最新刊期
卷 40 ， 期 11 ， 2019
- 摘要：In order to elucidate the effect of solvent on the luminescence of MoS2 quantum dots, MoS2 quantum dots were prepared by liquid phase stripping method in a mixed solvent of N-Methyl pyrrolidone(NMP) and 1,2-dichlorobenzene(DCB). The dialysis method was utilized to compare the luminescent properties of the solvent and the solution containing the MoS2 quantum dots. The results show that the quantum dot size distribution is uniform and the particle size is about 2.4 nm. The E2g1 and A1g Raman characteristic peaks of the MoS2 material were observed at 381 cm-1 and 406 cm-1 in the Raman spectrum. It was found that the presence of MoS2 quantum dots caused a significant change in the absorbance spectra around 260-400 nm, and the emission wavelength of MoS2 quantum dots in the mixed solvent seriously depended on the excitation wavelength. The results of dialysis experiments with water as the external environment show that the HOMO level of DCB solvent will cause multiple emission peaks in the luminescence of MoS2 quantum dots near 442 nm, but the emission wavelength will no longer change with the excitation wavelength, indicating the dependence of the luminescence of MoS2 quantum dots on the excitation wavelength is due to the luminescence of the organic solvent under ultraviolet excitation.关键词：MoS2 quantum dots;UV-Vis absorption spectroscopy;emission spectroscopy;optical properties148|115|0更新时间：2020-08-12
- 摘要：Lanthanide-doped upconversion luminescence generally features in narrow emission band and fixed emission wavelength. In order to obtain photo upconversion with wide-spectrum emission characteristic upon near-infrared laser excitation, upconversion luminescence of CaF2:Yb3+ and CaF2:Yb3+/Mn2+ materials is investigated. Yb3+ and Mn2+ ions are codoped into CaF2 materials as activators. CaF2:Yb3+ and CaF2:Yb3+/Mn2+ bulky materials are synthesized using high-temperature solid state reactions. The upconversion luminescence properties of Yb3+ doped and Yb3+-Mn2+ codoped CaF2 materials are investigated upon 980 nm laser excitation. The experimental results indicate that compared with CaF2:Yb3+ system, a new upconversion emission peaked at 620 nm is obtained in CaF2:Yb3+/Mn2+ materials. The cooperative energy transfer from Yb3+-dimers to Mn2+ is considered to be the main reason for populating excited state of Mn2+ ions and the emission peaked at 620 nm comes from its4T1→6A1 transition. The cooperative energy transfer from Yb3+-dimers to Mn2+ is efficient in CaF2:Yb3+/Mn2+ materials to populate excited Mn2+ and to obtain room-temperature upconversion emission of Mn2+ ions.关键词：Yb3+ dimers;transition metal;Mn2+ ions;cooperative energy transfer;upconversion luminescence198|246|1更新时间：2020-08-12
- 摘要：Due to the large optical absorption coefficient and low raw material cost, tin(Ⅱ) sulfide (SnS) has shown tremendous application foreground for the novel thin film solar cells. In order to achieve the controllable preparation and then investigate the photovoltaic property of SnS thin films, under different process parameters, we fabricate a series of SnS thin films with the pulse electro-deposition method. Then, the crystal structure and surface morphology of SnS thin film are investigated by X-ray diffraction(XRD) and scanning electron microscopy(SEM). And the relationship between the two different turn-on pulse potentials and optical band-gaps is explored by UV-Vis-NIR absorptance spectra. Meanwhile, both the conductivity type and doping concentration are evaluated by Mott-Schottky equation. On the basis of the content above, the Au/SnS/CdS/ITO heterojunction-based photovoltaic prototype device is designed and demonstrates the open circuit voltage of 111 mV and short circuiting current density of 20.81 μA/cm2, which will provide theoretic and experimental basis for further research of low-cost and high-performance absorbing layer of thin film solar cells.关键词：tin(Ⅱ) sulfide;thin film;pulse electro-deposition method;photovoltaic prototype device187|259|0更新时间：2020-08-12
- 摘要：Blue light-emitting fluorescent materials have great commercial application potential as blue-light emitter for organic light-emitting devices(OLEDs). In this work, a series of blue light-emitting fluorescent materials with twisting A-π-D-π-A configuration were designed and synthesized, in which 4-(9H-carbazol-9-yl)benzeneamine(CzPA) as electron donor unit and trifluoromethylphenyl (FMP) as electron acceptor unit. To investigate the relationship between π-conjugated bridge and photophysical properties, the benzene, 9,9'-dioctyl-9H-fluorene and di(9,9'-dioctyl-9H-fluorene) are introduced as π-conjugated bridge between CzPA and FMP, which are named as CzPA-B-FMP, CzPA-F-FMP, CzPA-DF-FMP, respectively. By comparing photophysical properties in detail, it can be concluded that combining with charge transfer characteristic, the local excitation characteristic of excited state can be enhanced with increasing length of π-conjugated bridge between CzPA and FMP, which can improve the fluorescent quantum efficiency of these materials and external quantum efficiency of blue light OLED. But, too longer π-conjugated units will also deteriorate photophysical properties for bigger intermolecular conjugating effect.关键词：OLED;blue light-emitting;fluorescent materials;charge transfer;EQE182|76|1更新时间：2020-08-12
