Afterglow Luminescence Research Articles

PEGylated BODIPY Photosensitizer for Type I Dominant Photodynamic Therapy and Afterglow Imaging.

Type I photodynamic therapy (PDT) exhibits outstanding therapeutic effects in hypoxic environments in tumors, but the design of type I photosensitizers (PSs), especially those with simple structures but dramatic properties, remains a challenge. Herein, we report a design strategy for developing type I PSs in one molecule with afterglow luminescence. As a proof concept, a 4,4-difluoro-4-bora-3a,4a-diaza-s-indacene (BODIPY) PS (BIP) bearing water-soluble poly(ethylene glycol) (mPEG550) chains is synthesized, and BIP can self-assemble into nanoparticles (BIPNs). Interestingly, BIPNs exhibit an O2•--triggered afterglow luminescence, which is scarce, especially for BODIPY derivatives. BIPNs demonstrate outstanding type I dominant PDT at an ultralow dose under both hypoxic and normoxic environments, which can significantly inhibit tumor growth under irradiation. This work highlights a high-performance PS with afterglow luminescence and excellent PDT effects, underscoring the significant potential of versatile PSs in clinical tumor theranostics.

Ultrabright and ultrafast afterglow imaging in vivo via nanoparticles made of trianthracene derivatives.

Low sensitivity, photobleaching, high-power excitation and long acquisition times constrain the utility of afterglow luminescence. Here we report the design and imaging performance of nanoparticles made of electron-rich trianthracene derivatives that, on excitation by room light at ultralow power (58 μW cm-2), emit afterglow luminescence at ~500 times those of commonly used organic afterglow nanoparticles. The nanoparticles' ultrabright afterglow allowed for deep-tissue imaging (up to 6 cm), for ultrafast afterglow imaging (at short acquisition times down to 0.01 s) of naturally behaving mice with negligible photobleaching, even after re-excitation for over 15 cycles, and for the accurate visualization of subcutaneous and orthotopic tumours and of plaque in carotid arteries. We also show that an afterglow nanoparticle that is activated only in the presence of granzyme B allowed for the tracking of granzyme-B activity in the context of therapeutic monitoring. The high sensitivity and negligible photobleaching of the organic afterglow nanoparticles offer advantages for real-time in vivo monitoring of physiopathological processes.

X‐ray–induced multicolor long afterglow and photostimulated luminescence from Pr3+‐doped Sr3(PO4)2

AbstractIn this paper, X‐ray–induced multicolor long afterglow and photostimulated luminescence from Sr3(PO4)2: Pr3+ was reported. The Rietveld refinement results have confirmed the as‐prepared sample was pure Sr3(PO4)2 phase with hexagonal crystal system. And Sr3(PO4)2: Pr3+ showed an excellent X‐ray–induced long afterglow luminescent performance. Under the excitation of X‐ray, the sample showed multicolor long afterglow luminescence from UVC to red region located at 268, 359, 466, 548, 604.3 and 685 nm, which can be ascribed to 4f5d‐3H4, 4f5d‐ 1D2, 4f5d‐3P0, 3P0→3H5 and 1D2→3H4, respectively. And the strongest afterglow emission intensity appeared at 468 nm. Furthermore, only 30 s X‐ray irradiation can induce 12 h afterglow emission, which afterglow emission intensity of 468 nm still reached 3.71 × 104 cps and was about 37.1 times stronger than the background intensity. In particular, the relation between 268 nm afterglow emission intensity and 468 nm afterglow emission intensity showed good linearity. And the UVC afterglow emission can be easily “observed” via the visible afterglow light. Furthermore, Sr3(PO4)2: Pr3+ possessed an excellent photostimulated luminescence (PSL) under the excitation of 980 nm NIR laser and the PSL intensity of the 12 circle still arrived at 1.26 × 105 cps, which was about 37.1 times stronger than the afterglow emission intensity after 5 h decay. All these results showed that the as‐prepared Sr3(PO4)2: Pr3+ phosphor was an excellent X‐ray–induced long afterglow luminescence phosphor, which possessed large potential applications in the medical field.

Heterogenous Core-Shell Persistent Luminescent Nanoparticles with Enhanced Afterglow Luminescence.

