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Glow-in-the-daylight is a fascinating luminescence phenomenon displayed by certain storage phosphors that emit ultraviolet light upon being stimulated by ambient lighting. In this study, we investigate the influence of indoor lighting on the glow-in-the-daylight emission of a co-doped garnet phosphor, Y3Al5O12:Pr3+,Eu3+, known for its deep trap that effectively retains energy. Our experimental results demonstrate an interesting observation that, following x-ray radiation at room temperature, this phosphor exhibits negligible persistent luminescence in darkness but emits intense ultraviolet light peaking at 318 nm under indoor lighting conditions. This emphasizes the crucial role played by ambient lighting in releasing stored energy. Our findings not only shed light on the influence of indoor illumination dose and spectral distribution on the persistently stimulated luminescence but also expand our exploration to various ultraviolet phosphors with deep traps, with the aim of uncovering novel materials applicable in glow-in-the-daylight scenarios. [ABSTRACT FROM AUTHOR]

The luminescence properties of green Ba4Si6O16:Eu2+, rare-earths (RE) (RE = Sc, Y, La and Lu except Pm) phosphors are reported. Their long-lasting phosphorescence is discussed in view of trap depths and concentrations determined from thermally stimulated luminescence experiments. A second emission band centered at 439 nm was evidenced at low temperatures, which stems from the substitution of Eu2+ in the two non-equivalent Ba2+ sites of Ba4Si6O16. The mechanoluminescence properties of Ba4Si6O16:Eu2+, RE phosphors are described, and a new mechanoluminescence mechanism is proposed, in the case where RE = Ho3+, involving a trap distribution from 0.694 to 0.924 eV. Mechanical loading (post UV irradiation) induces a decrease in depth of the trap distribution, leading to an increase of the luminescence intensity, whereas a drop of the luminescence intensity is observed upon unloading, following the faster release of the charge carriers. [ABSTRACT FROM AUTHOR]

Persistent luminescence materials have been widely studied due to their excellent optical properties. However, they can only be activated by UV light; in other words, the charging method for these phosphors is limited. In fact, materials that can continuously emit light when exposed to sunlight are highly sought after for their potential to reduce energy consumption. Warm‐colored persistent luminescence materials are particularly useful for information storage, security marking, and preventing counterfeiting. Nevertheless, creating effective warm‐color persistent luminescence materials that are activated by sunlight remains a challenging task. To address this issue, novel daylight‐activated red persistent luminescence materials, Gd3‐xCax‐0.02GaO6:0.02Eu2+ (x = 0.3 ‐ 0.7) are explored. The material can be effectively activated by sunlight under all weather conditions, as well as by bright light from indoor lamps, mobile phone screens, and any form of visible light. Moreover, it possesses excellent water resistance. The process of electron trapping and release within the material is investigated through thermoluminescence experiments, photoluminescence spectra, and persistent luminescence spectra. Importantly, this phosphor has been demonstrated for various applications, including night vision marking, anti‐counterfeiting, optical information storage, and positioning, among others. [ABSTRACT FROM AUTHOR]

Lanthanide ion doped garnet is one of the representative persistent luminescence (PersL) phosphors that have been widely investigated. However, the role of the trap centers, either intentionally added co‐dopants or intrinsic defects arising during the sintering process, and their effect on the performance of PersL has not been completely elucidated, especially when they coexist. In pursuit of clarifying the relationship among different trap centers and their impact on the afterglow, herein, low‐concentration Pr3+ and Cr3+/Yb3+ (electron trap) co‐doped Y3Al2Ga3O12 ceramic phosphors are synthesized using a solid‐state reaction method under a vacuum atmosphere and some of them are further subjected to annealing condition. The observed thermoluminescence glow curves are composed of two strong peaks related to oxygen vacancies and a weak peak formed by each Cr and Yb trap based on the relative concentration ratio. On the other hand, it is found that the Cr3+ and Yb3+ions act as prominent near‐infrared (NIR) PersL centers in the NIR‐I and NIR‐II region, respectively, matching with the first and the second biological window. This work allowed for an exploration of the properties of distinct trap centers and how they influence the PersL and are likely to hasten the development of new PersL materials. [ABSTRACT FROM AUTHOR]

Multi‐dimensional force sensing that combines intensity, location, area and the like could gather a wealth of information from mechanical stimuli. Developing materials with force‐induced optical and electrical dual responses would provide unique opportunities to multi‐dimensional force sensing, with electrical signals quantifying the force amplitude and the luminescence output providing spatial distribution of force. However, the reliance on external power supply and high‐energy excitation source brings significant challenges to the applicability of multi‐dimensional force sensors. Here we reported the mechanical energy‐driven and sunlight‐activated materials with force‐induced dual responses, and investigated the underlying mechanisms of self‐sustainable force sensing. Theoretical analysis and experimental data unraveled that trap‐controlled luminescence and interfacial electron transfer play a major role in force‐induced optical and electrical output. These materials were manufactured into pressure sensor with renewable dual‐mode output for quantifying and visualization of pressures by electrical and optical output, respectively, without power supply and high‐energy irradiation. The quantification of tactile sensation and stimuli localization of mice highlighted the multi‐dimensional sensing ability of the sensor. Overall, this self‐powered pressure sensor with multimodal output provides more modalities of force sensing, poised to change the way that intelligent devices sense with the world. [ABSTRACT FROM AUTHOR]

Recently, combining long afterglow materials with organic fluorescent dyes, particularly carbon dots (CDs) to produce heterojunction and improve its luminescence and persistence properties became an important research direction. However, the precise role of these internal defects in the energy transfer process of CD@inorganic matrix composite fluorescent materials has not been thoroughly discussed. Establishing matching trap level to promote the energy transfer between the trap level and CDs level not only helps to enhance the afterglow performance, but also can explain the heterogeneous structure interaction between organic–inorganic fluorescent materials. Herein, ZLAGC@CDs luminescent composite is successfully synthesized via coating CDs on Zn1‐x(Li/Al)xGa2xO4:0.005Cr3+ (ZLAGC, x = 0–1), which exhibits a unique double emission at ≈430 nm (the defect luminescence of CDs) and 718 nm (the 2E→4A2 transition of Cr3+). After coating, the energy transfer from the defect level of CDs to the excited state of Cr3+ enhanced the NIR emission. The electron transfer between the defect level of CDs and the split deeper trap level of ZLAGC also improved the visible and near‐infrared (NIR) afterglow. The fluorescence and afterglow signals of ZLAGC@CDs are highly sensitive to solution pH under acidic conditions, indicating that the prepared fluorescent composite has potential application in acid microenvironment fluorescence detection. [ABSTRACT FROM AUTHOR]

[Display omitted] Near-infrared (NIR)-emitting persistent luminescence nanoparticles (PLNPs) are ideal optical imaging contrast reagents characterized by autofluorescence-free optical imaging for their frontier applications in long-term bioimaging. Preparation of uniform small-sized PLNPs with excellent luminescence performance is crucial for biomedical applications, but challenging. Here, we report a facile magnesium doping strategy to achieve size-independent boost of NIR persistent luminescence in typical and most concerned ZnGa 2 O 4 :Cr3+ PLNPs. This strategy relies on the doping of Mg2+ ions that with similar size of Zn2+ ions in the host lattice matrix, and concomitant to the electron traps tailoring tuned by varying the feed ratio of Mg2+. The optimum Mg2+-doped PLNPs give a long afterglow time (signal-to-noise ratio (SNR) = 31.6 at 30 d) without changing the desirable uniform sub-10 nm size of the original nanocrystals. The appropriate increase of the depth and concentration of electron trap contribute jointly to the enhancement of lifetime (488 % longer, 20.57 s) and afterglow time for 700 nm persistent luminescence. Meanwhile, these PLNPs keep the original excellent rechargeability and promote over 60 times increase of SNR in renewable in vivo imaging. This simple strategy provides a basis for new opportunities to address the critical challenge of effective optical performance boost in small-sized PLNPs. [ABSTRACT FROM AUTHOR]

