0D metal halide hybrid with long persistence room temperature phosphorescence for time-resolved anti-counterfeiting

Abstract

Endowing metal halide hybrids (MHHs) with time-resolved emission and afterglow could significantly broaden their applications in fields such as information security and anti-counterfeiting. Nonetheless, there have been relatively few successes in developing organic cations with persistent room-temperature phosphorescence (RTP) to construct MHHs with afterglow. In this work, we synthesize a new polyazole, 3,5-di(1H-pyrazol-4-yl)-4H-1,2,4-triazol-4-amine (DPTA), with green persistent RTP up to 1.5 s. The afterglow of DPTA reaches up to ∼1.0 s even after being assembled into 0D (DPTAH₃)InCl₆·2.5H₂O (DIC). Due to strong overlap between the triplet emission of DPTA and ¹S₀ → ³P_x absorption of Sb³⁺, efficient triplet energy transfer (TET) with the highest yield of 65.3% and a near-unity photoluminescence quantum yield (PLQY) is achieved. More importantly, the afterglow persistence time of DIC:x% Sb can be easily tailored through Sb³⁺ doping. Given the Sb³⁺-dependent emission color and long persistence time, a series of DIC:x% Sb are successfully utilized to demonstrate high-security-level anti-counterfeiting application. This work shows an effective strategy for designing new MHHs with tunable emission and afterglow persistence time.