Xu Chen

Hybrid metal halides are promising scintillators due to their strong X-ray absorption and efficient self-trapped exciton (STE) emission. However, their practical applications are largely hindered by poor processability, severe light scattering, and substantial energy loss during secondary electron relaxation, leading to low spatial resolution in X-ray imaging. Here, we report a solvent-assisted rapid evaporation method for fabricating a class of hybrid metal halide glasses with excellent processability and high optical transparency. A molecular design strategy is further introduced by incorporating triphenylphosphonium-based organic phosphorescent cations to effectively reclaim the energy dissipated during the relaxation of secondary electrons. In addition to the direct X-ray excitation of the inorganic STE state, the harvested triplet excitons can further sensitize STE emission with near-unity energy transfer efficiency. This dual-sensitization pathway synergistically enhances the scintillation performance. A large-area scintillation screen is successfully fabricated, achieving high-resolution X-ray imaging with a spatial resolution of 22.5 lp mm–1.

High‐color‐purity deep‐blue emitters are essential for advanced display technologies targeting the Rec. 2020 standard, where narrow‐band emission is critical for achieving wide color gamut and accurate color reproduction. However, simultaneously achieving narrow emission, high efficiency, and robust stability in metal halide nanocrystals remains highly challenging. Here, a rigid 0D host‐lattice engineering strategy is demonstrated to enable thermally robust narrow‐band deep‐blue emission in Eu ²⁺ ‐activated Cs ₂ ZnBr ₄ nanocrystals. The structurally isolated [ZnBr ₄ ] ^2– tetrahedra create localized tetrahedral Eu ²⁺ luminescent centers that effectively suppress electron‐phonon coupling and spectral broadening while supporting efficient 5 d ‐4 f emission. As a result, the nanocrystals exhibit intense deep‐blue photoluminescence centered at 450 nm with a narrow full width at half maximum (FWHM) of 21 nm. Notably, the emitters retain 86.5% of their emission intensity at 150°C relative to 30°C and also show excellent photostability and environmental stability. When integrated into white light‐emitting devices, the resulting devices achieve a wide color gamut covering 127.1% of NTSC and 94.9% of Rec. 2020. This work establishes a viable strategy for developing thermally robust and high‐color‐purity emitters for next‐generation display backlight applications.

Low-dimensional halide perovskites are promising candidates for solar-blind ultraviolet photodetectors. However, simultaneously achieving high photoresponsivity and low dark current remains challenging, due to the restricted transport and collection of photogenerated carriers caused by strong electronic localization. Here, guided by theoretical calculations of electronic structures, we report a solar-blind family of CsCdCl₃ perovskite single crystals, which features a 3D structural framework, delivering high carrier mobility of 7.54 cm²V⁻¹ s⁻¹ and a long carrier diffusion length of 6.96 μm. These achievements stem from the 3D electronic structure, enabling balanced carrier effective mass isosurfaces and enhanced band dispersion. CsCdCl₃-based solar-blind photodetectors yield a photoresponsivity of 35.4 A W⁻¹ and dark current of 1.0 × 10⁻¹² A. Moreover, the devices demonstrate a narrowband spectral response of only 20 nm with a spectral-rejection ratio of 1.96 × 10³, which enables spectral-selectivity flame detection, distinguishing various types of flames and showcasing potential in offshore oil flame monitoring.

Spin-polarized light-emitting diodes (spin-LEDs) hold promise for next-generation photonic technologies owing to their ability to directly emit circularly polarized electroluminescence. Here, we report a multifunctional chiral ligand engineering strategy to realize high-performance pure-green spin-LEDs based on FAPbBr3 quantum dots (QDs). By introducing (R/S)-methylbenzenesulfinamide, strong coordination with surface Pb2+ ions simultaneously passivates defects and induces pronounced centrosymmetry-breaking lattice distortion in FAPbBr3 QDs. This structural asymmetry enhances chiroptical activity and prolongs spin-coherence lifetimes, enabling efficient spin-polarized carrier recombination. As a result, chiral FAPbBr3 QDs exhibit a high photoluminescence quantum yield (98.28%) and large dissymmetry factor (8.87 × 10–2). The spin-LEDs fabricated from these QDs exhibit pure-green emission, with a maximum luminance of 17 979 cd m–2, a peak external quantum efficiency of 15.1%, and a maximum electroluminescence dissymmetry factor of 1.76 × 10–1 at room temperature. This work demonstrates that chiral MBS ligands can simultaneously improve optoelectronic quality and introduce structural asymmetry in perovskite quantum dots, representing a promising route toward practical high-performance spin-LEDs.

