The development of compact light sources is urgently required for portable near-infrared(NIR)spec-trometers.In this context,phosphor-converted light-emitting diodes(pc-LEDs)show great promise.Among various candidates,Cr3+-activated NIR phosphors are considered highly competitive due to their high efficiency and tunable emission.However,most reported Cr3+-activated NIR phosphors suffer from a narrow full width at half maximum(FWHM<150 nm)and a short emission wavelength(λem<750 nm).In this work,a novel garnet-type NIR phosphor,Na2Lu2Ga4GeO12∶Cr3+(NLGG∶Cr3+),was designed and synthesized via a[Na+-Ge4+]co-substitution strategy.Under 468 nm blue light excitation,the optimized NLGG∶0.08Cr3+sample exhibits a broadband emission covering 600-1 100 nm with a peak at 780 nm and a FWHM of 196 nm,achieving an internal quantum efficiency(IQE)of 56%and an external quantum efficiency(EQE)of 22%.Spectral analysis and crystal field calculations confirm that the broadband emission originates from Cr3+ions occupying a single type of Ga3+site with an intermediate crystal field strength.The emission peak can be continuously tuned from 742 nm to 790 nm,accompanied by a broadening of the FWHM from 182 nm to 196 nm,by varying the Cr3+doping concentration.Finally,an NIR pc-LED device fabricated with this phosphor and a blue LED chip demonstrates its potential applications in biomedical imaging,night vision,and non-destructive testing.
This study introduces ethylene glycol(EG)as an alternative subphase to water in the Langmuir-Blodgett(LB)technique for fabricating high-quality quantum dot(QD)films,aiming to overcome the limitations of conven-tional aqueous-phase LB processes,such as QD degradation and increased device leakage current.By optimizing LB deposition parameters,a uniform and densely packed monolayer QD film was achieved and employed as the emitting layer in red QLEDs.The use of an EG subphase effectively prevents water-induced erosion of QDs,while the opti-mized LB film significantly suppresses leakage current.As a result,the device exhibits outstanding electrolumines-cence performance:red emission peaked at 630 nm with a narrow full width at half maximum of 22 nm,a maximum external quantum efficiency of 26.1%,and an operational lifetime(T95)of 3 272 h at an initial luminance of 1 000 cd·m-2,markedly surpassing both conventional aqueous-phase LB devices and spin-coated reference devices.These findings demonstrate that the EG subphase LB strategy,through the mitigation of interfacial defects and leakage pathways,offers a promising fabrication route toward high-efficiency and long-lifetime QLEDs.
Mn⁴⁺-activated red-emitting fluoride phosphors are among the research hotspots for white light-emitting diodes(WLEDs).Their macroscopic crystal forms demonstrate pronounced advantages in hydrolytic resistance,thermal quenching,and quantum efficiency.This review summarizes the representative systems,synthetic protocols and photoluminescence properties of Mn4+-activated fluoride crystals.The solvent evaporation,host-crystal synthesis followed by ion exchange,solvent exchange,fluoride-phase transformation and cooling crystallization are compared in detail,and their respective merits and limitations are highlighted.Key challenges that remain to be addressed dur-ing crystals growth are discussed,including stabilization of the Mn4+valence state,regulation of fluoride host solubili-ty,and the requirement for environmentally benign processes.Finally,future application prospects are outlined,with the aim of accelerating the development of high-performance Mn4+-activated red-emitting fluoride crystals.
