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Latest Issue
Issue 5 ， 2022
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Optimal Doping Content of Red Emitting Y4GeO8∶Bi3+,Eu3+ Phosphor Designed by Response Surface Methodology Enhanced Publication
Abstract：Herein, a more direct method, response surface methodology, is used to predict the strongest red emission of Y4GeO8∶Bi3+,Eu3+ samples. The concentrations of Bi3+ and Eu3+ of the optimal sample were predicted to be 31.03% and 67.36%(in mole ratio), respectively. The optimal sample was prepared and photoluminescent properties were measured and characterized. Y4GeO8∶31.03%Bi3+,67.36%Eu3+ has strongest red emission. The difference between the intensity of experimental value and theoretical value is very small. The color coordinate of the as-prepared sample is (0.645 7, 0.349 0), which is very close to the color coordinate of standard red light (0.670 0, 0.330 0). The luminous color of the sample is pure, and the calculated color purity reaches 98%. What’s more, the internal quantum efficiency of the sample is as high as 72.5%. In a word, this paper provides an approach for searching the optimal doping concentration of phosphors with the strongest luminescence directly, which can be used in exploring all types of co-doped phosphors.Keywords：Y4GeO8∶Bi3+,Eu3+ phosphors;response surface methodology;luminescent intensity- 975
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Published：2022-05-23
Cover Story
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Research Progress of Stimuli-responsive AIE-active Hydrogels Enhanced Publication
Abstract：Stimulus-responsive hydrogels, which can undergo physical and/or chemical changes in response to the minor variations in the environment, are widely applied in the fields of drug delivery, bioseparation, biosensors and tissue engineering. However, due to the aggregation-caused quenching(ACQ) of fluorescence, their applications in luminescence-related fields are extremely limited. Fortunately, aggregation-induced emission(AIE) phenomena perfectly resolved the problem. By incorporating fluorophores with AIE feature into hydrogels, stimuli-responsive AIE-active hydrogels can be obtained. And they have cut a figure in several high-tech fields including biomedical, information anti-counterfeiting, 3D hydrogel actuators and soft robots. In this article, we summarized and classified the recently reported stimuli-responsive AIE-active hydrogels into three categories: those are responsive to physical(temperature and light), chemical(pH, solvent and ion type) and biological(enzyme) stimulus. The preparation, responsive mechanism and applications of these stimuli-responsive AIE-active hydrogels were described respectively. And finally, the problems and challenges faced by stimuli-responsive AIE-active hydrogels are also prospected.Keywords：stimuli-responsive hydrogels;aggregation-induced emission;information anti-counterfeiting;soft robots;drug delivery- 780
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Published：2022-05-23 -
Available Manganese-containing Chemicals and Synthesis Methods for Mn4+-activated Phosphors Enhanced Publication
Abstract：The Mn4+ activated phosphors can emit wavelength-tunable red luminescence under blue light excitation, which is one of the hotspots in the field of red phosphor for white light-emitting diodes. There are several manganese-containing chemicals that were used as manganese source, including K2MnF6, KMnO4, Mn(HPO4)2, MnCO3, MnO2, MnO, Mn(NO3)2, and Mn(CH3COO)2. This mini-review summarized the types of these chemicals that have been chosen in literatures as the manganese source for the synthesis of Mn4+-doped fluoride, oxyfluoride, and oxide phosphors via different synthesis methods. The influences of choosing different manganese sources and synthesis methods on the photoluminescence properties(for example, the quantum efficiency) of the as-prepared phosphors were summarized. Finally, the methods for controlling the valence state of manganese ions in the as-synthesized phosphors were prospected.Keywords：phosphor;manganese ion;manganese-containing chemical- 790
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Published：2022-05-23
Invited Review
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Single-phase White Light-emitting Phosphor Cs2Li3Sr2B3(PO4)6∶Dy3+ with Excellent Thermal Stability Enhanced Publication