Persistent phosphors are widely investigated in indications, bio‐imaging, information storage, and anticounterfeiting. However, it remains a challenge to develop highly stable persistent phosphors with abundant and widely distributed traps. Here, a Ba0.58Sr0.4Al3Si3O4N5:0.02Yb2+ (Ba0.6Sr0.4Al3Si3O4N5:Yb2+) persistent phosphor with an excellent persistent luminescence (PersL) time of 383 min is reported before decaying to 0.32 mcd m−2 due to the existence of abundant intrinsic electron traps. Ba0.6Sr0.4Al3Si3O4N5:Yb2+ owns a trap distribution ranging from 0.41 to 1.04 eV and has a remarkably broad full width at half maximum (FWHM) of TL curve (169 K) among currently reported persistent phosphors. The robust stability of Ba0.6Sr0.4Al3Si3O4N5:Yb2+ is evidenced by immersing in hot water and annealing at the high temperature for different time, which showed PersL retention rates of over 90%. Temperature‐assisted information storage in this persistent phosphor is successfully demonstrated. Furthermore, a step‐by‐step write‐in method is implemented in anticounterfeiting, and the coded information can be optionally decoded at different temperatures due to the wide trap distribution in Ba0.6Sr0.4Al3Si3O4N5:Yb2+. This work demonstrates highly stable oxynitride persistent phosphors with widely distributed traps show great promise in information storage, anticounterfeiting, and photodetectors. [ABSTRACT FROM AUTHOR]

A series of Tb3+ substituted layered perovskite Sr(La 1- x Tb x)AlO 4 (x = 0–1) was synthesized via solid-state reaction. The influence of Tb3+ on the phase, structure, photoluminescence, and long afterglow properties of the SrLaAlO 4 product was investigated. The fully substituted product SrTbAlO 4 was found to be isostructural with its SrLaAlO 4 counterpart, and the crystal structure parameters were first reported in this work. Photoluminescence investigation found that benefiting from the unique layered crystal structure, the activator Tb3+ was well separated and the optimal doping concentration was found to be as high as 20 at%. Except for photoluminescence, the products simultaneously show long afterglow properties due to disorder cations distribution in the local structure and thus induced defect condition. When the UV light source is turned off, the afterglow luminescence of SrLaAlO 4 : 0.03 Tb3+ can last over 1 h. The trap distribution of SrLaAlO 4 : Tb3+ was analyzed in detail by thermoluminescence. The trap depth is calculated to be around 0.7–0.81 eV, the value of which highly coincides with the ideal energy level for trapping and releasing electrons at room temperature. On the basis of the experimental results, the mechanism of long afterglow luminescence of SrLaAlO 4 : Tb3+ is elaborated and discussed. [ABSTRACT FROM AUTHOR]

The high photoluminescence quantum yield (PLQY) orange-red phosphor, which is of great significance for the application of phosphor-converted light-emitting diode (LED). Herein, the novel BaSrLu 4 O 8 :Eu2+ orange-red phosphor was synthesized, and the PLQY is enhanced from 30 % to 91 % by Al 2 O 3 assisted sintering. Combined with the trap energy level analysis, it is considered that the addition of Al 2 O 3 introduces new vacancies, which release electrons during high temperature sintering, creating a more favorable environment for the reduction of Eu3+, increasing the Eu2+ luminescence center in the matrix and improving the PLQY. The white LED device prepared with BaSrLu 4 O 8 :Eu2+ and Y 3 (Al,Ga) 5 O 12 :Ce3+ has a color rendering index of 84.4 at a low correlated color temperature of 4295 K. Meanwhile, the luminous brightness of the orange LED prepared by BaSrLu 4 O 8 :Eu2+ can maintain 89 % of the original light intensity in the simulated foggy day illumination experiment, which proves its excellent lighting prospect as an automobile steering lamp in foggy and smog extreme conditions. The results indicate that this work provides a new strategy for the reduction of Eu2+ while realizing the multi-application of phosphors. [Display omitted] [ABSTRACT FROM AUTHOR]

Degradation of InGaN–GaN LEDs has been the subject of intense investigations in the past few years. While current- and temperature-induced degradation processes have been described, the impact of photon-induced degradation has not been investigated in detail in the literature. This paper aims at improving the understanding of the mechanisms responsible for the degradation of the InGaN subject to high photon densities by stressing the devices under a high-intensity laser beam in open-circuit conditions (i.e., in the absence of external current). We analyzed the degradation by means of electrical, optical, and deep-level characterization techniques. First, we demonstrate the existence of optically induced degradation processes in GaN LEDs: from photoluminescence measurements, we observed a decrease in the luminescence after stress, more prominent in the region irradiated during stress. Second, we ascribe this effect to a decrease in internal quantum efficiency due to the generation of non-radiative defects within the active region. Third, by steady-state photocapacitance measurements, we reveal the presence of a shallow level with an energy of EC–2.2 eV, which can be ascribed to gallium vacancies and its complexes with oxygen and nitrogen and can be related to the increase in yellow luminescence. [ABSTRACT FROM AUTHOR]

Due to its short radiation length, moderate light output (8000‐9000 photons/MeV), high density (7.13 g cm−3), and non‐hygroscopicity, etc., Bi4Ge3O12 (BGO) material has been widely utilized as an advanced scintillator for irradiation detection. However, pure BGO cannot meet the requirements for future physics experiments and state‐of‐art industrial facilities coupled with a silicon photomultiplier (SiPM) due to its slow response time, poor radiation resistance, and excessive light output. Herein, a Ce‐doping strategy is reported for efficiently improving the overall performance (e.g., irradiation resistance, decay time, radioluminescence, and light output) of BGO that can be expectedly applied in future high energy physics detection. Ce‐doped BGO (BGO:Ce) displays higher radiation resistance ability under 10 h UV irradiation (97% of original) and a faster fluorescence lifetime (269 ns), superior to pure BGO. Furthermore, BGO:Ce shows ≈30% luminescence intensity of pure BGO, well eliminating the oversaturation of SiPM coupled with scintillation detectors. Theoretical calculations imply that an intense competition between electron or hole traps and Ce ions (Ce3+, Ce4+) can effectively reduce the concentration of color centers, thus enhancing irradiation resistance ability. [ABSTRACT FROM AUTHOR]

In this paper, a low dose X-ray induced long afterglow luminescent phosphor Sr 3 MgSi 2 O 8 :Pr3+ has been reported. The structure analysis shows the as-prepared samples possess good crystallinity and the emitting center Pr3+ is more likely to occupy the lattice position of Sr2+ due to their similar ionic radius. And under 471.1 nm excitation, Sr 3 MgSi 2 O 8 :Pr3+ shows bright visible lights peaked at 545.5, 617.1 and 648.6 nm, respectively, corresponding to the transitions of 3P 0 →3H 5 , 3P 0 →3H 6 and 3P 0 →3F 2 of Pr3+. After the X-ray irradiation, this phosphor shows strong ultraviolet C (291.7 nm), blue (493.2 nm) and red lights (617.1 nm). More important, only 5 s X-ray irradiation X-ray irradiation can easily charge Sr 3 MgSi 2 O 8 :Pr3+ to produce 5400 s afterglow emission. Even after 5400 s, its afterglow emissions still remain strong, which is about 20 times of the background intensity. The thermoluminescent results indicate that Sr 3 MgSi 2 O 8 possesses a high absorption rate for X-rays and thus X-ray irradiation can excite the host to produce large number of electrons, Secondary electron, which would rapidly fill up the traps and thus produce excellent long afterglow luminescence. In addition, the existing suitable traps with 0.76 eV trap depth are also favorable for persistent luminescence at room temperature. Thus, Sr 3 MgSi 2 O 8 :Pr3+ is confirmed to be a very efficient low dose X-ray induced long afterglow luminescent phosphor. [ABSTRACT FROM AUTHOR]