Persistent luminescent nanoparticles (PLNPs) are promising for many bioapplications due to their unique afterglow luminescence following the stoppage of light excitation. However, PLNPs are prone to surface quenching that results in weak afterglow luminescence. Although some efforts have been made to reduce surface quenching through designing homogeneous core-shell PLNPs, the enhancement in afterglow luminescence was insignificant. We hypothesize that the independent absorption and emission of the shell caused less energy to reach the activator ions in the core. Hence, a heterogeneous core-shell PLNP where the shell has a higher band gap than the core would reduce the absorption and emission of the shell. In this work, ZnGa2O4 and Zn2GeO4 were coated on Zn1.2Ga1.6Ge0.2O4:Cr and Zn3Ga2Ge2O10:Eu nanocrystals, respectively, to form heterogeneous core-shell PLNPs and significant luminescence enhancement was achieved compared to their traditional homogeneous core-shell nanostructures.

X-ray induced long afterglow luminescence from UVC to red region in Ca2P2O7:Pr3+

In this paper, we developed low dose X-ray induced long afterglow phosphor Ca2P2O7:Pr3+, which shows excellent afterglow luminescence from ultraviolet C (UVC) to red region. The photoluminescent results show that under 445.7 nm excitation, Ca1.995P2O7:0.5%Pr3+ displays red emissions peaked at 598.3 and 651.9 nm, corresponding to 1D2-3H4 and 3P0-3F2 transitions of Pr3+, respectively. Due to its pure red emission (CIE coordinates (0.59101,0.39926)), Ca1.995P2O7:0.5%Pr3+ can be regarded as a potential LED red phosphor. More importantly, Ca2P2O7:Pr3+ shows long afterglow luminescence from UVC to red region, which consists of four continuous emissions with similar intensity including 260, 359, 466 and 598.3 nm. Since these afterglow continuous emissions are fitted to the absorption of most photodynamic therapy (PDT) agents, Ca2P2O7:Pr3+ can be regarded as excellent PDT agents. Furthermore, 30 s X-ray irradiation can induce 5400 s decay of Ca1.997P2O7:0.3%Pr3+, and its afterglow emission intensity still reaches 5×104 cps after 5400 s decay. Even only 5 s X-ray irradiation also can produce 4.75×104 cps afterglow emission after 10 s decay. In addition, the repeat 980 nm laser irradiations can induce continuous strong photo-stimulated (PSL) luminescent peaks, which can be utilized to conduct high efficiency PDT without another X-ray irradiation. The thermoluminescence results reveal that the existence of shallow (0.89 eV) and deep traps are responsible for the excellent X-ray induced long afterglow and PSL luminescence. All these results suggest that Ca2P2O7:Pr3+ possesses great potential to be regarded as high efficiency PDT agents.

Study on the Luminescence Performance and Anti-Counterfeiting Application of Eu2+, Nd3+ Co-Doped SrAl2O4 Phosphor.

This manuscript describes the synthesis of green long afterglow nanophosphors SrAl2O4:Eu2+, Nd3+ using the combustion process. The study encompassed the photoluminescence behavior, elemental composition, chemical valence, morphology, and phase purity of SrAl2O4:Eu2+, Nd3+ nanoparticles. The results demonstrate that after introducing Eu2+ into the matrix lattice, it exhibits an emission band centered at 508 nm when excited by 365 nm ultraviolet light, which is induced by the 4f65d1→4f7 transition of Eu2+ ions. The optimal doping concentrations of Eu2+ and Nd3+ were determined to be 2% and 1%, respectively. Based on X-ray diffraction (XRD) analysis, we have found that the physical phase was not altered by the doping of Eu2+ and Nd3+. Then, we analyzed and compared the quantum yield, fluorescence lifetime, and afterglow decay time of the samples; the co-doped ion Nd3+ itself does not emit light, but it can serve as an electron trap center to collect a portion of the electrons produced by the excitation of Eu2+, which gradually returns to the ground state after the excitation stops, generating an afterglow luminescence of about 15 s. The quantum yields of SrAl2O4:Eu2+ and SrAl2O4:Eu2+, Nd3+ phosphors were 41.59% and 10.10% and the fluorescence lifetimes were 404 ns and 76 ns, respectively. In addition, the Eg value of 4.98 eV was determined based on the diffuse reflectance spectra of the material, which closely matches the calculated bandgap value of SrAl2O4. The material can be combined with polyacrylic acid to create optical anti-counterfeiting ink, and the butterfly and ladybug patterns were effectively printed through screen printing; this demonstrates the potential use of phosphor in the realm of anti-counterfeiting printing.