This study investigates the regulatory mechanism of Sb3+co-doping on the luminescent properties of Ba-Si2O2N2∶0.05Eu2+phosphors.A series of Ba(Si1-xSbx)2O2N2∶0.05Eu2+(x=0-0.10)samples were synthesized via the high-temperature solid-state method.It was found that trace Sb3+co-doping effectively modulates the local crystal field environment of Eu2+,thereby enhancing its luminescence performance.Combined with post-treatment ball mill-ing to optimize the particle size distribution,the sample with the optimal co-doping level(x=0.03)exhibited signifi-cantly improved properties.Its emission intensity increased to three times that of the undoped sample.The emission intensity under 400 nm excitation reached 91%of that under 380 nm excitation.The internal and external quantum efficiencies were enhanced from 20.7%and 18.9%to 47.7%and 43.6%,respectively.The phosphor retained 87.2%of its initial luminescence intensity at 120℃.A violet-light-excited sunlight-like white LED device fabricat-ed using the optimized phosphor demonstrated excellent performance under a driving current of 35 mA(0.5 W):a color rendering index(Ra)of 98,a color fidelity(Rf)of 97.25,a color gamut(Rg)of 100.4,and a luminous effi-cacy(η)of 121.5 lm/W.This study indicates that Sb3+co-doping is an effective strategy for enhancing the perfor-mance of such phosphors,showing promising potential for applications in high-quality sunlight-like lighting.
With the booming global market economy and continuous advancement of science and technology,estab-lishing an efficient anti-counterfeiting technology system to tackle the increasingly rampant counterfeiting and shoddy goods has become a key research focus in materials science and information security.Traditional single-mode optical encryption,which typically produces monochromatic luminescence under a single excitation mode,suffers from limi-tations such as susceptibility to replication.In contrast,optical information encryption represents a critical technolog-ical pathway for achieving advanced anti-counterfeiting capabilities,multi-mode optical encryption,leveraging multi-band light emission characteristics,offers an innovative pathway for anti-counterfeiting applications with high securi-ty,concealment,and reliability.In this work,BaSi2O5∶Eu3+,Tb3+crystals were successfully synthesized via a high-temperature solid-state method.Their optical and structural properties were systematically investigated using charac-terization techniques such as photoluminescence(PL)spectroscopy,X-ray diffraction(XRD),and scanning elec-tron microscopy(SEM).XRD analysis confirmed the successful synthesis of the material.Furthermore,the lumines-cent properties were explored through spectral characterization.Finally,the material was applied in the field of anti-counterfeiting utilizing binary encoding.The results indicate that the designed phosphors exhibit strong orange-yellow and vermilion emission under 377 nm and 395 nm excitation,respectively,meeting the performance requirements for multi-mode optical encryption.Additionally,a novel dual-mode excitation scanning device,employing light-emitting diodes with excitation wavelengths of 377 nm and 395 nm,was designed.This device enables efficient dual-mode op-tical anti-counterfeiting functionality,providing a new technical solution and theoretical foundation for the advance-ment of anti-counterfeiting technologies.
Flexible mechanoluminescent(ML)materials hold significant promise for applications in wearable op-toelectronics and intelligent sensing.However,conventional materials are largely limited to visible and near-infra-red emissions and often require pre-irradiation activation,which restricts their operational stability in complex en-vironments.Recently,Lv et al.reported a pioneering development of a solar-blind deep-ultraviolet(UVC)ML elastomer(Sr3(BO3)2∶Pr3+/PDMS)driven by interfacial triboelectrification.This material integrates self-powering and self-recovery capabilities with exceptional cyclic stability.Without the necessity of pre-irradiation,the elasto-mer emits solar-blind UVC light peaked at 272 nm upon mechanical stimulation.The elastomer film exhibits excel-lent optical stability over 10 000 stretching cycles,and its luminescence intensity can recover to 90.2%of the ini-tial value after a 24-hour resting period.This work not only extends the spectral range of ML into the solar-blind ul-traviolet region but also provides new strategies for background-free optical tagging and self-powered microbial ster-ilization applications.
