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Lead-free alkali halides have gained increasing attention owing to their desired optoelectronic properties across a variety of light-emitting applications. However, state-of-the-art alkali halide emitters commonly are bulky crystals functionalized with highly toxic elemental doping, hindering their integration into emerging flexible, wearable and large-area optoelectronic devices. Herein, we have developed environmental friendly and solution-processable alkali halide nanocrystals that exhibit intense self-trapped emission facilitated by Sn2+ ionic doping. We find that the presence of Sn2+-interstitial leads to the tilting of cubic structures of RbI and thus triggers the self-trapped emission. The resultant tin(II)-doped RbI and RbxCs1−xI nanocrystals display an impressive maximum photoluminescence quantum yield of 91.9% and exhibit remarkable stability under ambient conditions. These findings pave the way for a new class of bright, solution-processable alkali halides, with diverse applications such as energy down conversion and flexible scintillation technologies. [ABSTRACT FROM AUTHOR]

Copper halides, a new class of attractive and potential scintillators, have attracted tremendous attention in X‐ray imaging. However, the ambiguity surrounding their exciton properties and the unclear effect of crystal structure on their photophysical performance hinder an in‐depth understanding of their luminescence mechanism and their further application in the X‐ray imaging field. Herein, copper halide scintillators Cs3Cu2X5 (X = I, Br, and Cl) with a 0D crystal structure is prepared, and their photophysical properties and luminescence mechanism are revealed using both theoretical calculation and experimental verification. The small exciton Bohr diameter together with the high exciton binding energy can cause Cs3Cu2X5 to hold strongly confined excitons and lack quantum‐size effects. The 0D Cs3Cu2X5 materials exhibit a structural framework with a soft crystal lattice and Frenkel excitons with strong confinement effects, further resulting in a luminescence mechanism with self‐trapped excitons. In particular, Cs3Cu2I5 is demonstrated as an efficient scintillator with high radioluminescence efficiency and high spatial resolution of ≈106 µm in radiography, which is primarily attributed to strongly confined excitons to improve the radiative recombination probability of electron‐hole pairs. Overall, this work provides a pathway for developing 0D scintillators with strongly confined excitons to improve X‐ray imaging performance. [ABSTRACT FROM AUTHOR]

Supramolecular multifunctional metal–organic networks offer immense potential in drug delivery, bioimaging, catalysis, and therapeutics. However, the creation of multiple stimuli‐responsive fluorescent hollow nano/microparticles is a formidable challenge in this field. In this study, a novel strategy is reported for synthesizing photochromic hollow microparticles that exhibit responsiveness to light, pH, and glutathione (GSH). With the assistance of templating coordination from zeolitic imidazolate framework‐8 microparticles, bisphosphonate‐merocyanine ligands are successfully assembled to create hollow bisphosphonate‐spiropyran (BPSP)‐Zn2+ microparticles. The photochromic and pH responses stem from the reversible conversion between spiropyran and zwitterionic merocyanine components and between merocyanine and protonated merocyanine, respectively. The GSH response is attributed to the stronger affinity of Zn2+ to thiol groups than to phosphonate groups. These remarkable features render the hollow BPSP‐Zn2+ microparticles highly suitable for applications in stimulus‐triggered drug delivery, and these findings provide a platform for developing innovative materials that have the potential to transform the biomedical field. [ABSTRACT FROM AUTHOR]

In the era of intelligence, the output colors of foundational phosphors are expected to be controlled by programs, while current activators‐determined afterglow candidates with fixed spectral channel have limitations in creating customized colors. Here, a long‐lived warm‐white emission is successfully demonstrated originating from self‐trapped excitons (STEs) in non‐toxic Cs2NaInCl6:Ag,Bi, ranging from 400 to 850 nm, of which the afterglow color can be easily customized using filters. This investigation indicates that 3% of Ag alloying breaks the dark STEs and introduces traps for efficient afterglow, while 3% Bi doping further improves the quantum yield to ≈100% and greatly enhances afterglow by ≈100‐fold compared with the initial intensity, allowing for an impressive afterglow persistence of over 20,000 s. Intriguingly, the self‐trapped defect bands from Jahn‐Teller distortions are prolonged from hundreds of femtoseconds to several hours, and they are first detected in the steady‐state absorption spectra after the cessation of excitation sources, contributing to the concluded dynamic afterglow model for STEs. And its intelligent application is corroborated by designed multi‐channel information system. These findings offer a novel scheme for understanding dynamic luminescence of STEs and supply an exemplification of designing white afterglow phosphors. [ABSTRACT FROM AUTHOR]

With the increasing demands of X‐ray detection and medical diagnosis, organic scintillators with intense and tunable X‐ray excited emission have been becoming important. To guarantee the X‐ray absorption, heavy atoms were widely added in reported organic scintillators, which led to emission quenching. In this work, we propose a new strategy to realize organic scintillators through the host‐guest doping strategy. Then the X‐ray absorption centers (host) and emission centers (guest) are separated. Under X‐ray excitation, these materials displayed intense and readily tunable emissions ranging from green (520 nm) to near infrared (NIR) regions (682 nm). Besides, the relationship between the X‐ray absorption and spatial arrangement of the heavy atoms in the host matrix was also revealed. The potential application of these wide‐range color tunable organic host‐guest scintillators in X‐ray imaging were demonstrated. This work provides a new feasible strategy for constructing high‐performance organic scintillators with tunable luminescence properties. [ABSTRACT FROM AUTHOR]

The search for color‐tunable, efficient, and robust scintillators plays a vital role in the development of modern X‐ray radiography. The radioluminescence tuning of copper iodide cluster scintillators in the entire visible region by bandgap engineering is herein reported. The bandgap engineering benefits from the fact that the conduction band minimum and valence band maximum of copper iodide cluster crystals are contributed by atomic orbitals from the inorganic core and organic ligand components, respectively. In addition to high scintillation performance, the as‐prepared crystalline copper iodide cluster solids exhibit remarkable resistance toward both moisture and X‐ray irradiation. These features allow copper iodide cluster scintillators to show particular attractiveness for low‐dose X‐ray radiography with a detection limit of 55 nGy s−1, a value ≈100 times lower than a standard dosage for X‐ray examinations. The results suggest that optimizing both inorganic core and organic ligand for the building blocks of metal halide cluster crystals may provide new opportunities for a new generation of high‐performance scintillation materials. [ABSTRACT FROM AUTHOR]

Mn2+ dopants introduce a new emission center in semiconductor luminescent materials, endowing them promising photoluminescence (PL) properties, such as a wide color tuning range, reversible color change, reduced self‐absorption etc. Recently, rapid development of Mn2+ doped metal halide perovskites (MHPs) promote their promising applications in displays, photovoltaics, scintillators, etc. The emission color, luminous efficiency, and energy transfer pathway of doped perovskites are affected by condition of host lattice that accommodates Mn2+ ions. In this review, the optical properties determined by host materials with diverse geometries involving perovskite nanocrystals and perovskite derivatives is focused on, and the possible energy transfer routes in different doping systems are analyzed. An overview of recent advances of different doped systems with assigned emission channels together with the influence factors, strategies to enhance PL intensity and finally potential applications are summarized. To the end, the underlying challenges and possible solutions for further research in Mn doped perovskites are proposed. [ABSTRACT FROM AUTHOR]

Nanoscintillators (nanocrystals with X‐ray scintillation performance) lay a fundamental for their practical application in high‐resolution and low‐dose medical examination due to their excellent photoelectric properties. The optical properties and scintillation performance of nanocrystals (NCs) can be significantly affected by adjusting their size. However, the mechanism of the size effect of NCs on optical properties and X‐ray scintillation performance has not been revealed. Here, a mathematical model and experimental results are combined to demonstrate the impact of the size of NCs on their scintillation performance. The results show that the surface area and volume of NCs exhibit a positive and negative impact on the change rate of the bandgap, respectively. This model further verifies that the photoluminescence quantum yield of NCs decreases with the decrease of their size, and their light yield is remarkably affected by the size of NCs. Overall, this work provides some enlightenment for researchers to design NCs with the appropriate size for their applications in high‐performance X‐ray scintillation. [ABSTRACT FROM AUTHOR]