NIR afterglow nanosystem for photodynamic therapy.

Within the milieu of immune dysfunction, reactive oxygen species (ROS) play a pivotal role in inducing immunogenic cell death (ICD), countering the dysregulated tumor microenvironment. However, the administration of ROS at indiscriminate dosages may provoke deleterious immune responses. Therefore, precise regulation of ROS production is crucial to achieve efficacious therapeutic outcomes. We engineered an innovative afterglow nanosystem which is capable of real-time monitoring of ROS levels. Our findings reveal that Ru/CYQ@CPPO exhibits a markedly enhanced and prolonged afterglow luminescence, coupled with superior singlet oxygen (O2) generation, compared to the commercially available indocyanine green (ICG). In vitro studies demonstrated that Ru/CYQ@CPPO exhibits remarkable efficacy in photodynamic therapy (PDT) under irradiation at a wavelength of 450 nm. Furthermore, a significant correlation (R 2 = 0.987) was observed between the intensity of afterglow luminescence and the rate of cancer cell inhibition.

Boric Acid Matrix‐Activated nπ* Transition of Guest Chromophores: from Pure Fluorescence to Efficient Afterglow

AbstractEl‐Sayed rule highlights the important role of heteroatoms (e.g., N, O, and S) and the corresponding nπ* transition in designing efficient organic phosphors. Nevertheless, for some heteroatom‐rich fluorophores, their phosphorescence is quite weak (e.g., fluorescein), since the nπ* components are absent in the whole transitions. Here, these chromophores (mainly with n electron‐containing twisted structure) are found doping into the boric acid (BA) matrix can activate the nπ* transition for efficient afterglow luminescence. For example, doping purely green‐emitting fluorescein into BA yielded a high afterglow quantum yield (≈24%) and a long‐lasting, blue‐shifted cyan afterglow (>10 s). The covalent/non‐covalent interactions between the BA matrix and the guests resulted in twisting the n electron‐containing structure to promote the spin‐orbit coupling process, leading to the generation of new excited state triplet transition pathways. Since the guest chromophores feature visible light absorption, a series of multi‐color afterglow phosphors with visible or white light excitation are successfully constructed.

Near‐Infrared Afterglow Luminescence Amplification via Albumin Complexation of Semiconducting Polymer Nanoparticles for Surgical Navigation in Ex Vivo Porcine Models

AbstractAfterglow imaging, leveraging persistent luminescence following light cessation, has emerged as a promising modality for surgical interventions. However, the scarcity of efficient near‐infrared (NIR) responsive afterglow materials, along with their inherently low brightness and lack of cyclic modulation in afterglow emission, has impeded their widespread adoption. Addressing these challenges requires a strategic repurposing of afterglow materials that improve on such limitations. Here, an afterglow probe, composed of bovine serum albumin (BSA) coated with an afterglow material, a semiconducting polymer dye (SP1), called BSA@SP1 demonstrating a substantial amplification of the afterglow luminescence (≈3‐fold) compared to polymer‐lipid coated PFODBT (DSPE‐PEG@SP1) under same experimental conditions is developed. This enhancement is believed to be attributed to the electron‐rich matrix provided by BSA that immobilizes SP1 and enhances the generation of 1O2 radicals, which improves the afterglow luminescence brightness. Through molecular docking, physicochemical characterization, and optical assessments, BSA@SP1's superior afterglow properties, cyclic afterglow behavior, long‐term colloidal stability, and biocompatibility are highlighted. Furthermore, superior tissue permeation profiling of afterglow signals of BSA@SP1's compared to fluorescence signals using ex vivo tumor‐mimicking phantoms and various porcine tissue types (skin, muscle, and fat) is demonstrated. Expanding on this, to showcase BSA@SP1's potential in image‐guided surgeries, tumor‐mimicking phantoms within porcine lungs and conducted direct comparisons between fluorescence and afterglow‐guided interventions to illustrate the latter's superiority is implanted. Overall, the study introduces a promising strategy for enhancing current afterglow materials through protein complexation, resulting in both ultrahigh signal‐to‐background ratios and cyclic afterglow signals.