High-brightness edge-emitting semiconductor lasers,with advantages such as high electro-optical con-version efficiency,high beam quality,and high peak power,have been widely applied in various fields,including material processing,medical treatment,and light detection and ranging(LiDAR).However,it remains challenging to achieve edge-emitting lasers with both high output power and high beam quality,and this challenge has become a research focus in the field of high-brightness edge-emitting semiconductor lasers.First,this paper systematically summarizes the research progress of high-power and high-beam-quality edge-emitting semiconductor lasers both do-mestically and internationally in recent years,outlines the methods for lateral mode control and vertical far-field di-vergence angle optimization of such lasers.Second,it presents the pulsed driving technology,which helps alleviate thermal accumulation in the active region,achieve high peak power output,and thereby enable high-brightness oper-ation of the device.The brightness of the multi-active-region tunnel junction lasers can reach 300 MW·cm-2·sr-1 at a peak power of 100 W.The High-brightness vertical broad-area edge-emitting(HiBBEE)laser can reduce the verti-cal far-field divergence angle,further improving the coupling efficiency of the optical system and lowering the cost of collimating and focusing lenses.Finally,combined with the current development status and future requirements of driving technologies and high-brightness lasers,this paper provides an outlook on the realization of high-performance pulsed-driven high-brightness semiconductor lasers.
Quantum dot light-emitting diodes(QLEDs),renowned for their high color purity,wide color gamut,and solution processability,are considered a pivotal technology for next-generation high-resolution displays.Howev-er,achieving high-resolution patterning without compromising the optical properties of quantum dots(QDs)remains a critical challenge hindering their practical application.Addressing this patterning bottleneck in high-resolution QLEDs fabrication,this work presents a novel patterning strategy based on nanoimprint lithography and thermally regulated transfer printing.The proposed method involves fabricating honeycomb microstructures on a polyvinyl buty-ral(PVB)surface using a silicon template,followed by selective filling of QDs controlled by solution wettability.Through a subsequent thermal-regulated transfer process,highly uniform QDs arrays with a feature size as small as 1.5 µm and a resolution of 9 072 pixels per inch(PPI)are successfully prepared.By employing higher-resolution templates,we have further achieved QDs array with a maximum pixel density of 25 400 PPI.Furthermore,we suc-cessfully fabricated high-resolution red QLEDs device(9 072 PPI)by integrating the QDs array onto hole trans-port layer(HTL),achieving a maximum external quantum efficiency(EQE)of 10.91%and a peak luminance of 164 421 cd/m².This work provides a stable and reproducible patterning pathway for the fabrication of high-resolution QLEDs.
High-reflectivity AlGaN-based nanoporous distributed Bragg reflectors(DBRs)are ideal candidates for constructing high-quality resonant cavities in ultraviolet resonant-cavity light-emitting diodes(RCLEDs)and vertical-cavity surface-emitting lasers(VCSELs).The 20.5 pairs n/n+-Al0.6Ga0.4N epitaxial stack structure was prepared on c-plane sapphire substrate using metal-organic chemical vapor deposition(MOCVD).The influence of the Si doping strategy in the n+-Al0.6Ga0.4N layers and the electrochemical etching voltages on the morphology and the reflection spectra of the nanoporous DBRs were systematically discussed.Compared with the conventional fixed Si doping con-centration,the graded Si doping with an increasing concentration profile can mitigate the electrochemical etching rate variation among n+-Al0.6Ga0.4N layers,significantly improve the uniformity of the pore diameter and porosity of the nanoporous channels,thus enhance the reflectivity of the nanoporous DBR.With an optimized electrochemical etch-ing voltage of 33 V,the Al0.6Ga0.4N nanoporous DBR achieved a reflectivity of 93.7%at the target wavelength of 310 nm with a stopband width of 36 nm.The photoluminescence intensity was increased by 110%for the multiple quantum wells deposited on the nanoporous DBR.These results would provide important reference for developing electrically injected ultraviolet RCLED and VCSEL devices.
