Huilin Gou,Yanfeng Liu,Guiyang Zhang,Qiaobo Liao,Xin Huang,Fangyi Ning,Can Ke,Zhen Meng,Kai Xi
Despite the excellent room-temperature phosphorescence (RTP) property of carbon dot (CD)-based RTP composites, the development of these emerging materials with finely tunable afterglow lifetimes still remains a challenge. Herein, for the first time, we report a series of pure organic RTP composite materials based on adjustable polyaniline carbon dots (PACDs) and polymer matrices (polyacrylic acid, polyacrylamide, and polyvinyl alcohol) with tunable RTP lifetimes. By using different polymer matrices and adjusting the functional groups of PACDs, the strength of hydrogen bonding between each polymer matrix and PACDs was regulated, and green RTP emissions with a tunable average lifetime ranging from 184 ms to 652 ms were also realized. In addition, taking advantage of their different persistent afterglow lifetimes, naked-eye-observable and time-resolved anti-counterfeit and data encryption patterns were prepared using these PACDs/polymer composites, demonstrating the potential application of these materials.
Bin Xu,Zifei Wang,Jian Shen,Jie Li,Yuehan Jia,Tianlong Jiang,Zhenhua Gao,Xue Wang,Xiangeng Meng
Carbon dots (CDs) that simultaneously exhibit full-color and wide-range lifetime-tunable room-temperature phosphorescence (RTP) are of particular interest for potential applications in encryption and information security. However, achieving such CDs remains a great challenge thus far. This work reports on the development of a straightforward host–guest approach, where a metal–organic framework (MOF) host acts as an RTP activator of fluorescent CDs, with the RTP color dependent on the fluorescent component. The developed CDs@MOF composites exhibited RTP with a tunable emission wavelength from blue (478 nm) to red (631 nm), while the lifetime was tunable from 85.67 to 1064.21 ms. As far as is known, this is the report of CD-based RTP materials with simultaneous full-color and wide-range lifetime-tunable properties for the first time. In comparison to conventional 3D coding applications of CDs, the wide-range lifetime-tunable property allows for the creation of an additional dimension in encryption. Thus, the developed RTP CDs@MOF composites have potential as writable security inks for advanced 4D coding applications. This study paves a path for development of RTP CD-based nanomaterials with multiple controllable factors to meet the requirements of advanced applications.
Upconversion luminescence materials have stimulated growing attention in photovoltaic cell owning to the ability of converting a few low-energy photons into a single high-energy photon. However, there still remains a daunting challenge to achieve upconversion emission covering the entire visible spectrum in a single material. Here, an incandescent broadband white upconversion emission covering the entire visible region is realized in a single Gd 2 O 3 :Yb 3+ nanoparticles by utilization of adverse multiphonon relaxation. Importantly, tunable long fluorescence lifetime can be synchronously implemented in the single material, where the lifetime range spans one order of magnitude. Furthermore, benefiting from the broadband emission, the luminescence intensity achieves 482-fold improvement as the power increase from 0.53 W to 1.51 W. These broadband emissions are enabled by engineering the pathways of nonradiative de-excitation via multiphonon relaxation. Based on the kinetic analysis and mechanism research, the photon avalanche is demonstrated to play an important role for broadband emission. The warm white emission together with its tunable long lifetime provides a new avenue for developing single emitter-based white-light-emission materials for next-generation display and lighting technologies.
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