The effect of the degree of hydration of aluminium oxide thin films on the afterglow luminescence phenomena

The occurrence of afterglow luminescence in aluminum oxide thin films obtained by non-electrolytic aluminum oxide conversion coating has been proved. The kinetic parameters of luminescence decay and its spectral distribution were determined using the single photon counting method. The obtained samples of hydrated aluminum oxide, supported on metallic aluminum, were subjected to dehydration and dehydroxylation. The process of dehydroxylation led to a significant (by over two orders of magnitude) increase in the efficiency of afterglow luminescence. On the basis of the luminescence decay spectrum, the emitters in the systems studied were identified to be oxygen vacancies in the structure of Al2O3, including F, F2, F+. Moreover, a high probability of involvement of electrons from the conductivity band and F and F+ states photoconversion in determination of the character of afterglow luminescence was indicated. Durations of afterglow luminescence measured for the barrier layers and porous aluminum oxide films, obtained by electrochemical oxidation, were compared. Significant differences were detected between the kinetic parameters of luminescence decay and the character of emission spectra, whose analysis permitted proposing mechanisms of the processes.

Strain-Programmed Adhesive Patch for Accelerated Photodynamic Wound Healing.

As an alternative to tissue adhesives, photochemical tissue bonding has been investigated for advanced wound healing. However, these techniques suffer from relatively slow wound healing with bleeding and bacterial infections. Here, we present the versatile attributes of afterglow luminescent particles (ALPs) embedded in dopamine-modified hyaluronate (HA-DOPA) patches for accelerated wound healing. ALPs enhance the viscoelastic properties of the patches, and the photoluminescence (PL) and afterglow luminescence (AL) of ALPs maximize singlet oxygen generation and collagen fibrillogenesis for effective healing in the infected wounds. The patches are optimized to achieve the strong and rapid adhesion in the wound sites. In addition, the swelling and shrinking properties of adhesive patches contribute to a non-linear behavior in the wound recovery, playing an important role as a strain-programmed patch. The protective patch prevents secondary infection and skin adhesion, and the patch seamlessly detaches during wound healing, enabling efficient residue clearance. In vitro, in vivo, and ex vivo model tests confirm the biocompatibility, antibacterial effect, hemostatic capability, and collagen restructuring for the accelerated wound healing. Taken together, this research collectively demonstrates the feasibility of HA-DOPA/ALP patches as a versatile and promoting solution for advanced accelerated wound healing, particularly in scenarios involving bleeding and bacterial infections. This article is protected by copyright. All rights reserved.

Lanthanide Inorganic Nanoparticles Enhance Semiconducting Polymer Nanoparticles Afterglow Luminescence for In Vivo Afterglow/Magnetic Resonance Imaging.

Dual/multimodal imaging strategies are increasingly recognized for their potential to provide comprehensive diagnostic insights in cancer imaging by harnessing complementary data. This study presents an innovative probe that capitalizes on the synergistic benefits of afterglow luminescence and magnetic resonance imaging (MRI), effectively eliminating autofluorescence interference and delivering a superior signal-to-noise ratio. Additionally, it facilitates deep tissue penetration and enables noninvasive imaging. Despite the advantages, only a limited number of probes have demonstrated the capability to simultaneously enhance afterglow luminescence and achieve high-resolution MRI and afterglow imaging. Herein, we introduce a cutting-edge imaging platform based on semiconducting polymer nanoparticles (PFODBT) integrated with NaYF4@NaGdF4 (Y@Gd@PFO-SPNs), which can directly amplify afterglow luminescence and generate MRI and afterglow signals in tumor tissues. The proposed mechanism involves lanthanide nanoparticles producing singlet oxygen (1O2) upon white light irradiation, which subsequently oxidizes PFODBT, thereby intensifying afterglow luminescence. This innovative platform paves the way for the development of high signal-to-background ratio imaging modalities, promising noninvasive diagnostics for cancer.

Preparation of AIEgen-based near-infrared afterglow luminescence nanoprobes for tumor imaging and image-guided tumor resection.