The development of color converters with high luminescence saturation thresholds presents a critical challenge for next-generation high-brightness laser lighting technology.In this work,a novel transmissive Y3Al5O12∶Ce3+(YAG)phosphor-in-glass film(PiGF)featuring a double-sided sapphire sandwich structure(S@PiGF@S)was designed and fabricated via thermocompression sintering.This configuration significantly enhances tolerance to high laser power density through efficient dual-side heat dissipation and a"photothermal-decoupling"effect.Experimen-tal results show that the optimized S@PiGF@S color converter achieves a luminous flux of 2 761 lm at 16.6 W·mm-²,representing a 125.3%improvement over the conventional PiGF@sapphire structure(1 205 lm at 8.5 W·mm-²).More importantly,by incorporating a rotational dynamic cooling mechanism,the core temperature remains as low as 47℃even under a laser power density of 18 W·mm-².These findings confirm that the S@PiGF@S converter exhibits outstanding opto-thermal performance,demonstrating great potential for applications in high-brightness laser lighting.
X-ray imaging plays a vital role in nuclear medical diagnostics,industrial non-destructive inspection,and security inspection,where high-performance scintillators serve as the core materials for efficient X-ray detection and imaging.Developing new scintillator crystals that combine high absorption efficiency,high light yield,fast de-cay time,and low detection limit is a key challenge for improving imaging quality and reducing radiation dose.In this work,Cs3Lu2Cl9 crystals doped with various Ce3+concentrations were successfully prepared by the Bridgeman method,and their photoluminescence and scintillation properties were systematically investigated.The undoped crys-tal exhibits intrinsic broad-band luminescence originating from self-trapped excitons(STE).Ce3+doping significantly enhances the X-ray excited luminescence intensity.Among them,the Cs3Lu2Cl9∶5%Ce crystal exhibits the best over-all scintillation performance.It shows a radioluminescence(RL)emission peak at 425 nm and achieves a steady-state X-ray light yield of 20 700 photons·MeV-1,which is seven times higher than that of the undoped sample.Its scintillation decay time is 36.5 ns.Furthermore,this crystal achieves a low X-ray detection limit of 152 nGyair·s-1 and a high spatial resolution of 14.5 lp·mm-1.This work elucidates the mechanism by which Ce3+synergistically en-hances STE luminescence efficiency in Cs3Lu2Cl9,achieved by suppressing non-radiative recombination and facilitat-ing energy transfer.It thus confirms the great potential of Cs3Lu2Cl9∶5%Ce as a high-performance,fast-response X-ray scintillator for low-dose,high-resolution imaging applications.
SrAl2O4∶Eu2+is one of the most outstanding mechanoluminescent(ML)materials and has attracted consider-able interest for its applications in stress distribution sensing and structural health monitoring.A systematic investigation of its ML behavior and underlying mechanisms under different mechanical stimuli is essential for guiding practical application.In this study,SrAl2O4∶Eu2+powders were embedded in an epoxy resin matrix to fabricate composite samples subjected to uniaxi-al compressive stress during compression-release cycles.The ML behavior during unloading after stress loading with different holding time was systematically investigated.The results show that no discernible ML is observed during unloading when the stress holding time is≤2 s,whereas a pronounced ML peak appears during unloading when the holding time exceeds 2 s.This behavior can be attributed to a trap-mediated mechanism:during the stress-holding stage,the piezoelectric effect induc-es polarized charges on the grain surfaces,driving electrons to be captured by traps near the positively charged regions.With increasing holding time,these traps become progressively filled.Upon stress unloading,the rapid disappearance of the po-larized charges triggers the release of trapped electrons,which subsequently recombine with luminescent centers,giving rise to mechanoluminescence during unloading.In contrast,insufficient trap filling at short holding time prevents observable ML emission.These findings reveal the characteristic stress-unloading ML behavior of SrAl2O4∶Eu2+and its strong dependence on the stress holding time,providing important insights into the ML mechanism and guidance for its practical applications.
