Bright Emission Research Articles

Tunable Emissions in Zero‐Dimensional (C6H5CH2NH3)3InBr6 Enabled by Controlled Structural Amorphization

ABSTRACTZero‐dimensional (0D) hybrid metal halides (HMHs) hold great promise as multifunctional emitters. However, precise functionalization of organic moieties and controlled modulation of self‐trapped exciton (STE) emission from inorganic polyhedra remain challenging. This study introduces 0D (PMA)3InBr6 (PMA+ = C6H5CH2NH3+) as a multifunctional emitter, leveraging pressure‐induced structural regulation to control photoluminescence properties. Increasing pressure leads to simultaneous contraction and distortion of InBr63− octahedra, shifting the STE emission color from orange to green. At high compression, structural amorphization quenches STE emission, but upon pressure release, a bright cyan emission from the PMA+ cation emerges, with intensity approximately 21 times stronger than that of the initial STE emission. The enhanced emission is attributed to altered molecular configurations, disrupted intermolecular contacts, and reduced lattice vibrations, collectively suppressing excimeric coupling and minimizing nonradiative losses in the recovered amorphous phase. Furthermore, emission conversion is also achieved via laser‐induced structural amorphization, expanding the potential of (PMA)3InBr6 for direct laser writing and sensitive laser detection applications.

Mitigating Slow Reverse ISC Rates in TAPC-PBD Exciplex via Rapid Förster Energy Transfer to TTPA

There have been many advances in the development of thermally activated delayed fluorescence (TADF) materials for organic light emitting diode (OLED) applications in recent years. In particular, intramolecular exciplex systems have been highly studied and found to produce OLED devices of high external quantum efficiency (EQE) due to triplet harvesting via TADF. The proposed next generation of OLEDs uses hyperfluorescence to overcome the problem of broad emission associated with exciplexes. This process involves Förster resonance energy transfer (FRET) from the TADF host to a fluorescent dopant. In this work we revisited the photophysics of the TAPC:PBD exciplex (formed between the electron donor di-[4-(N,N-di-p-tolyl-amino)-phenyl]cyclohexane (TAPC) and the electron acceptor, 2-(4-biphenyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole (PBD)) as a host capable of simultaneously performing triplet harvesting and work as a donor transferring energy to a bright fluorescent emitter. The aim is to investigate the interplay between energy transfer and intersystem crossing in this hyperfluorescence system. Contrarily to previous findings, films of the TAPC:PBD blend show relatively slow reverse intersystem crossing rate (RISC) and weak luminescence efficiency (PLQY). Despite this, when doped with the strong fluorescent emitter TTPA, the luminescence quantum yield is greatly improved due to the highly efficient energy transfer rate from TAPC:PBD to TTPA. The rapid FRET from the exciplex to the fluorescent emitter overcomes the non-radiative losses affecting the luminescence efficiency of the blend. This study shows that the hyperfluorescence mechanism not only allows colour purity in OLEDs to be optimised, but also facilitates suppressing major loss mechanisms affecting luminescence efficiency, thus creating conditions to maximizing EQE.

Designing Robust Quasi-2D Perovskites Thin Films for Stable Light-Emitting Applications.

Quasi-2D perovskite made with organic spacers co-crystallized with inorganic cesium lead bromide inorganics is demonstrated for near unity photoluminescence quantum yield at room temperature. However, light emitting diodes made with quasi-2D perovskites rapidly degrade which remains a major bottleneck in this field. In this work, It is shown that the bright emission originates from finely tuned multi-component 2D nano-crystalline phases that are thermodynamically unstable. The bright emission is extremely sensitive to external stimuli and the emission quickly dims away upon heating. After a detailed analysis of their optical and morphological properties, the degradation is attributed to 2D phase redistribution associated with the dissociation of the organic spacers departing from the inorganic lattice. To circumvent the instability problem, a diamine is investigated spacer that has both sides attached to the inorganic lattice. The diamine spacer incorporated perovskite film shows significantly improved thermal tolerance over maintaining a high photoluminescence quantum yield of over 50%, which will be a more robust material for lighting applications. This study guides designing quasi-2D perovskites to stabilize the emission properties.