Fluorescence imaging represents a vital tool in modern biology, oncology and biomedical applications. Afterglow luminescence (AGL), which circumvents the light scattering and tissue autofluorescence interference associated with real-time excitation source, shows remarkably increased imaging sensitivity and depth. Here we present a protocol for the design and synthesis of AGL nanoprobes with an aggregation-induced emission (AIE) effect to simultaneously red shift and amplify the afterglow signal for tumor imaging and image-guided tumor resection. The nanoprobe (AGL AIE dot) is composed of an enol ether format of Schaap's agent and a near-infrared AIE fluorogen (AIEgen) (tetraphenylethylene-phenyl-dicyanomethylene-4H-chromene, TPE-Ph-DCM) to suppress the nonradiative dissipation pathway. Pre-irradiating AGL AIE dots with white light could generate singlet oxygen to convert Schaap's agent to its 1,2-dioxetane format, thus initializing the AGL process. With the aid of AIEgen, the AGL shows simultaneously red shifted emission maximum (from ~540 nm to ~625 nm) and enhanced intensity (by 3.2-fold), facilitating better signal-to-background ratio, imaging sensitivity and depth. Intriguingly, the activated AGL can last for over 10 days. Compared with conventional approaches, our method provides a new solution to concurrently red shift and amplify afterglow signals for better in vivo imaging outcomes. The preparation of AGL AIE dots takes ~2 days, the in vitro characterization takes ~10 days (less than 1 day if not involving afterglow kinetic profile study) and the tumor imaging and image-guided tumor resection takes ~7 days. These procedures can be easily reproduced and amended after standard laboratory training in chemical synthesis and animal handling.

Fabrication of Translucent and Chemically Durable Crystal‐Glass Composite with Multicolor Persistent Luminescence

AbstractLong persistent luminescence materials (LPLMs) are promising candidates for various photonic applications, owing to their ability to store light. In spite of advancements in exploring of new LPLMs, the fabrication of transparent centimeter‐sized LPLMs with pre‐designed shapes, high productivity, long afterglow multicolor luminescence, and high chemical stability, is still challenging. Here, high‐throughput manufacture of translucent crystal‐glass composites via a classical injection molding (IM) technique is demonstrated, in which persistent phosphors (PPs)‐amorphous silica nanoparticles‐polymer composites are molded into different shapes then thermally treated at elevated temperatures to obtain glass composites with embedded PP particles and customized shapes. The structural characterizations endorse that the PP particles are preserved during high temperature sintering, and the resultant crystal‐glass composites combine the unique benefits of both PPs and silica glass. Remarkably, the total production time to manufacture 100 pieces of centimeter‐sized crystal‐glass composites is 35 h, thus enabling high‐throughput production of glass composite articles by the IM method. In addition, the injection molded crystal‐glass composites demonstrate long afterglow multicolor luminescence and ultrahigh chemical durability. This study provides a massive production strategy for the fabrication of translucent and stable multicolor persistent luminescent objects with customized shapes, which can be used in numerous applications.

A novel “off–on” ratiometric aptasensor based on dual-emissive persistent luminescent nanoparticles for the detection of dopamine

Dopamine, a neurotransmitter with multiple functions in the brain. The abnormal of dopamine levels are generally considered to be associated with various nervous system diseases. Herein, a novel ‘‘off–on” single-excited dual-emissive ratio luminescent aptasensor for highly sensitive and accurate monitoring of DA levels has been prepared via electrostatic interaction connecting persistent luminescent nanoparticles (PLNPs) ZnGaO:Sm and ZnGeO:Mn with different emission wavelengths. ZnGaO:Sm@Cy5.5-ZnGeO:Mn (ZGS@Cy5.5-ZGM), this ratiometric aptasensor exhibits two-emission peaks at 533 and 700 nm under a single-excitation wavelength of 254 nm. The afterglow luminescence of ZnGaO:Sm-apt@Cy5.5 at 700 nm is effective quenched by complementary chains of Cy5.5-modified DA aptamers with 710 nm specific absorption and only efficiently recovered by DA; meanwhile, the afterglow luminescence of ZnGeO:Mn as reference at 533 nm remains unchanged. The as-designed autofluorescence-free and exogenous-free interference ratiometric sensing system ZGS@Cy5.5-ZGM showed high selectivity for DA in complex biological samples. Under optimal detection conditions, the luminescence intensity ratio Δ(I700/I533) showed a good linear relationship with the concentration of DA in the range of 0.02–80 μM and the detection limit as low as 4 nM. The recoveries of DA in serum, urine and sweat were 97.4 % to 105.3 %, 96.4 % to103.4 %, and 95.1 % to 104.4 %, respectively. Current strategies based on PLNPs ratiometric sensors provide an effective method with high selectivity and accuracy for the detection of DA in clinical samples.