- 摘要：Perovskite type LaFe0.75Cr0.25O3 and La0.75Mg0.25Fe0.75Cr0.25O3 powders were prepared by high temperature solid state reaction at 1 300℃ for 2 h. In order to study the theoretical mechanism affecting the emissivity, the phases structure of the material and the emission characteristics in near-infrared band were analyzed and characterized by XRD, FT-IR, SEM, XPS and Upward IntegratIRTM etc, the electronic structure was analyzed by first-principles calculation. The results show that the emissivity of the powder in the 1-5 μm band increases, but the absorption rate of the Cr single-doped sample increases little, while the Mg-Cr co-doped powder increases greatly, and the absorption rate in the near-infrared above 0.9. The reason is that the crystal is distorted after Cr single-doped, but the concentration of free carriers does not increase. After Mg-Cr co-doped, the distortion is intensified and more oxygen vacancies and small polarized molecules are formed, which enhance the free carriers absorbtion. The hybrid energy level that formed by orbitals of Cr 3d and O 2p causes the powder forbidden band width to be narrowed, the same as the Cr 3d orbital in the near-Fermi level conduction zone. Although Mg does not directly affect the band gap value, it indirectly changs the morphology of B-position elemens, and more small polarized molecules are produced. Therefore, comopared with the LafeO3 band gap value (3.817 eV), the Mg-Cr co-doped(0.109 eV) has the largest decrease, and the single-adoped(2.406 eV) secondly.关键词：lanthanum ferrite;doping;infrared emissivity;bandgap width147|85|0更新时间：2020-08-12
- 摘要：Solar pump laser can directly convert sunlight into laser, which has great application prospect in space solar power station, deep sea and other fields. Cr,Nd:YAG is a kind of solar pump laser medium with great potential. 0.1%Cr,1.0%Nd:YAG transparent ceramics with high optical quality were fabricated by solid-state reactive sintering using high-purity Y2O3, α-Al2O3, Nd2O3 and Cr2O3 powders as raw materials. The spectral characteristics and laser parameters of 0.1%Cr,1.0%Nd:YAG ceramics were studied in this paper. According to the solar irradiance spectrum, the absorption and fluorescence spectra of Cr,Nd:YAG ceramics, the laser parameters of Cr,Nd:YAG ceramic laser, such as pump rate, threshold solar concentration ratio, effective emission cross section, saturation intensity, and the threshold input power were calculated under different conditions. The study found that the in-line transmittance of 0.1%Cr,1.0%Nd:YAG ceramics with the thickness of 1.0 mm reaches 81.5% at 370 nm and 84.0% at 1 064 nm, the cell density is 4.57 g/cm3, and the optical scattering loss is about 1.4% cm-1, the solar irradiance in the absorption band is about 42% of the solar constant. The results show that Cr,Nd:YAG ceramics are ideal laser media for solar pumping. High power laser output can be obtained by optimizing the focusing system, pumping mode and ceramic size.关键词：Cr;Nd:YAG ceramics;solar pump;spectral properties;laser parameters199|342|2更新时间：2020-08-12
- 摘要：Three samples of GaAs/AlAs multiple quantum wells with different quantum-well widths are grown on semi-insulating (100) p-type GaAs substrates by the molecular beam epitaxy with Be acceptors δ-doped at the center of GaAs well layers. Three corresponding two-terminal devices are fabricated by photolithographic and semiconductor manufacturing technologies based on these samples. The device current-voltage characteristics are measured at temperatures in a range of 4-200 K. The resonant tunneling of heavy- and light-holes through Be δ-doped GaAs/AlAs multiple quantum wells are clearly observed. It is found that the position of resonant tunneling for light-heavy holes shifts to higher voltage with decreasing quantum-well sizes, which is in good agreement with the results calculated by the AlAs/GaAs/AlAs double-barrier theoretical model. However, as the measured temperatures increase, two peaks of resonant tunneling of light-holes move toward lower voltage, while one of the resonant peaks behaves as an oscillating mode at 150 K.关键词：resonant tunneling;heavy- and light-holes;GaAs/AlAs multiple quantum wells;current-voltage characteristics;δ-doped184|39|0更新时间：2020-08-12
- 摘要：Photothermal therapy is based on the heat generated by photothermal agents under laser irradiation, and then kills tumor cells at high temperature. Real-time monitoring of microscopic temperature changes in photothermal process plays a very important role in optimizing the therapeutic effect. Europium(Ⅲ) chelates display line spectrum, long fluorescence lifetime and a highly temperature-dependent emission, which can be used to detect the temperature of photothermal process. The nanosystem, integrating temperature monitoring and the photothermal property, is promissing in the field of photothermal therapy. Herein, we designed a gold nanospheres-attached Eu(TTA)3-(TPPO)2-loaded functional nanomaterials. The functional nanoparticle displays good temperature-dependent fluorescence performance. The emission peak(615 nm) of Eu3+ decreases up to 52.7% from 35℃ to 65℃, indicating that the nanoparticles has high temperature sensitivity. Under laser irradiation, functional nanoparticles can produce photothermal effects, and real-time temperature monitoring of photothermal process can be performed based on its own temperature sensitivity.关键词：europium(Ⅲ) chelates;temperature-sensitive nanoprobe;gold nanospheres;temperature monitor180|93|1更新时间：2020-08-12
- 摘要：Zn1-xCuxAl2O4 (x=0, 0.05, 0.10, 0.15, 0.20) nanoparticles with different doping ratios were synthesized by hydrothermal method and heat treatment technology. The crystal structure, morphology, element distribution, binding energy and optical property of the samples were characterized by X-ray diffraction(XRD), field emission transmission electron microscopy(FETEM), