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Long wavelength near-infrared (LWNIR) light (1000–2000 nm) has great potential in the field of biomedical imaging, non-visual illumination, and non-destructive detection. However, currently, such as Cr3+ and Ni2+ can achieve broadband NIR emission, but their emission wavelengths are under 1600 nm with limited tunability. Herein, we developed Ni2+-doped (Sr/Ba)2MgMoO6 double perovskite molybdate-based solid-solution LWNIR phosphors via the high-temperature solid-state method. By adjusting the ratio of Sr/Ba in the phosphors, NIR emission peaks can be tuned from 1400 nm to 1610 nm under 400 nm excitation. Based on the analysis of crystal structures and luminescence characteristics and simulation results, we propose that the main reason for the shift of NIR peak emission is the difference in charge density and symmetrical polarizability of Ni2+ ions in the center of the octahedron due to the crystal structural changes of the matrices from tetragonal Sr2MgMoO6 to cubic phase Ba2MgMoO6. We constructed a LWNIR pc-LED with the optimal phosphors and a commercially near-ultraviolet LED chip, which efficiently emitted LWNIR light. The utility of this new LWNIR pc-LED as the NIR light source for non-invasive imaging and non-destructive detection of biological and non-biological objects was demonstrated. [ABSTRACT FROM AUTHOR]

This study explores the integration of X‐ray‐induced photochromism and photoluminescence in a single material, offering innovative multi‐mode applications in optical memory, anti‐counterfeiting, and X‐ray detection and imaging. The photochromic phosphor LiAlSi2O6:Sm3+ is synthesized, which undergoes a color change from white to dark green under bright field conditions and displays orange photoluminescence in dark field conditions after X‐ray exposure due to defect formation. The phosphor shows accelerated bleaching and recovery under 473 nm laser stimulation. The distinct X‐ray‐induced color contrast and luminescence intensity modification in LiAlSi2O6:Sm3+ highlight its potential in advanced luminescent material design. Moreover, a LiAlSi2O6:Sm3+‐based flexible film demonstrates "dual‐mode" 3D X‐ray imaging and detection capabilities, paving the way for future X‐ray detecting and imaging device research. [ABSTRACT FROM AUTHOR]

Photochromic glass shows great promise for 3D optical information encryption and storage applications. The formation of Ag nanoclusters by light irradiation has been a significant development in the field of photochromic glass research. However, extending this approach to other metal nanoclusters remains a challenge. In this study, we present a pioneering method for crafting photochromic glass with reliably adjustable dual‐mode luminescence in both the NIR and visible spectra. This was achieved by leveraging bimetallic clusters of bismuth, resulting in a distinct and novel photochromic glass. When rare‐earth‐doped, bismuth‐based glass is irradiated with a 473 nm laser, and it undergoes a color transformation from yellow to red, accompanied by visible and broad NIR luminescence. This phenomenon is attributed to the formation of laser‐induced (Bi+, Bi0) nanoclusters. We achieved reversible manipulation of the NIR luminescence of these nanoclusters and visible rare‐earth luminescence by alternating exposure to a 473 nm laser and thermal stimulation. Information patterns can be inscribed and erased on a glass surface or in 3D space, and the readout is enabled by modulating visible and NIR luminescence. This study introduces a pioneering strategy for designing photochromic glasses with extensive NIR luminescence and significant potential for applications in high‐capacity information encryption, optical data storage, optical communication, and NIR imaging. The exploration of bimetallic cluster formation in Bi represents a vital contribution to the advancement of multifunctional glass systems with augmented optical functionalities and versatile applications. [ABSTRACT FROM AUTHOR]

Lanthanide‐based NIR‐II‐emitting materials (1000–1700 nm) show promise for optoelectronic devices, phototherapy, and bioimaging. However, one major bottleneck to prevent their widespread use lies in low quantum efficiencies, which are significantly constrained by various quenching effects. Here, a highly oriented (222) facet is achieved via facet engineering for Cs2NaErCl6 double perovskites, enabling near‐complete suppression of NIR‐II luminescence quenching. The optimally (222)‐oriented Cs2Ag0.10Na0.90ErCl6 microcrystals emit Er3+ 1540 nm light with unprecedented high quantum efficiencies of 90 ± 6% under 379 nm UV excitation (ultralarge Stokes shift >1000 nm), and a record near‐unity quantum yield of 98.6% is also obtained for (222)‐based Cs2NaYb0.40Er0.60Cl6 microcrystallites under 980 nm excitation. With combined experimental and theoretical studies, the underlying mechanism of facet‐dependent Er3+ 1540 nm emissions is revealed, which can contribute to surface asymmetry‐induced breakdown of parity‐forbidden transition and suppression of undesired non‐radiative processes. Further, the role of surface quenching is reexamined by molecular dynamics based on two facets, highlighting the drastic two‐phonon coupling effect of a hydroxyl group to 4I13/2 level of Er3+. Surface‐functionalized facets will provide new insights for tunable luminescence in double perovskites, and open up a new avenue for developing highly efficient NIR‐II emitters toward broad applications. [ABSTRACT FROM AUTHOR]