Going Forward to Unveil the Nature of γ Cas Analogs

The star γ Cas and its analogs are a subset of Be stars that display particularly hard and bright thermal X-ray emission, which has no equivalent among other massive stars. Here, I will review their characteristics and present the latest results of our optical and X-ray monitoring campaigns, including an assessment of the links between the circumstellar environment and the high-energy properties. Possible scenarios to explain this phenomenon will be presented in light of these observational results.

Planetary inward migration as the potential cause of GJ 504 's fast rotation and bright X-ray luminosity. New constraints from eROSITA

The discovery of an increasing variety of exoplanets in very close orbits around their host stars raised many questions about how stars and planets interact and to what extent host stars' properties may be influenced by the presence of close-by companions. Understanding how the evolution of stars is impacted by the interactions with their planets is indeed fundamental to disentangling their intrinsic evolution from star-planet-interaction (SPI) induced phenomena. In this context, GJ 504 is a promising candidate for a star that underwent strong SPI. Its unusually short rotational period (rm P_ rot ∼ 3.4 days), while being in contrast with what is expected of single-star models, could result from the inward migration of a close-by, massive companion (rm M_ pl ≥ 2 M_ J ), pushed towards its host by the action of tides. Moreover, its brighter emission in the X-ray luminosity may hint at a rejuvenation of the dynamo process sustaining the stellar magnetic field, which is a consequence of the SPI-induced spin-up. We aim to study the evolution of GJ 504 and establish whether by invoking the engulfment of a planetary companion we can better reproduce its rotational period and X-ray luminosity. We simulated the past evolution of the star by assuming two different scenarios: `star without close-by planet' and `star with close-by planet'. In the second scenario, we use our SPI code to investigate how the inward migration and eventual engulfment of a giant planet driven by stellar tides may spin-up the stellar surface and rejuvenate its dynamo. We compare our theoretical tracks with archival-rotational-period and X-ray data of GJ 504 collected from the all-sky surveys of the ROentgen Survey with an Imaging Telescope Array (eROSITA) on board the Russian Spektrum-Roentgen-Gamma mission (SRG). Despite the large uncertainty on the stellar age, we find that the second evolutionary scenario characterised by the inward migration of a massive planetary companion is in better agreement with the short rotational period and the bright X-ray luminosity of GJ 504; thus, it strongly favours the inward migration scenario over the one in which close-by planets have no tidal impact on the star.

Dual-Functional Carbon Dot Films: Blue-Light Filtration and Cyan-Light Conversion for Healthier White Light-Emitting Diodes.

Blue light emitted by commercial white light-emitting diodes (WLEDs) in the 440-470 nm range poses ocular health risks with prolonged exposure. Effective filtration is crucial for health-conscious lighting, but traditional filters often cause color distortion by completely removing blue emission. In this study, we address this challenge by synthesizing carbon dots (CDs) with strong absorption at 460 nm and bright cyan emission at 485 nm, featuring a photoluminescence quantum yield of 65% and a narrow full width at half-maximum of 30 nm. When embedded in a poly(vinyl alcohol) (PVA) matrix, the CDs@PVA films effectively filter UV-to-blue light, reducing the blue-light ratio from 27.2% to 2.7%. At the same time, the cyan emission preserves the white light's spectral composition, achieving a color rendering index of 83 ± 5. This dual functionality demonstrates the potential of CDs to enable safer WLEDs that improve both ocular health and lighting quality.

Boosting Multicolor Emission Enhancement in Two-Dimensional Covalent-Organic Frameworks via the Pressure-Tuned π-π Stacking Mode.