Abstract：In this paper, a series of single-phase white light-emitting Cs2Li3Sr2B3(PO4)6∶Dy3+ phosphor were synthesized by high-temperature solid-phase method. Their structure characteristics, photoluminescence excitation and emission spectra, lifetime and temperature-dependent emission spectra have been discussed. The results show that the emission peaks of the sample are mainly located at 490 nm and 577 nm, and can produce uniform white light under the excitation of near-ultraviolet light/ultraviolet light. The concentration quenching mechanism has been investigated and demonstrated to be a dipole-dipole interaction. The thermal stability based on the temperature-dependent PL spectra of Cs2Li3Sr2B3(PO4)6∶Dy3+ demonstrated that this phosphor showed superior thermal behavior. Cs2Li3Sr2B3(PO4)6∶Dy3+ is a potential single white light-emitting material with excellent thermal stability.Keywords：single-phase;Dy3+;white light-emitting;phosphor- 224
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Published：2022-05-23 -
Temperature Sensing Properties in NaScF4∶Yb3+/Er3+ Nanoparticles Enhanced Publication
Abstract：In this paper, NaScF4∶20%Yb3+/2%Er3+ nanoparticles(NPs) with a size of about 35 nm are prepared by a solvothermal process. Under the excitation of 980 nm wavelength, the NPs exhibit strong red upconversion(UC) emission and weak green UC emission. The corresponding intensity ratio of red emission to green emission is approximately 6. Meanwhile, the green and near-infrared(NIR) emission of the UCNPs own excellent temperature sensing performances within the studied temperature range, which can be used for optical thermometry based on fluorescence intensity ratio(FIR) technology. The maximums of relative sensitivity SR for thermally coupled 2H11/2 level and 4S3/2 level of Er3+ and non-thermally coupled Yb3+ 2F5/2 level and Er3+ 4I13/2 level are 1.17%·K-1 and 0.73%·K-1, respectively. The results show that the UCNPs are a kind of high efficient red UC material and show promising temperature sensing performances in visible and NIR region.Keywords：rare earth;nano particles;upconversion;optical thermometry;NaScF4- 244
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Photoluminescence Properties and Energy Transfer of Sn2+-Mn2+ Co-doped Gd2O3-Al2O3-SiO2 Glass Enhanced Publication
Abstract：The Sn2+-Mn2+ co-doped Gd2O3-Al2O3-SiO2(GAS∶0.5Sn2+,yMn2+) glass was prepared by traditional high temperature melt-quenching technology. The photoluminescence properties of the glass and the energy transfer process of Sn2+-Mn2+ were studied. Under 365 nm excitation wavelength, with the increase of Mn2+content(1.0%, 1.5%, 2.0%, 2.5%, 3.0%, 3.5%, 4.0%), the emission intensity of the Sn2+ center gradually decreases, and the emission intensity of the Mn2+ center gradually increases. Moreover, the decay time of the Sn2+center decreases with the increase of Mn2+ content, indicating that energy transfer from Sn2+ to Mn2+ ions occurs in the glass. The photoluminescence quantum yield(PLQY) decreases with the increase of Mn2+ content, the maximum of PLQY of GAS∶0.5Sn2+,yMn2+ glass is 25.48%. When the Mn2+ ions concentration reaches 4.0%, the chromatic coordinate of the glass is (0.323, 0.273), which is close to the standard white light emission. In addition, the thermal quenching behavior of Sn2+-Mn2+ co-doped glass was also studied. The thermal activation energy required to overcome the electronic transition of the Sn2+ emission center is approximately 0.23 eV.Keywords：Aluminum-silicate glass;Sn2+-Mn2+ co-doped;energy transfer;white light emission- 222
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Synthesis and Properties of Electron Transport Materials Based on Imidazo [1,2-a] pyridine-triazine Enhanced Publication
Abstract：The development of electron transport materials is crucial for reducing the driving voltage of organic light emitting diodes(OLEDs). Two novel electron-transporting materials based on imidazo [1,2-a] pyridine-triazine were designed and synthesized, namely 2-(3'-(4-([1,1'-biphenyl] -4-yl)-6-phenyl-1,3,5-triazin-2-yl)-5'-phenanthrene-9-yl)- [1,1'-biph-enyl] -4-yl)-3-Phenyli midazo [1,2-a] pyridine(TRZ-PA-Dp) and 2-(5″-(4-([1,1'-biphenyl] -4-yl)-6-Phenyl-1,3,5-triazine-yl)- [1,1'∶2',1″∶3″,1‴-tetraphenyl] -4‴ -yl)-3-phenyli-midazo [1,2-a] pyridine(TRZ-PP-Dp), and their structures were characterized by NMR and mass spectrometry. The single-electron device results of compounds TRZ-PA-Dp and TRZ-PP-Dp show high electron mobility, which can effectively reduce the driving voltage of blue and green devices. Using these two materials as electron transport materials, the turn-on voltages of blue-light devices were 3.2 V and 3.1 V, compared with the devices using conventional electron transport material TPBi, the turn-on voltages were