最新刊期
卷 42 ， 期 5 ， 2021
- 摘要：Metal halide perovskite materials are widely used as luminescent materials to prepare perovskite light-emitting diodes(PeLEDs) due to their outstanding optical properties such as high photoluminescence quantum yield, high color purity, and adjustable band gap. Although good research progress has been made, its large-scale preparation for commercialization is still very slow, and further efforts are needed. In order to realize the large-area preparation of perovskite thin film light-emitting diodes, this paper uses inkjet printing technology to study the influence of different substrate structures on the spreading and crystallization of the perovskite precursor liquid and the comparison of device performance. Then a kind of inorganic small molecule material lithium fluoride(LiF) with hole blocking ability was introduced as a buffer layer and deposited on TFB to obtain a pixelated and evenly distributed perovskite film, so that the highest brightness with uniform light emission was obtained. And we get a printed perovskite light-emitting diode with 4 861cd/m2 and a maximum current efficiency of 5.41 cd/A. The studies showed that the LiF buffer layer has a certain blocking effect on the injection of holes, and effectively prevents the exciton quenching caused by the contact between the perovskite luminescent layer and the TFB after plasma treatment.关键词：inkjet printing;Perovskite light-emitting diodes;electroluminescence;Substrate modification
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发布时间：2021-05-20
Cover Story
- 摘要：Although the research of perovskite materials in the fields of luminescence and optoelectronic devices has developed rapidly, there are still some key issues, such as how to break through the limit efficiency, improve stability and expand new applications. In recent years, the author of this article has made unique explorations in rare-earth doping and hybridization of organic heterojunctions around the theme of how to expand the spectral response range of perovskite materials and devices, and has achieved some iconic results. The author recently accepted a special interview with Light: Science & Applications. This article is sorted out on this basis, hoping to share some experience and opinions with you.关键词：perovskite;rare earth ions;spectra control;solar cell;photodiode;photodetector
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发布时间：2021-05-20
Expert Perspectives
- 摘要：As the fourth-generation lighting source, solid-state lighting has developed rapidly in the past 30 years due to its advantages of high efficiency and environmental protection. It is widely used in various scenes such as automobile headlights, projection displays, industrial production, and long-distance lighting. High-power, high-brightness white light-emitting diodes(W-LED) and laser lighting technology put forward new requirements for the service stability of color conversion materials. Phosphor ceramics have emerged with their unique advantages of withstanding high power excitation density. This article comprehensively reviews the latest research progress of phosphor ceramics for solid-state lighting/display, clarifies the evaluation criteria of light sources, summarizes the development and application of white light and several monochromatic fluorescent ceramics in high-power lighting and projection displays. The improvement strategies of light extraction efficiency, color rendering index(CRI) and correlated color temperature(CCT) in phosphor ceramics are described. And the problems of luminous saturation and light uniformity in laser illumination are discussed. Finally, the prospects and challenges of fluorescent ceramics in solid-state lighting/display applications are envisioned.关键词：color conversion;phosphor ceramics;high luminous efficiency;high luminous quality
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发布时间：2021-05-20
Invited Review
- 摘要：Cesium lead halide(CsPbX3, X=Cl, Br, I) perovskite quantum dots have attracted wide attention of researchers due to their excellent photoelectric properties such as adjustable emission spectra, high color purity and high quantum efficiency. Poor water stability, thermal stability, and light stability greatly limit its application in optoelectronic devices. At present, an effective way to improve the stability of cesium lead halide perovskite quantum dots is adding CsX and PbX2 to the glass ceramic matrix. As long as the energy provided by the outside can overcome the energy barriers of nucleation and crystal growth, cesium lead halide perovskite quantum dots will be precipitated from glass. This paper focuses on four inducing factors for the precipitation of cesium lead halide perovskite quantum dots from glass, namely heat treatment, laser, stress and water. Finally, this paper analyzes the advantages and disadvantages of each inducing factor, and puts forward the suitable glass ceramics and some suggestions for each inducing factor.关键词：perovskite quantum dot;glass ceramics;inducing factor;photoluminescence