Rechargeable Afterglow Nanotorches for In Vivo Tracing of Cell‐Based Microrobots

AbstractAs one of the self‐luminescence imaging approaches that require pre‐illumination instead of real‐time light excitation, afterglow luminescence imaging has attracted increasing enthusiasm to circumvent tissue autofluorescence. In this work, we developed organic afterglow luminescent nanoprobe (nanotorch), which could emit persistent luminescence more than 10 days upon single light excitation. More importantly, the nanotorch could be remote charged by 660 nm light in a non‐invasive manner, which showed great potential for real‐time tracing the location of macrophage cell‐based microrobots.

Rechargeable Afterglow Nanotorches for In Vivo Tracing of Cell-Based Microrobots.

As one of the self-luminescence imaging approaches that require pre-illumination instead of real-time light excitation, afterglow luminescence imaging has attracted increasing enthusiasm to circumvent tissue autofluorescence. In this work, we developed organic afterglow luminescent nanoprobe (nanotorch), which could emit persistent luminescence more than 10 days upon single light excitation. More importantly, the nanotorch could be remote charged by 660 nm light in a non-invasive manner, which showed great potential for real-time tracing the location of macrophage cell-based microrobots.

Acidity-activatable upconversion afterglow luminescence cocktail nanoparticles for ultrasensitive in vivo imaging

Activatable afterglow luminescence nanoprobes enabling switched “off-on” signals in response to biomarkers have recently emerged to achieve reduced unspecific signals and improved imaging fidelity. However, such nanoprobes always use a biomarker-interrupted energy transfer to obtain an activatable signal, which necessitates a strict distance requisition between a donor and an acceptor moiety (<10 nm) and hence induces low efficiency and non-feasibility. Herein, we report organic upconversion afterglow luminescence cocktail nanoparticles (ALCNs) that instead utilize acidity-manipulated singlet oxygen (1O2) transfer between a donor and an acceptor moiety with enlarged distance and thus possess more efficiency and flexibility to achieve an activatable afterglow signal. After in vitro validation of acidity-activated afterglow luminescence, ALCNs achieve in vivo imaging of 4T1-xenograft subcutaneous tumors in female mice and orthotopic liver tumors in male mice with a high signal-to-noise ratio (SNR). As a representative targeting trial, Bio-ALCNs with biotin modification prove the enhanced targeting ability, sensitivity, and specificity for pulmonary metastasis and subcutaneous tumor imaging via systemic administration of nanoparticles in female mice, which also implies the potential broad utility of ALCNs for tumor imaging with diverse design flexibility. Therefore, this study provides an innovative and general approach for activatable afterglow imaging with better imaging performance than fluorescence imaging.

Mechanism analysis on manipulation of long afterglow luminescence properties of Y3Al5-xGaxO12:Ce3+, Cr3+ phosphors

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 Y3Al5-xGaxO12(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 CBM-Ce5d 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 (εcfs), centroid shift (εc), and the degree of dodecahedral distortion (D (YO)) on trap depth (ET) were discussed to manipulate the trap depth, demonstrating there is a significant positive correlation between εc-εcfs(2(1-10D(YO))) and ET values for the garnet structure A3B2C3O12, 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.

Design and Characterization of Eu2+/Ln3+ Co-doped SrAl2Si2O8 Photostimulated Phosphors for Optical Information Storages

In this paper, a series of Sr0.96Al2Si2O8 phosphors doped with 0.02Eu2+ and 0.02Re3+ (where Re = Tm, Dy, Er, Nd, Sm, La, Ho) were synthesized using the high-temperature solid-phase method at 1350 °C for 4 hours. The samples underwent characterization for structural and phase analysis using XRD-6000. Fluorescence and photostimulated properties were evaluated with F-4600. The pyroluminescence curve indicates a trap depth of 0.6-0.8 eV for Sr0.96Al2Si2O8: 0.02Eu2+, 0.02Re3+ (where Re = Dy, Er, Sm, La, Ho), making it suitable for prolonged afterglow luminescence. In comparison with deep trap material Sr0.96Al2Si2O8: 0.02Eu2+, 0.02Nd3+, the generated traps approach or exceed 1 eV, suggesting its potential for use as a light excitation and optical storage material. Additionally, the correlation between sample TL and PSL was examined, confirming that the augmentation of initial photostimulated luminescence intensity is closely associated with the generation of new traps. Furthermore, considering the effect of different trivalent lanthanide rare earth ion doping on trap depth from a trap regulation perspective offers a potential avenue for elucidating the nuanced processes underlying photostimulated luminescence.