Copper–iodide hybrids have emerged as promising candidates for eco‐friendly light‐emitting diodes (LEDs). Although high‐efficiency LEDs based on multidentate‐ligand copper–iodide hybrids have been reported, those utilizing monodentate‐ligand ones remain challenges because their surface ligands are prone to dissociation, producing exposed Cu ⁺ ions that induce non‐radiative recombination. Herein, we propose a coordination compensation stabilization strategy to achieve efficient monodentate‐ligand copper–iodide LEDs by incorporating pyridine‐terminated semiconducting molecules. We demonstrate that the strong electron‐withdrawing moieties of pyridine are integrated to stabilize Cu ₄ I ₄ core by increasing the electron cloud density of termini contacting with cluster, which enhances the coordination with exposed Cu ⁺ ions. This strategy synergistically passivates the ionized metallic defects to reduce non‐radiative recombination and increases the carrier mobility to promote electron/hole transport within emitters. Consequently, we fabricate LEDs reaching a record‐high electroluminescence efficiency of 20.4% with an average of 19.8% over 60 devices, half‐lifetime of 1117.5 h, large‐area of 81 cm ² , and demonstrate a broad universality applicable to various monodentate‐ligand hybrids, representing a sufficiently striking advance over existing copper‐iodide systems. The study provides a new strategy to pave the way for enhanced device performance of copper–iodide hybrid LEDs toward practical applications.

Dynamic multicolor luminescent materials are highly promising for advanced anti‐counterfeiting and information encryption, yet conventional systems largely rely on lanthanide rare‐earth ions with fixed emission wavelengths and high costs. Here, we report a lanthanide‐free strategy by doping transition‐metal ions Sc ³⁺ and Cr ³⁺ into the CaGa ₄ O ₇ host. The dopant ions synergistically interact with the host lattice, creating multiple trap‐regulated emission channels and simultaneously introducing multilevel trap states, which enable time‐dependent carrier capture and release as the basis for dynamic multicolor luminescence. Under 254 nm UV excitation, CaGa ₄ O ₇ :Sc exhibits yellow‐to‐blue evolution, while CaGa ₄ O ₇ :Cr shows red‐to‐blue transitions. Importantly, the dynamic multicolor luminescence is also tunable at higher temperatures, where carriers from shallow traps are depleted, and the blue emission is thermally quenched. Thermoluminescence and optical studies reveal that Sc is associated with deep traps in the host and long‐term memory of dynamic luminescence, whereas Cr is associated with shallow traps and short‐term memory. Leveraging these features, we demonstrate advanced anti‐counterfeiting and information encryption schemes, including time‐gated patterns and ASCII‐coded matrices. This work establishes transition‐metal doping as a general, low‐cost approach to high‐performance dynamic multicolor luminescent materials, highlighting its potential to provide multifunctional, time‐ and temperature‐resolved optical responses for secure information technologies.

Delayed x‐ray imaging based on storage phosphors enables spatial and temporal separation of exposure and readout, offering advantages over conventional scintillators in complex environments. However, oxide phosphors with high storage capacity and tunable deep traps remain limited. Here, we report In‐doped CaSb ₂ O ₆ as a robust oxide storage phosphor with engineered deep traps for high‐temperature and delayed x‐ray imaging. In substitution introduces charge‐compensating defects significantly increasing trap depth and density. The optimized CaSb ₂ O ₆ :0.4%In exhibits enhanced persistent luminescence lasting over 20 h and stable retention of detectable trapped carriers exceeding 30 days. Remarkably, anti‐thermal quenching behavior enables luminescence intensity at 433 K to reach 3.7 times that at room temperature, supporting high‐temperature operation. The phosphor demonstrates linear x‐ray dose response, excellent radiation stability, and repeatable write‐store‐read cycles. Flexible composite films fabricated from the material enable conformal imaging and delayed thermal readout. Using this platform, we demonstrate high‐resolution flexible x‐ray imaging and a proof‐of‐concept for conformal x‐ray imaging of 3D objects. This work establishes trap engineering in antimonate phosphors as an effective route toward stable, flexible, and high‐performance x‐ray storage and imaging systems.