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发布时间：2021-05-20 - 摘要：Ag-In-Zn-S quaternary semiconductor nanocrystals(AIZS NCs) not only have the excellent luminescent proeprties including the tunable optical band gap and high photoluminescence quantum yield and so on, but also possess low toxicity and simple synthesis technique. These NCs were widely used in the fields of light-emitting diodes, biomedicine, photoelectric conversion devices and so on, which was regarded as one of the substitutes for cadmium-based nanomaterials. In this paper, highly luminescent Ag-In-Zn-S NCs were synthesized by one-step reaction method, and the emission region was tuned effectively by varying the element ratios, which led to the emission color from green to red. On the basis of the reaction, the formation mechanism of AIZS NCs was studied through a hot-injection method, indicating that the partial cation exchange dominated the formation of AIZS NCs. In order to further optimize the luminescence performance, the alloyed AIZS-ZnS NCs were obtained by further incorporation of Zn source into AIZS NCs through a seeded-mediated growth method, which exhibited a high photoluminescent quantum yield of 47%. Finally, red, yellow and green electroluminescent light-emitting diodes were fabricated by using AIZS-ZnS NCs as the emissive layer, and the yellow device exhibited a current efficiency of 1.07 cd·A-1.关键词：Ag-In-Zn-S;Semiconductor nanocrystals;Controllable synthesis;Component tunable;Electroluminescent light-emitting didoes
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发布时间：2021-05-20 - 摘要：Undoped and Si-doped gallium arsenide(GaAs) nanowires(NWs) were carried out on Si(111) substrates by molecular beam epitaxy(MBE). The one-dimensional properties of the nanowires were confirmed by scanning electron microscopy(SEM).The presence of Si in doped GaAs NWs was confirmed by X-ray diffraction(XRD) and Raman spectroscopy. The luminescence source of undoped and Si doped GaAs NWs was studied by photoluminescence(PL). The PL results showed that doping changed the radiation recombination mechanism of GaAs NWs. Compared with undoped NWs, the doping results that in the free exciton emission peak and the defect-related emission peak of wurtzite and zinc blende mixed structure disappear simultaneously.关键词：spectroscopy;GaAs nanowires;Si doping;photoluminescence;MBE
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发布时间：2021-05-20 - 摘要：As a new generation of green solid-state lighting source, white light-emitting diode(LED) devices not only have been widely used in lighting, liquid crystal display(LCD) backlighting and other fields, but also are related to intelligent lighting, the Internet of Things technology and other high-tech industries. White light devices consisting of yellow emitting YAG∶Ce3+ (Y3Al5O12∶Ce3+) phosphors and blue chip are commonly used but lacking the components of red spectrum, resulting in the device's narrow spectrum, low color rendering index(CRI) and high correlated color temperature(CCT). Therefore, red phosphors play an important role in improving the color quality of white LED. Herein, red carbon dots with 28% quantum yield(QY) are synthesized and then combined with cellulose to form red phosphors(QY≈18%). Red phosphors are mixed with commercial YAG∶Ce3+ (Y3Al5O12∶Ce3+) to obtain warm white LED. Compared to the LED encapsulated with YAG∶Ce3+ phosphors, the CIE color coordinate of the LED which is encapsulated with YAG∶Ce3+ phosphors and red phosphors changes from (0.30, 033) to (0.33, 0.35), the CCT declines from 7 396 K to 5 714 K and the CRI raises from 78.2 to 82.9 under the excitation of 460 nm emitting blue chip. It achieves that cold white light-emitting diodes(WLED) with high CCT and low CRI were adjusted to warm WLED with low CCT and high CRI.关键词：Red Carbon Dots;Cellulose;Warm White Light-Emitting Diodes;Lighting
