Host-guest doped organic room temperature phosphorescence with a dual-fused-ring effect for near-infrared multiple-anticounterfeiting applications

The near-infrared (NIR) emission host–guest doped organic room temperature phosphorescence (ORTP) materials provide significant advantages and application for information anti-counterfeiting applications. The fused-ring structure of guest molecules is considered to be an effective method for redshirting the emission wavelength. Herein, we present a dual-fused-ring (DFR) guest strategy to develop NIR emission host–guest doped ORTP system. Five guest molecules with DFR effect were synthesized, incorporating a fused-ring core (1,2,3,4-tetraphenylnaphthalene, TPN) and various fused-ring substituents (benzene, naphthalene, anthracene, and pyrene). Using benzophenone (BPO) as the host, BPO/TPNs system exhibited excellent phosphorescence properties with emission wavelength ranging from 541 to 766 nm and lifetime from 27 to 355 ms. The experimental and theoretical studies prove that DFR strategy effectively lowers the lowest triplet excited state (T₁) level and improve intersystem crossing (ISC) efficiency. The outstanding color- and time-dependent features of BPO/TPNs enable multi-anticounterfeiting applications. This work provides a facile and effective strategy for designing ORTP materials with both long wavelengths and extended lifetimes with DFR effect.