The color of micro‐structured glass can be tuned by adjusting the cross‐relaxation between Er3+ ions through the mechanism of up‐conversion, although the range of color change is very limited. Here, we report the simple and reproducible synthesis of transparent oxy‐fluoride glass‐ceramics co‐doped with Yb3+/Er3+ by melting and secondary heat treatment. By adjusting the doping content of Er3+ ions from 0.2 to 10 mol%, followed by the secondary heat treatment, the intensity of up‐conversion luminescence under 980 nm laser excitation was increased by more than 100 times, and the glass‐ceramics showed an Er3+ doping content‐depended color change of the up‐conversion luminescence from green light to red light. The elemental analysis with TEM–EDS mapping and the measurement of the lifetime of up‐conversion luminescence suggest that changes in the cross‐relaxation between Er3+ ions is the principal mechanism behind the color change of up‐conversion luminescence. As a result, the red emission due to the electronic transition of 4F9/2 is much greater than that of the green emission (4S3/2). Therefore, we present a simple and reproducible strategy to achieve an efficient up‐conversion luminescence from glass‐ceramics with a broad range of color tunability and high color purity. [ABSTRACT FROM AUTHOR]

The demand for accurate temperature readings in harsh high-temperature environments includes miniaturization, flexibility, visualization, and integrability of temperature sensors with the growing need for human development. Rare earth-doped non-contact fluorescence intensity ratio (FIR) temperature sensors have received widespread attention due to their high detection accuracy and fast response ability. However, the limitations of thermal quenching (TQ) and thermal coupling energy level differences restrict their applications. In this work, a novel temperature sensing method in Eu3+/Tb3+-doped Y2Mo3O12 negative thermal expansion (NTE) materials is proposed, which depends on different energy transfer characteristics of Eu3+- and Tb3+-doped NTE materials. Under a 295 nm excitation laser, the Y2Mo3O12:Eu3+ phosphor achieved 600% enhancement due to the charge-transfer band (CTB) absorption between O2− and MoO42−. At 573 K, the luminescence intensity of Y2Mo3O12:Tb3+ is reduced by 30 times due to the absence of energy transfer between the Tb3+ ions and Y2Mo3O12 NTE materials. The Y2Mo3O12:Eu3+/Tb3+ mixing materials enhance the relative luminescence intensity and solve the thermal coupling energy level differences, achieving high sensitivity and resolution (maximum Sr = 2.56% K−1 at 453 K). The Y2Mo3O12:Eu3+/Tb3+ flexible thin film achieves multiple naked-eye color spans, breaking free from the limitations of optical detection instruments and demonstrating strong potential for robust and direct temperature reading without equipment. This demonstrates their superior advantages for visualizing real-time high-temperature sensing with nonplanar surfaces, thermal defect diagnosis systems, intelligent battery monitoring systems, and other high-temperature sensing fields. [ABSTRACT FROM AUTHOR]

Scintillators with high spatial‐resolution and high‐stability are highly desirable for X‐ray imaging applications at unpredictable environments. To challenge state‐of‐the‐art technology, it is necessary to design high thermal stable scintillators with high‐resolution and high light yield. In this work, the zero‐thermal‐quenching Lu3Al5O12:Ce3+ (LuAG: Ce3+) transparent ceramics (TCs) is synthesized with high optical transparency. The thermoluminescence (TL) curves of the as‐obtained TCs demonstrate that the formation of the oxygen vacancies, acting as the trapping centers, can capture the carriers and then contribute to the enhancement of its thermals stability via the thermal compensation effect. The exceptional thermal‐stability of the TCs scintillator endows the monitoring of the dynamic changes of the internal structure of the objective samples without any ghosting effects during heating. In addition, given the ultra‐high uniform, transparency, and fast light decay of the TCs scintillator, the excellent spatial resolution (≈112 lp mm−1) of the X‐ray microscopic imaging is realized. These results undeniably demonstrate that the as‐obtained LuAG: Ce3+ TCs have great prospects for advancement in X‐ray detectors. [ABSTRACT FROM AUTHOR]

Owing to the large storage capacity, the transparent luminescent glass with photo‐induced coloration properties has attracted considerable interest in recent years. However, lots of the photochromic (PC) mechanisms for glass are related to the ionic valence transformation, and the study associated with the defects‐induced photochromism of glass is limited. Herein, a kind of Sm3+ doped PC cadmium glass is fabricated, for which the PC mechanism is systematically investigated by various techniques, such as XPS spectra, thermoluminescence spectra, EPR spectra, etc. The results show that the mechanism of coloration for such glass should be due to the presence of oxygen vacancy‐related electron centers. Under 365 nm light irradiation, the color of the glass turns from colorless to brown, exhibiting a large color contrast, of 62%. Utilizing the re‐absorption process between absorption spectra and emission/excitation spectra, the emission intensity of Sm3+ is reversibly regulated, indicating their promising applications as an optical storage medium. [ABSTRACT FROM AUTHOR]

Inorganic chiral materials have attracted increasing attention due to their application prospects. In this work, we synthesized the chiral nanostructured bismuth oxychloride co‐doped with Er3+/Yb3+ phosphor (D‐BYEP) by hydrothermal growth with a subsequent air‐annealing strategy using chiral sugar alcohols as the chiral inducer. The D‐BYEP emitted bright red light under the excitation of 980 nm near‐infrared laser. The temperature sensing behavior was evaluated by employing the thermally coupled (TCLs) or non‐thermally coupled (NTCLs) levels of Er3+. The maximum relative sensitivities (SR) obtained are 0.84% K−1 and 1.30% K−1 (298 K), respectively. The results show that the D‐BYEP may be ideal candidates for optical temperature sensors. We anticipate that this new type of inorganic chiral phosphor may have a range of applications in temperature measurement of light sources. [ABSTRACT FROM AUTHOR]