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发布时间：2021-05-20 - 摘要：A series of SrGe4-xO9∶xMn4+(SGOM) phosphors were prepared at 1 100 ℃ by traditional solid-state method. The crystal structure, luminescent properties and temperature-dependent of SGOM were investigated. Local structure of SrGe4O9(SGO) was modulated by the introducing of Ba2+ ions. The results of XRD showed that both Mn4+ and Ba2+ ions were successfully doped into the SGO, and no other impurity phase was detected. Fluorescent measurement indicates that SGOM phosphors produce red emission(600~750 nm) upon UV(275 nm) light excitation, which can be attributed to2Eg→4A2g of Mn4+. The optimal Mn4+ concentration in these phosphors equals 0.015. The emission spectra of SrGe3.985O9∶0.015Mn4+ was tuned by the introducing of Ba2+ ions. The luminescent intensity of SGOM was improved up to 50% when the Ba2+ doping concentration is 0.4, and an emission spectra broadening was also observed. This phenomenon is thought to be originated from the expanding of the local structure of Sr1O10 polyhedron caused by the Ba2+ doping. The phosphor-in-glass(PiG) technique was used to explore the properties of SGOM phosphor to overcome the decomposing issue of the organic materials. These phosphors exhibit potential application in WLED.关键词：crystal structure;SGOM phosphors;Ba2+ modulated;phosphor in glass
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发布时间：2021-05-20
Synthesis and Properties of Materials
- 摘要：Perovskite quantum dots(QDS) are attracting materials for realizing new efficient light-emitting diode(LED) due to their merits such as high photoluminescence quantum yield, adjustable luminous spectrum, narrow spectral width, high defect tolerance and unique quantum confined effect. This paper introduces the latest progress in the research of perovskite-based quantum dot light-emitting diodes in recent years. Firstly, the unique crystal structure of perovskite quantum dot and the working principle of perovskite light-emitting device are introduced. Secondly, the method of synthesizing high photoluminescence quantum yield(PLQY) quantum dot and several methods of improving the LED efficiency of perovskite quantum dot are described. Finally, we analyzed the challenges faced by perovskite QDS such as instability, toxicity and the prospects for developing efficient LED for applications in display and lighting. This review is expected to provide helpful insights for promoting the efficiency and safety of QDS.关键词：quantum dots;perovskite led;photoluminescence quantum yield;external quantum efficiency;current efficiency
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发布时间：2021-05-20 - 摘要：The ultrathin MoS2 nanosheet dispersion saturable absorber is prepared by ultrasonic peeling method. The quartz cell is used as a container and insert into the flat-concave cavity of the Nd∶YAG laser. By adjusting the position of the resonant cavity mirror and increasing the pump power, the passive Q-switched pulse output of the Nd∶YAG laser is successfully achieved. Experimental results show that when the pump power is 2.46 W, the laser starts Q-switched operation. When the pump power is 14.55 W, the maximum pulse laser output power of 485 mW is achieved, the repetition frequency is 189.75 kHz, the pulse width is 1.2 μs, and the corresponding maximum pulse energy is 2.56 μJ. The results show that the ultrathin MoS2 aqueous solution is a saturable absorber material suitable for passive Q-switching operation of 1 064 nm wavelength solid-state lasers.关键词：ultrathin MoS2 nanosheet dispersion;saturable absorber;Nd∶YAG laser;passive Q-switched pulse
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发布时间：2021-05-20 - 摘要：Due to small size, light weight, high efficiency and long operation life, high power semiconductor laser array chips have gradually entered into mass-markets and emerged applications, such as laser pumping, materials processing, medical therapy and lidar. However, limited by high-temperature working environments such as material processing, the development of high power semiconductor laser is hindered. Since laser diode arrays work in high-temperature working environments and generate great quantity during operating, the output power and reliability of high power semiconductor laser is decreased, which is caused by reducing in slope efficiency, increasing in threshold current, and wavelength redshift. Hence, it is vital to research the optoelectronic performance and laser diode array optimization of semiconductor laser under high temperature. To improve the high temperature performance of high-power semiconductor laser chips, firstly, the influence mechanism of environment temperature on internal quantum efficiency is analyzed theoretically. Secondly, in order to quantify the main factors affecting the stability of the chip, the high-power semiconductor laser array chips test system was built to study the characteristics of