最新刊期
卷 42 ， 期 9 ， 2021
- 摘要：This work has studied the effect of co-doping Er3+ enhanced BaSi2O2N2∶Eu2+ luminescence, mainly focusing on the internal difference and possible mechanism. The Er3+ co-doped crystal structure was demonstrated through XRD test, and the purity of the sample and the difference in growth were confirmed by analysis. In order to find out the sources of differences, the emission spectra of doped ions with different valence states have been monitored, and the emission spectra of the changes with the content of Er3+ have been compared. The internal physical mechanism of co-doping Er3+ enhanced luminescence is seen from the change of the luminescence. The internal physical mechanism of the co-doping Er3+ enhanced luminescence is to control the crystal texture and adjust the valence state. For practical applications in the future, a temperature characteristic test was carried out to show the emission spectrum changes under temperature variation. This research provides new ideas for the work of regulating the luminous intensity and improving quantum efficiency.关键词：rare earth material;BaSi2O2N2∶Eu2+ phosphor;photoluminescence;thermal stability
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发布时间：2021-09-13
Cover Story
- 摘要：In recent years, all-inorganic CsPbX3(X=Cl, Br, I) perovskite quantum dots have made great progresses in the optoelectronic field, but their practical applications are limited by deterioration and decomposition failure under the stimulation of external environment (such as light, heat and humid air). Through in situ growth of perovskite quantum dots inside the glass matrix, the quantum dots are seamlessly coated by the dense network structure of inorganic glass, and the quantum dots are isolated from the external environment. As a consequence, the stability of quantum dots can be effectively solved, which make them have a broader application prospect in the fields of solid-state lighting, liquid crystal display, anti-counterfeiting and so on. The preparation methods and excellent properties of all-inorganic CsPbX3 perovskite quantum dots-embedded glass are described, and the progresses in various application fields in recent years are summarized. This review could provide ideas and references for the development and application of all-inorganic CsPbX3 perovskite quantum dots fluorescent glass.关键词：perovskite quantum dot;glass;in-situ nucleation/growth;stability;lighting and display
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发布时间：2021-09-13 - 摘要：Mn4+-doped red phosphors have attracted much attention in the fields of white LED indoor lighting, agricultural plant growth and backlight displaying, due to the advantages of broad-band absorption, narrow-band emission, high color purity and low cost. This work reviews recent progress of Mn4+ activated typical LED red phosphors. First, the crystal field theory of Mn4+ is discussed. Then, the research progress of Mn4+ activated fluorides and aluminates is summarized. Next, how to improve luminescence performance, thermal stability and moisture resistance are discussed theoretically. Finally, the main problems in the development of Mn4+ doped red phosphors are presented and the future trends are prospected.关键词：LED;photoluminescence;Mn4+;red phosphors
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发布时间：2021-09-13
Invited Review
- 摘要：A series of new K4CaGe3O9∶xBi3+(0.003≤x≤0.10) phosphors are prepared via traditional high-temperature solid solution route. The detailed crystal structure and photoluminescence properties of K4CaGe3O9∶xBi3+(0.003≤x≤0.10) materials are studied through precise Rietveld structure refinement, photoluminescence excitation and emission spectra, XPS and thermal stability measurements. According to experimental data, Bi3+ displays narrow blue emission with spectral width at around 43 nm under n-UV light excitation. The main reason is that K4CaGe3O9 shows highly-symmetric crystal structure. Meanwhile, the as-prepared K4CaGe3O9∶xBi3+(0.003≤x≤0.10) phosphors show excellent thermal stability, of which photoluminescence intensity at 423 K remains 83% than that at 298 K. The above results confirm that the as-prepared K4CaGe3O9∶xBi3+(0.003≤x≤0.10) phosphors show potential application in white LED lighting and backlight display areas. This work proposes that Bi3+ can achieve narrow-band emission when doping into highly-symmetric crystal structure. This approach can provide theoretical basis and guidance to exploit Bi3+ activated narrow-band emitting phosphor materials.关键词：Bi3+ doping;highly symmetric crystal structure;narrow emission;blue light
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发布时间：2021-09-13 - 摘要：In this paper, a series of broadband-emitting and tunable Ba1-xAl12O19∶xCe3+(0.01≤x≤0.09) phosphors were successfully synthesized by the high-temperature solid-phase method. The results of X-ray diffraction, scanning tunnel electron microscopy and EDS mapping proved that we synthesized aluminate phosphor with pure phase and uniform element distribution. Under the excitation of near-ultraviolet light wavelength of 361 nm, we found that the luminous intensity of Ba1-xAl12O19∶xCe3+ samples gradually increased and the luminous color of Ba1-xAl12O19∶xCe3+ samples gradually change from blue to cyan as the Ce3+ concentration increased. When x=0.05 mol, the luminescence intensity of the Ba0.95Al12O19∶0.05Ce3+ sample reaches the maximum, and the fluorescence internal quantum yield is 30.8%. Steady-state spectroscopy and fluorescence