Covalent-organic frameworks (COFs) are dynamic covalent porous organic materials constructed from emissive molecular organic building blocks. However, most two-dimensional (2D) COFs are nonemissive or weakly emissive in the solid state owing to the intramolecular rotation and vibration together with strong π-π interactions. Herein, we report a pressure strategy to achieve the bright multicolor emission from yellow to red in the 2D triazine triphenyl imine COF (TTI-COF). Intriguingly, the TTI-COF experiences a 24-fold enhancement under a mild pressure of 2.7 GPa compared with the initial state. Joint experimental and theoretical results reveal that the restricted intramolecular chemical bond vibrations and the reduced π-π interactions originating from the offset stacking mode account for the significant pressure-induced emission enhancement. Furthermore, such piezochromic behavior may be ascribed to the decreased energy gap and enhanced intermolecular interaction. Our investigation offers constructive guidelines for designing 2D COF materials with high photoluminescence performance.

The SRG/eROSITA All-Sky Survey: Large-scale view of the Centaurus cluster

The Centaurus cluster is one of the brightest and closest clusters. Previous comprehensive studies were done only in its brightest part (r<30'), where the centers of the main substructures (Cen 30 and Cen 45) are located, and only a small fraction of the outskirts has been studied. Through this work, we aim to characterize the intracluster medium (ICM) morphology and properties of the Centaurus cluster out to the radius within which the density is 200 times the critical density of the Universe at the redshift of the cluster, R_ We utilized the combined five SRG/eROSITA All-Sky Survey data (eRASS:5) to perform X-ray imaging and spectral analyses in various directions out to large radii. We employed some image manipulation methods to enhance small- and large-scale features. Surface brightness profiles out to 2R_200 were constructed to quantify the features. We acquired the gas temperature, metallicity, and normalization per area profiles out to R_200. We compared our results with previous Centaurus studies, cluster outskirts measurements, and simulations. Comprehensive sky background analysis was done across the field of view in particular to assess the variation of the eROSITA Bubble emission that partially contaminates the field. The processed X-ray images show the known sloshing-induced structures in the core, such as the cool plume, cold fronts, and ram pressure-stripped gas. The spectra in the core (r≤11 kpc ) are better described with a two-temperature (2T) model than an isothermal model. With this 2T analysis, we measured a lower temperature from the cooler component (∼!1.0 keV ) and a higher metallicity (∼!1.6Z_⊙), signifying an iron bias. In the intermediate radial range, the temperature peaks at ∼!3.6 keV and we observed prominent surface brightness and normalization per area excesses in the eastern sector (Cen 45 location). Temperature enhancements near the location of Cen 45 imply that the gas is shock-heated due to the interaction with Cen 30. We reveal that the eastern excess emission extends even further out, reaching R_500. The peak excess of normalization is located at ∼!23' from the center ($8'$ behind the center of Cen 45) with a $45%$ and $7.7σ$ above the full azimuthal value. This might be the tail or ram pressure-stripped gas from Cen 45. There is a temperature decrease of a factor of about two to three from the peak to the outermost bin at -R_ . We find good agreement between the outer temperatures (r>R_2500) with the temperature profile from simulations and the temperature fit from cluster outskirts measurements. We detect significant surface brightness emission to the sky background level out to R_200 with a $3.5σ$, followed by $2.9σ$ at 1.1R_200. The metallicity at -R_ is low but within the ranges of other outskirts studies. We present the first whole azimuth beyond ∼!30' measurement of the ICM morphology and properties of the Centaurus cluster, and increasing the probed volume by a factor of almost 30. While the cluster core is rich in features as a result of active galactic nucleus feedback and sloshing, the cluster outskirts temperature of Centaurus follows the temperature profile of clusters in simulations as well as the temperature fit from other cluster outskirts measurements.

Black hole-disc coevolution in the presence of magnetic fields: refining the Thorne limit with emission from within the plunging region

Abstract The accretion of material onto a black hole modifies the properties of that hole owing to the capture of both matter and radiation. Adding matter to the hole through an accretion disc generally acts to increase the hole’s spin parameter, while the capture of radiation generally provides a retarding torque. The balance between the torques provided by adding matter and radiation leads to a maximum spin parameter that can be obtained by a black hole which grows by accretion, known as the Thorne limit. In the simplest theory of thin disc accretion this Thorne limit has the value a•, lim ≃ 0.998. The purpose of this paper is to highlight that any modification to theories of accretion flows also modify this limiting value, and to compute precisely the modification arising from a particular extension of accretion theory: the inclusion of bright emission from within the plunging region which is sourced from the magnetohydrodynamic stresses ubiquitously observed in simulations. This extra emission further suppresses black hole spin-up and results in new, lower, limits on the final black hole spin. These limits depend on the details of the magnetic stresses acting within the plunging region, but typical values seen in simulations and observations would lower the limit to a•, lim ≃ 0.99, a subtle but not negligible deviation.