Broadband cyan‐emitting phosphors are crucial to close the cyan gap of phosphor‐converted white light‐emitting diodes (pc‐WLEDs) for full‐spectrum illumination. In this work, efficient cyan‐emitting Eu2+‐activated phosphor is achieved through structural modulation, which exhibits anti‐thermal quenching behavior. Redshift from blue (469 nm) to cyan (500 nm) emission and enhancement of emission is achieved by codoping Mg2+ and Ge4+ into Eu2+‐activated Na‐beta‐alumina phosphor. The introduction of Mg2+ ions dominates the redshift, while Ge4+ dominates the enhancement of emission. Furthermore, the introduction of Mg2+ and Ge4+ reduces the content of deep trap levels related to VNa defect, which decreases the degree of anti‐thermal quenching and results in better thermal stability. The prototype pc‐WLED by using the cyan‐emitting phosphor exhibits higher color‐rendering index and potential to close the cyan gap of pc‐WLEDs for full‐spectrum illumination. This work presents a paradigm for exploring phosphors with highly efficient and thermally stable emissions. [ABSTRACT FROM AUTHOR]

Chromium-doped persistent luminescence nanoparticles (PLNPs) have promising biomedical applications in X-ray charged near-infrared (NIR) luminous imaging. The persistent luminescence (PersL) property was usually adjusted by co-doping with other ions. Impurity phases were thought to be adverse to the PersL. In this study, a composite material, LiInSi 2 O 6 :Cr,Pr·2SiO 2 (LICP-S), was synthesized with a PersL peak at 800 nm after being charged by 1 Gy X-ray while LiInSi 2 O 6 :Cr (LIC) and LiInSi 2 O 6 :Cr,Pr (LICP) possessed no or very weak PersL. Distinctively, excess metastable cristobalite silica was found essential for the much more intense PersL of LICP-S than LICP and LIC. Thermostimulated luminescence spectra studies indicated that cristobalite adjusted the Pr-related traps from deep traps to shallow ones, which facilitated the room temperature PersL. The low dose X-ray charged PersL of LICP-S was applied to demonstrate the luminous labeling of a medical silicone prosthesis that was supposed to be imbedded in body for years via X-ray activated PersL imaging in vitro and in vivo. This work not only provides a kind of PLNPs with 800 nm emission suitable for low dose X-ray activation, but also an unusual strategy for trap engineering in PersL materials by designing multi-phase composites. Metastable cristobalite SiO 2 induces 10-times enhanced NIR persistent luminescence of LiInSi 2 O 6 :Cr,Pr after X-ray activation. [Display omitted] [ABSTRACT FROM AUTHOR]

Reversible and repeatable control of rare earth ions doped down-shift luminescence materials induced by the external field stimulation can be applied more widely. However, there is still a challenge on reversible luminescence regulation of photochromism-induced rare earth ions doped down-shift luminescence materials by light fields stimulation. The MoO 3 : Eu3+ phosphors changed color from light green to blue due to the formation of color centers caused by the trapping of electrons by oxygen vacancy defects under near infrared irradiation at 808 nm, and recovered from blue to initial light green after heating at 500 °C, showing a reversible change in color. The down-shift luminescence intensity of MoO 3 : Eu3+ phosphors reaches the maximum quenching degree, about 87%, after 20 s irradiation by 808 nm laser, which has the characteristics of fast response and great regulation rate. Moreover, the down-shift luminescence intensity can recover to the initial intensity after heating at 500 °C for 90 s, indicating reversible regulation of photochromism-induced down-shift luminescence. The application of MoO 3 : Eu3+ phosphors as the anti-counterfeiting labels and information storage of binary encoding was designed, these results suggest that it have certain potential applications in anti-counterfeiting and optical storage field. [Display omitted] [ABSTRACT FROM AUTHOR]

Persistent luminescence (PersL) phosphors are considered as promising candidates for the next generation of information storage medium. Mg4Ga4Ge3O16 (MGG) is an electron trapping material which exhibits defect luminescence, and the luminescent properties are easily tuned via doping various activated ions. In this work, undoped and Mn2+/Pr3+/Tb3+ single‐doped MGG phosphors were synthesized via high temperature solid phase reactions. X‐ray diffraction and scanning electron microscope results confirm that the activated ions tend to occupy Mg2+ sites. Excited at 265 nm, the MGG host exhibits a defect emission band peaked at 450 nm. Red, pink and green emissions are observed in the Mn2+/Pr3+/Tb3+ single‐doped MGG samples, which are ascribed to the Mn2+: 4T1(G) → 6A1(S), Pr3+: 1D2 → 3H4 and Tb3+: 5D4 → 7F5 transitions, respectively. All the samples exhibit bright PersL for minutes after the cessation of excitation. The energy transfer, concentration quenching, luminescence decay and afterglow mechanisms are also discussed in detail. The phosphors exhibit efficient thermal and optical stimuli response, showing great potentials in the optical information storage. [ABSTRACT FROM AUTHOR]

X‐ray luminescence spectra, thermally stimulated luminescence, and thermally stimulated conductivity of undoped cesium iodide (CsI) crystal are investigated in order to reach better understanding of the factors which govern the emission processes in this material. X‐ray luminescence spectra are recorded in the temperature range from 15 to 293 K. The low energy band at 2.2 eV emerging at heating above 120 K is assigned to the emission of residual impurities. Other two bands peaking at 3.6 and 4.3 eV at 15 K are attributed to the intrinsic emission of CsI due to the self‐trapped excitons (STEs). The parameters of the peaks observed in the thermally stimulated luminescence and conductivity of CsI crystal are calculated. Investigations of the thermally stimulated processes in CsI lead to the conclusion that the increase of luminescence of 4.3 eV observed above 70 K is due to release of trapped electrons, which subsequently interact with Vk centers and form on‐center STEs. The considerable ionic conductivity observed above 250 K can be explained by the influence of uncontrolled impurities of divalent metal atoms as well as Na+ ions. [ABSTRACT FROM AUTHOR]

Tenebrescence has been reported to have a high potential for personal ultraviolet (UV) detection. Color changes can detect UV doses and can also be used as visual sensors for X-rays. Hackmanite is known to exhibit tenebrescence. This study investigated the kinetics of electron-trapping levels contributing to the luminescence of Na8Al6Si6O24(Cl,S)2 hackmanite using thermoluminescence. The glow curves were measured at a heating rate of 5 K/s on hackmanite irradiated with X-rays. The physical parameters of the electron-trapping levels were evaluated by analyzing them using the deconvolution, peak shape, and initial rise methods. The Na8Al6Si6O24(Cl,S)2 hackmanite had at least five trapping levels, with activation energies of 0.78, 1.12, 1.86, 1.26, and 1.18 eV and corresponding peak trap lifetimes of 3.59, 2.71, 1.47, 3.34, and 3.91 s, respectively. The estimated migration time was 15.0 s. [ABSTRACT FROM AUTHOR]