reduced by 0.1 V and 0.2 V, respectively. The turn-on voltages of green devices are both 2.2 V, which are 0.2 V lower than that of TPBi. The turn-on voltages of red devices are similar to that of TPBi device. Moreover, the devices based on the two materials in this paper show good efficiency, especially in the green phosphorescent device with the matrix complex as the host. Compared with the device of TPBi, the life time is increased by 4 times, and the current efficiency(CE) and external quantum efficiency(EQE) are increased by about 5% at 100 cd/m2. In particular, the power efficiency(PE) increased by more than 28%, proving that TRZ-PA-DP and TRZ-PP-DP are excellent electron transport materials.Keywords：imidazo [1,2-a] pyridine;triazine;electron transport material;drive voltage;efficiency- 197
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Published：2022-05-23 -
Water-driven Photoluminescence Reversibility in CdSe/CdS Quantum Dots Polymer Composite Enhanced Publication
Abstract：Quantum dots are a promising star material in the field of new optoelectronic devices due to their excellent optical and electrical properties. In this work, we prepare the CdSe/CdS@PDMS-PUa composite by encapsulating core/shell CdSe/CdS quantum dots into an amino-terminated polydimethylsiloxane(PDMS-PUa) polymer matrix, which shows water-driven enhanced photoluminescence(PL) intensity and photoluminescence quantum yield(PLQY). After the analysis of fluorescent decay curve and diffuse reflectance spectrum, the reason for this enhancement is found to be the passivation of the surface defects of the quantum dots by H3O+ and OH- in water, making the unit cell of the quantum dots more idealized. However, when the composite is taken out of the water for drying, the defect states are exposed again, and both PL and PLQY return to their original values. Inspired by the water-driven PL reversibility in CdSe/CdS@PDMS-PUa composite, a liquid height sensor with fluorescence response is proposed based on the CdSe/CdS@PDMS-PUa composite, which can judge the liquid height value in the container through the change of fluorescence intensity. These findings not only reveal the reversible characteristics of CdSe/CdS quantum dots, but also broaden the application of quantum dots polymer composites in the field of optoelectronics, which has important scientific significance and application prospects.Keywords：CdSe/CdS quantum dots;polymer;water;photoluminescence reversibility;sensing- 170
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Published：2022-05-23 -
A Simple Method to Enhance Performance of Inverted Planar Perovskite Solar Cells by Using PEDOT∶PSS Doped with DMSO as Hole Transport Layer Enhanced Publication
Abstract：In this work, the photovoltaic properties of inverted planar perovskite solar cells are promoted via a simple method by adding Dimethyl sulfoxide(DMSO) into Poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate)(PEDOT∶PSS) hole transport layer. Compared to the control device based on pristine PEDOT∶PSS, the device with DMSO doping shows different enhancement in short circuit current(Jsc), fill factor(FF) and power conversion efficiency(PCE), respectively. The Jsc is increased from 21.29 mA/cm2 to 22.15 mA/cm2, the FF is increased from 76.35% to 80.09%, and the PCE is increased from 16.02% to 17.01%, showing 4%, 5% and 6% enhancement, respectively. A combination of characterizations has been utilized to systematically investigated the effect of DMSO doping on properties of PEDOT∶PSS and perovskite film. It can be found that the incorporation of DMSO leads to a moderate phase separation of PEDOT∶PSS, which causes the PEDOT component to form a better conductive channels, enhancing the conductivity and hole transport ability of PEDOT∶PSS. The steady-state photoluminescence spectra exhibit significant fluorescence quenching, indicating promoted hole extraction ability of PEDOT∶PSS after doping with DMSO. Thus, a more efficient hole transfer between the perovskite active layer and the anode is achieved, which contributes to the high fill factor above 80%. So that an effective and easy approach to improve the photovoltaic performance of inverted planar perovskite solar cells or organic solar cells is provided.Keywords：Hole transport layer;conductivity;perovskite solar cell;photovoltaic performance- 146
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Published：2022-05-23
Synthesis and Properties of Materials
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Research Progress of High-speed 1 550 nm Vertical Cavity Surface Emitting Laser Enhanced Publication