Ultrahigh‐resolution X‐ray detection has always been a goal pursued in industrial inspection and medical diagnosis. However, the resolution of the corresponding image generally suffers from serious light scattering and crosstalk. Here, a low‐temperature thermoplastic scintillator ink of [Bmmim]2MnCl4 (Bmmim = 1‐butyl‐2,3‐dimethylimidazolium) is designed, achieving an astonishing spatial resolution of over 22 lp mm−1 (≥22.5 µm). A customized X‐ray imaging can be realized with the as‐explored [Bmmim]2MnCl4 scintillator to the targets through brushing feasibly exhibiting a high adhesion and processability thanks to the superior rheological properties. It is demonstrated that the coordination number determines the melting point of the corresponding scintillator, and an appropriate melting point (323 K) endows a superior viscosity of the sample as print ink. Accordingly, the as‐explored scintillator not only exhibits a high light output with 3.63 times of the commercial Bi4Ge3O12 (10 000 photons MeV−1) under steady‐state X‐ray illumination but also performs excellent recyclability even after 100 re‐uses. This work brings a new perspective for solving the problems of light scattering and light crosstalk for X‐ray imaging, as well as promoting the development of scintillator ink for recycling utilization. [ABSTRACT FROM AUTHOR]

Lead‐free rare‐earth‐based perovskites have received widespread attention for their unique optical properties, although achieving efficient broadband near‐infrared (NIR) emission with these materials remains a challenge. Here the synthesis of a rare earth‐based double perovskite (Cs2NaScCl6) by an improved solid phase method is reported. The doping of Cr3+ led to the formation of [CrCl6]3− octahedron, which exhibited a broadband NIR emission peaked at 950 nm and a half‐peak width of 162 nm. It is worth noting that with the same actual Cr3+ content, the luminous intensity of Cs2NaScCl6 synthesized by the improved solid‐phase synthesis is four times higher than the product synthesized by the hydrothermal method. an efficient Cl−‐Cr3+ charge transfer sensitization facilitated by localized electrons in [CrCl6]3− octahedron is the mechanism for the strong NIR emission of Cr3+ is proposed. Calculations based on density functional theory and Bader charge analysis support the notion that electrons in [CrCl6]3− octahedrons are strongly localized in Cs2NaScCl6:Cr3+, which is conducive to the Cl−–Cr3+ charge transfer process, resulting the internal quantum efficiency of 100% and external quantum yield as 42.3%. The highly efficient ultra‐broadband NIR emission with excellent stability offers many opportunities for applications in the field of NIR night vision and bio‐imaging. [ABSTRACT FROM AUTHOR]

In this work, a novel series of oxyfluoride glasses‐ceramics (GCs) is developed by enhancing the phase separation through the substitution of LaF3 for La2O3. The thus‐derived GCs exhibit a remarkable 2700‐fold increase in up‐conversion (UC) luminescence of Er3+ ions compared to the precursor glass. From the 19F Nuclear Magnetic Resonance analysis, this enhancement is attributed to the structural disorder‐to‐order transition in the fluoride‐rich phase. Upon isothermal heat treatment, the translucent GCs transform into transparent ones, making UC luminescence even stronger. The enhanced UC luminescence leads to strong temperature‐sensing ability of the studied glasses. The nano‐micro phase separation is clarified by atomistic simulations and scanning electron microscopy. This study implies that phase separation engineering is a powerful way to achieve superior photonic performances. [ABSTRACT FROM AUTHOR]

The development of highly stable and ultra‐long organic room temperature phosphorescence (RTP) materials holds great promise for applications in anti‐counterfeiting and information protection. To improve the encryption level, the exploration of organic materials with tunable phosphorescence and afterglow features is in urgent need. Hereby, a series of long‐lived organic systems with RTP is developed by incorporating benzocarbazole derivatives into a polyvinyl alcohol (PVA) matrix (BCz@PVA). Notably, the BCz@PVA film exhibits outstanding RTP behavior with an ultralong phosphorescence lifetime (τp) of 2.09 s, high phosphorescence quantum yield (Φp) of 46.335%, and an ultra‐long afterglow duration of 15 s. Moreover, the BCz@PVA film maintains excellent RTP performance even after being placed in ambient conditions for 60 days. Theoretical calculations reveal that the excellent RTP performance of BCz@PVA film is attributed to the stronger intermolecular interactions, the smaller energy gap (ΔEst) between the singlet and triplet states, and stable molecular stacking mode. Furthermore, color‐tunable photoluminescence (PL), distinct τp, and afterglow duration are successfully achieved by adjusting the position of the Br substituent on the benzene ring. Based on their diverse RTP performances and excellent stability, the corresponding BCz@PVA film provides successful application for multi‐level high‐security anti‐counterfeiting and information protection. [ABSTRACT FROM AUTHOR]

The reversible luminescence modification of inorganic phosphors has emerged as a promising field, enabling innovative applications such as optical memory, multiple anti‐counterfeiting, and photoswitches. Traditional luminescence modulation techniques, such as core–shell structure design and energy transfer‐related luminescent ions regulation, face challenges in achieving reversible luminescence modification. Chromism induces reversible color changes in materials when stimulated by external fields such as electricity, heat, and light. Combining chromism with luminescence enables the creation of chromism‐driven reversible luminescence manipulation in a single material. This review summarizes recent advances in reversible luminescence modification of inorganic phosphors based on chromism reaction and highlights their potential applications in optical data storage, fingerprint acquisition, and anti‐counterfeiting areas. The potential prospective research directions are also discussed and the challenges and opportunities of chromism‐based reversible luminescent materials are presented for further extended applications. [ABSTRACT FROM AUTHOR]

Monitoring the real‐time quality and validity of thermo‐sensitive foods during storage and transportation can be achieved with time‐temperature indicators (TTIs). However, the available TTIs still need to be improved in terms of accuracy, recoverability, environmental tolerance, and quantitative monitoring. Here, a novel TTI based on the optical signals originating from the as‐explored Sr3Y2Ge3O12: Mn2+, Er3+ (SYGO: Mn2+, Er3+) phosphor is developed. Thanks to the fact that the release of the captured carriers is tightly related to the storage time and ambient temperature, distinct optical signals of the as‐obtained TTI under multi‐stimulus (980 nm laser irradiation, thermal stimulation, and mechanical force) can be distinguished to judge the validity of temperature‐sensitive products. This work reveals the promising potential of SYGO: Mn2+, Er3+ phosphors with cryogenic optical storage properties as advanced TTIs, especially for packaged products in cold chain logistics. [ABSTRACT FROM AUTHOR]

Double perovskite (DP) phosphors attract extensive attention due to their potential applications in the field of optoelectronics. Photochromism‐induced luminescence modulation can extend their application fields. However, designing and preparing DP phosphors with expected photochromic and luminescent properties is still challenging. Herein, the photochromic Ba2YTaO6: Yb3+, Er3+, Co2+ DP with upconversion luminescence properties is developed. The color of the sample turns from white to pink upon 254 nm UV light irradiation, which is fast fading upon 473 nm laser illumination. The mechanism of photochromism is related to the formation of color centers, and the doping of Co2+ ions is crucial for the improvement of photochromism, which is from the increasing of traps depth, the oxygen vacancies, and the carrier concentration of the matrix caused by Co2+ doping. The upconversion luminescence of Er3+ ions can be reversibly modulated by the photochromic effect, exhibiting excellent reproducibility and high stability. The potential application of photochromic Ba2YTaO6: Yb3+, Er3+, Co2+ phosphor is demonstrated in the field of anticounterfeiting and three‐dimensional (3D) artwork. This work not only offers insight into the photochromic mechanism of DP but also presents guidance for developing other photochromic DP phosphors. [ABSTRACT FROM AUTHOR]

White light-emitting diodes (WLEDs), which typically combine a yttrium aluminum garnet doped with Ce3+ (YAG:Ce) with a blue LED, have been widely applied as illumination devices because of their high efficiency and long-term stability. However, the color of YAG:Ce-based WLEDs is cold and the color rendering index (CRI) is low due to the lack of a red component in the spectra. Here, we have successfully fabricated Eu-doped oxy-fluoride glass-ceramics (GCs) containing Na5Gd9F32 and NaAlSiO4 nano- and micro-crystals via melting-quenching and post-annealing with aluminum powder doping processes for synthesizing mono-host warm WLEDs. Annealing at 640 °C led to the two crystalline phases precipitated in the amorphous glass matrix, and the GCs exhibited broad emission from 430–600 nm and sharp orange-red emissions around 610 nm originating from Eu2+ and Eu3+ ions co-excited by a UV source. The GCs excited with an InGaN UV chip show adjustable warm white emission, while the correlated color temperature could be tuned via aluminum powder doping to <3500 K, with a CRI of around 78 and a photoluminescence quantum yield of >46%. Moreover, we examined the laser-driven photoluminescence properties of the prepared GCs, and the results show that the Eu-doped GCs exhibit both a high luminous saturation threshold and color stability. [ABSTRACT FROM AUTHOR]

X‐ray time‐lapse imaging allows for precise radiographic imaging of the item after X‐ray has been terminated, which is important for simplifying legacy X‐ray detectors and avoiding health hazards caused by ionizing radiation during the imaging process. However, the premature discharge of carriers from shallow traps at room temperature over time leads to the loss of imaging information, making an accurate representation of the recorded information to achieve accurate time‐lapse imaging still a challenge. Here, it is demonstrated that monodispersed NaLuF4: Tb3+ nanocrystals with the replacement of Na+ by Cs+ ions in the lattice matrix realize a superior X‐ray time‐lapse imaging. It is found that the incorporation of Cs+ ions amplifies the deep trap storage capacity, which ensures the stable presence of carriers under thermal perturbation at room temperature. Imaging information with a spatial resolution of 12.0 lp mm−1 can be accurately represented even after the irradiation of the X‐ray has been terminated for 192 h. X‐ray time‐lapse imaging not only allows accurate reading of long‐term stored imaging information but also endows the visualization of X‐ray imaging independent of the dangerous radiation, which will offer great opportunities for X‐ray inspection on a larger scale. [ABSTRACT FROM AUTHOR]