Optical information encryption based on luminescence materials have received much attention recently. However, the single luminescence mode of the luminescence materials greatly limits its anti-counterfeiting application with high safety level. Here, a series of luminescence materials of Tb3+ and Bi3+ co-doped ZnGa 2 O 4 phosphors with great correspondence in photoluminescence (PL), persistent luminescence (PersL), and thermoluminescence (TL) modes was synthesized by the conventional solid-phase method for the application in multi-modal anti-counterfeiting fields. Under the excitation of 254 nm, ZnGa 1.99 O 4 :0.01 Tb3+, yBi3+ (y = 0.001,0.002) sample exhibited a broad blue emission band (the transition from [GaO 6 ]) at 440 nm and the characteristic emission peaks of Tb3+ at 495 nm, 550 nm, 591 nm and 625 nm, corresponding to the transitions of 5D 4 -7F n (n = 6, 5, 4, 3), respectively. Interestingly, the co-doping of Bi3+ ions improve the crystallinity and particle size of the phosphor, subsequently enhanced the PL intensity of Tb3+ to 6 times that of Tb3+ singly doped ZnGa 2 O 4 phosphor. Further, the flexible films with multi-modal luminescence properties have been fabricated through the unique TL and PersL characteristics of ZnGa 2 O 4 : Tb3+, Bi3+ phosphors, including "Optical information storage film", "snowflake and characters" and "QR code". Moreover, a set of optical information encryption is obtained by combining ZnGa 2 O 4 :Tb3+, Bi3+ phosphor and red emitting phosphor. The results indicate that ZnGa 2 O 4 :Tb3+, Bi3+ phosphor with multi-modal stimulus response can be expected to be potentially used in the applications of optical information storage and anti-counterfeiting fields. [ABSTRACT FROM AUTHOR]

MAPbBr3 quantum dots in SiO2 mesopores (∼ 4. 4 nm) were prepared by the spin-coating method, and their luminescence and nonlinear optical properties were studied by time-resolved photoluminescence (TRPL) and Z-scan techniques. The results showed that the absorption and photoluminescence peaks are at 464 nm and 476 nm, respectively. The TRPL spectroscopy showed two relaxation processes, a short lifetime (1.04 ns) and a long lifetime (4.49 ns), attributed to the trap–capture recombination and the electron–hole radiative recombination, respectively. Two-photon absorption (TPA) coefficient was 529 cm/GW at 800 nm. The nonlinear signal changed from TPA to saturable absorption with increase in light intensity. [ABSTRACT FROM AUTHOR]

For the conventional persistent luminescence (PersL) charging processes, carriers are photo‐pumped to the conduction band (CB) or high‐energy excited states (HES) under short‐wavelength UV or coherent near‐infrared (NIR) laser excitation. Herein, electron tunneling charging behavior is reported in Cr3+, Sm3+ co‐doped NIR PersL magnetoplumbite SrGa12O19, which allows for efficient charging by incoherent visible light. First, the electrons are efficiently captured by the neighboring GaII‐O2− electron–hole trap centers via a tunneling process, and then these excited electrons are transferred to shallow traps via a persistently energetic optical pump. This work further optimizes the PersL performance via engineering the energy band through partial substitution of In3+ for Ga3+. Consequently, tunneling charging occurring near the neighboring Cr3+‐traps dimers enables Sr(Ga,In)12O19:Cr3+,Sm3+ to display brighter NIR PersL (≈760 nm, peak; ≈100 nm, FWHM) than gallate spinel under sunlight irradiation. This work provides insights into electron tunneling charging under low‐energy excitation for NIR PersL, which may inspire more PersL explorations for practical applications. [ABSTRACT FROM AUTHOR]

The effect of thermal treatment on relaxation phenomena in Kr matrices irradiated with a low-energy electron beam has been studied. The experiments were carried out using measurements of the relaxation emissions of preirradiated Kr samples, which were unannealed and annealed before exposure to an electron beam. Three types of emissions were monitored in a correlated real-time manner: thermally stimulated luminescence, thermally stimulated exoelectron emission, and total yield of particles via pressure measurements. The energy levels of defects were estimated from the thermally stimulated luminescence data of the annealed sample. Two types of electron-hole traps created by electronic excitation were identified: close pairs and distant ones. Additional confirmation of the "excited state" mechanism of defect formation was obtained. Analysis of the correlation of yields and the effect of thermal treatment gave additional arguments in support of the crowdion model of anomalous low-temperature post-desorption from pre-irradiated Kr matrices. [ABSTRACT FROM AUTHOR]

Eu3+-doped BaLa 2 WO 7 and SrLa 2 WO 7 phosphors were prepared using the conventional solid-state reaction synthesis. The experiments have confirmed that the luminescence properties are completely different although they the isostructural monoclinic structure with a monoclinic space group of P21/b: compared with SrLa 2 WO 7 :Eu3+, BaLa 2 WO 7 :Eu3+ has stronger luminescence and higher thermal stability. The dynamic characteristics were studied via the laser site-selective excitation and luminescence technique. The two distinct Eu3+ centers Eu3+(A) and Eu3+(B) were confirmed corresponding to the substitution for La1 and La2, respectively. Eu3+(A) could transfer energy to Eu3+(B) in BaLa 2 WO 7 :Eu3+, but Eu3+(B) cannot realize back transfer to Eu3+(A). However, a mutual energy transfer could be achieved between Eu3+(A) and Eu3+(B) in SrLa 2 WO 7 :Eu3+ resulting in excitation energy diffusion. The energy dispersion may cause the excited electrons to be trapped in some defects and impurities, thereby reducing the luminescence effect. The results could help develop new reddish-orange emitting materials by introducing Eu3+ as a structural probe for doping sites and microstructure. [ABSTRACT FROM AUTHOR]

ZnGa2O4:Mn, as a distinct long persistent luminescence (PL) phosphor with green emission, has attracted intensive interest for display devices and security applications. We have systemically investigated the role of intrinsic defects in the PL of pristine and Mn doped ZnGa2O4 by first-principles calculations. It is found that the self-activated PL is attributed to the electron traps induced by VO and hole traps by VZn and ZnGa. The doped Mn will be energetically favored at the tetrahedral sites rather than octahedral sites under an Mn-rich condition. In contrast, the site preference of Mn largely depends on the chemical potentials of Zn and Ga under Mn-poor condition. The existence of the antisite defect ZnGa, however, promotes the stability of Mn at octahedral sites significantly, forming corresponding defect complexes. The crystal field strength is significantly enhanced, while the spin splitting is reduced on Mn in the defect complex, which introduces additional near-infrared luminescence of PL as confirmed by our experiment. [ABSTRACT FROM AUTHOR]

ZnGa2O4:Mn, as a distinct long persistent luminescence (PL) phosphor with green emission, has attracted intensive interest for display devices and security applications. We have systemically investigated the role of intrinsic defects in the PL of pristine and Mn doped ZnGa2O4 by first-principles calculations. It is found that the self-activated PL is attributed to the electron traps induced by VO and hole traps by VZn and ZnGa. The doped Mn will be energetically favored at the tetrahedral sites rather than octahedral sites under an Mn-rich condition. In contrast, the site preference of Mn largely depends on the chemical potentials of Zn and Ga under Mn-poor condition. The existence of the antisite defect ZnGa, however, promotes the stability of Mn at octahedral sites significantly, forming corresponding defect complexes. The crystal field strength is significantly enhanced, while the spin splitting is reduced on Mn in the defect complex, which introduces additional near-infrared luminescence of PL as confirmed by our experiment. [ABSTRACT FROM AUTHOR]