lifetime results confirm that when the doped Ce3+ concentration is greater than 0.05 mol, the Ba1-xAl12O19∶xCe3+ sample undergoes concentration quenching, and the concentration quenching is mainly due to the energy transfer between adjacent Ce3+-Ce3+. The Ba0.95Al12O19∶0.05Ce3+ sample exhibits a cyan emission with a spectral coverage of 365-650 nm, a main peak at 450 nm, and its full width at half maximum is 120 nm. The asymmetric broad emission band mainly originates from the two Ce3+ emission centers occupying the Ba1 and Ba2 sites in the host lattice. Simple dichromatic pc-WLEDs with UV excitation(λex=365 nm), full-visible-spectrum white light with adjustable color index and associated color temperature were prepared by mixing Ba0.95Al12O19∶0.05Ce3+ with a commercial red phosphor. The Ba0.95Al12O19∶0.05Ce3+ phosphor with broadband cyan luminescence developed in this work has potential applications in the field of full-spectrum lighting.关键词：broadband emission;cyan spectral gap;Ce3+ doped;aluminate;full spectrum
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发布时间：2021-09-13 - 摘要：The organic thermally activated delayed fluorescence materials with dual-emission characteristics have possessed great application in fields of white organic light emitting diodes, multifunction probes and sensors, high quality bioimagings, anti-counterfeiting and so on, owing to their different wavelengths and at least one long lifetime more than microseconds. Moreover, it is critical to study the structure-property relationships for designing thermally activated delayed fluorescence moleculars with dual-emission based on donor-acceptor system. In this paper, the thermally activated delayed fluorescence materials with dual-emission based on donor-acceptor system are divided into three categories according to their luminescent properties: thermally activated delayed fluorescence-fluorescence dual emission, thermally activated delayed fluorescence-phosphorescent dual emission and dual thermally activated delayed fluorescence emission. The molecular design principle, luminescence mechanism and the progress are reviewed, noting the remaining challenges and directions for future work.关键词：thermally activated delayed fluorescence;dual emission;molecular design;luminescence mechanism
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发布时间：2021-09-13 - 摘要：This paper reports the temperature-dependent photoluminescence properties of Cs0.05FA0.79MA0.16PbI2.52-Br0.48 perovskite thin film. The Cs0.05FA0.79MA0.16PbI2.52Br0.48 perovskite thin film was prepared by one-step spin coating with chlorobenzene anti-solvent treatment, and the surface morphology and crystallization quality were characterized. The X-ray diffraction(XRD) indicates that the Cs0.05FA0.79MA0.16PbI2.52Br0.48 has a typical tetragonal perovskite structure. The perovskite film has a uniform and dense surface, and the grain size is about 300 nm. The photoluminescence intensity was measured in the temperature range of 5-200 K. The photoluminescence spectra show a continuous blue shift of about 9.36 nm, and there is no reversal redshift induced by phase transition. The photoluminescence intensity shows a bi-exponential quenching with the increase of temperature, and two thermal activation energies are obtained by Arrhenius equation. The optical bandgap is fitted by the Bose-Einstein double harmonic oscillator model, and the non-renormalized bandgap energy, the energies of acoustic phonon and optical phonon were fitted. The photoluminescence broadening mechanism was studied by the Segall formula. At 10 K and 100 K, the photoluminescence is mainly from exciton recombination, while at 200 K, the radiation recombination is mainly from free-to-bound and donor-acceptor pairs, which means the defect associated photoluminescence arises at high temperature. The detailed optical parameters in our paper can provide a physical foundation for further optimization of perovskite optoelectronic devices.关键词：Perovskite thin film;Photoluminescence;Exciton-phonon interaction
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发布时间：2021-09-13 - 摘要：In recent years, great strides have been made in improving the luminous efficiency of semiconductor materials by using surface plasmon resonance. However, there still exist some disadvantages, such as sophisticated nanofabrication techniques, poor repeatability and so on. Here, a novel ultra-thin, large-area and tunable planar bilayer media is reported, which is composed of deep-subwavelength and high absorptive CuO thin films and Au substrate. Experimental results show that reflectance spectra of CuO/Au bilayer can be sensitively tuned by changing the thickness of CuO film. Compared with the bare quartz based reference sample, photoluminescence (PL) enhancement factor of quantum dots/CuO/Au trilayer can be achieved by up to 7 times. Theoretical analysis shows that PL enhancement effect is attributed to the high efficient absorption caused by Fabry-Perot thin film interference and the accelerated spontaneous emission rate resulted from local field enhancement.关键词：photoluminescence enhancement;CsPbBr3 quantum dots;deep-subwavelength;F-P interference;spontaneous emission rate