the laser diode array chips at 15-60 ℃, and analyze energy loss distribution at various temperatures. The experimental results show that when the temperature rises from 15 ℃ to 60 ℃, the percentage of carrier leakage loss increases sharply from 2.30% to 11.36%, which is the main factor affecting the high temperature operation of semiconductor laser array chips. Finally, the chip structure simulation shows that increasing the Al composition of the waveguide layer to 20% can effectively limit carrier leakage, balance the increase in series resistance caused by the increase of Al composition, and obtain high electro-optical conversion efficiency. This research can provide a reference for the design of high-temperature laser diode array chips.关键词：high power;laser diode array chips;high temperature characteristic;energy loss distribution
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发布时间：2021-05-20 - 摘要：A typical perovskite solar cell(PSC) structure involves the light absorbing perovskite layer sandwiched between the electron-transport layer(ETL) and the hole-transport layer(HTL). The charge recombination at the interface between the perovskite layer and the charge-transport layer is considered to be the major cause of the voltage loss of the device. With the modification of the charge-transport layer, it can not only improve its charge transport properties, but also passivate the interface defects, thus enhancing the power conversion efficiency(PCE) and stability of the PSCs. The interface between ETL and perovskite is modified by introducing Na [(CF3SO2)2N] (NaTFSI) on the planar TiO2 layer. Experimental results show that the ETL modified with the NaTFSI interface layer could not only increase the size of the perovskite grains, but also reduce the grain boundaries and the interface carrier recombination. In addition, the ETL modified with the Na-TFSI can also enhance the conductivity of the ETL and decrease its work function. Finally, we achieved a significant increase in device efficiency from 18.62% to 19.83% by optimizing the NaTFSI interface layer.关键词：perovskite solar cells;TiO2;NaTFSI;interface modification;photoelectric conversion efficiency
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发布时间：2021-05-20 - 摘要：The performance improvement of organic light-emitting diodes(OLED) devices has always been one of the research topics in the field of organic electroluminescence. Optimization of carrier balance in OLED devices is a critical method to improve the performance of OLED devices. However, it is often neglected to optimize the carrier balance in the OLEDs by tuning the molecular orientation in the hole transport layer or electron transport layer. In this paper, the molecular orientation in the hole transport layer was altered by heat annealing at different temperatures to study the influence of molecular orientation on the hole mobility and the performance of OLED device. It showed that the proportion of molecules with vertical orientation in the hole transport layer was increased with the rise of annealing temperature, which promoted the increase of the hole mobility. When the hole transport layers with different molecular orientations were applied to OLED devices, the effect of the carrier balance factor on the device performance can be clearly observed.关键词：organic light-emitting diodes(OLED);charge carrier balance;hole-only device;molecular orientation
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发布时间：2021-05-20 - 摘要：By adjusting the para-hexabiphenyl(p-6P) induction layer and zinc phthalocyanine(ZnPc) evaporation process conditions, the relationship between the crystal growth of organic semiconductor small molecules and the electrical properties of ZnPc OTFT devices was studied. The results showed that p-6P films can form larger crystal domains and better surface coverage on silicon dioxide substrate under the substrate growth temperature of 180-190 ℃ and the growth thickness of 3-4 nm. This was beneficial to induce the crystal growth of ZnPc molecules and make the arrangement of the crystal domains more orderly. At the same time, the crystal structure was analyzed by X-ray diffraction. The results showed that the rise in temperature of the p-6P substrate would significantly improve the crystallinity of the ZnPc films. Combined with the study of electrical properties, the increase of ZnPc vapor deposition thickness will significantly increase the saturation current and device mobility of the device. Under heterogeneous induction conditions, when the p-6P film thickness is 3 nm and the ZnPc film thickness is 20 nm, the saturation current of the device is 1.08×10-6 A, and the mobility is 1.66×10-2 cm2·V-1·s-1.关键词：p-6P;zinc phthalocyanine(ZnPc);films growth;organic thin film transistor(OTFT);electrical properties
