摘要:In recent years, organic⁃inorganic hybrid metal halide materials have attracted great attention due to their excellent luminescent properties. In particular, low-dimensional copper(Ⅰ) based halides, as a representative of highly efficient luminescent materials, show great potential in scintillators for radiation detection. In this paper, the research of organic⁃inorganic hybrid copper(Ⅰ) based halides as luminescent materials is reviewed. Based on the [CuXn](X=Cl, Br, I) structural unit and its connection modes, ionic organic⁃inorganic hybrid copper(Ⅰ) based halides are systematically classified, and the relationship between their composition, structure, and properties is discussed. We focus on the photophysical process and luminescence mechanism of organic-inorganic hybrid copper(Ⅰ) based halides. Finally, we summarize the latest progress in organic⁃inorganic hybrid copper(Ⅰ) based halide scintillators for X-ray detection, and make a prospect for this novel research perspective.
关键词:organic⁃inorganic hybrid copper(Ⅰ) based halides;low⁃dimensional structure;luminescent materials;scintillators
摘要:Resolution is a critical parameter in assessing the performance of a display. The demand for higher resolution displays extends beyond the competitive needs of consumer electronics manufacturers to the urgent requirements of fields such as scientific research, industry, and medicine, which need high-resolution displays to present more precise images. In addition, virtual and augmented reality technologies enable ultra-high-resolution displays to provide richer human-computer interaction experiences. Ultra-high-resolution display technology has gradually become a popular research direction. This article introduces the technical means and solutions for achieving high-resolution displays in various new display technologies based on light-emitting diodes, summarizes the applicable conditions and advantages and disadvantages of each solution, and points out the main challenges facing each technology at this stage. Our team has long been committed to the electroluminescent patterning and high-resolution display research of quantum dot light-emitting diode displays. This article introduces the groundbreaking research results from our team has achieved recently.
摘要:The enhancement of the zero phonon line (ZPL) emission of the red⁃emitting Mn4+⁃activated phosphors, will lead to the enhancement of the short wavelength emission in the whole luminescence spectrum, and usually the luminescence will decay faster. The Mn4+-activated fluoride phosphors with intense ZPL, 28 kinds in total, with intense zero phonon line (ZPL) emission were reviewed, on aspects of the chemical composition, preparation method, crystal structure and photoluminescence property. Several rules were found: (1) The Mn4+-activated fluoride phosphors with intense ZPL can be classified into four categories based on whether Mn4+ is equivalent with the cation being substituted and whether the substituted cations form octahedral coordination structures in the matrix. (2) Distortion of the [MnF6] coordination octahedra after doping is necessary to achieve intense ZPL. (3) For most of the fluoride phosphors with intense ZPL, the Mn4+ doping is heteroequivalent, substituting a cation with 3+ valence state; when the substituted ion is tetravalent and six-coordinated, the crystal structure achieving intense ZPL emission is mainly in trigonal crystal system with space group such as P321 and P3m1. (4) For most of the fluoride phosphors with intense ZPL, the intensity of ZPL is weaker than that of Stokes ν6 phonon sideband emission (except for five kinds like Na2TiF6∶Mn4+ in which the ZPL is more intense than the ν6 peak). (5) Their ZPLs are located within 617-628 nm, mainly at 620 nm. (6) The ZPL/ν6 (Stokes) intensity ratio is not only dependent on the chemical composition of the phosphor, but also varies with the preparation method for a specific phosphor.
摘要:Zero-dimensional (0D) organic-inorganic hybrid metal halides, as an important functional material, have received widespread attention in the fields of lighting, display, and X-ray scintillator for their excellent luminescent properties. In 0D organic-inorganic hybrid metal halides, the polyhedral anions of metal halides are surrounded by organic cations and completely isolated, forming a unique “host-guest” structure. Hence, 0D organic-inorganic hybrid metal halides generally exhibit the intrinsic properties of single metal-halide polyhedrons. However, 0D organic-inorganic hybrid metal halides, as an emerging luminescent material, not only contain significant spatial confinement characteristics, but also have tunable micro interactions. Therefore, different components have a significant impact on their photophysical mechanism. Based on this, this review first introduces the solution synthesis methods, crystal structure characteristics, and photophysical mechanism of 0D organic-inorganic hybrid metal halides, and then analyzes in detail the regulation of the photophysical mechanism and optoelectronic applications of 0D organic-inorganic hybrid metal halides. Finally, we summarize and prospect the future applications and research of 0D organic-inorganic hybrid metal halides.
