最新刊期
卷 45 ， 期 3 ， 2024
- 摘要：Doping Mn2+ into the copper-based halide Cs3Cu2I5 is an important approach to broaden the luminescence performance. However， most of the reported doping methods require high temperature， inert atmosphere， long reaction time， and specialized equipment. In this work， by directly adding CsI powders into a hydroiodic acid solution of CuI and MnCl2， Mn2+-doped Cs3Cu2I5 microcrystals were rapidly synthesized at a relatively low temperature （60 ℃） under ambient air conditions within 3 minutes. Through a series of control experiments， we propose a “slow-release growth-doping” mechanism controlled by the solubility of the reactants. It is confirmed that the slow dissolution rate of CsI powders in a concentrated hydroiodic acid can reduce the growth rate of Cs3Cu2I5 crystals， providing favorable kinetic conditions for controllable Mn2+ doping. This work provides a new approach for the study of doping luminescence and doping kinetics in all-inorganic metal halide systems.关键词：Mn2+ doping;Slow-release growth-doping;Cs3Cu2I5
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发布时间：2024-04-08
Cover Story
- 摘要：Since the size-dependent up-conversion fluorescence thermal enhancement phenomenon was found in rare earth-activated nano-fluorescent materials， the development of materials with noteworthy fluorescence thermal enhancement effect has become a research hotspot. Recent explorations have found that the fluorescence thermal enhancement effect can be achieved in non-nanoscale fluorescent material systems and non-up-conversion luminescence processes， which will further expand the application scenarios of this interesting optical phenomenon. In this review， the latest research progress of rare earth-activated fluorescent thermal enhancement materials is summarized. The proposed mechanisms and potential applications of rare earth-activated fluorescent thermal enhancement materials are overviewed， and the research directions are outlooked.关键词：rare earth activated luminescence materials;luminescence thermal enhancement;nanomaterials;up-conversion luminescence
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发布时间：2024-04-08 - 摘要：The efficiency of perovskite solar cells has been improved to 26.1% in just ten years， which is very close to the certification efficiency of crystalline silicon solar cells （26.81%）. This demonstrates the significant potential for industrialization. Currently， efforts are still being made to further enhance the efficiency of perovskite solar cells. However， various inseparable factors affect the performance of perovskite solar cells during the device preparation process. Traditional methods often rely on trial and error to optimize the preparation process， resulting in time-consuming procedures. Bayesian optimization， a global optimization algorithm， has achieved remarkable success in addressing artificial intelligence's black box problem. In this work， the Bayesian optimization is employed to optimize four key process parameters involved in the perovskite layer： excess percentage of lead iodide （PbI2）， annealing temperature， annealing time， and vacuum extraction time. The costs of research and development have been significantly reduced， as well as the required time for such activities has also been shortened. The improvement was achieved through five rounds of experimental iterations and 34 sets of process conditions， ultimately resulting in the preparation of an inverse perovskite solar cell with a device efficiency rating of 23.56%.关键词：perovskite solar cells;machine learning;process optimization;high efficiency
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发布时间：2024-04-08 - “荧光转换型近红外发光二极管研究取得新进展，LiScSi2O6∶Cr3+荧光材料性能调控分析为新一代NIR光源发展提供解决方案。”摘要：Near-infrared phosphor-converted light-emitting diodes （NIR pc-LEDs） are expected to be the next-generation NIR light sources， which have the advantages of small size， broad bandwidth， and easy tuning of emission peaks. The key for NIR pc-LEDs is to develop highly efficient broadband NIR phosphors that can be effectively excited by blue light. LiScSi2O6∶Cr3+can be excited by blue light and emits NIR light peaked at 845 nm with a broad bandwidth of 156 nm and an internal quantum efficiency of 64.4%. Herein， Sc3+ is replaced by M ions （M = Ga3+， Lu3+， Y3+， Gd3+） to regulate the NIR luminescence. The introduction of M ions is easy to form heterogeneous phases or undergo phase transformation， thus reducing the NIR luminescence of the titled material. The regulation processes are analyzed based on the crystal structure.关键词：LiScSi2O6∶Cr3+;cation substitution;crystal structure
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发布时间：2024-04-08 - 摘要：Na+/In3+/Ge4+ singly-doped or co-doped LiScSi2O6∶Cr3+ phosphors were prepared by high-temperature solid-state reaction. Light absorption and photoluminescence （PL） properties were studied by diffuse reflection spectrum， PL excitation/emission spectrum and quantum efficiency measurements. The results show that the absorption to the blue light at 460 nm can be enhanced for the LiScSi2O6∶Cr3+ phosphor by single ion substitution， such as Na+ for Li+， In3+ for Sc3+， and Ge4+ for Si4+. The absorption efficiency （AE） can be further increased by multisite cation substitution with Na+， In3+ and Ge4+， from an AE value of 50.5% for the LiScSi2O6∶Cr3+ phosphor to 60.9% for the Li0.8Na0.2Sc0.4In0.6Si1.6Ge0.4O6∶Cr3+ phosphor. The light absorption enhancement can be attributed to the increased distortion degree of Cr3+ coordination octahedron caused by single ion substitution or multisite cation substitution. The optimized LiSc0.4In0.6Si1.6Ge0.4O6∶Cr3+ phosphor exhibits a broadband near-infrared （NIR） emission peaking at ~860 nm， with a full width at half maximum （FWHM） of ~160 nm and an internal （external） quantum efficiency of 72.5% （41.8%）. The fabricated phosphor-converted LED （pc-LED） device shows a NIR output power of 63.1 mW and an energy conversion efficiency of 22.3% at 100 mA drive current. The study provides an effective approach to enhance the light absorption capacity of Cr3+-activated NIR phosphors.关键词：NIR phosphor;Cr3+ activated;multisite cation substitution;light absorption regulation
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发布时间：2024-04-08 - 摘要：In this paper， a novel Mg3Y2Ge3O12∶Pr3+ persistent luminescent material with multicolor luminescence was prepared by high temperature solid phase method. The properties of photo-luminescence （PL） and persistent luminescence （PersL） were studied by a series of characterization methods such as X-ray diffraction （XRD）， PL spectra， PersL spectra， PersL decay curves and thermoluminescence （TL） curves. The PL spectra exhibit two strong spikes emission at 485 nm and 609 nm under excitation of 283 nm， which can attributed to 3P2→3H4 and 3P0→3H6 energy transitions of Pr3+， respectively. By regulating the concentration of Pr3+， the relative emission intensity of green and red emission is effectively changed which achieving the multicolor PL. In addition， the material also exhibits multicolor PersL emission after the cessation of the activating light source， and the PersL decay time for the optimal sample （Mg3Y2Ge3O12∶0.015Pr3+） can last more than 1 200 s. Afterwards， we further investigated the distribution of the trap and the charge， discharge process of the PersL. The results indicate that the concentration of shallow trap in Mg3Y2Ge3O12∶Pr3+ is relatively low， which leads to weak PersL performance at room temperature. In addition， because the material has an ultra-wideband trap distribution in the high temperature region， we further explored its multi-color PersL performance at high temperatures. In summary， we have successfully prepared a PersL material with single ion activation which can adjust PL and PersL color. Considering its color change characteristics at both room temperature and high temperature conditions， the material has potential application value in the field of high temperature warning signs and anti-counterfeiting.关键词：persistent luminescent materials;Mg3Y2Ge3O12∶Pr3+;multicolor;anti-counterfeiting
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发布时间：2024-04-08 - 摘要：Y3Al5O12∶Ce3+ （YAG∶Ce） phosphor is the main luminous material for white light emitting diode（LED）or laser diode （LD） at present， but it has some drawbacks such as aging due to poor heat dissipation. In this paper， Y2MgAl4SiO12∶Ce3+（YMAS∶Ce）transparent ceramic fluorophores were prepared by simple pressureless sintering， which can replace traditional fluorescent powder and regulate luminescence performance. The precursor powder was prepared by chemical coprecipitation method and calcined at high temperature. Green body disks were formed by cold isostatic pressing using the sintered powder. Finally， transparent fluorescent ceramics were prepared by calcining the disks at 1 600 ℃ temperature in a muffle furnace. The effect of Ce3+ doping concentration and sample thickness on the properties of the material was studied. The sample doped 0.5% of Ce3+ possessed 56% transmittance at 800 nm， and its luminescence intensity at 450 K is still maintain 84% of that at room temperature. The device combined with the fluorescent ceramics can emit white light under the excitation of blue LEDs/LDs. The corresponding CIE chromaticity coordinates were （0.307 6， 0.332 9） and （0.308 0， 0.331 6）， and the luminous efficiency was 62.6 lm/W and 146.3 lm/W， respectively. The results show that YMAS∶Ce fluorescent ceramics can be applied to white LEDs/LDs.关键词：pressureless sintering;Y2MgAl4SiO12∶Ce;fluorescent ceramic;white LEDs/LDs