Metal halide perovskite light-emitting diodes offer a promising platform for low-cost full-color displays, yet achieving high-performance pure-red emission remains challenging. Here, we report a crystallization regulation strategy for mixed bromide/iodide quasi-two-dimensional perovskites using a multifunctional molecule, 4-(trifluoromethyl)benzenesulfonamide, which simultaneously coordinates with organic spacer cations, Pb ²⁺ ions and halide ions. Moreover, the combination of large steric hindrance and ordered molecular assembly in the precursor solution plays a decisive role in directing the formation of nanocrystals, thereby suppressing defect formation, inhibiting halide ions migration, and enhancing exciton binding energy. The resulting light-emitting diodes exhibited pure-red emission at ~635 nm, delivering a peak external quantum efficiency of 30.2%, a maximum luminance exceeding 25,000 cd m ^-2 , and a half-lifetime of 8426 min. Achieving perovskite light-emitting diodes with performance comparable to that of quantum-dot or organic light-emitting diodes would mark a major milestone toward commercialization. This work would expand opportunities beyond conventional light-emitting diode technologies.

Self‐trapped excitons (STEs) in lead‐free metal halide perovskites offer a powerful toolbox for next‐generation optical thermometry, yet tailoring their heat‐assisted detrapping dynamics to optimize luminescent thermal responses for high‐performance applications remains elusive. Herein, we report a portable and intelligent colorimetric thermography platform based on cation‐engineered double perovskites, integrating hue‐saturation‐value (HSV) color encoding with deep learning for accurate thermal imaging. By tailoring the trivalent cation sites, size‐dependent lattice hardness enables stronger electron‐phonon coupling and a lowered thermal activation barrier for de‐trapping. In indium‐based perovskites, pronounced fourth‐order phonon anharmonicity arising from high bond ionicity drives significant lattice thermal expansion and softened bond force constant, yielding an ultralow thermal activation energy of 45.08 meV and the strongest thermal quenching, while maintaining a photoluminescence quantum yield of 85.27%. Furthermore, we incorporate Er ³⁺ as a spectrally stable emitter to produce distinct thermochromic behavior, and propose an HSV‐based colorimetric thermography with robust color recognition. To further mitigate artifacts from ambient lighting and viewing‐angle variations, we employ a deep‐learning algorithm that delivers end‑to‑end thermal mapping with a high accuracy of 92.20%. This work establishes a materials‐by‐design framework for on‑demand tuning of STE thermal behavior and provides an advanced thermal sensing platform enhanced by artificial intelligence.

Lead-free halide double perovskites have emerged as ideal host materials for ion doping due to their inherent structural stability, low toxicity, and unique ability to accommodate multiple luminescent centers. These characteristics render them highly promising candidates for advanced applications such as intelligent optical anti-counterfeiting and information encryption. In this work, we present a multimodal excitation luminescence design of co-doped Cs2NaScCl6:Er3+, Yb3+, and Sb3+ phosphors. The incorporation of Er3+ and Yb3+ ions not only enables both downconversion and upconversion luminescence with different excitations but also endows multi-color emissions from green to red light through the unique cross-relaxation effect. Furthermore, the introduction of Sb3+ ions creates an efficient energy transfer pathway from self-trapped excitons to Er3+ ions and also achieves a synergistic enhancement of the photoluminescence quantum yield, reaching an outstanding value of 71.24%. Leveraging these excitation-dependent multi-color luminescent properties, we implement multilevel anti-counterfeiting and information encryption applications. This work highlights the significant advantages of ion-doped rare-earth-based double perovskites in advanced optical security technologies.