关键词:zero-dimensional metal halides;organic-inorganic hybrid;efficient broadband emission;photophysical properties;optoelectronic applications
摘要:NaGd(MoO4)2∶Tb3+ phosphors with different Tb3+ concentrations were prepared by a high-temperature solid-state reaction method. The crystal structure analysis by means of X-ray diffraction (XRD) revealed that the samples prepared were pure-phased. Fluorescence spectroscopy measurements were utilized to investigate the phosphor's fluorescence quenching, and the results indicated that the fluorescence concentration quenching resulted from exchange interactions between Tb3+ ions, and the Ozawa model held for the fluorescence quenching process. The self-generated quenching model proposed by Auzel was used to analyze the 5D4 level fluorescence dynamics of Tb3+, and it was found that the Auzel model can well explain the concentration dependence of fluorescence lifetime. The dependences of the luminescence intensity and lifetime of the 5D4 level of Tb3+ on the sample temperature were investigated. A method for temperature sensing using the fluorescence lifetime was proposed, and the absolute and relative sensitivities of temperature sensing were analyzed.
摘要:Photothermal therapy (PTT) is in dire need of an accurate, efficient and high-resolution thermometer working in the deep tissues to assist its treatment process. In this paper, the high temperature solid state method is employed to synthesize the BaY2O4∶Nd3+ powder, in which the thermally coupled Stark sublevels of Nd3+: 4F3/2 are utilized to measure the temperature based on the fluorescence intensity ratio (FIR) technology. The optimal value of its absolute sensitivity, relative sensitivity and temperature resolution is 0.09%·K-1, 0.69%·K-1 and 0.05 K, which are superior to majority of the same type thermometers. Moreover, the penetration depth of the present sample in the biological tissues can be reached to 8 mm, benefiting from the fact that its excitation and emission wavelength are all located in the biological windows. Beyond that, the sample owns photothermal conversion ability under the irradiation of 808 nm wavelength. All the findings show the potential of Nd3+ single-doped BaY2O4 in deep-tissue PTT.
摘要:Rare earth ions doped materials, organic dyes and quantum dots are employed to realize the fluorescence temperature sensing which has great significance in aerospace, biomedicine, food storage, etc. Fluorescent materials of inorganic halide perovskite QDs(PeQDs) possess great application prospects in the field of fluorescence temperature sensing due to high quantum yield and strong temperature dependence. However, PeQDs have only one photoluminescence(PL) peak whose intensity and position are highly susceptible to interference from factors such as concentration and size, resulting in low accuracy in temperature sensing using this PL peak alone. In this work, we propose a novel temperature sensing structure using microsphere-cavity-array(MCA)capped PeQDs film(MCA/PeQDs). Fluorescence temperature sensing is realized using the temperature dependent PL peak intensity ratio between the MCA/PeQDs structure and the bare one. Through the Purcell effect induced by microsphere cavity supported whispering-gallery modes(WGMs) in the microsphere cavity, the spontaneous emission rate is enhanced, and the phonon assisted thermal quenching effect is suppressed, which results in better fluorescence enhancement of PeQDs. As a result, when the concentration of PeQDs is 0.131 6 mg/mL and the diameter of the microsphere is (19±1) μm, the absolute sensitivity(Sa) and relative sensitivity(Sr) can achieve 0.75 K-1 and 1.95%·K-1. The present work overcomes the poor accuracy of temperature sensing in single PL peak and opens up a new way for fluorescence materials used in fluorescence temperature sensing with high performance.
摘要:NaI∶Zn(0, 0.05%, 0.08%, 0.4%),Tl(0.18%) crystals were grown using Bridgman method respectively. The crystal samples were tested by X-ray powder diffraction, inductively coupled plasma emission spectra, and ultraviolet-visible near-infrared transmission spectra. The results show that the grown crystals have a single phase, and the crystal structure of NaI does not change with Zn and Tl ions doping. As the doping concentration of Zn increases, the concentration of Zn2+ ions in the crystal increases, while the concentration of Tl+ ions decreases. The transmittance shows a trend of firstly increasing and then decreasing with the increase of Zn doping concentration. When the doping concentration of Zn is 0.08%, the transmittance of the sample is the highest. The transmittance of all the NaI∶Zn,Tl crystals is higher than 70% in the 350-700 nm wavelength range. After cutting, polishing, and packaging processes, NaI∶Zn,Tl crystals were enveloped into radiation detection components. The scintillation performance test results showed that under the excitation of a 137Cs radiation source, the energy resolution of NaI∶Zn,Tl crystals with Zn doping of 0.05% and 0.08% were less than 6.80%, and the light output increased 6%-10% compared with that of NaI∶Tl crystal. This is conducive to the further application of NaI crystals in the field of high-energy particle detection.