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发布时间：2024-04-08 - 摘要：This study explores the use of atomic layer deposition（ALD） technology for encapsulating and modifying the surface of K2SiF6∶Mn4+（KSFM） red phosphors for white light emitting diodes（LEDs），and its impact on the structural properties， luminescent characteristics， and stability in a humid and hot environment. The findings reveal that by employing ALD technology with trimethylaluminum as the precursor and ozone as the oxidant， an alumina coating can be formed on the surface of KSFM. X⁃ray diffraction and surface morphology analyses indicate that the ALD treatment process does not affect the crystal phase and morphology of the KSFM phosphors. Moreover， luminescence spectroscopy analysis demonstrates that the alumina coating， owing to its passivation properties， can enhance the luminescent intensity of KSFM phosphors without altering their emission wavelength. Furthermore， compared to uncoated KSFM phosphors， the coating layer can significantly enhance the damp⁃heat stability of KSFM powders. Following a 24⁃hour aging treatment in an 85% humidity/85 ℃ environment， samples coated with ALD maintain 84% of their initial luminescent intensity.关键词：K2SiF6∶Mn4+;red phosphor;surface modification;atomic layer deposition;damp⁃heat stability
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发布时间：2024-04-08 - 摘要：In order to develop efficient and stable single matrix white light emitting fluorescent materials， a series of La4GeO8∶Bi3+，Eu3+ phosphors were successfully synthesized by high-temperature solid-state method. The structural and luminescent properties of the experimental samples were studied by X-ray diffraction， room temperature spectra， and variable temperature spectra. It was found that Bi3+ ions occupy two different lattice positions （Bi3+（Ⅰ） and Bi3+（Ⅱ）） in this structure， and exhibit two broadband emission peaks at 475 nm and 620 nm under UV excitation， respectively. The tunable emission from blue to red and orange red to red can be achieved due to the competitive absorption process of Bi3+（Ⅰ） and Eu3+， energy transfer of Bi3+（Ⅰ） →Bi3+（Ⅱ） and Bi3+（Ⅱ） →Eu3+. Specially， excellent white light emission with CIE （0.335， 0.319） was obtained in sample of La4GeO8∶0.07Bi3+，0.06Eu3+ under 313 nm excitation. In addition， the white light emission sample presents excellent luminescent thermal stability （the integrated emission intensity at 380 K remains 59% of that at room temperature）， indicating that the material has potential application in white light-emitting diodes.关键词：La4GeO8∶Bi3+，Eu3+;tunable emission;luminescence thermal stability;white light emitting diodes
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发布时间：2024-04-08
Synthesis and Properties of Materials
- 摘要：Optical frequency comb （OFC） have great potential in the field of communication as an excellent multi-wavelength light source. By combining OFC light source with wavelength-division-multiplexing （WDM） and space-division-multiplexing （SDM） technologies， the communication system can have a transmission rate in the order of a hundred Tbit/s， which is valuable in 5G/6G communications， Internet of Things， autonomous driving and many other aspects. At present， there are mainly four methods to obtain OFC， which are femtosecond OFC based on mode-locked laser， OFC based on optical microcavity， OFC based on electric-optical modulator and OFC based on traveling wave four-wave mixing. All of them have their own characteristics， but all of them are hard to satisfy wide spectrum， high signal-to-noise ratio， high flatness， high single comb power and wide range adjustable of comb spacing at the same time， which affected the application of OFC in the field of optical communication in some extent. In this paper， we put forward to get seed comb from stimulated Brillouin laser cavity， compress the pluse by negative dispersion highly nonlinear fiber， and further on， widen the spectrum with dispersion-controlled fluorotellurite glass fiber， finally get OFC. The result of numerical simulation shows that， by using this system， we can obtin flat-top OFC with wide range adjustable comb spacing， spectral coverage the hole band form O-U， and the standard deviation of comb power in O-U band less than 5 dB， proved the feasibility of OFC generation based on system with stimulated Brillouin laser cavity and dispersion-controlled fluorotellurite glass fiber.关键词：optical frequency comb;dispersion-controlled fluorotellurite glass fiber;pulse compression;spectral broadening out of cavity;O-U band flat