Local surface plasmon resonance (LSPR) offers exciting prospects for optical signal amplification. In this study, we designed a composite hetero-structure of Au and defective MoS2 (Au/D-MoS2) for a charge transfer type LSPR modulator. D-MoS2 produces strong defect plasma absorption in the visible and near-infrared optical regions and injects a large number of its generated electrons into the composite Au nanoparticles via surface charge transfer under near-infrared laser excitation, enabling strong plasmon resonance in the Au nanoparticles. As a result, the NaYF4:Yb–Er nanoparticles are effectively modulated in their luminescence intensity by the dual coupling enhancement effect of the MoS2 nanoparticles plasmon resonant excitation field and the Au nanoparticles plasmon resonant emission field under near-infrared excitation. Due to the strong LSPR induced electric field, a maximum enhancement factor of 15-fold in the luminescence intensity is achieved. This intelligent approach enables efficient modulation of NaYF4:Yb–Er in terms of both excitation and emission field enhancement, opening a new avenue to enhance the intensity of up-conversion luminescence. [ABSTRACT FROM AUTHOR]

Lithium metal has been considered one of the most promising anodes for next‐generation rechargeable batteries, but its practical application is largely hindered by the uncontrollable dendrite growth and infinite volume change. Here, inspired by superior catalytic effects of single‐atom catalysts, carbon‐supported single atomic Co with asymmetric N, O‐coordination (Co‐N/O) is developed for Li metal battery. Experimental results and theoretical calculations indicate that single atomic Co atoms with asymmetric N, O‐coordination present enhanced binding ability toward Li in comparison with N‐coordinated atomic Co site and isolated O site, enabling uniform Li plating/stripping. Moreover, the asymmetric N, O‐coordination around Co atoms induces co‐activation effects, lowering the energy barriers toward Li+ to Li0 conversion and largely promoting the deposition kinetics. When used as a Li deposition host, the Co‐N/O achieves a high average coulombic efficiency of 98.6% at a current density of 1 mA cm−2 and a capacity of 2 mAh cm−2, long cycling life of 2000 h in symmetrical cells, and excellent rate performance (voltage hysteresis of 23 mV at 8 mA cm−2). This work provides a comprehensive understanding of single atomic metals with asymmetric heteroatom coordination in the design of Li metal anode. [ABSTRACT FROM AUTHOR]

Near-infrared phosphor-converted light-emitting diodes (NIR pc-LED) are a new type of solid-state NIR light source that has been used in integrated near-infrared spectroscopy and biomedical imaging. However, the NIR phosphors currently used in pc-LEDs have disadvantages such as low luminescence quantum efficiency and poor thermal stability. In this work, a new type of SrTiO3:Ni2+ perovskite-based broadband near-infrared phosphor was prepared by a high-temperature solid-state synthesis method. A combined synergistic enhancement strategy was proposed to significantly improve the NIR luminous performance of the phosphor both in terms of luminous intensity and thermostability by ion substitution with Yb3+ and co-doping with high-valence charge compensators Ta5+, which caused the distortion of octahedral unit cells. Compared to SrTiO3:Ni2+, SrTiO3:Ni2+ co-doped with Yb3+ and Ta5+ enhanced the NIR emission by about ∼23.3 fold (PLQY ∼27.46%), and improved the heat stability by 19.54%. An efficient NIR pc-LED was constructed by encapsulating the optimized phosphors with UV LED chips, and its NIR emission properties meet the requirements of high-power laser lighting. Its potential for application was further demonstrated in the bioimaging of veins of a human hand. Our work provides a new option for highly-efficient near-infrared broadband emitting phosphors and pc-LED-based NIR light sources. [ABSTRACT FROM AUTHOR]

Lead-free bismuth metal halide perovskites and their analogues have attracted much research interest for their excellent photoelectric properties. However, the synthesis of low-dimensional bismuth-based metal halide perovskites from bismuth-based perovskite-based precursors has rarely been reported. In this work, we report the synthesis of Cs3BiCl6 and Cs3Bi2Cl9 using an improved room temperature, supersaturated recrystallization method, whereby the two precursors can be interconverted by addition of raw material post-synthetically, and both can be used as precursors together with suitable Mn2+ and other cations (Cs+, Bi3+), to synthesize fully inorganic, layered double perovskites, such as Cs4MnBi2Cl12, which exhibit the bright orange-yellow light that is characteristic of Mn2+. We further demonstrate that partial replacement of Mn2+ by Cd2+ in Cs4MnBi2Cl12 can weaken the strong coupling effect between Mn2+ and Mn2+, which inhibits the energy transfer to defects where non-radiative decay is likely to occur, and so achieves an effective energy transfer and thus improves the photoluminescence efficiency (PLQY). In the partially Cd2+-substituted, layered double perovskites, Cs4Mn1−xCdxBi2Cl12, when x = 0.7 the PLQY reaches a maximum value of 57.2%. Our study provides a new approach for the design and synthesis of low-dimensional bismuth-based metal halides with flexibility in adjusting their optical properties. [ABSTRACT FROM AUTHOR]