摘要:Three novel linear dimeric luminescent materials, BtCzPPQ, DCPPQ and PZPPQ, were synthesized by linking two quinoline receptors together into an electron acceptor (A) using the Suzuki coupling reaction, and by linking donor groups (D) with different electronic donated moiety. All the three materials have good rigidity, thermal stability (Tg>220 ℃), and high photoluminescence quantum yields (PLQYs more than 70%). The effects of structural factors such as the rigidity of molecules, linear length, and the donor group on the electroluminescence properties of the materials were analyzed by characterizing the orbital distribution, thermal stability, and photophysical properties of the materials.
摘要:We present the results of a high-speed direct modulation 850 nm oxide confined vertical cavity surface emitting laser(VCSEL),optimize the design of strain InGaAs/AlGaAs quantum wells to achieve high differential gain, and adjust the photon lifetime through surface etching to achieve response flattening. The developed VCSEL with an oxide aperture of about 7 µm has a flat frequency response, a 3 dB modulation bandwidth of 24 GHz, and a relative noise intensity value of -155 dB/Hz. Without any pre-emphasis and equalization technology, the PAM4 modulation data transmission rate can reach 80 Gb/s.
摘要:The wide bandgap semiconductor ZnO ultraviolet (UV) photodetector has many advantages, such as high stability, low cost, and has important application prospects in fields such as national defense, medical care, and environmental monitoring. In this work, ZnO thin films were fabricated on SiO2 substrate using radio frequency magnetron sputtering. Subsequently, a ZnO UV photodetector with a high-gain metal-semiconductor-metal (MSM) structure was achieved. At a bias voltage of 10 V, the detector exhibited a responsivity of 4.90 A/W and an external quantum efficiency of 1668%. This high gain was attributed to the hole trapping at the semiconductor-metal interface under illumination. Furthermore, the modulation rules and influence mechanisms of gain effect, applied bias voltage, and depletion layer width on the responsivity of ZnO UV photodetector were thoroughly investigated. This research provides an important reference for the development and performance control of high-performance UV photodetectors.
摘要:With the development of artificial intelligence, big data, cloud computing, Internet of Things, mobile electronics, and so on, the transmission capacity of the traditional optical fiber communication system carried by the rare earth ion-doped single-core single-mode fiber amplifier has gradually approached the limit of Shannon's law. It is necessary to develop a new material system to broaden the transmission capacity of the optical fiber communication system. Compared with rare earth ions, quantum dots(QDs) have a wide luminescence bandwidth and tunable wavelength, and the luminescence properties of QDs can be modulated by a variety of chemical means. QDs-doped optical amplifier shows broadband optical gain properties, which has attracted wide attention from academia and industry. In this context, this paper proposes to integrate chemically synthesized PbS/CdS core-shell QDs with low-loss polymer to obtain QDs -doped fiber amplifier(QDFA), realize tunable wavelength and broadband optical amplification in the near-infrared (NIR) communication band. This paper studies and reveals the factors and mechanisms affecting the continuity of polymer fiber. It proposes to reduce the additional pressure related to surface tension, contraction force during solidifying, the friction force by the inner wall of fiber core, and improve the traction force from the pumping by vacuum pump to obtain continuous optical fiber. By optimizing these factors, we obtained continuous fiber core based on heat curing PDMS and light curing NOA61 and NOA85 UV glue. Consequently, the QDFAs realize the highest gain of 6.5 dB, and gain bandwidth of more than 100 nm. The results of this paper will facilitate the development of quantum dot fiber optic devices and broadband optical communication technologies.
摘要:Metal halide perovskite has excellent photoelectric characteristics such as high defect tolerance, tunable peak position and narrow full width at half maximum, which exhibits great potential in the development of high-performance light-emitting diodes. Perovskite light-emitting diodes can be applied to the large-scale commercial production in the display and lighting fields due to low-cost solution preparation. However, the adverse defects are formed in the process of film formation accompanied by the organic solvent volatilization, which are not conducive to the realization of high performance devices. Introducing additive in perovskite precursor solution is a simple and effective strategy to passivate defects. It is reported that the Lewis base is one of the effective additives. Based on analysis, in this work, we propose to introduce a small molecule Lewis base additive (sorbitol) into the precursor solution to passivate the defects of perovskite film, and fabricate perovskite light-emitting diodes. The experiment results show that the introduction of sorbitol can significantly improve the film quality. And when the concentration of sorbitol is 0.3 mol·L-1, the corresponding device achieves the best electroluminescence performance with the maximum external quantum efficiency and luminance of 6.71% and 7 654 cd·m-2, respectively. In addition, the resulting device also shows good spectral stability and repeatability. This work is of great significance to improve the polycrystalline film forming quality and boosting the performance of perovskite light-emitting diodes.