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发布时间：2024-04-08 -
Microcavity Effect on Modulation Bandwidth Characteristics in Organic Light-emitting Diodes 增强出版 AI导读
摘要：Visible light communication （VLC） technology ingeniously integrates communication and illumination or display， providing an efficient and convenient solution for communication. Organic light-emitting diodes （OLEDs）， serving as an artificial light source closest to natural sunlight， exhibit tremendous application potential at the transmitter end of VLC systems. However， constrained by the slow radiative recombination rate of organic luminescent dyes， OLEDs always demonstrate a sluggish response speed under high-frequency signal excitation. To overcome this limitation， we propose the utilization of a microcavity structure with the aim of enhancing the spontaneous emission rate of organic emitters through the microcavity effect， thereby improving the device's frequency response. Research results indicate that the Purcell effect induced by an optical microcavity with a specific cavity length can elevate the photon density at the emitter position， accelerating its spontaneous emission rate. This enhancement successfully increases the modulation bandwidth from 4 kHz to 7 kHz， expanding the response frequency range by nearly 75%.关键词：organic light-emitting device;microcavity;spontaneous emission rate;visible light communication;modulation bandwidth- 303
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发布时间：2024-04-08 - 摘要：Ga2O3 thin films were deposited on p-GaAs（100） substrates by metal-organic chemical vapor deposition（MOCVD） process for the preparation of n-Ga2O3/p-GaAs heterojunction solar-blind UV photodetectors（PDs）.The surface morphology and crystal quality of Ga2O3 thin films were measured and analyzed by X-ray diffractometer， atomic force microscope， and field emission scanning electron microscope. The results showed that the Ga2O3 thin films exhibited a single crystal orientation， with a flat surface and Volmer-Weber mode epitaxy. The characterization indicated that the n-Ga2O3/p-GaAs heterojunction detector exhibited an obvious rectification characteristic. The device achieves a photo-dark current ratio of more than 3.0 × 104， a responsivity of 7.0 A/W， an external quantum efficiency of 3412%， and a detectivity of 4.6 × 1013 Jones under 5 V reverse bias and UV（254 nm） illumination. The device structure was simulated using TCAD software， obtaining the electric field distribution and band structure inside the device， and the working principle of the device was analyzed. The performance of the heterojunction detector was excellent and the manufacturing process was simple， providing a new avenue for the development of Ga2O3 ultrasensitive solar-blind UV photodetectors.关键词：Ga2O3;metal⁃organic chemical vapor deposition（MOCVD）;heterojunction;solar⁃blind UV photodetectors
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发布时间：2024-04-08 - 摘要：The photonic crystal surface-emitting laser（PCSEL） achieves surface-emitting laser operation by utilizing the Bragg resonance of a two-dimensional photonic crystal grating. It possesses unique advantages， including single-mode performance， on-wafer testing， high power output， and low divergence angles. Compared to vertical-cavity surface-emitting lasers（VCSELs）， PCSELs have nearly double the active region confinement factor， showcasing their potential for high-speed operation. This paper explores the fundamental structure and working principles of PCSEL and provides a detailed analysis of the key factors influencing the achievement of high-speed performance in PCSEL lasers. Subsequently， the article systematically introduces the efforts made by researchers in recent years to achieve high-speed performance in PCSEL， with a particular focus on enhancing in-plane confinement in PCSELs. Relevant research directions and guidance are also provided.关键词：photonic crystal;high-speed;surface-emitting laser