Long persistent luminescence materials developed to commercial standards are primarily concentrated in the blue and green regions, with only a few in the red region. Red, as one of the three basic colors, can be mixed in various proportions with blue and green to yield various colors. The development of red persistent phosphors has a broader application potential but remains a challenge. A solid-state reaction method was used to synthesize new red persistent luminescent materials of Ba 1- x Sr x Ga 2 O 4 :Sm3+ (x = 0–0.09). In BaGa 2 O 4 , both Sr2+ and Sm3+ preferentially occupy the Ba2+ site rather than the Ga3+ site. When exposed to UV light at 254 nm, the phosphors emit the characteristic red emission of Sm3+ at wavelengths ranging from 500 nm to 750 nm. After removing the UV light source, an intense red afterglow that lasted more than 1400 s was observed. The red afterglow signal reappears after a heating process. Doping Sr2+ reduces the trap depth and improves the red persistent luminescence significantly. Because the escaped electrons from traps compensate for the emission loss of Sm3+ during the heating process, the red phosphors have unimaginably luminescent thermal stability. Thus, the emission intensity at 200 °C is 1.6 times that at room temperature. The prepared red persistent phosphors show multimode luminescence, with the output signal being time and temperature sensitive, indicating that they are potential luminescent materials for anti-counterfeiting applications. Finally, a building-block strategy for advanced anti-counterfeiting applications of dynamic display information is proposed, with red persistent phosphors serving as an important component combined with upconversion phosphors of NaYF 4 :Yb3+, Tm3+, and green persistent phosphors of SrAl 2 O 4 :Eu2+, Dy3+. [ABSTRACT FROM AUTHOR]

Deep-red persistent luminescence (PersL) materials have promising applications in fluorescence labeling and tracking. PersL spectral range and PersL duration are considered to be the key factors driving the development of high-performance deep-red PersL materials. To address these two key issues, the performance of PersL materials was continually optimized by doping with cations (Si4+ and Al3+ ions), relying on the material of Li2ZnGe3O8:Cr3+ from the previous work of our group, and a 4.8-fold increase in PersL radiation spectrum intensity and more than twice the PersL duration was achieved (PersL duration up to 47 h). Ultimately, the obtained PersL materials are used to demonstrate their potential use in multi-level anti-counterfeiting, tracking and localization, respectively. This study provides a unique and novel entry point for achieving high-performance PersL materials by optimizing the PersL material host to modulate the electronic structure. [ABSTRACT FROM AUTHOR]

The persistent luminescence (PersL) materials Ca 2 Sb 2 O 7 :Pr3+ were prepared by traditional high-temperature solid-state method. We systematically investigated the crystal structure, band structure, photoluminescence, PersL performance by X-ray diffraction diagrams, Materials Studio calculation, photoluminescence (PL) spectra, PersL spectra and CIE coordinate analysis. The PL and PersL are attributed to the Sb5+ → O2− transition of the matrix and the 4f-4f transition of Pr3+ ion. For the sake of explaining the impact of various traps on PersL performance, thermoluminescence (TL) tests were performed on the optimal sample after diverse charging and discharging times. It was concluded that shallow traps have priority over deep traps in capturing electrons, and the electrons in the shallow traps were preferentially released. The highlight of this work is that the PL and PersL color can be adjusted by regulating the Pr3+ doping concentration when these samples were excited by a single excitation wavelength, so as to achieve a double anti-counterfeiting effect. Furthermore, the color change of PersL is different from that of PL. The luminescent patterns can make a difference as the change of concentration and time, forming a dynamic anti-counterfeiting mark that distinguishes in color and time. Thus, Ca 2 Sb 2 O 7 :Pr3+ has a bright application prospect in dynamic anti-counterfeiting field. [ABSTRACT FROM AUTHOR]

Ion doping is one of the most effective strategies to induce interesting luminescence properties of materials. In this work, the Bi3+ and Eu3+ are introduced into a '114' host material YBaZn 3 GaO 7 (YBZG) to generate photoluminescence (PL), long-persistent luminescence (LPL) and colour change properties. The co-doped YBZG:0.003Bi3+/ y Eu3+ can generate multi-color emissions from green, through yellow to orange with the increasing of Eu3+ concentration. There are F-like color centers around conduction band (CB) of YBZG host with shallow or deep energy levels. The electrons trapped by deep levels response to the PC properties, whereas these for shallow levels response to the LPL properties. The PC process from white to apricot is reversible. By alternating thermal treatment and irradiation, YBZG:0.003Bi3+ was proved to have a good fatigue resistance of 3.1 %. For YBZG:0.003Bi3+/0.05Eu3+, it shows bright orange LPL emission when the irradiation is removed after 24 min. The achievement of this paper provides a design idea that if the host structure of a phosphor is of flexible and easy to occur defect, not only PL property, but also PC and LPL properties are probably able to realize. [Display omitted] • This work prepare a new phosphor YBZG:Bi3+/Eu3+ with photochromism and long-persistent luminescence. • The photochromism process from white to apricot is reversible. • The long-persistent luminescence can last more than 24 min. • This paper provides a design idea for multi-functional materials. [ABSTRACT FROM AUTHOR]

Red long afterglow phosphors have significant implications for the realization of multicolor long-afterglow phosphors, but their insufficient luminescence intensity and afterglow duration still cannot meet the demands of practical applications. In this study, a novel orange-red phosphor, Y 2 Ge 2 O 7 :Pr3+, was synthesized for the first time. This phosphor not only exhibits exceptional thermal resistance but also shows a marked enhancement in long-afterglow performance upon co-doping with Sm3+. Remarkably, an orange-red afterglow can still be distinctly observed with the naked eye even 5 min after the removal of the excitation source in darkness. Further investigations involving thermoluminescence spectrum tests and the construction of an independent host-referred binding energy (HRBE) diagram reveal that the introduction of Sm3+ effectively mitigates the trap depth (1.02 eV) of the Y 2 Ge 2 O 7 :Pr3+ phosphor and significantly augments the quantity of electrons in shallow traps. This modification facilitates the effective release of electrons under room temperature conditions by the improved phosphor, thereby actualizing the long-afterglow luminescence phenomenon. Additionally, our findings indicate that a trap depth within the range of 0.60–0.80 eV is the optimal range for releasing electrons at room temperature. This research offers a crucial reference for future endeavors aimed at enhancing the performance of long-afterglow phosphors. • A novel orange-red long afterglow phosphor, Y 2 Ge 2 O 7 :Pr3+, Sm3+, was successfully synthesized using the high-temperature solid-state method. • Co-doping with Sm3+ successfully reduces the trap depth of Y 2 Ge 2 O 7 :Pr3+, increases the number of electrons in shallow traps, and exhibits long afterglow luminescence. • Both YGO:Pr3+ and YGO:Pr3+, Sm3+ phosphors exhibit excellent thermal stability, indicating potential application value in information storage. [ABSTRACT FROM AUTHOR]

Lithium metasilicate ( L i 2 S i O 3) has recently been shown to display outstanding stimulated luminescence properties, which are governed by defects and/or impurities. Here, the possible contribution and character of native point and complex defects to stimulated luminescence of lithium metasilicate have been investigated employing calculations based on the density functional theory (DFT). Under high concentrations of acceptor defects, isolated lithium interstitials were found to be the defects with the lowest formation energy (0.41 eV) but it is shown that they cannot contribute to luminescence. On the other hand, O i − 2 are the most favorable and stable defects under high concentrations of donor defects. F-centers and oxygen peroxides were identified as first- and second-order processes of point defects, which would explain experimental observations in the literature. Bridging oxygen vacancies were shown to introduce shallow electron traps able to trap up to four electrons. On the contrary, non-bridging oxygen vacancies lead to the formation of deep color centers with the capability of trapping up to two carriers/center, which could be the final state for the radiative process of luminescence. These results provide guidance for the interpretation of experimental measurements of luminescence. [Display omitted] • The current study investigated the possible TL contribution of native point and complex of Li 2 SiO 3. • Bridging oxygen vacancies introduced shallow electron traps able to trap up to four electrons. • The non-bridging oxygen vacancies produced deep color centers with trapping up to two centers. [ABSTRACT FROM AUTHOR]

