Dongbo Chen,Yu-e Shi,Song Shen,Song Liu,Dongpeng Yan,Zhenguang Wang
Dual-mode afterglow, integrating ultralong phosphorescence and delayed fluorescence, offers promising opportunities for developing high-temperature resistant luminescent materials. However, there is an obvious gap between the emission lifetime of delayed fluorescence and phosphorescence. In this work, a dehydration-induced doping strategy is proposed to achieve high-temperature resistant afterglow by balancing phosphorescence and delayed fluorescence lifetime. The critical role of structural defects is demonstrated in the afterglow mechanism, where energy transferred between the defect states and guest molecules determines the lifetime of afterglow. In addition, efficient reverse intersystem crossing processes are achieved between the defect states and singlet states, facilitating the long-lived fluorescence. These synergistic effects result in the prolonged lifetime of delayed fluorescence to approach that of phosphorescence, which produced high-temperature resistant afterglow materials, even up to 125 °C. These results provide a clue for modulating the emission dynamics of afterglow materials for applications in information security, biomedical diagnosis, and chemical sensing.
Circularly polarized (CP) light has attracted wide attention for its great potential in broad applications. However, it remains a challenge to generate left-handed and right-handed circularly polarized (LCP and RCP) light from cellulose nanocrystal (CNC)-based materials only with an intrinsic left-handed chiral structure, owing to the pattern of CP light emission primarily based on the chirality of materials. Herein, a separation structure of luminophore layers and chiral CNCs was provided to achieve dual-mode CP light emission by building a luminophore–chiral CNC interface. By directly exciting the back and front of two-layer films, LCP and RCP light could be easily emitted without any assisting means and specific setting angles. In addition, owing to the formation of the luminophore–chiral CNC interface, metal-enhanced fluorescence (MEF) was achieved to offset the brightness loss caused by circular polarization. By incorporating gold triangular nanoprisms in CNC chiral layers, the fluorescence enhancement of the ensemble was as high as 6.5-fold. The decisive role of the luminophore–chiral CNC interface in enhancing luminescence and dual-mode CP light emission was carefully investigated by contrasting the systems with and without luminophore–chiral CNC interfaces in this study. We believe that this dual-mode CP light emission film with MEF enables a promising approach to extending the application of CP light materials.
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