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发布时间：2021-09-13 - 摘要：The fluorescent glasses for broadband phosphor-converted light-emitting diodes(pc-LED) have good thermal stability and optical properties, which can avoid the poor stability and reabsorption problems of the traditional style of multi-component phosphors dispersed in silicone resin, and improve the service life and luminous efficiency of pc-LED. In this work, a single-component Ce3+/Mn2+ co-doped fluorosilicate glass with continuous tunable broadband emission was prepared by melt-quenching method, and luminescence properties were studied. In order to explore the energy transfer from Ce3+ to Mn2+, Ce3+ doped and Mn2+ doped fluorosilicate glass were prepared. The experimental results show that Ce3+ can strongly sensitize the luminescence of Mn2+ under the excitation of UV light. The blue emission of Ce3+ doped glass and the yellow emission of Mn2+ doped glass were extended to broadband emission(380-780 nm) of white light with Ce3+/Mn2+ co-doped glass. Compared with Mn2+ doped glass, the luminescence intensity of Mn2+ in Ce3+/Mn2+ co-doped glass was increased by 3 times. With the concentration of Mn2+ increasing from 0.8% to 2.0%, the energy transfer efficiency from Ce3+ to Mn2+ increases from 12.5% to 24.2%. Continuous tunable broadband emission from blue to red can be obtained by controlling the excitation wavelength. This new type of single-component Ce3+/Mn2+ co-doped glass is expected to replace the current conventional multi-component phosphor for pc-LED in optical spectroscopy including spectrophotometer, fluorescence spectrometer.关键词：fluorescent glasses;Ce3+/Mn2+ co-doped;broad spectrum;energy transfer
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发布时间：2021-09-13
Synthesis and Properties of Materials
- 摘要：A single-longitudinal-mode(SLM) thulium-doped fiber laser based on an F-P narrowband filter and compound rings cavity is proposed. The compound rings incorporated in the cavity can help to achieve SLM lasing by adjusting the cavity FSR and it also plays the role of narrowband filtering. A theoretical model which can numerically calculate the transmission spectrum of the complex multi-ring sub-cavity filter is proposed. The output wavelength of the laser source is 1 941.56 nm, and the optical signal-to-noise ratio is 55.8 dB. The wavelength and power fluctuations within 70 min were less than 0.019 nm and 1.464 dB, respectively. Experimental results also show that the laser operates in a stable SLM state. The frequency noise characteristic of the proposed SLM laser was measured by a homemade unbalanced Michelson interferometer, and laser linewidth under different measurement time was estimated from the frequency noise spectra based on the β-separation line method. The calculated laser linewidth in 2 ms measurement time is 14.194 kHz.关键词：fiber laser;thulium-doped fiber;single longitudinal mode;fiber Bragg grating
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发布时间：2021-09-13
Device Fabrication and Physics
- 摘要：A novel Schiff base fluorescent probe (N'-(4-(diphenylamino)benzylidene)-3-hydroxy-2-Naphtho-hydrazide)(L) was designed and synthesized using 3-hydroxy-2-naphthoic acid hydrazide and 4-diphenylaminobenzaldehyde as raw materials. The structure of L was characterized through 1H NMR, 13C NMR, HR-MS, IR and X-ray. The study found that probe L showed high sensitivity and selectivity response to copper ions(Cu2+) in H2O/DMSO(V∶V=3∶7, pH=7) solution. The possible mechanism of coordination between L and Cu2+ was studied by HR-MS, 1H NMR and DFT calculation. PAML was prepared by the method of doping L into polyacrylamide(PAM). PAML had high adsorption of Cu2+ and the removal rate of Cu2+ by PAML in water reached 96.99%, in addition, the color change could be distinguished by naked eyes under UV lamp. The microscopic morphology of PAML before and after adsorption of Cu2+ was observed by SEM-EDS.关键词：Schiff base;Cu2+;fluorescence probe;polyacrylamide(PAM) doping
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发布时间：2021-09-13
Luminescence Applications and Interdisciplinary Fields
- 摘要：The uniformity of light emission on the top surface of high-power-density LED devices with ceramic packages is a key indicator of this type of device when working at high currents. In this paper, the blue high-power LED flip chip(1.905 mm×1.830 mm(75 mil×72 mil)) is soldered on an aluminum nitride ceramic substrate(3.5 mm×3.5 mm) through Au-Sn eutectic welding, and then were made into white light emitting device and blue light components. The uniformity of micro-area luminescence on the top surface of these devices was also studied. The results show that when the current is less than 4 A, the light intensity distribution on the top surface of the blue device is uniform, and the uniformity is less affected by the N electrode hole and the electrode gap. When the current is 4-8 A, the light intensity distribution on the top surface of the blue light device is uneven. The light passing through the test area of the N electrode hole is stronger than the light intensity of the test area between the electrode holes. The light intensity of the electrode gap area is the lowest, which is far from the N electrode hole. The farther the test point, the lower the light intensity. The overall light intensity of the blue light device reaches saturation at 8 A, but the degree of light saturation and peak wavelength of different micro-area vary with the current change; when the white light device is at a current of 0-4 A, the light intensity distribution on its top surface is uniform.关键词：micro-luminescence;flip chip;electrode hole;electrode gap
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发布时间：2021-09-13
Luminescence Industry and Technology Frontier
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