摘要:Deep ultraviolet light-emitting diodes (DUV-LEDs) can physically destroy the structure of viruses and bacteria, thus achieving efficient disinfection. Compared with the mature blue LED process, how to improve the packaging reliability and light output efficiency of DUV-LEDs is still a key problem. In this paper, a semi-inorganic packaging DUV-LED was prepared by using substrate preheating method of micro-cured encapsulation adhesive and combining with array dispensation method to bond quartz glass in plated dam copper. The output wavelength of the device is 275 nm and its half-peak width is approximately 11 nm. Quartz-packaged DUV-LEDs have higher light output than traditional devices packaged with transparent materials. DUV-LED devices using the packaging technique presented herein exhibit high air hermeticity in vacuum red ink and helium environments. Moreover, in the accelerated aging test, the light decay rate of this packaged device is less than 20%. Experimental results show that using array dispensing to bond quartz glass under substrate preheating is a packaging method to improve the reliability of DUV-LEDs compared with organic packaging.
摘要:Ultraviolet communication has extensive applications in laser radar, tactical communication, internal security communication in aerospace plane and on-chip integrated optical communication. Both of the bandwidth and light output power of the traditional deep ultraviolet communication LED were low, and the manufacturing process was complex, which limited their widespread application in long-distance, high-speed communication, and on-chip integrated optical communication fields. Experiments have shown that the increasing of the light emitting area of single device can improve the light output power, but the device capacitance has a negative effect on the bandwidth. Therefore, an important research direction for ultraviolet communication LEDs in the future is to improve the bandwidth and the optical power density of the devices simultaneously. UVC Micro-LEDs with higher light extraction efficiency, lower time constant, shorter carrier lifetime, faster modulated rate and higher current density than traditional LED have been widely favored by the scientific and industrial communities. This paper summarizes the UV LED, especially UVC Micro-LEDs related research progress, and their applications in optical communication and integration on a chip interconnection. It is found that deepening study on the preparation and performance improvement of UVC Micro-LEDs and their arrays will be one of the best solutions for improving the performance of free space and on-chip integrated ultraviolet communication systems in the future.
摘要:A series of conjugated compounds EB1-EB4 have been synthesized with different positions and numbers of triphenylethylene/tetraphenylethylene groups and the same ethyl benzoate (EB) skeleton via the Suzuki coupling reaction. The UV-Vis absorption and fluorescent emission experiment show that all four compounds exhibit obvious aggregation-induced emission (AIE) properties. More importantly, these materials can identify and recognize nitro explosives for the aqueous phase as fluorescent probes. The fluorescent titration results indicate compounds EB1-EB4 possess the potential sensing properties for picric acid (PA), with a low detection limit of 1.35 × 10-6, 1.69 × 10-6, 1.12 × 10-6, 8.88 × 10-7 mol/L, respectively. Interestingly, the best result of the test paper detector is 1.14 ng/cm2 for PA. These conjugated compounds and their derivatives containing EB structure provide important ideas for the manufacture of future fluorescent materials.
摘要:In order to overcome the influence of environmental change on fluorescence detection, a ratio fluorescence probe was designed and prepared, and dual-wavelength fluorescence emission was used to effectively eliminate background interference. Using o-phenylenediamine, sodium tetraborate and 1-methyl-3-allyl imidazolium bromide as precursors, a one-step hydrothermal method has been developed to synthesize a ratio fluorescent probe based on carbon dots (L-CDs), and to achieve a double signal response to heavy metal ions (Cu2+). L-CDs exhibited fluorescence double emission phenomenon, and showed double emission peaks at 440 nm and 570 nm when the excitation wavelength was 380 nm. The addition of Cu2+ can reduce the fluorescence emission intensity at 440 nm and increase the fluorescence emission peak value at 570 nm. The concentration of Cu2+ in the range of 0.04-0.244 mmol/L showed a good linear correlation with the fluorescence ratio signal (F570/F440), and the detection limit (LOD) was 0.6 μmol/L. The fluorescence probe can be used for the detection of Cu2+ in actual water samples with the recovery of 99.4%-101.4%.