Dynamic Phosphorescence Behavior of Carbene-Metal-Amide Complexes from the Perspective of Excited State Modulation.

Carbene-metal-amide (CMA) complexes have diverse applications in luminescence, imaging and sensing. In this study, we designed and synthesized a series of CMA complexes, which were subsequently doped into a PMMA host. These materials demonstrate light-induced dynamic phosphorescence, attributed to their long intrinsic triplet state lifetime (τP,int, in the μs-ms scale), high intersystem crossing (ISC) rate constant (kISC, up to 107 s-1), and bright phosphorescence. The extended τP,int, and elevated kISC facilitate efficient sensitization of singlet oxygen (1O2) under light irradiation, which is rapidly consumed by the host material, creating a localized anaerobic environment conducive to bright phosphorescence emission. The Sn-T1 process exhibits a large spin-orbital coupling matrix element (SOCME) value, while the SOCME value between T1 and S0 is comparatively smaller, resulting in a large kISC and long τP,int, Computational results indicate that the hole-electron configuration in the lowest triplet state exhibits low contributions from gold. Based on the dynamic phosphorescence properties, an encryption material capable of achieving a "burn after reading" effect was developed. This work illustrates that those phosphorescent emitters with minimal heavy atom contribution can produce dynamic phosphorescent phenomena, providing a novel strategy for designing stimuli-responsive phosphorescent materials.

Highly Photoreactive Semiconducting Polymers with Cascade Intramolecular Singlet Oxygen and Energy Transfer for Cancer-Specific Afterglow Theranostics.

Afterglow luminescence provides ultrasensitive optical detection by minimizing tissue autofluorescence and increasing the signal-to-noise ratio. However, due to the lack of suitable unimolecular afterglow scaffolds, current afterglow agents are nanocomposites containing multiple components with limited afterglow performance and have rarely been applied for cancer theranostics. Herein, we report the synthesis of a series of oxathiine-containing donor-acceptor block semiconducting polymers (PDCDs) and the observation of their high photoreactivity and strong near-infrared (NIR) afterglow luminescence. We reveal that PDCDs absorb NIR light to undergo a photodynamic process to generate singlet oxygen (1O2), which intramolecularly transfers to and efficiently reacts with the oxathiine block to form the afterglow oxathiine intermediates due to the low Gibbs free energy changes required for this photoreaction. Following intramolecular afterglow energy transfer from the oxathiine donor block to the acceptor block, NIR afterglow emission is produced from PDCDs. Owing to the efficient cascade intramolecular photochemical process, PDCD-based nanoparticles achieve a higher brightness and longer NIR emission compared to most reported afterglow agents, even after ultrashort photoirradiation for only 3 s. Furthermore, the cascade photochemical process within PDCD can be inhibited after bioconjugation with a quencher-linked peptide. This allows the construction of a cancer-activatable afterglow theranostic probe (CATP) that only switches on the afterglow signal and photodynamic function in the presence of a cancer-overexpressed enzyme. Thereby, CATP represents the first afterglow phototheranostic probe that permits cancer-specific detection and photodynamic cancer therapy under preclinical settings. In summary, this study provides a molecular guideline to develop afterglow probes from photoreactive polymers.

A Multiresonant Thermally Activated Delayed Fluorescent Dendrimer with Intramolecular Energy Transfer: Application for Efficient Host-Free Green Solution-Processed Organic Light-emitting Diodes.

