最新刊期
卷 42 ， 期 6 ， 2021
- 摘要：Zero-dimensional(0D) metal halides belong to a new kind of luminescent materials, and they have the unique "host-guest" structure, in which the isolated anionic metal halide polyhedrons are regularly distributed in the main body of organic cations or alkali metal ions. Generally, 0D metal halides with relatively "soft" lattice usually present broad band emission with large Stokes shift, and their luminescence mechanism is mainly derived from self-trapped excitons(STEs) recombination. By screening different metal halide polyhedrons with diversified configurations, one can combine them with appropriate organic cations or alkali metal ions to form new 0D metal halides with different structure types. The obtained 0D metal halides show rich STEs luminescence properties, and their tunable fluorescence emission can be available to cover the entire visible light region. Moreover, it can also realize single-phase white light emission or near infrared emission, making them become a hot spot in the field of photoluminescence materials. Based on our work and others in this field, the photoluminescence mechanisms of 0D metal halides are firstly discussed in this review. Secondly, the luminescence properties and applications of 0D metal halide materials with different polyhedron configurations are introduced. Finally, the key scientific problems of 0D metal halides during the development are summarized, and the future research direction is briefly proposed.关键词：metal halides;photoluminescence;LED application
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发布时间：2021-06-18
Cover Story
- 摘要：Recently, three-dimensional lead-halide perovskites have been extensively studied as new semiconductor materials for optoelectronic devices(such as solar cells, light emitting diodes and lasers) for their exceptional optical and electronic properties. However, the lead toxicity and poor stability of three-dimensional lead-halide perovskites have severely hindered their commercial applications. Low-dimensional perovskite materials have attracted widespread attention in the field of optoelectronic applications due to their excellent photoelectric properties and enhanced stability. In addition to photovoltaics and light-emitting diodes, low-dimensional perovskite has become a promising candidate for future photodetectors. This paper briefly introduces the structure of low-dimensional perovskites, the types and performance parameters of photodetectors, and focuses on the research progress of low-dimensional perovskite photodetectors. Meanwhile, the promising future directions in this research field are discussed.关键词：low-dimensional;perovskites;stability;photodetector
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发布时间：2021-06-18
Invited Review
- 摘要：Polymer dots(PDs) have attracted intensive attention due to their advantages of tunable electrical and optical properties based on suitable manipulation of the structure and composition. As a new type of dots, the classification, synthetic methods and properties of PDs still lack systemic summarization. In this review, the polymer dots are divided into two kinds based on their structures: conjugated polymer dots(CPDs) and carbonized polymer dots(carbonized PDs). The definitions, synthetic methods and photoluminescence mechanisms of the two PDs will be discussed. Besides, their applications are demonstrated including bioimaging and fluorescent labelling, drug and gene delivery, sensing, photocatalysis and anti-counterfeiting.关键词：polymer dots;conjugated polymer dots(CPDs);carbonized PDs;photoluminescence
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发布时间：2021-06-18
Mini Review
- 摘要：Near-infrared phosphor-converted LEDs(NIR pc-LEDs)play an important role in the applications of food analysis, biomedicine, security monitoring, etc. In this study, a broadband near-infrared phosphor LaSc3(BO3)4∶Cr3+(LSB∶Cr3+) is presented. Under 460 nm excitation, the emission band of LSB∶Cr3+covers the spectral range of 650-1 200 nm with a full width at half maximum (FWHM) of 170 nm. Furthermore, the performance of LSB∶Cr3+ phosphor is improved by Yb3+ co-doping, leading to the broadened FWHM(up to 223 nm), increased photoluminescence quantum yield(PL QY, from 14% to 35%) and reduced PL thermal quenching. Based on the analysis of PL spectrum, PL QYs, PL decay curves and PL thermal stability, it is revealed that the improvement of PL thermal stability by Yb3+ co-doping principally originates from the efficient energy transfer from Cr3+ to more thermally stable Yb3+ emitters. Finally, a NIR pc-LED is fabricated by combining the LSB∶Cr3+,Yb3+ phosphor with blue LED chip, which exhibits a maximum NIR output power of 16 mW at 60 mA drive current. These results suggest that LSB∶Cr3+,Yb3+ phosphor is a promising luminescent converter for broadband NIR pc-LED.关键词：Near-infrared phosphor;Cr3+/Yb3+ co-doping;energy transfer;near-infrared phosphor-converted LED(NIR pc-LED)