With the fast‐growing amount of data, the state‐of‐the‐art optical data storage has become a front‐runner in the competing data storage technologies. However, two‐dimensional (2D) spatial resolution in the conventional optical data storage media has almost reached the limit. Herein, LiGa5O8:Cr3+ nanoparticles (NCs) precipitated in situ from a transparent medium are prepared. The transparent LiGa5O8:Cr3+ glass ceramics show excellent deep‐trap carriers storage ability under blue light irradiation and can realize the bit‐by‐bit optical data in 3D space for write‐in and read‐out in a photon trapping/detrapping mode. Moreover, this optical storage mechanism is also extended to 4D by realizing temperature optical encryption. Notably, the written information can still be clearly displayed even after being recorded for 200 days. This work enables 4D high‐precision storage of information and provides new insights into the design and fabrication of next‐generation storage materials. [ABSTRACT FROM AUTHOR]

In recent years, upconversion luminescent materials doped with rare-earth ions have been widely used in anti-counterfeiting applications. However, in practical applications, single-mode photoluminescence is difficult to meet the increasingly complex anti-counterfeiting requirements of today’s society. In this article, dual-mode-excited, dual-color emitting Yb3+/Er3+ co-doped Bi4TaO8Cl nano-phosphor has been successfully synthesized via the one-step molten salt method. Bi4TaO8Cl: Yb3+/Er3+ nano-phosphor can emit green and red luminescence under 980 nm excitation, and the emission color changes from green to red by controlling the dopant concentration; whereas under 1550 nm excitation, it is mainly a single band red emission. The multicolor emission improves the security of multimode anticounterfeiting. The possible UC mechanisms were investigated under different excitation light sources at 980 and 1550 nm. Meanwhile, the anti-counterfeiting properties of the prepared nano-phosphor were evaluated according to the luminous intensity ratio of red and green light. The results demonstrate that Bi4TaO8Cl: Yb3+/Er3+ nano-phosphor will be expected to have excellent applications in the field of multimode anticounterfeiting. [ABSTRACT FROM AUTHOR]

Mechanical sensors execute multi‐mode response to external force, which are cornerstones for applications in human–machine interactions and smart wearable equipments. Nevertheless, an integrated sensor responding to mechanical stimulation variables and providing the information of the corresponding signals, as velocity, direction, and stress distribution, remains a challenge. Herein, a Nafion@Ag@ZnS/polydimethylsiloxanes (PDMS) composite sensor is explored, which realizes the description of mechanical action via optics and electronics signals simultaneously. Combined with the mechano‐luminescence (ML) originated from ZnS/PDMS and the flexoelectric‐like effect of Nafion@Ag, the corresponding explored sensor achieves the detection of magnitude, direction, velocity, mode of mechanical stimulation, and the visualization of the stress distribution. Moreover, the outstanding cyclic stability, linearity response character, and rapid response time are demonstrated. Accordingly, the intelligent recognition and manipulation of a target are realized, which indicate a smarter human–machine interface sensing applied for wearable devices and mechanical arms can be expected. [ABSTRACT FROM AUTHOR]

Mechanoluminescence (ML) materials with long‐wavelength emission bands are essential for future in vivo bioimaging, non‐destructive testing of solids, etc. The lack of a defined mechanism, however, prevents the application of near infrared ML materials above 650 nm in several new fields. Here, the addition of Ga3+ ions to Y3Al5O12: Cr3+ manipulates matrix microstructure evolution, boosting near‐infrared (NIR) zero‐phonon line (ZPL) stress optical output of the Cr3+ ion at 688 nm. The key factor changing the crystal field intensity Dq/B due to the addition of Ga3+ ions is what causes the luminescence amplification of ZPL. The ML fabricated by composite polydimethylsiloxane and Y3Al4GaO12: Cr3+ (YAGG: Cr3+) may penetrate chicken feet epidermal tissue and 4 mm pork tissue thanks to the strong NIR ZPL emission of YAGG: Cr3+ phosphor. This discovery of enhancing near‐infrared ZPL intensity by solid solution provides us with a new technique for optimizing NIR ML materials, as well as a new prospect for NIR ML materials in biological applications. [ABSTRACT FROM AUTHOR]

Developing full‐spectrum photocatalysts with simultaneous broadband light absorption, excellent charge separation, and high redox capabilities is becoming increasingly significant. Herein, inspired by the similarities in crystalline structures and compositions, a unique 2D–2D Bi4O5I2/BiOBr:Yb3+,Er3+ (BI‐BYE) Z‐scheme heterojunction with upconversion (UC) functionality is successfully designed and fabricated. The co‐doped Yb3+ and Er3+ harvest near‐infrared (NIR) light and then convert it into visible light via the UC function, expanding the optical response range of the photocatalytic system. The intimate 2D–2D interface contact provides more charge migration channels and enhances the Förster resonant energy transfer of BI‐BYE, leading to significantly improved NIR light utilization efficiency. Density functional theory (DFT) calculations and experimental results confirm that the Z‐scheme heterojunction is formed and that this heterojunction endows the BI‐BYE heterostructure with high charge separation and strong redox capability. Benefit from these synergies, the optimized 75BI‐25BYE heterostructure exhibits the highest photocatalytic performance for Bisphenol A (BPA) degradation under full‐spectrum and NIR light irradiation, outperforming BYE by 6.0 and 5.3 times, respectively. This work paves an effective approach for designing highly efficient full‐spectrum responsive Z‐scheme heterojunction photocatalysts with UC function. [ABSTRACT FROM AUTHOR]