The development of narrowband emissive, bright, and stable solution-processed organic light-emitting diodes (SP-OLEDs) remains a challenge. Here, a strategy is presented that merges within a single emitter a TADF sensitizer responsible for exciton harvesting and an MR-TADF motif that provides bright and narrowband emission. This emitter design also shows strong resistance to aggregate formation and aggregation-cause quenching. It is based on a known MR-TADF emitter DtBuCzB with a donor-acceptor TADF moiety consisting of either tert-butylcarbazole donors (tBuCzCO2HDCzB) or second-generation carbazole-based donor dendrons (2GtBuCzCO2HDCzB) and a benzoate acceptor. The TADF moiety acts as an exciton harvesting antenna and transfers these excitons via Förster resonance energy transfer to the MR-TADF emissive core. The SP-OLEDs with 2GtBuCzCO2HDCzB and tBuCzCO2HDCzB thus show very high maximum external quantum efficiencies (EQEmax of 27.9 and 22.0%) and minimal efficiency roll-off out to 5000cd m-2.

Delocalized Nonbonding Orbitals of Thioxanthone in Polycyclic Aromatic Hydrocarbons for Reduced Energy Gap and Narrowband Emission.

Chalcogen-containing carbonyls, specifically thioxanthone (TX), hold great potential in organic light-emitting diodes (OLEDs). While the development of narrowband OLEDs with chalcogen-containing carbonyls remains challenging due to difficulties in achieving both high device efficiency and narrow emission spectra. Herein, via a strategic incorporation of the TX moiety, two orange-red narrowband emitters, 2TXBN and BNTXBN, are designed and synthesized for the first time. Both 2TXBN and BNTXBN exhibit bright orange-red emissions with peaks at 582 and 585 nm, respectively, along with narrow full widths at half maximum of 30 and 32 nm. Notably, 2TXBN demonstrates delocalization of the nonbonding orbital within the TX segment, which raises the first triplet energy level and reduces the singlet-triplet energy gap. This electronic structural adjustment effectively shortens the delayed fluorescence lifetime, leading to enhanced device performance. Accordingly, OLED employing 2TXBN as the emitter achieves remarkable performance, with a maximum external quantum efficiency of 31.0%, a current efficiency of 69.0 cd A-1, and a power efficiency of 76.0 lm W-1, highlighting the efficacy of the nonbonding orbital delocalization strategy in achieving bathochromic-shifted narrowband OLED materials.

Excited-State and Steric Hindrances Engineering Enable Fast Spin-Flip Narrowband Thermally Activated Delayed Fluorescence Emitters with Enhanced Quenching Resistance.

Multi-resonance thermally activated delayed fluorescence (MR-TADF) materials have great potential for applications in ultrahigh-definition (UHD) organic light-emitting diode (OLED) displays, that benefit from their narrowband emission characteristic. However, key challenges such as aggregation-caused quenching (ACQ) effect and slow triplet-to-singlet spin-flip process, especially for blue MR-TADF materials, continue to impede their development due to planar skeletons and relatively large ΔESTs. Here, an effective strategy that incorporates multiple carbazole donors into the parent MR moieties is proposed, synergistically engineering their excited states and steric hindrances to enhance both the spin-flip process and quenching resistance. As expected, the designed materials namely 5Cz-BNO and 5Cz-BN exhibit bright blue and green emissions with narrow full-width at half-maximums (FWHMs) around 23 nm, together with significantly improved reverse intersystem crossing (RISC) rates. The OLEDs based on 5Cz-BNO and 5Cz-BN with doping concentrations from 5 to 20 wt% achieve high maximum external quantum efficiency (EQEmax) values exceeding 30% with suppressed efficiency roll-offs and improved operational stability. This work offers an effective approach for designing doping-insensitive blue and green MR-TADF materials with fast spin-flip processes by integrating the engineering of excited states and steric hindrances.

Hydrogen-bonded organic framework nanotransducers enabled sono-optogenetics for Parkinsonian rats.