Abstract：Vertical cavity surface emitting laser(VCSEL) has the advantages of low production cost and high modulation rate, and plays an important role in the field of optical communication. With the rapid growth of data demand, the 1 550 nm wavelength VCSEL with low loss has aroused the interest of researchers in long-distance information transmission. In this paper, the structure of 1 550 nm VCSEL is introduced firstly, the bandwidth limitation factors and corresponding improvement methods are then discussed, and then the research progress of high-speed 1 550 nm VCSEL in recent years is reviewed from the aspects of NRZ(Non-zero) modulation and PAM4(Four-level pulse amplitude) modulation. Finally the development and application of high-speed 1 550 nm VCSEL in the field of optical communication in the future are prospected.Keywords：1 550 nm;high-speed vertical cavity surface emitting laser(VCSEL);non-return to zero modulation(NRZ);four-level pulse amplitude modulation(PAM4)- 404
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Research Progress of Fast Response 2D Material Photodetectors with Metal-semiconductor-metal Structure Enhanced Publication
Abstract：Fast response photodetectors are widely used in optical communication, high-speed photography, biomedical imaging and other fields. Most of the fast response photodetectors used in the market are based on traditional inorganic semiconductor materials such as silicon and gallium arsenide, but their fabrication process is complex, the cost is high, and the mechanical flexibility is poor. Two-dimensional materials, such as graphene and molybdenum disulfide, due to their unique layered structure and good optical, electrical, thermal and mechanical properties, are ideal materials for fabricating photodetectors. In particular, two-dimensional materials with ultra-high carrier mobilities are very suitable for developing fast response photodetectors. In recent years, a series of metal-semiconductor-metal photodetectors(MSM-PDs) based on two-dimensional materials have been reported, and their response time is often less than 1 μs. In this paper, rapid response two-dimensional materials based MSM-PDs are reviewed. Firstly, the basic structure and working principle of MSM-PDs are introduced, and the main factors that determine the response speed of MSM-PD are given. Then, the molecular structure, optical and electrical properties of graphene, transition metal sulfide, black phosphorus, two-dimensional perovskite and other two-dimensional materials are introduced. After that, research progress of Ohmic-contact type, Schottky-contact type and surface plasmon polarization enhanced MSM-PDs with the response time less than 1 μs is given. Finally, we summarize the full text, and prospect the application and development trend of two-dimensional materials in rapid response photodetectors.Keywords：photodetectors;fast response;two-dimensional materials;graphene;transition metal sulfide;black phosphorus;two-dimensional perovskites;metal-semiconductor-metal- 285
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High-efficiency Blue Phosphorescent OLEDs Based on Mixed-host Structure by Solution-processed Method Enhanced Publication
Abstract：Blue phosphorescent organic light-emitting diodes(PHOLEDs) which utilized TcTa and CzSi as the mixed-host were fabricated to improve the efficiency by solution-processed method. Additionally, three electron transport materials Tm3PyP26PyB, TmPyPB and TPBi were employed to further enhance the efficiency of devices. The efficiency was improved by optimizing the ratio of host materials and the selection of electron transport material. Finally, the optimal device with the doping ratio TcTa∶CzSi of 6∶1 and 70 nm TPBi layer exhibited the maximum brightness(Bmax), current efficiency(CEmax), power efficiency(PEmax) and external quantum efficiency(EQEmax) of 6 662 cd·m-2, 39.40 cd·A-1, 23.33 lm·W-1 and 19.7%, respectively. Moreover, outstanding current efficiency and external quantum efficiency as high as 33.43 cd·A-1 and 16.7%, respectively, were obtained, even at the practical brightness of 1 000 cd·m-2.Keywords：organic light-emitting diodes;high efficiency;solution-processed;mixed-host structure;blue emission- 172
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Effect of Al Composition of Electron Blocking Layer on Photoelectric Performance of GaN-based Blue Laser Diode Enhanced Publication