The strategy of using near-ultraviolet (UNV) or blue chips to excite phosphors and enable continuous broadband near-infrared (NIR) emission is ideal for new-generation NIR illumination light sources. Therefore, it has become extremely urgent to develop broadband NIR emitting phosphors to realize the application of phosphor-converted NIR light-emitting diodes (pc-NIR-LEDs). Here, Ni2+-activated NIR phosphor Zn1−xMgxAl2O4 solid-solution was synthesized by a high-temperature solid state reaction method. The optimum phosphor with a broadband NIR emission band of 1000–1600 nm and a full-width half maximum (FWHM) of 232 nm was obtained. Structural results indicate that the substitution of Mg2+ for Zn2+ in the spinel host leads to the change in the bond length and angle in the [NiO6] octahedron and adjustable emission at 1201–1251 nm in the NIR region under excitation by UV light at 365 nm. The optimized phosphor was encapsulated in NUV LED chip to obtain pc-NIR LED device, and the application of broadband pc-NIR LED lighting was achieved. In addition, the optimum NIR phosphor exhibits luminescence stability without reaching luminescence saturation when coupled with a λ = 360 nm laser, resulting in great potential application in laser-driven NIR illumination. [ABSTRACT FROM AUTHOR]

Negative lattice expansion-induced upconversion luminescence (UCL) thermal enhancement can be used to efficiently solve the problems of thermal quenching of lanthanide ions, and it can be combined with traditional fluorescence intensity ratio technology to obtain temperature-sensing characteristics. In this work, linear negative thermal expansion of the lattice of Na2MoO4:Yb3+, Er3+ transparent glass ceramics was examined after fabrication by a low-temperature co-sintering approach. Thermal enhancement of UCL at 525 and 806/860 nm for the glass ceramics was caused by an increase in energy transfer between Yb3+ and Er3+ ions induced by the linear negative thermal expansion properties of orthorhombic Na2MoO4 nanoparticles. Combining the UCL characteristics of a positive thermal expansion tellurite glass matrix and negative thermal expansion Na2MoO4:Yb3+, Er3+ nanoparticles, a novel glass ceramic temperature sensor was obtained. The temperature relative sensitivity was manipulated by selecting different UCL spectral modes up to 3.14% K−1 (313 K), which provided a more optimal performance than many glass ceramics previously reported. The cycle measurement of the UCL response alternating between 313 and 573 K indicates excellent repeatability, and thus, there is the potential for successful application of Na2MoO4:Yb3+, Er3+ transparent glass ceramics as a new generation of temperature sensors. [ABSTRACT FROM AUTHOR]

In-situ observation of the growth and decomposition processes is significantly important for guiding the fabrication of up-conversion nanocrystals (UCNCs) with high performance. However, the high crystallization energy and rapid nucleation rate of the corresponding crystals make real-time observation still a huge challenge. Herein, the in-situ nucleation-growth-degradation processes of the UCNCs are investigated by employing tailored metastable intermediates, which possess a slowing-down nucleation rate under electron beam irradiation. The non-classical nucleation processes of the UCNCs, containing the coalescence of clusters and the subsequent crystallization, are demonstrated. Moreover, the Ostwald ripening and oriented attachment processes, which determine the particle size and morphology, are unambiguously recorded. Furthermore, the degrading process of the UCNCs is observed to be triggered by surface defects. Our work provides an insight into the real-time evolution dynamics of the UCNCs, which further sheds light on the fabrication of nano-sized up-conversion phosphors. [ABSTRACT FROM AUTHOR]

All‐inorganic CsPbBr3 perovskite nanocrystals (NCs) have stimulated the enthusiasm of the research on light emitting diodes (LEDs), laser, X‐ray detection, and information encryption, thanks to their excellent optical performance. Exploiting CsPbBr3 NCs with fascinating long persistent luminescence (LPL) is significantly important for expanding their potential applications. In this work, the room temperature LPL is successfully achieved in CsPbBr3 glass‐ceramics (GCs) through the optical write with a femtosecond (fs) laser. The carriers captured by the generated trapping centers for the crack of non‐bridged oxygen bonds in the glassy matrix are released by the thermal disturbance of room temperature. Moreover, the LPL performance is modulated flexibly for doping with La3+, Dy3+, Nd3+, and Lu3+ ions in the CsPbBr3 GCs, endowing the successful construction of a time‐resolved anti‐counterfeiting mode. Furthermore, the high stability and high color purity (97.04%) of the as‐obtained CsPbBr3 GCs are demonstrated. The results open a window for fs laser induced perovskite with myriad applications in optical storage devices. [ABSTRACT FROM AUTHOR]

A novel strategy explores the reversible modulation of visible and NIR luminescence in rare earth ion‐doped photochromic bismuth‐based glasses for information encryption and multi‐dimensional optical storage. [ABSTRACT FROM AUTHOR]

