Synergistically Modulating the Excited States of Perovskites by Hydrogen-Bond Interactions and Mn ^{2 +} Doping for Near-Unity Orange Fluorescence and Dynamic Room-Temperature Phosphorescence

In the field of anticounterfeiting materials, simultaneously achieving highly efficient fluorescence and dynamic room-temperature phosphorescence (RTP) remains a major challenge. Conventional systems often suffer from an intrinsic conflict between long lifetime and high quantum efficiency, limiting full utilization of both the "on" and "off" states under UV irradiation. Here, we developed (3-FPA)₂CdCl₄(3-FPA, 3-fluorophenylammonium), where intermolecular C-H···F hydrogen bonding among 3-FPA molecules influences the excited-state relaxation behavior, and Mn²⁺ incorporation further tailors the emissive centers, enabling multimodal anticounterfeiting combining efficient fluorescence and dynamic RTP. Mn²⁺ doping introduces new emissive centers and alters the excited-state relaxation pathways, enabling a nearly unity photoluminescence quantum yield (98.10%) under 270 nm excitation and a red-to-green dynamic RTP under 365 nm excitation. Femtosecond transient absorption (fs-TA) spectroscopy further revealed that the Mn²⁺ concentration strongly modulates the energy-transfer rate, thereby allowing precise control of the dynamic RTP process. Moreover, the designed anticounterfeiting patterns demonstrate dual-mode protection through the integration of efficient fluorescence and dynamic phosphorescence. This work provides new insights and strategies for the development of advanced multimodal luminescent anticounterfeiting materials.