Abstract：The influence of Al composition-graded of AlxInyGa1-x-yN electron blocking layer(EBL) on the photoelectric performance of GaN-based laser diode was numerically investigated using SiLENSe(Simulator of light emitters based on nitride semiconductors) software to achieve high output power and high conversion efficiency. The four Al composition graded modes in this paper are traditional uniform composition, right step-graded composition(0-0.07-0.16), triangle-graded composition(0-0.16-0), and left-step graded composition(0.16-0.07-0) respectively. Comparing with the traditional homogeneous composition EBL, it was found that Al composition step-graded EBL not only could significantly enhance band offset of conduction band result in reducing the electron leakage, but also could decrease band offset of valence band in order to improve holes injection efficiency and enhance radiative recombination efficiency. This is mainly due to the fact that Al step-graded composition structure could effectively restrain the electron leakage to the p-side and improve holes injection efficiency, so as to increase the carrier concentration and radiation recombination in the active zone. The Al step-graded composition EBL could effectively reduce opening voltage from 5.1 V to 4.9 V and decrease optical loss from 3.4 cm-1 to 3.29 cm-1, thus the output power was increased from 335 mW to 352 mW and the conversion efficiency was increased from 12.5% to 13.4% respectively at the current density of 6 kA/cm2. In addition, the influence mechanism of Al step-graded composition EBL on the photoelectric performances of GaN-based laser diode was discussed. This structure will provide experimental data and theoretical support for the epitaxial growth of high-power GaN-based laser diode.Keywords：GaN-based blue laser diodes;electron blocking layer;Al composition;photoelectric performance- 161
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Low Temperature 808 nm High Efficiency Semiconductor Laser Enhanced Publication
Abstract：In order to improve the performance of 808 nm semiconductor laser operating at low temperature, the temperature dependence of electro-optical conversion efficiency was studied. Combining the suppression of carrier leakage and the optimization of the series resistance, the carrier confinement phenomenon in the quantum well was analyzed theoretically. Moreover, the potential barrier height and the corresponding quantum well structure for low temperature operating were proposed, including the optimization of important parameters such as the material composition and thickness of the barrier layer, which showed significant benefit for operation under low temperature. Basing on the optimized epitaxial structure, semiconductor laser bars with a cavity length of 2 mm were fabricated. Under the temperature of -50 ℃, an electro-optical conversion efficiency of 71% was demonstrated with a slope efficiency of 1.34 W/A and an injection current of 600 A. Record high electro-optical conversion efficiency of 73.5% was reached with the injection current of 400 A, while the carrier confinement efficiency was as high as 99%, and the series resistance was as low as 0.43 mΩ. In the temperature range of -60-60 ℃, the shift coefficient of the center wavelength with temperature was about 0.248 nm/℃.Keywords：semiconductor laser;carrier leakage;low temperature;high efficiency;temperature effects- 186
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Published：2022-05-23
Device Fabrication and Physics
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Progress of Zinc Sulfide Electroluminescent Materials in Intelligent Wearable Field Enhanced Publication
Abstract：In recent years, with the rapid development of flexible electronics industry, as an indispensable part of wearable integrated devices, light-emitting display has been put forward additional requirements such as flexibility, stretchability and self-healing. Electroluminescent devices based on zinc sulfide materials have received extensive research and attention in the field of intelligent wearables due to their advantages of long life and simple structure of luminescent components. In this paper, the research progress of zinc sulfide electroluminescent materials in the field of smart wearables is summarized, and the luminescence mechanism, research hotspots and future applications of zinc sulfide electroluminescent materials are mainly introduced, in order to play a beneficial enlightenment and guidance role in the field of smart wearables.Keywords：electroluminescence;flexibility;Extensibility;Smart Wearables- 383
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Published：2022-05-23
Luminescence Industry and Technology Frontier
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