• Electron trapping centers in the range of 2.95–3.1 eV was studied by vacuum ultraviolet and thermal activation spectroscopy; • Sulfate anion and D y 3 + ( O 2 - → D y 3 + ) and the creation of a combined radiative state S O 4 3 - → S O 4 - , • During thermal or optical excitation process, D y 2 + and S O 4 3 - electronic centers are ionized. The formation of new radiative states from the combination of D y 2 + - S O 4 - and S O 4 3 - - S O 4 - electron trapping centers in the range of 2.95–3.1 eV has been investigated using VUV and thermal activation spectroscopy. During the excitation process, there is a charge transfer between the oxygen ion of the sulfate anion and D y 3 + leading to the formation of a combined emissive state S O 4 3 - → S O 4 -. These states can be formed from the electron-hole trapping centers of D y 2 + - S O 4 - and S O 4 3 - - S O 4 -. The combined radiative state at 2.95–3.1 eV and impurity emission at 2.16 eV and 2.56 eV are excited simultaneously by photons of 3.95 eV and 4.5 eV, respectively. During the thermal or optical excitation process, the D y 2 + and S O 4 3 - electronic centers are ionized. Electrons recombine with a hole trapped by the ground state of the impurity (S O 4 - - D y 3 +), and the released energy is transferred to the D y 3 + impurities. [ABSTRACT FROM AUTHOR]

This study presents the impact of temperature and pressure on AlN:Mn2+ luminescence kinetics. Unusual behavior of Mn2+ optical properties during UV excitation is observed, where a strong afterglow luminescence of Mn2+ occurs even at low temperatures. When the temperature increases, the contribution of the afterglow luminescence is further enhanced, causing a significant increase in the luminescence intensity. The observed phenomena may be explained by an energy diagram in which the ON–VAl complex in AlN:Mn2+ plays a key role. Hence the ON–VAl complex defect in AlN:Mn2+ plays a double role. When the ON–VAl defect is located close to Mn2+ ions, it is responsible for transferring excitation energy directly to Mn2+ ions. However, when the ON–VAl defect complex is located far from Mn2+ ions, its excited state level acts as an electron trap responsible for afterglow luminescence. Additionally, three models have been tested to explain the structure of the emission spectrum and the strong asymmetry between the excitation and emission spectra. From the most straightforward configuration coordinate diagram through the configuration coordinate diagram model assuming different elastic constants in the excited and ground-states ending by a model based on the Jahn–Teller effect. We proved that only the Jahn–Teller effect in the excited 4T1 electronic state with spin–orbit coupling could fully explain the observed phenomena. Finally, high-pressure spectroscopic results complemented by the calculations of Racah parameters and the Tanabe–Sugano diagram are presented. [ABSTRACT FROM AUTHOR]

This study presents the impact of temperature and pressure on AlN:Mn2+ luminescence kinetics. Unusual behavior of Mn2+ optical properties during UV excitation is observed, where a strong afterglow luminescence of Mn2+ occurs even at low temperatures. When the temperature increases, the contribution of the afterglow luminescence is further enhanced, causing a significant increase in the luminescence intensity. The observed phenomena may be explained by an energy diagram in which the ON–VAl complex in AlN:Mn2+ plays a key role. Hence the ON–VAl complex defect in AlN:Mn2+ plays a double role. When the ON–VAl defect is located close to Mn2+ ions, it is responsible for transferring excitation energy directly to Mn2+ ions. However, when the ON–VAl defect complex is located far from Mn2+ ions, its excited state level acts as an electron trap responsible for afterglow luminescence. Additionally, three models have been tested to explain the structure of the emission spectrum and the strong asymmetry between the excitation and emission spectra. From the most straightforward configuration coordinate diagram through the configuration coordinate diagram model assuming different elastic constants in the excited and ground-states ending by a model based on the Jahn–Teller effect. We proved that only the Jahn–Teller effect in the excited 4T1 electronic state with spin–orbit coupling could fully explain the observed phenomena. Finally, high-pressure spectroscopic results complemented by the calculations of Racah parameters and the Tanabe–Sugano diagram are presented. [ABSTRACT FROM AUTHOR]

The glass‐ceramics (GC) of gadolinium aluminum gallium garnets with the expected composition of Gd3Al3Ga2O12:Ce and Gd3Al3Ga2O12:Ce,Be (GAGG:Ce and GAGG:Ce,Be, respectively) are fabricated by crystallization from the Gd2O3–Al2O3–Ga2O3–CeO2–SiO2–BeO (Gd:Ga:Al ratio is close to 3:2:3) glasses. The influence of Be2+ co‐doping (including doping level) on the luminescent properties of the GAGG is demonstrated. In particular, Be co‐doping results in the suppression of the Ce3+‐related radioluminescence (RL) and as a consequence, the light yield is lowered as well. The conclusion is made that Be2+ creates effective electron or hole trapping centers. [ABSTRACT FROM AUTHOR]

The appearance of the ultraviolet Bi3+-related emission band in the thermally stimulated luminescence (TSL) spectrum is observed around 465 K after selective irradiation of the YAlO 3 :Bi perovskite in the Bi3+-related absorption bands. The excitation spectrum of the TSL glow curve peak at 465 K, activation energies of its creation by photons of different energies, and the dependence of the TSL peak intensity on the irradiation duration are measured. The origin of the optically created electron centers and the mechanisms of photostimulated creation of the electron and hole centers under irradiation in the Bi3+-related absorption bands of YAlO 3 :Bi are discussed. The TSL glow curve peak at 465 K is suggested to appear as a result of electrons release from the electron centers intrinsic to the YAlO 3 lattice and their recombination with the hole Bi4+ centers. The same processes are shown to take place in the X-ray-irradiated YAlO 3 :Bi perovskite. The obtained results are important for possible applications of the investigated material in thermoluminescent dosimetry. • YAlO 3 :Bi3+ demonstrates UV thermally stimulated luminescence (TSL) with a main peak at around 465 K. • The TSL is created by the UV irradiation at about 6.1 eV. • X-ray irradiation produces the same TSL. • TSL appears as a result of electrons release from the electron traps intrinsic to YAlO 3 and their recombination with Bi4+ centers. [ABSTRACT FROM AUTHOR]