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发布时间：2021-05-20
Device Fabrication and Physics
- 摘要：A continuous-wave high-power thulium-doped fiber laser was proposed and its biological tissue cutting was studied. A linear cavity thulium-doped fiber laser source was built by using homemade fiber gratings. The output wavelength of the laser source was 1 941.10 nm, and the optical signal-to-noise ratio is 75 dB. The wavelength and power fluctuations within 50 min were less than 0.04 nm and 0.265 dB, respectively. The slope efficiency and the maximum output power were 5.6% and 186 mW, respectively. According to the master-oscillator power amplifier technology, a pre-amplifier and a main-amplifier were built. The slope efficiencies of the two amplifiers were 14.3% and 35.86%, respectively. After two-stage amplification, the final output power was 21.9 W. The biological tissue cutting experiment was carried out by using the laser beam after beam shaping. Several groups of experiments were designed to observe the cutting depth of the laser under different power and moving speed. The experimental results show that the thulium-doped fiber laser has good cutting effect, and it has potential application in biomedical field.关键词：fiber laser;thulium-doped fiber;high-power;tissue cutting
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发布时间：2021-05-20 - 摘要：Sr2MgAl22O36∶Mn4+-(SiO2-Al2O3-ZnO-BaO-B2O3) phosphor in glass(SMA∶Mn4+-PiG) was prepared by a two-step co-sintering technology at low temperature. The phase, composition and luminescent properties of PiG samples were investigated by X-ray diffraction(XRD), scanning electron microscope(SEM), excitation and photoluminescence spectra, fluorescence decay curve, etc. Experimental results show that the phase and elemental composition of SMA∶Mn4+ phosphor were well preserved after forming PiG. Under 328 nm excitation, PiG samples with different SAM∶Mn4+ content all showed strong emission band peaked at 661 nm due to2E→4A2 transition of Mn4+ ions. The emission spectrum of SMA∶Mn4+-PiG well matches absorption spectra of plant phytochromes. With the increase of phosphor content, the photoluminescence intensity of SAM∶Mn4+-PiG gradually increases. Internal quantum efficiency(IQE) and external quantum efficiency(EQE) of 15% SMA∶Mn4+-PiG samples are 26% and 20%, respectively, which are lower than 59% and 40% of SMA∶Mn4+ phosphor. Compared with SMA∶Mn4+ phosphor, absorption efficiency and thermal stability of SAM∶Mn4+-PiG are slightly enhanced. With packaging with high-power UV chip, SMA∶Mn4+-PiG red LED device exhibits high electroluminescence intensity, and the highest value is measured at 100 mA.关键词：phosphor-in-glass;plant growth;Mn4+;LED
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发布时间：2021-05-20 - 摘要：Luminescent solar concentrator(LSC) attracts extensive attention due to the potential application in the building integrated photovoltaics. In this work, the CsPbBr3 nanocrystal is chosen as the luminescent center and the thiol-ene polymer is used for the transparent optical waveguide matrix of LSC. The photoluminescence emission spectra, absorption spectra, and time-resolved emission spectra are performed to evaluate the optical efficiency, respectively. It is found that the emission peak blue-shifts by 11.0 nm and the full width at half maximum(FWHM) widens by 20.4 nm, which can be attributed to the dielectric screen effect of thiol-ene polymer matrix. Meanwhile, the introducing thiol-ene polymer matrix can greatly improve the photoluminescence emission stability of CsPbBr3 nanocrystals. When the amount of CsPbBr3 nanocrystals in the thiol-ene polymer matrix is 5.6%, the corresponding optical efficiency of LSC can reach 8.9%, which is higher than that of nanocrystals-based LSC reported in most previous studies. Further, the commercial polycrystalline silicon solar cell is designed to install in the edge of an LSC. Under the standard AM1.5 solar simulator, the device demonstrated the attractive attributes of open-circuit voltage of 0.47 V, short-circuit current density of 7.14 mA/cm2, fill factor of 24.01%, and high power conversion efficiency up to 2.30%.关键词：perovskite nanocrystal;thiol-ene polymer;luminescent solar concentrator;photoluminescence;optical efficiency
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发布时间：2021-05-20
Luminescence Applications and Interdisciplinary Fields
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