Cell-type-specific activation of parvalbumin (PV)-expressing neurons in the external globus pallidus (GPe) through optogenetics has shown promise in facilitating long-lasting movement dysfunction recovery in mice with Parkinson's disease. However, its translational potential is hindered by adverse effects stemming from the invasive implantation of optical fibers into the brain. In this study, we have developed a non-invasive optogenetics approach, utilizing focused ultrasound-triggered mechanoluminescent nanotransducers to enable remote photon delivery deep in the brain for genetically targeted neuromodulation. These mechanoluminescent nanotransducers consist of sonosensitized hydrogen-bonded frameworks and chemiluminescent L012, serving as a nanoscale light source through ultrasound-induced cascade reactions. This system offers high ultrasound-triggered brightness and long-lasting light emission, facilitating repeatable deep brain stimulation. Our sono-optogenetics technology demonstrated effective modulation in the mouse motor cortex for limb motion control and activation of PV-GPe neurons for rescuing movement dysfunction over time in dopamine-depleted Parkinson's disease rats. This approach demonstrates the pathway for achieving genetically targeted and non-invasive neuromodulation for long-lasting treatment of Parkinson's disease, towards non-human primate models and clinical applications.

Optimized solution combustion synthesis of NUV excitable Tb3+ activated Ca9Gd(PO4)7 nanophosphor: A downshifting bright green emitter for advanced solid state lighting prospects

In present work, it is reported that Tb3+ doped Ca9Gd(PO4)7 phosphors synthesized via eco-friendly solution combustion method possess exceptional potential in lighting technology. Based on high-quality X-ray diffraction and advanced electron microscopy practices, structural and morphological properties of synthesized nanophosphors were investigated. The X-ray diffraction patterns recognized trigonal phase of R3c (161) space group with size in the range of 45–60 nm evaluated via Scherrer’s and W-H method. Photoluminescent properties investigated via excitation under 379 nm radiance, suggest intense absorption in 400–600 nm (attributed to vivid green emission peaking at 547 nm). Quadrupole-quadrupole interactions results in cross relaxation among Tb3+ ions resulting in concentration quenching as explained via Dexter’s and Van-Uitert’s theoretical model. Auzel’s method expressed value of radiative decay lifetime for the quantum mechanical state 5D4. Optical band-gap of optimized nanophosphor is 4.05 eV, revealed by Tauc’s hypothesis. Colorimetric investigations displayed excellent features which validated potential applications of Ca9Gd(PO4)7: Tb3+ nanophosphors in optoelectronic technology.

Defect dependent electronic properties of two-dimensional transition metal dichalcogenides (2H, 1T, and 1T' phases).

Transition metal dichalcogenides (TMDs) exhibit a wide range of electronic properties due to their structural diversity. Understanding their defect-dependent properties might enable the design of efficient, bright, and long-lifetime quantum emitters. Here, we use density functional theory (DFT) calculations to investigate the 2H, 1T, and 1T' phases of MoS2, WS2, MoSe2, WSe2 and the effect of defect densities on the electronic band structures, focusing on the influence of chalcogen vacancies. The 2H phase, which is thermodynamically stable, is a direct band gap semiconductor, while the 1T phase, despite its higher formation energy, exhibits metallic behavior. 1T phases with spin-orbit coupling show significant band inversions of 0.61, 0.77, 0.24 and 0.78 eV for MoS2, MoSe2, WS2 and WSe2, respectively. We discovered that for all four MX2 systems, the energy difference between 2H, 1T and 1T phases decreases with increasing concentration of vacancies (from 3.13% to 21.88%). Our findings show that the 2H phase also has minimum energy values depending on vacancies. TMDs containing W were found to have a wider bandgap compared to those containing Mo. The band gap of 2H WS2 decreased from 1.81 eV (1.54 eV with SOC included) under GGA calculations to a range of 1.37 eV to 0.79 eV, while the band gap of 2H MoSe2 reduced from 1.43 eV (1.31 eV with SOC) under GGA to a range of 0.98 eV to 0.06 eV, depending on the concentration. Our findings provide guidelines for experimental screening of 2D TMD defects, paving the way for the development of next-generation spintronic, electronic, and optoelectronic devices.

Silver(I)-iodine cluster with efficient thermally activated delayed fluorescence and suppressed concentration quenching.