Lead-free metal halide perovskites have become emerging candidates for white light emitting diodes and X-ray imaging, and exploration of the corresponding down-conversion phosphors and scintillators based on perovskite structures with a high-performance for advanced devices is ongoing. Here, we synthesized Cs2HfCl6: Te4+ crystals with a yellow emission at 557 nm and a wide full width at half maximum around 104 nm, which is attributed to the transition from the triplet state to the ground state (3P1 → 1S0) of Te4+ ions. Moreover, the energy transfer process from the self-trapped exciton of Cs2HfCl6 to Te4+ ions is demonstrated. Accordingly, the white light emitting diodes show a color rendering index of 61.8, which was manufactured by employing the Cs2HfCl6:3% Te4+ crystals with a photoluminescence quantum yield of 74.2%. Furthermore, the Cs2HfCl6: Te4+ crystals exhibit a fascinating steady-state X-ray light yield reaching 76,194 photons MeV−1, a low detection limit of 36.2 nGy s−1 and a high spatial resolution of 11 lp mm−1. Hence, this study offers new insight for the development of lead-free metal halide perovskites and promotes their versatile application in white light emitting diodes and X-ray imaging. [ABSTRACT FROM AUTHOR]

Halide perovskite (HP)-based optoelectronics, particularly lasers, have attracted considerable attention thanks to their outstanding low threshold and tunable bandgaps. Surface coating is one of the most common strategies for significantly improving the phase stability and suppressing the leakage of lead, but HPs are vulnerable to most coating chemistries because of their natural weakness against polar solvents. Herein, polyvinylidene fluoride (PVDF) encapsulated CsPbBr3 microcrystals are synthesized by using an in situ growing method. Subsequently, a Fabry–Pérot (F–P) CsPbBr3 micro-laser with a low threshold (14.4 μJ cm−2), a well-controlled mode spacing, and even ultra-high long-term stability is experimentally realized at room temperature. In addition, the optical performance of the PVDF wrapped CsPbBr3 microcrystals is sustained in water for 35 days. This work enables a convenient and effective route to controllably fabricate perovskite microlasers with long-term stability. [ABSTRACT FROM AUTHOR]

Non‐toxic halide double perovskite materials have many advantages of lead halide perovskite. Whereas, they usually exhibit poor stability and very low intrinsic photocatalytic CO2 reduction activity due to the insufficient separation of photogenerated charges and the lack of active sites. In this work, stable chlorine‐deficient 3D hierarchical Cs2NaBiCl6 porous microspheres assembled by highly crystalline nanoflakes were prepared by a simple grinding method. An unprecedented CO yield of 30.22 µmol g−1 h−1 was achieved in the gas‐solid photocatalytic reduction of CO2 without sacrificial agents, which is the highest value among lead‐free halide perovskite photocatalysts. Experimental results and density‐functional theory calculations show that the chlorine vacancy plays the triple role of suppressing photogenerated electron‐holes recombination, enhancing CO2 adsorption, and significantly reducing the free energy barrier for the key intermediate COOH* generation. In comparison with the pristine Cs2NaBiCl6, coupling of surface and defect engineering of the hierarchical sample brings 12.34 times enhancement of CO2 photoreduction activity. This work proposes a simple method to synthesize a chlorine‐vacancy rich 3D hierarchical lead‐free halide perovskite and offers a new design idea to substantially enhance the photocatalytic activity, opening a door for the prospective contribution of these materials to carbon neutralization. [ABSTRACT FROM AUTHOR]

The detection of the stress distribution in a mechanical structure signifies a timely prediction of the deformation and damage of the corresponding object, which is crucial for engineering security management and construction safety. However, current strategies with 3-dimensional force detection of the targets are challenged by complicated mechanical structures. Herein, dynamic recording via stress memory with visualization detection for a gear with a highly curved surface is achieved using the explored mechanoluminescent film combined with Sr4Al14O25:Eu2+, Tm3+ microparticles. The regulated depth of the traps from 0.74 to 1.0 eV with the addition of foreign ions in Sr4Al14O25:Eu2+ allows for the stabilization of the captured carriers. Moreover, the external force accelerates the release of the captured carriers, with no stress-induced generation of long persistent luminescence, and the residual carriers could be readout by the introduction of a near-infrared light. This realizes the visualization of the stress distribution of complicated mechanical structures directly. Hence, the stress memory properties of mechanoluminescent films provide a novel approach for the stress detection of non-planar mechanical components in different scenarios. [ABSTRACT FROM AUTHOR]

Nanowire lasers are potential light sources that can be used in photonic integrated circuits (PICs) for inter‐chip optical communication. However, due to the size incompatibility between a nanoscale laser and a micrometer‐scale optical waveguide, their integration within a PIC remains challenging. Here, an in situ growth strategy to directly construct perovskite nanolasers inside the long polymethyl methacrylate (PMMA) fibers is explored. As the perovskite nanolasers are embedded inside the PMMA fibers, effective coupling of lasing light to the PMMA fibers is expected. Furthermore, due to the protection of PMMA coating, the perovskite nanolasers exhibit high robustness in water and demonstrate significant improvement in photostability. Stable single‐mode and polarization operations are obtained at room temperature from the lasers with a low excitation threshold. Hence, these results pave the way to realize ultra‐stable perovskite‐based PICs suitable for inter‐chip optical communication. [ABSTRACT FROM AUTHOR]