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发布时间：2024-04-08 - 摘要：Nowadays， there is a growing interest in studying coupled cavity structures in vertical-cavity surface-emitting lasers（VCSEL）. These structures achieve a bandwidth enhance by adding a modulated current to the main cavity and a direct current to each feedback cavity. However， the impact on device performance when the main cavity is driven separately has not been thoroughly investigated. To gain a more comprehensive understanding of coupled cavity lasers， we designed and fabricated a square transverse-coupled-cavity VCSEL（TCC-VCSEL） with a side length of 30 μm×30 μm and investigated the variation of the device performance when the main cavity is driven separately. At room temperature， the -3 dB bandwidth was up to 30.1 GHz， under non-return-to-zero（NRZ） modulation， clear eye diagrams were obtained at a back-to-back transmission rate of 40 Gbit/s， and relative intensity noise （RIN） was -160 dB/Hz. It has been proven that a feedback cavity can have a positive impact on the characteristics of the main cavity， even without driving conditions. The TCC-VCSEL device only requires one power supply， making it highly practical for high-density integration and providing new ideas for package integration applications.关键词：vertical-cavity surface-emitting lasers（VCSEL）;transverse coupled cavity;high-speed
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发布时间：2024-04-08 - 摘要：A 808 nm semiconductor laser was applied to a mode-selected and beam waist splitting polarization combining external cavity. A laser with high beam quality high brightness and narrow-linewidth was obtained. The beam quality of the fast and slow axes of the obtained laser was M2=1.85×18.2， the slow axis beam quality was improved by 48%. The output power and brightness of the laser was 5.08 W and B=22.74 MW·cm-2·sr-1 respectively. The brightness was 1.3 times that of the laser under free running. The spectral linewidth of obtained laser was 0.47 nm， 0.14 times compressed to the same laser.关键词：semiconductor laser;beam combining;external cavity
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发布时间：2024-04-08
Device Fabrication and Physics
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Laser Welding and Packaging Technology of Three-dimensional Direct Plated Copper Ceramic Substrate 增强出版 AI导读
摘要：Hermetic sealing is a crucial packaging method that promotes the high reliability development of electronic devices. Traditional hermetic packaging technologies have some problems， such as high welding temperatures and thermal shock and limited application ranges， which cannot meet requirements for hermetic packaging of three-dimensional direct plated copper ceramic substrate （3-D DPC）. In this study， combining with the technical advantages of pulsed laser welding， we investigated the achievement of hermetic packaging of 3-D DPC using pulsed laser welding. The interaction mode between pulsed laser and materials during the welding process was discussed， and the interface microstructure， hermeticity， and mechanical properties of the welding samples were analyzed. The research indicates that the formation of cracks in welded metal area is closely related to the diffusion of copper from the base metal to the Kovar side. The heat conduction mode and transition mode with stable welding process and low depth of fusion can avoid the formation of welding cracks. The welding process parameters were optimized through experiments. At a peak laser power of 120 W， a pulse width of 1 ms， and an overlap rate of 80%， the three-dimensional ceramic substrate cavity packaging structure achieved the optimal high hermeticity， with a leakage rate of 5.2×10-10 Pa·m3/s and a joint shear strength of 278.06 MPa， meeting the requirements for high-reliability hermetic packaging of third-generation semiconductor devices.关键词：pulsed laser;welding mode;hermetic packaging;three-dimensional direct plated copper ceramic substrate （3-D DPC）- 211
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发布时间：2024-04-08 - 摘要：The primary packaging of high-power white LEDs （WLEDs） is divided into phosphor-in-glass （PiG） package and phosphor-in-silicone （PiS） package. We proposed a PiS packaging method to optimize the uniformity of the light-emitting surface of high-power WLEDs， and analyze the photothermal performance. The experimental results show that the luminous flux of the WLED packaged by PiS is 576.07 lm at 1 400 mA， which is 15.5% higher than that of the WLED packaged by PiG. During the process of temperature increase from 25 ℃ to 125 ℃， the luminance of the PiS packaged device decreased by 20%， and the color temperature increased from 5 882.11 K to 6 024.22 K. The thermal resistance of the PiS package is 1.7 K/W at 25 ℃， which is close to that of the PiG package. The relative light intensity of PiS package remains stable at 97% during 840 h of high temperature and high humidity aging and 1 600 h of high temperature aging test.关键词：high power WLEDs;PiG;PiS;Photothermal performance;thermal performance
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发布时间：2024-04-08
Luminescence Industry and Technology Frontier
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