Reports on highly efficient silver(I)-based thermally activated delayed fluorescence (TADF) materials are scarce due to challenges in molecular design, although these materials show great potential for photoluminescent and electroluminescent applications. Herein, a silver(I)-iodine cluster, namely Ag2I2(dppb-Ac)2, is synthesized by employing a donor-acceptor (D-A) type bisphosphine ligand. Due to the introduction of electron-donating iodine ligands, Ag2I2(dppb-Ac)2 exhibits an emissive singlet state characterized by (metal + iodine)-to-ligand charge transfer and intra-ligand charge transfer transitions, as well as a small singlet-triplet energy gap. Additionally, its non-planar, highly distorted D-A structure efficiently separates adjacent molecules in aggregated state. As a result, Ag2I2(dppb-Ac)2 exhibits efficient TADF and suppressed luminescence concentration quenching in thin films. For instance, the 10 wt%-doped PMMA film and neat film of Ag2I2(dppb-Ac)2 display bright bluish-green and green emission, peaking at 506 and 532 nm, with photoluminescence quantum yields (PLQYs) of 70% and 52%, and lifetimes of 18.9 and 7.9 μs, respectively. The high PLQYs and efficiently suppressed emission concentration quenching of Ag2I2(dppb-Ac)2 in films are outstanding among reported Ag(I)-based TADF emitters.

Engineering the multifunctionality of Li3Y3Te2O12 garnets with Sm3+ and Tb3+ activators for solid-state lighting and luminescence thermometry.

Tuning the photophysical response is indispensable in realizing the full potential of phosphors to meet the demands of multifunctional applications, such as solid-state lighting and optical thermometry. Herein, orange-red emission from an Sm3+-based Li3Y3Te2O12 system was studied for the first time with CIE coordinates of (0.488, 0.406), an internal quantum efficiency of 26%, T1/2 of 500 K, CCT of 2346 K and color purity of 68%. The fabricated orange-emitting devices presented bright orange-red emission and superior color stability even at higher input currents suitable for plant growth and lighting applications with CIE coordinates of (0.444, 0.276) at 50 mA. The enhancement in temperature sensitivity of the system was achieved via a co-doping strategy by introducing Tb3+ ions. An improved relative temperature sensitivity of 1.8% K-1 in the physiological temperature range was obtained based on the fluorescence intensity ratio method aided by the efficient energy transfer from Tb3+ to Sm3+. Thus, the present work demonstrates the multifunctional properties of the Li3Y3Te2O12:Tb3+/Sm3+ phosphor in solid-state lighting and ratiometric temperature sensing.

Highly efficient tunable white emission with ultralong afterglow in Sb3+/Mn2+-codoped CsCdCl3 crystals for multifunctional applications.

Recently, metal halides have attracted much attention due to their fascinating optical properties. However, achieving efficient white emission with ultralong afterglow remains a great challenge. Herein, we report Sb3+/Mn2+-codoped CsCdCl3 and multiple emission bands can be observed, which are derived from the self-trapped exciton emission of the Sb-Cl moiety and the d-d transition of Mn2+. Thus, tunable emission from cyan to orange light can be obtained. Moreover, efficient white emission with a luminous efficiency of 74% is observed when the energy-transfer efficiency from Sb3+ to Mn2+ is 34.5%. In particular, Sb3+/Mn2+-codoped CsCdCl3 shows bright orange afterglow emission, and the afterglow intensity is 1000 times that of CsCdCl3 and 20 times that of CsCdCl3:Mn2+. Upon combining this with thermoluminescence spectra, it is found that Mn2+/Sb3+ codoping can effectively regulate the depth and density distribution of trap defects, resulting in the ultralong afterglow duration exceeding 12 h at room temperature. Surprisingly, white light stimulation can provide additional photonic energy for Sb3+/Mn2+-codoped CsCdCl3, which enables the rapid release of trapped carriers to the emission center and rejuvenates afterglow emission after 12 h pre-delay. Finally, we demonstrated the applications of the as-synthesized compounds in single-component white light illumination, multiple optical anti-counterfeiting and information encryption.