An inverse thermal quenching effect is actualized in uniform lanthanide-doped Na₃ZrF₇ by artificially introducing defect state with an appropriate energy level. These kinds of systems are very suitable for anti-counterfeiting with high security.

External manipulation of emission colour is of significance for scientific research and applications, however, the general stimulus-responsive colour modulation method requires both stringent control of microstructures and continously adjustment of particular stimuli conditions. Here, we introduce pathways to manipulate the kinetics of time evolution of both intensity and spectral characteristics of X-ray excited afterglow (XEA) by regioselective doping of lanthanide activators in core-shell nanostructures. Our work reported here reveals the following phenomena: 1. The XEA intensities of multiple lanthanide activators are significantly enhanced via incorporating interstitial Na⁺ ions inside the nanocrystal structure. 2. The XEA intensities of activators exhibit diverse decay rates in the core and the shell and can largely be tuned separately, which enables us to realize a series of core@shell NPs featuring distinct time-dependent afterglow colour evolution. 3. A core/multi-shell NP structure can be designed to simultaneously generate afterglow, upconversion and downshifting to realize multimode time-dependent multicolour evolutions. These findings can promote the development of superior XEA and plentiful spectral manipulation, opening up a broad range of applications ranging from multiplexed biosensing, to high-capacity information encryption, to multidimensional displays and to multifunctional optoelectronic devices.

Scintillators are of significance for the realization of indirect X-ray detection and X-ray excited optical luminescence (XEOL) imaging. However, commercial bulk scintillators not only require complex fabrication procedures, but also exhibit non-tunable XEOL wavelength and poor device processability. Moreover, thick crystals usually generate light scattering followed by evident signal crosstalk in a photodiode array. Lanthanide doped fluoride nanoscintillators (NSs) prepared with low-temperature wet-chemical method possess several advantages, such as low toxicity, cheap fabrication cost, convenient device processability and adjustable emission wavelengths from ultraviolet to visible and extending to second near infrared window. In addition, they exhibit X-ray excited long persistent luminescence (XEPL) making them suitable for broadening the scope of their applications. This review discusses and summarizes the XEOL and XEPL characteristics of lanthanide doped fluoride NSs. We discuss design strategies and nanostructures that allow manipulation of excitation dynamics in a core–shell geometry to simultaneously produce XEOL, XEPL, as well as photon upconversion and downshifting, enabling emission at multiple wavelengths with a varying time scale profile. The review ends with a discussion of the existing challenges for advancing this field, and presents our subjective insight into areas of further multidisciplinary opportunities.

Solvothermal synthesis of Mn-doped CsPbCl ₃ nanocrystals with dual-color luminescence and superior stability was reported for the first time.

Lanthanide-doped fluoride nanoparticles (NPs) showcase adjustable X-ray-excited persistent luminescence (XEPL), holding significant promise for applications in three-dimensional (3D) imaging through the creation of flexible X-ray detectors. However, a dangerous high X-ray irradiation dose rate and complicated heating procedure are required to generate efficient XEPL for high-resolution 3D imaging, which is attributed to a lack of strategies to significantly enhance the XEPL intensity. Here we report that the XEPL intensity of a series of lanthanide activators (Dy, Pr, Er, Tm, Gd, Tb) is greatly improved by constructing dual heterogeneous interfaces in a double-shell nanostructure. Mechanistic studies indicate that the employed core@shell@shell structure could not only passivate the surface quenchers to lower the non-radiative relaxation possibility, but also reduce the interfacial Frenkel defect formation energy leading to increase the trap concentration. By employing a NPs containing flexible film as the scintillation screen, the inside 3D electrical structure of a watch was clearly achieved based on the delayed XEPL imaging and 3D reconstruction procedure. We foresee that these findings will promote the development of advanced X-ray activated persistent fluoride NPs and offer opportunities for safer and more efficient X-ray imaging techniques in a number of scientific and practical areas.