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发布时间：2021-06-18 - 摘要：Tb3+ doped transparent germanate glass ceramics embedded with LaF3 nanocrystals were successfully prepared via melt-quenching and subsequent thermal treatment. The luminescent properties of the as-prepared glass and the glass ceramics were investigated in detail. The X-ray diffraction results prove that the crystalline phase precipitated in the glass matrix was pure LaF3 crystal and the crystal size was between 16 nm and 21 nm. Under the excitation of 377 nm ultraviolet light and X-ray, Tb3+ glass ceramics embedded with LaF3 nanocrystals show much intense green emission than Tb3+ doped germanate glass, and the green emission intensity increases with the increment of thermal treatment temperature and time. The maximum integrated X-ray excited luminescence intensity of the glass ceramics is about 40.3% of that of Bi4Ge3O12 crystal which is the commercial scintillating crystal. Our research shows that Tb3+ doped germanate glass ceramics embedded with LaF3 nanocrystals have potential application prospects in X-ray detection.关键词：Luminescence;Tb3+;Germanate glass;Glass ceramics;Glass scintillator
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发布时间：2021-06-18 - 摘要：Nonpolar a-AlN is the fundamental method to eliminate quantum-confined Stark effect, and further improve the efficiency of AlGaN-based devices such as light-emitting diodes. However, it is hard to obtain high quality nonpolar a-AlN on heterogeneous substrates because the large and inhomogeneous mismatch between the heterogeneous substrate and the epitaxial layer. High temperature annealing is an effective and repeatable method to improve the quality of AlN templates. However, the physical mechanism is still not clear on how the high temperature annealing method effects the surface morphology of non-polar AlN, which affects the quality improvement of a-AlN. In this work, the surface evolution of the a-AlN with high temperature annealing has been investigated and the mechanism of how the thermal annealing effects on the surface evolution has been explored both by experiment and first-principles calculations. It is found that the Al/N atoms tend to decompose along a-/m-plane AlN and reabsorb along c-plane AlN, which result in the phenomenon that the area of ordered stripes along c-axis increases with higher annealing temperature or longer annealing time. The research will provide deeper understanding on the mechanism of the HTA effect on a-AlN, which will be benefit to the fabrication of a-AlN related devices.关键词：a-AlN;high temperature annealing;surface morphology evolution;binding energy
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发布时间：2021-06-18 -
Pr3+ Doped SrZnOS to Achieve Tunable Mechanoluminescence Color and Mechanoluminescence Mechanism 增强出版
摘要：The development of new mechanoluminescence(ML) materials for stress sensor and imaging is of great importance, owing to their unique physical, chemical, and optical properties. A series of novel Sr1-2xPrxLixZnOS phosphor were successfully synthesized by the high temperature solid state reaction method. The crystal structure, morphology, photoluminescence(PL), ML properties and luminescence mechanism of Sr1-2xPrxLixZnOS were studied in detail. The unit cell volume of Sr1-2xPrxLixZnOS decreased from 0.153 52 to 0.153 05 nm3 with the concentration Pr3+ increasing from x=0.005 to 0.04. The emission bands of the Pr3+ ion at 522 and 674 nm originated from the transition from excited state 3P0 to lower energy levels 3H5 and 3F2. The PL intensity reaches the maximum when the Pr3+ ion concentration reached 0.015. The decay time decreases from 17.79 to 5.93 μs with increasing Pr3+ concentration. At the same time, the emission peaked at 522 and 674 nm were observed under the load of 5 000 N. Meanwhile, the ML intensity first increases reaching the maximum of the Pr3+ ion concentration at x=0.02, and then decreases with the doped concentration increasing. In addition, the relative intensity IG/IR value of the two emission bands at 522 and 674 nm decreased with the Pr3+ concentration increasing from x=0.005 to 0.04. Moreover, the ML color transition from yellow-green light to orange-yellow light emission can be observed in both the color coordinate diagram and the sample photos under pressure. Therefore, these materials offer a new approach to controlling luminescent colors in the ML field, with potential applications in the fields of stress display, imaging and stress sensors.关键词：mechanoluminescence;SrZnOS;Pr3+- 540
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发布时间：2021-06-18 - 摘要：In recent years, the poor stability of perovskite quantum dots CsPbX3(X=Cl, Br, I) has attracted extensive attention. In this paper, we synthesized stable CsPbBr3/Si3N4 green phosphors at room temperature and applied to white light emitting diodes(WLEDs). The structure, morphology, element composition and luminescent properties of CsPbBr3 and CsPbBr3/Si3N4 phosphors were investigated by X-ray diffraction(XRD), scanning electron microscopy(SEM), energy dispersive spectrometer(EDS), excitation and emission spectra(PL, PLE). The thermal stability, water and color stability of CsPbBr3/Si3N4 green phosphor were obviously improved. The emission intensity of CsPbBr3/Si3N4 phosphor can maintain 87.4% of the initial emission intensity at 80 ℃, and maintain 75.5% of the initial emission intensity after being immersed in deionized water for 120 min. The quantum efficiency of CsPbBr3/Si3N4 composite is increased from 15.4% of CsPbBr3 quantum dots powder to 35.4%. By packing the CsPbBr3/Si3N4 phosphor with K2SiF6∶Mn4+ red phosphor and InGaN based blue LED chip, the color gamut of the WLED device is 113.4% NTSC and the luminous efficiency is 49.4 lm/W.关键词：perovskite quantum dots;green phosphor;stability