In luminescence thermochronometry, the thermal stability of feldspar minerals is conventionally constrained from isothermal decay experiments. However, despite recent refinement of the measurement protocol, measurements take several days and are routinely done for each individual sample. Following that most other thermochronometric methods usually use only a single reference set of thermal kinetic parameters, and that recent studies on direct physical probing of feldspar sample properties have shown that trap depth and band-tail width are broadly similar despite large variations in chemical composition, we sought to optimise luminescence thermochronometry measurements by exploring whether a single set of thermal kinetic parameters can describe luminescence thermal decay in feldspar. We explored the effect of using averaged thermal kinetic parameters rather than sample-specific thermal kinetic parameters to model luminescence signal accumulation under different thermal conditions. A set of K- and Na-feldspar minerals extracted from all over the world were analysed after being measured with a multi-elevated temperature protocol, comprising four different IRSL signals at 50, 100, 150, and 225 °C. Comparisons were done between the thermal kinetic parameters of each IRSL signal depending on different variables such as geographic region, transect, lithology, or mineralogy of the analysed feldspar grains. Even though it is not possible to generalise the thermal kinetic parameters between IRSL signals measured at different temperatures, the variance between the thermal kinetic parameters of different samples measured at the same IRSL temperature is consistent with the uncertainties on the individual parameters (i.e., <2–10%), suggesting that averaged, rather than sample-specific values may be appropriate. We then explored the effect of using these averaged parameters to model luminescence signal accumulation under different synthetic and natural thermal conditions. For our dataset, results show minimal impact on the obtained cooling histories and exhumation rates. We therefore propose the use of averaged rather than sample-specific thermal kinetic parameters for rapid investigation of luminescence thermochronometry samples. Based on careful initial characterisation of a few samples to verify the validity of using averaged thermal kinetic parameters, this would reduce measurement times by ca. 50% (i.e., 3–4 days per sample), allowing higher resolution sampling and measurement. • Feldspar thermal kinetic parameters are similar between different samples. • Variance between samples is consistent with uncertainties on the parameters. • We explore whether a single set of thermal kinetic parameters can be used. • Averaged parameters have minimal impact on the obtained thermal histories. • Averaged parameters can be a useful for high resolution sampling and measurement. [ABSTRACT FROM AUTHOR]

Herein, ultraviolet B (UVB) persistent luminescence phosphors containing SrAl 12 O 19 : Ce3+, Sc3+ nanoparticles were reported. Thermoluminescence (TL) spectrum analysis reveals that the shallow trap induced by Sc3+ co-doping plays an important role in photoluminescence persistent luminescence (PersL) development, while the deep trap dominates the generation of optical stimulated luminescence (OSL). Owing the appearance of deep trap, the OSL is observed under light (700 nm - 900 nm) excitation. UVB luminescence exerts good bactericidal effects on pathogenic bacteria involved in the process of food spoilage. Thus, the smart window with SrAl 12 O 19 : Ce3+, Sc3+/PDMS produces UVB PersL to efficiently inactivate Escherichia coli and Staphylococcus aureus. In addition, the presence of the smart window delays the critical point of pork decay, and greatly reduces the time of pork spoilage. It maximizes the convenience of eradicating bacteria and preserving food, thus offering a fresh perspective on the use of UV light for food sterilization and preservation. • PL, PersL and OSL in the UVB range are demonstrated in SrAl 12 O 19 doped with Ce3+. • The shallow trap induced by the Sc3+ co-doping plays an important role in PersL. • The deep trap dominates the generation of OSL. • Smart window can inactivate Escherichia coli and Staphylococcus aureus. • This smart windows dramatically delay pork spoilage. [ABSTRACT FROM AUTHOR]

Phosphorescence of beta irradiated Sr 4 Al 14 O 25 :Eu2+,Dy3+ has been analysed. The persistent luminescence that defines this phosphor is phosphorescence hence the justification for this study. A set of phosphorescence decay curves were measured at various temperatures T ph between 20 and 352 °C following irradiation to 2 Gy. The residual thermoluminescence (R-TL) was recorded at 1 °C/s after the phosphorescence decay. A conventional TL glow curve recorded at the same rate following irradiation to 2 Gy produces two composite glow peaks P1 and P2 at 63 and 252 °C respectively. The decay curves measured between T ph = 28–60 °C and 200–240 °C associated with peaks P1 and P2 respectively give the values of the activation energy of peaks P1 and P2 as 0.59 ± 0.01 and 0.80 ± 0.04 eV. The effective frequency factors associated with the traps are 6.2 × 109 and 6.4 × 105 s−1 respectively. Peaks P1 and P2 are affected by thermal quenching with activation energy W = 0.69 ± 0.06 eV and 0.66 ± 0.03 eV respectively. The R-TL glow curves show two maxima R1 and R2 at ∼72 and 260 °C respectively. Kinetic analysis of R-TL peak R2 shows a Gaussian distribution of trap energy whereas the same analysis on R-TL peak R1 shows a non-Gaussian distribution of trap energy. The mean values of activation energy corresponding to the respective electron traps of R1 and R2 are estimated to be 0.62 ± 0.07 and 1.04 ± 0.06 eV. For peak R2, the Gaussian distribution curve shows the maximum at ∼1.06 eV which indicates that most electron traps corresponding to peak R2 have this trap depth. • Phosphorescence of beta irradiated Sr 4 Al 14 O 25 :Eu2+,Dy3+ has been studied. • The sample shows two TL glow peaks P1 and P2 at 63 and 252 °C respectively. • The activation energy for thermal quenching is ∼0.69 ± 0.06 eV. • The sample possesses a Gaussian and a non-Gaussian distribution of trap-energy. [ABSTRACT FROM AUTHOR]

Herein, ZMGGO:Cr3+ nanoparticles were prepared by incorporating Mg2+ ions into Cr3+-doped zinc gallogermenate nanoparticles through a hydrothermal path in combination with a vacuum heating. The average size of ZMGGO:Cr3+ nanoparticles minishes from 59 to 12 nm with growing Mg2+ concentration. Meanwhile their luminescence intensity at 696 nm of ZMGGO:Cr3+ nanoparticles was only decreased by less than half of that of the undoped nanoparticles due to the decreased particle size after Mg doping. Meanwhile, the integral luminescence intensity of their entire emission band shows an increasing trend with increasing temperature due to the enhanced phonon sideband luminescence at high temperature. More important, it is found that the formation energies associated with Mg′ Ga -Gao Zn and Zn′ Ga -Gao Zn defects are −1.2 and 1.69 eV, respectively, suggesting the enhanced afterglow intensity of ZMGGO:Cr3+ can be ascribed to Mg doping leading to the increased number of these anti-site traps. Finally, the dual-level time-gate optical encryption was demonstrated using phosphorescent inks containing ZMGGO:Cr3+ nanoparticles with different afterglow intensities. • Mg2+ and Cr3+ codoped zinc gallogermanate (ZMGGO:Cr3+) nanoparticles were prepared. • Their average size decreases from 59 to 12 nm with increasing Mg concentration. • The presence of new anti-site traps improves their afterglow intensity. • The dual-level time-gate encryption was demonstrated using different afterglow inks. [ABSTRACT FROM AUTHOR]

Near-infrared phosphor-converted light-emitting diodes (NIR pc-LEDs) are compact light sources of great interest for NIR spectroscopy applications. Beyond typical Cr3+-activated NIR-emitting phosphors, there exists a strong demand for Cr3+-free alternatives with high efficiency and broadband emission to rich the landscape of NIR luminescent materials and extend their range of application fields. Here, we report a series of Fe3+-activated Ca 3 Ga 2 Sn 3 O 12 garnet-type phosphors exhibiting broadband NIR emission in the 650–1000 nm range attributed to 4T 1 (G) → 6A 1 (S) transition, with a maximum at 754 nm and a FWHM of 89 nm upon UV excitation. The spectroscopic results were analyzed according to the Tanabe-Sugano theory from which the crystal field parameter D q and Racah parameters B and C were obtained for the octahedrally coordinated Fe3+ ion. Notably, the NIR persistent luminescence lasting over 1 h was detected following UV or X-ray irradiation. The possible mechanism involving electron traps was proposed to explain the observed persistent luminescence. Furthermore, a NIR pc-LED was fabricated by coating synthesized phosphor on a UV chip, and its performance was evaluated to assess its potential suitability as a NIR light source. Our discovery of novel type of nontoxic Fe3+-activated broadband NIR luminescence phosphors with efficient NIR persistent luminescence paves the way for discovering Cr3+-free multifunctional NIR luminescence materials, thereby expanding their application possibilities. • Fe3+-activated Ca 3 Ga 2 Sn 3 O 12 garnet-type phosphors which emit broadband NIR luminescence were are firstly reported. • The phosphor exhibits efficient NIR persistent luminescence lasting over an hour following UV or X-ray irradiation. • The possible mechanism involving electron traps was proposed for observed persistent luminescence. • The work paves the way for discovering Cr3+-free multifunctional NIR luminescence materials. [ABSTRACT FROM AUTHOR]

