The trivalent lanthanides have been broadly utilized as emitting centers in persistent luminescence (PersL) materials due to their wide emitting spectral range, which thus attract considerable attention over decades. However, the origin of the trivalent lanthanides’ PersL is still an open question, hindering the development of excellent PersL phosphors and their broad applications. Here, the PersL of 12 kinds of the trivalent lanthanides with the exception of La3+, Lu3+, and Pm3+ is reported, and a mechanism of the PersL of the trivalent lanthanides in wide bandgap hosts is proposed. According to the mechanism, the excitons in wide bandgap materials transfer their recombination energy to the trivalent lanthanides that bind the excitons, followed by the generation of PersL. During the PersL process, the trivalent lanthanides as isoelectronic traps bind excitons, and the binding ability is not only related to the inherent arrangement of the 4f electrons of the trivalent lanthanides, but also to the extrinsic ligand field including anion coordination and cation substitution. Our work is believed to be a guidance for designing high-performance PersL phosphors.

The rapid development of near‐infrared (NIR) spectroscopic techniques has greatly stimulated the discovery of novel broadband NIR‐emitting phosphors as advanced light sources. Herein, a novel double‐perovskite phosphor La2MgHfO6:Cr3+/Yb3+ that displays ultra‐broadband NIR emissions with a full‐width at half maximum (FWHM) of 333 nm is reported. The remarkable luminescence property stems from the multiple crystallographic sites, relatively weak crystal field, and efficient Cr3‐to‐Yb3+ energy transfer (ET). The site occupation of Cr3+ is elaborately verified by the Rietveld refinement and first‐principles calculation. By controlling the ET process, the internal/external quantum efficiency (IQE/EQE), bandwidth, and thermal stability of NIR emissions are substantially improved. The as‐prepared phosphors are further integrated into a miniaturized NIR light‐emitting diode (LED) package, demonstrating superior performance in rapid nondestructive detection of structural failure in thin electronic cables. The results described here provide a novel pointcut for designing broadband NIR‐emitting phosphors with desired optical properties toward applications in industrial inspection and medical diagnosis.

No abstract

No abstract

The highest relative thermal sensitivity for Er3+-based thermometers is reported following 980 nm laser excitation.