In recent years,luminescence thermometry techniques have gained widespread favor among researchers in the field of non-contact temperature measurement,owing to their advantages such as excellent temperature resolu-tion,spatial resolution,high environmental compatibility and rapid response.Among these,the luminescence ther-mometry based on luminescence intensity ratio(LIR)demonstrates significant application potential due to its superi-or interference resistance and inherent self-calibration characteristics.Thermally coupled levels(TCLs)have long served as the core physical mechanism for LIR thermometry,and exceptional universality and reliability have estab-lished TCLs as the prevailing approach in luminescence thermometry.However,an inherent constraint of this mecha-nism——the strong correlation between the energy gap ΔE and relative sensitivity(Sr=ΔE/kT2)poses a fundamental trade-off where high sensitivity and broad temperature range constitute mutually exclusive characteristics.To overcome this technological limitation,extensive research over the past decade has focused on innovating thermometric mecha-nisms,yielding significant advances in thermometric studies based on novel mechanisms such as intervalence charge transfer states,redshift of charge transfer band,and temperature-induced phase transition.This article aims to sys-tematically review recent research advances in the physical mechanisms of LIR luminescence thermometry,intending to provide theoretical references and technical insights for subsequent research in this field.
This research,in response to the urgent demand for high-performance near-infrared(NIR)light sources in fields such as tunnel lighting,has successfully developed a BaMg1.072Al9.928O17∶Eu(BMAO∶Eu)NIR phosphor with excellent luminous efficiency and thermal stability,aiming to provide a new material solution for the construc-tion of night vision compatible intelligent lighting systems.BaMg1.072Al9.928O17(BMAO)has been synthesized by high-temperature solid-state sintering.The material exhibits a NIR emission at 780 nm with an internal quantum effi-ciency of 55.7%.The NIR emission originated from oxygen vacancy(VÖ)defects is confirmed by introducing Eu3+ions,changing the sintering atmosphere,and introducing charge compensators.The coupling mechanism of defect-induced charge imbalance,coexistence of reduced valence states,multi-band emission,and energy transfer have been demonstrated.Finally,the NIR pc-LEDs fabricated by combining BMAO∶0.03Eu with a 365 nm ultraviolet chip showed application potential in night vision lighting and biological penetration.The synthesis method of this ma-terial provides a reference for guiding the synthesis of fluorescent materials for night vision lighting.
The instability in performance testing of large-area perovskite solar cell modules originates from the metastable state of internal interfacial charge distribution and transport.This study proposes the use of forward bias voltage as an electrical activation method to regulate this metastability,and reveals its spatially heterogeneous evolu-tion mechanism through in-situ electroluminescence imaging.It is found that applying a 10 V bias enables rapid and stable activation within 30 min(efficiency recovery to 99%).The underlying mechanism is the optimization of charge extraction and reduction of series resistance,which simultaneously enhances the fill factor and open-circuit voltage,and significantly improves the spatial uniformity of module luminescence.However,excessive bias voltage(≥12.5 V)induces localized heating accumulation,leading to irreversible quenching damage in the perovskite material or inter-faces,manifested as dark spots originating from the positive electrode side in electroluminescence images.Starting from the coupled relationship of photogeneration,recombination,and transport of charge carriers,this research clari-fies the optimization pathway and failure threshold of electrical activation,providing a solution with both theoretical and practical value for reliable testing and performance regulation of perovskite modules.
Due to its significant anisotropy and open interlayer gaps,the layered host structure offers greater poten-tial for the luminescence modification of rare-earth ions.In this paper,K+ion-doped Bi2ErO4Cl layered phosphors were prepared by a high-temperature solid-state method,and the effects of K+doping on the crystal structure,upcon-version luminescence,and temperature sensing properties were systematically investigated.The results indicate that K+ions preferentially occupy the interlayer gap positions of the host,thereby inducing a unique anisotropic lattice dis-tortion characterized by"lateral expansion-longitudinal compression,"which further reduces the local symmetry of the Er3+ions.Under excitation of 980 nm laser,the fluorescence lifetime of the 4F9/2→4I15/2 transition of Er3+was ex-tended upon K+doping,and its intensity was enhanced three times by doping K+ions(mole fraction 3%).Based on the fluorescence intensity ratio temperature measurement technique,the material exhibited excellent temperature sensing performance and thermal cycling stability,with absolute sensitivity(SA)and relative sensitivity(SR)reach-ing 0.19%·K-1 and 0.48%·K-1,respectively.The research results indicate that large ion radius K+can achieve lat-tice distortion and local crystal field regulation of layered matrices through interstitial doping,providing new ideas for the development of high-performance upconversion optical temperature sensing materials.