Blue-light activated long afterglow luminescence phosphors have attracted much attention because of their potential application in many fields. Herein, the influence of trap depth and the quantity of electrons captured by the traps on the long afterglow luminescence properties were systematically revealed through a comparative analysis of the long afterglow luminescence performance of the series of Y 3 Al 5-x Ga x O 12 (YAGG):Ce3+, Cr3+ (x = 0, 1, 2, 3, 4, 5) phosphors. To achieve long afterglow luminescence, it requires that the traps can effectively capture electrons, and possess an appropriate trap depth. Additionally, it is discovered that the quantity of electrons captured by the traps is the main factor affecting the duration of long afterglow luminescence. The more electrons are captured, the longer the afterglow lasts. The quantity of trapped electrons is inversely proportional to the energy differences between CB M -Ce 5d and trap depth. The sample exhibits the high quantity of trapped electrons attributable to its small energy differences which allows electrons to be directly captured by traps through the tunneling effect. On this basis, the effects of crystal field splitting (ε cfs), centroid shift (ε c), and the degree of dodecahedral distortion (D (YO)) on trap depth (E T) were discussed to manipulate the trap depth, demonstrating there is a significant positive correlation between ε c -ε cfs (2(1-10D(YO))) and E T values for the garnet structure A 3 B 2 C 3 O 12 , when the ion doped at the A-position remains constant and the ions at the B and C positions vary. Notably, A larger D (YO) value corresponds to a deeper trap depth. This study provides a new perspective toward the development and design of long afterglow materials with superior afterglow emission. • The effect of trap depth and the quantity of trapped electrons in mechanism processes of persistent luminescence properties were systematically demonstrated. • The quantity of trapped electrons is inversely proportional to the energy differences between CB M -Ce 5d and trap depth. • A mathematical model is developed to reveal the effects of crystal field splitting (ε cfs), centroid shift (ε c), and the degree of dodecahedral distortion (D (YO)) on trap depth (E T) to manipulate the trap depth. [ABSTRACT FROM AUTHOR]

A new Eu2+: NaBa 4 (BO 3) 3 phosphor, synthesized under conventional solid state approach, exhibits bright yellow persistent luminescence with the co-doping of Eu2+, Ln3+ (Ln = Dy3+, Ho3+, Nd3+). XRD investigation reveals that all samples are pure phase phosphors with cubic structure, indicating the doped Eu2+and Ln3+ cations were incorporated into the lattice that did not form inclusive phase in the material. Since there are two coordination forms ([EuO6] and [EuO8]) of Eu2+ cations in the matrix, the above yellow luminescence can be divided into two different emissions centering at 558 nm and 627 nm, confirming the crystallographic environment on the photoluminescence from Eu2+ center. Optimal doping concentrations for each cations were further determined as 2% atm for Eu2+, 2% atm for Dy3+, 3% atm for Ho3+ and 2% atm for Nd3+. Afterglow behaviors are also observed for samples with Ln3+ co-doping, which reveal typical double exponential decay model. Among the phosphors synthesized, the sample 2 at%Eu2+/3 at%Ho3+: NaBa 4 (BO 3) 3 displays the best performance with higher initial brightness and longer lifetime, which can be attributed to the formation of electron traps with high concentration and suitable energy level, as confirmed by the result from thermal stimulated luminescence (TSL) analysis. [ABSTRACT FROM AUTHOR]

By estimating the trap depth from the relative position of the zigzag curve of divalent lanthanoid ions and conduction band bottom, the YSiO2N:Ce3+‐based blue persistent phosphors are developed, and their persistent luminescence and thermoluminescence properties are characterized to identify the electron trap distributions. Taking the nephelauxetic effect caused by covalent nitrogen into account for the vacuum referred binding energy diagram, it is predicted that Tm3+ and Sm3+ ions with the trap depth of 0.726 and 1.04 eV are an optimal codopant to obtain Ce3+ persistent luminescence. The prepared YSiO2N:Ce3+‐Ln3+ (Ln = Sm or Tm) samples enhance the Ce3+: 5d → 4f blue persistent luminescence intensity. In the thermoluminescence glow curves, the Ce3+ singly doped sample shows two glow peaks related to intrinsic defects; on the other hand, the Ln3+ codoped samples show an additional glow peak related to the Ln3+ traps. The thermoluminescence glow curve analyses through the initial rise method combined with the thermal cleaning and trap density methods reveal that the electron traps of Ln3+‐related defects have a distribution with ≈0.25 eV width and depths of 0.802 eV (Tm3+) and 1.10 eV (Sm3+). [ABSTRACT FROM AUTHOR]

The luminescent property of 2D perovskite materials promotes their applications in light emitting diodes, phosphor powders, and scintillators. Recently, an interesting extrinsic low‐energy broadband luminescence is hotly investigated. However, the understanding of such emissions is still at the early stage. In this study, based on a modified solvent evaporation method, centimeter‐size (BDA)PbI4 (BDA = NH3C4H8NH32+) single crystals are grown which, besides the band–band emission, show a large Stokes‐shifted broadband luminescence. We find such emission can be effectively excited by sub‐gap photons and conclude defects‐induced shallow traps are the corresponding luminescence centers. Density functional theory (DFT) calculations indicate that in‐plane iodine vacancies can introduce shallow electron traps in the band gap and give rise to the broadband emission. [ABSTRACT FROM AUTHOR]

By employing time‐dependent density functional theory for solid‐state chemistry, the research presented by Andrii Shyichuk [Acta Cryst. (2023), B67, 437–449] significantly contributes to the understanding of electron/hole traps in doped materials. [ABSTRACT FROM AUTHOR]

A new Eu2+, Dy3+: Sr 2 B 5 O 9 Cl phosphor with long persistence was synthesized in a reducing atmosphere by a solid-state reaction process. The pure-phase phosphor was obtained by calcination at 900 °C. The introduction of Eu2+ into the lattice of the matrix resulted in a broad blue emission centered at 423 nm, which was due to the characteristic 4f65d1 to 4f7 energy transfer of Eu2+ ions. Both Eu-doped and Dy/Eu-codoped phosphors displayed afterglow behaviors due to the electron traps generated by the incorporation of tri-valanced rare earth cations into the original Sr lattice sites. The afterglow of Eu2+: Sr 2 B 5 O 9 Cl and Eu2+, Dy3+: Sr 2 B 5 O 9 Cl phosphors showed standard double exponential decay behaviors, and the Eu2+/Dy3+ co-doped sample demonstrated better afterglow properties than Eu2+-doped one. A longer lifetime for the electrons was confirmed after the afterglow decay curve simulation. Based on the analysis of thermally stimulated luminescence (TSL), the difference in afterglow was attributed to the different trap concentrations induced by the Dy3+ (Eu3+) doping in the Sr 2 B 5 O 9 Cl matrix. [ABSTRACT FROM AUTHOR]