Zhaorun Tang,Jianwen Zeng,Yuewei Zheng,Zhihao Guan,Xinghai Liu
Ultralong afterglow materials has special optical properties and a broad application prospect in the field of information encryption. A single afterglow color largely limits the application of afterglow materials in the direction of advanced encryption, and materials with dynamic afterglow are more popular. However, most of the dynamic afterglow materials are doped with multiple chromophores, and these materials with a single chromophore are rarely reported and have low lifetimes. Herein, a series of dynamic afterglow materials with time-dependent phosphorescence is obtained by a simple one-step strategy, and the longest lifetime reached 1.39 s, the maximum PLQY reached 85.9%, and the naked-eye duration reached 20 s, which is the best level reported so far. The dynamic afterglow phenomenon is attributed to the multiple phosphorescence emission centers of the guest molecule with different decay rates, which results in a dynamic shift of the phosphorescence color. It is demonstrated through a series of characterizations that the covalent bonding interaction between the guest molecule and the host boric acid largely inhibits the nonradiative leaps of the guest molecule and provides it with a rigid matrix environment. Crucially, the dynamic afterglow material has been successfully applied in the field of displays and advanced information encryption.
Bandgap tunability plays an important role in controlling the photophysical properties of semiconductor material. In this work, we propose a powerful carbon component engineering strategy for regulating the optical bandgap of scandium/cysteine functional materials (Sc/Cys-FMs) that are synthesized by a facile one-pot hydrothermal method. The band structure of Sc/Cys-FMs is closely related to the Cys ligands. As Cys amount rises, the obtained Sc/Cys-FMs exhibit the red-shifted room-temperature phosphorescence (RTP) emission from Sc/Cys-FMs-50 (3.01 eV) to Sc/Cys-FMs-150 (2.14 eV), accompanied by a decrease in quantum efficiency and an increase in lifetime. Meanwhile, the Sc/Cys-FMs show a unique time-dependent phosphorescence color (TDPC) phenomenon, with a dynamic transition of RTP color from yellow to green as the decay time prolongs because of the emission-dependent lifetime. As the amount of Cys further increases, the bandgap can be continuously reduced to 1.88 eV (Sc/Cys-FMs-300) and 1.56 eV (Sc/Cys-FMs-600), causing the quenching of RTP emission and significantly enhanced photothermal properties. The continuously decreasing bandgap has been proven to be directly ascribed to the increase of carbon component in Sc/Cys-FMs. Considering the TDPC properties, Sc/Cys-FMs can be well used for dynamic phosphorescent anti-counterfeiting. This work not only develops a scalable method for preparing functional materials with superior RTP and photothermal properties, but also proposes the carbon component engineering strategy to achieve bandgap tunability of materials.
Li Ya Liang,Ya Ting Gao,Shuai Chang,Jian Lv,Bin Bin Chen,Da Wei Li
Achieving dynamic optical tunability of ultralong room temperature phosphorescence (RTP) materials is critical for the design of advanced multi-level information encryption. In this work, we develop a facile metal–organic thermal polymerization strategy for the preparation of aluminium/phenylalanine phosphorescent materials (Al/Phe-PMs) with a production capacity on a kilogram scale. The Al/Phe-PMs show an ultralong lifetime of up to 1015.3 ms, with a phosphorescent quantum yield of 7.98%. Most importantly, the Al/Phe-PMs have a unique time-dependent phosphorescence color (TDPC) phenomenon because of the presence of multiple emission peaks with diverse decay times, causing the dynamic transition of RTP color from yellow to chartreuse and then to green with the extension of the decay time. Furthermore, NaOH can be used for effectively regulating the optical properties of Al/Phe-PMs, causing a great blue shift in RTP emission and a decrease in RTP efficiency. NaOH-stimulated color tunability is proven to be ascribed to the sodiation reconfiguration effect that results in the depolymerization of Al/Phe-PMs and the destruction of the rigid conformation. Benefitted by the advantages of both TDPC and color-tunability, the proposed Al/Phe-PMs can be designed for constructing dynamic colored 5D information encryption systems.
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