A magnetic-fluorescent nanocomposite(CDs-MNPs)was synthesized via a facile one-pot microwave hy-drothermal method using polyethyleneimine(PEI)as a bridging agent.PEI connected magnetic nanoparticles(MNPs)and carbon dots(CDs),forming a fluffy clustered structure with nanoscale gaps,which effectively sup-pressed aggregation-induced photoluminescence quenching(AIQ).CDs-MNPs exhibited a saturation magnetization of 10.4 emu/g and stable solid-state green fluorescence.Benefiting from integrated magnetism,fluorescence,and strong adsorption to fingerprint residues,it achieved clear latent fingerprint(LFP)visualization on dark substrates.
High-power semiconductor lasers,as core pumping sources for solid-state and fiber laser systems,are of sig-nificant application value in the fields such as industrial processing and national defense.This paper reports on a pump la-ser developed to meet the requirements of mid-infrared fiber laser systems.As a pump source for fiber lasers,the device must possess high output power and high efficiency.By optimizing quantum well materials,waveguide structures,and doping profiles,a single-emitter laser with a 200 µm stripe width was fabricated,achieving an output power of 16.12 W and a maximum conversion efficiency of 53%.Through beam combining and coupling modules,the laser was coupled into a 105 µm optical fiber with a numerical aperture(NA)of 0.18,delivering a maximum output power of 113 W.Test re-sults indicate that the laser exhibits excellent power and temperature stability,thereby enhancing its reliability.
In this study,natural biomass Peristrophe baphica Bremk was used as the carbon source,and biomass-derived carbon dots(HCDs)with dual-emission properties were prepared via pyrolysis.Their fluorescent response performance in wide-range pH detection scenarios was systematically investigated.Under excitation at 440 nm,HCDs exhibit dual emission at 510 nm(green light)and 610 nm(red light).Within the wide range covering the full pH scale of 0-14,the intensity ratio of the dual emission peaks(F610/F510)shows a high linear relationship with pH value in both pH 0-3 and pH 4-14 ranges.The correlation coefficients(R²)are as high as 0.998 9 and 0.992 8,re-spectively,and the detection limits are as low as 0.08 pH unit and 0.48 pH unit,respectively,demonstrating excel-lent sensitivity and selectivity.This radiometric probe has excellent self-calibration ability,which can effectively overcome the limitation that traditional single-emission probes are susceptible to environmental interference.With the core advantage of wide-range detection,it has broad application prospects in environmental monitoring,bioimaging and other fields.
Broadband photodetectors are of significant application value in fields such as imaging,communication,and spectral analysis.In this work,high-crystalline-quality micrometer-sized Sb2S3 single crystals were prepared by chemical vapor deposition,exhibiting a low defect density of only 4.8×1010 cm-3.An Sb2S3/GaAs heterojunction mod-el was established using SCAPS-1D software,and simulations indicated that the low defect density in Sb2S3 contrib-utes to enhancing the output current and spectral responsivity of the heterojunction,particularly in the ultraviolet and visible wavelength ranges.Based on this,a self-powered heterojunction photodetector based on Sb2S3 single crystal/n-GaAs was fabricated.The device demonstrates excellent photoelectrical response across a broad spectral range from 300 nm to 1 000 nm.Under an optical power density of 0.4 mW·cm-2,it achieves a peak responsivity of over 200 mA·W-1 at 830 nm,a specific detectivity exceeding 3×1010 Jones,a-3 dB bandwidth higher than 1 kHz,and rise/fall response times of 134 µs and 223 µs,respectively.This study provides a feasible approach for the design and fabrication of high-performance,broadband,low-power photodetectors,showing promising potential for applications in integrated optoelectronics and sensing systems.