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发布时间：2021-06-18 - 摘要：Organic-inorganic hybrid perovskite solar cells have attracted much attention due to their high photoelectric conversion efficiency and low preparation cost. An important factor limiting the further performance improvement of perovskite solar cells is defects existed in perovskite active layers. The passivation of these defects depends on the development of perovskite preparation techniques. The two-step method is one of the most popular methods to prepare perovskite films and photovoltaic devices. In order to fabricate high-quality perovskite films and high-efficiency solar cells, the modified two-step method via introducing additives has been developed. However, effects of additives introduced into the lead halide precursor on the crystallization process and defect density of perovskite films fabricated via the two-step method are not yet fully understood. In this work, the impacts of potassium iodide(KI) on colloidal properties of the lead halide precursor, perovskite transformation, film quality and cell performance were investigated by means of spectroscopy, X-ray diffraction, scanning electron microscopy and various electrical measurements. Our results show that the introduction of appropriate amount of KI facilitates the formation of iodide-rich iodoplumbates, which is beneficial to accelerating perovskite transformation from lead halide and improving perovskite film quality. The photoelectric conversion efficiency of the solar cell incorporating appropriate KI has been increased to 19.17% from 17.49% for the control device. The results of this work not only help to deepen the understanding of the crystallization of perovskite films in the two-step preparation process, but also help to further improve perovskite film quality and device performance.关键词：Perovskite solar cells;Potassium iodide;"two-step" deposition;Defect passivation;Iodoplumbates
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发布时间：2021-06-18 - 摘要：All-inorganic perovskite CsPbBr3 microrods were prepared on mica substrates by chemical vapor deposition(CVD) method. The morphology and crystal structure of the samples were characterized by scanning electron microscopy(SEM) and X-ray diffraction(XRD). The CsPbBr3 exciton luminescence was studied by temperature-dependent photoluminescence(PL) spectra from 10 K up to room temperature. The results reveal that there are two emission peaks at 10 K, which were attributed to exciton emission. The peak energy at 2.328 eV with a full width at half maximum(FWHM) of 20 meV was identified to free exciton recombination, and the peak energy at 2.313 eV with a FWHM of 29 meV was assigned to bound exciton emission. The peak energy of the free exciton monotonically blueshifts with the temperature increases, and so does the bound exciton until 120 K. Above 120 K, however, the peak energy of bound exciton tends to be flat when the temperature increases. Furthermore, the FWHM of the free exciton or bound exciton increases gradually. We have demonstrated these temperature-dependent photoluminescence properties are mainly due to the interaction between exciton and longitudinal optical phonons(LO). Our results could provide deeply understanding of intrinsic excitonic properties of CsPbBr3 perovskites, which may be helpful to the development of high-performance optoelectronic devices.关键词：perovskite;exciton;phonon;Temperature dependence photoluminescence
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发布时间：2021-06-18
Synthesis and Properties of Materials
- 摘要：A novel perylene diimide(PDI) derivative bearing siloxane moieties(PDI-TES) was synthesized as fluorescent sensor by simple one-step reaction with high yield. The crystal structure, self-assembly behavior and detection property of the compound were then elucidated via a combination of different experimental techniques such as small-angle X-Ray scattering, UV-Vis absorption spectra, photoluminescence spectra and dynamic light scattering experiments. The experimental results reveal that PDI-TES has good thermal stability and ordered crystal structure. Moreover, due to the cleavage of Si—O bonds, PDI-TES exhibits high selectivity and sensitivity to F-, with a detection limit as low as 1.58×10-6 mol/L. These excellent detection performances, in combination with the simple and low-cost synthesis method, make PDI-TES a practical fluorescent sensor for detection of F-.关键词：perylene diimide;fluorescent sensor;siloxane;fluoride ions
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发布时间：2021-06-18 - 摘要：Er3+ doped ZnO nanorod arrays were prepared by hydrothermal method, the morphology and luminescence properties were characterized by field emission scanning electron microscopy, X-ray single crystal diffraction, transmission electron microscopy and micro spectrometer. The experimental results show that Er3+ is successfully and uniformly doped into ZnO nanorods, and the formation of Er2O3 is not found. After Er3+ doped, the photoluminescence spectrum shows a broad band peaked at 400 nm. With the increasing of Er3+ concentration, the proportion of the blue part decreases, which indicates that Er3+ fills part of the Zn vacancy defects and suppresses part of the O vacancy defects. At the same time, combined with the fluorescence lifetime spectrum, it can also be found that the lifetime of the radiative part is prolonged, which indicates that the fluorescence radiation efficiency is improved. Finally, ZnO nanorod contented Er3+ with a mass concentration of 30% was selected to fabricate ZnO/GaN light-emitting diodes. Compared with the samples without Er3+, the electroluminescence intensity of ZnO/GaN light-emitting diodes increased by five times. This paper provides a simple and feasible method to improve the performance of ZnO based electroluminescent devices.关键词：ZnO nanorod array;Er3+ doping;defect control;electroluminescence device
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发布时间：2021-06-18 - 摘要：The electrical properties and the ammonia sensing transistor characteristics of ultrathin film laminated transistors based on donor-acceptor conjugated polymer bis(2-oxoindole-3-ylidene)-benzodifuran-dione and bithiophene(PBIBDF-BT) were studied. The PBIBDF-BT ultrathin films with different stacking layers were prepared by phase separation method and transfer-etching step. The relationship between the number of PBIBDF-BT ultrathin film stacks and the performance of the device were systematically studied. Experimental results indicate that the single-layer PBIBDF-BT ultrathin film device has good sensing performance for ammonia, but the electrical performance is poor. Ultrathin film stacking can effectively improve the electrical performance of the device. As the number of ultrathin film stacks increases, the device mobility increased. When the number of ultrathin film layers increases to 3 layers or more, the increasing trend of mobility slows down and the maximum mobility is 0.58 cm2·V-1·s-1. The ammonia sensing performance of ultrathin film laminate devices shows a downward trend when the number of layers is 2. Through the PBIBDF-BT ultrathin film stacking method, an OFET ammonia gas sensor with good performance was prepared under 1.0×10-5 ammonia environment, with a mobility of 0.23 cm2·V-1·s-1, the source-drain current change percentage of 90.7%.关键词：Organic ultra-thin film transistor;donor-acceptor conjugated polymer;ammonia gas detection;ultrathin film stack
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发布时间：2021-06-18
Device Fabrication and Physics
- 摘要：In this paper, a two-solvent quantum dot ink system based on cyclohexylbenzene and octadecene was designed, and the film formation and luminescent properties of green quantum dots(QDs) with CdSe@ZnS/ZnS core/shell structure were investigated. The double solvent ink designed with high boiling point, low surface tension of octadecene and high boiling point, low surface tension of cyclohexylbenzene benzene can enhance the Marangoni effect, weaken the quantum dots accumulation on the edge of the pixel pits, and uniform pixel QDs films were achieved. The green quantum dot array light-emitting device with upside-down and top-emitting structure was fabricated with the threshold voltage of 2.7 V, a maximum brightness of 132 510 cd/m2 and a maximum external quantum efficiency of 14.0%. The results may provide a reference for the preparation of high-performance QD-LEDs array by inkjet printing technology.关键词：ink jet printing;ink formulation;quantum dot film;inverted structure;quantum dot light-emitting diodes
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发布时间：2021-06-18 - 摘要：Inductively coupled plasma(ICP) etching parameters for GaN grating fabrication are investigated. The effects of etch parameters, including the etching gas BCl3/Cl2 flow ratio and pressure, on the roughness and steepness of the mesa sidewall and etching rate are discussed. It is found that by using SiO2 as the hard mask, the roughness and steepness of the etching mesa sidewall was greatly influenced by the etching parameters. A controllable etching rate of 200.6 nm/min, angle of 85.3° and smooth mesa sidewall are obtained using BCl3/Cl2 ratio of 1∶1, 1.33 Pa(10 mTorr) pressure, ICP power of 300 W and RF power of 100 W. Finally, the angle of the sidewall is increased while ensuring the smooth sidewall of the grating. Steep and smooth gratings are very important for improving the device performance and stability of GaN-based distributed feedback laser diode.关键词：gallium nitride;distributed feedback;grating;inductively coupled plasma etching;BCl3/Cl2
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发布时间：2021-06-18
Luminescence Industry and Technology Frontier
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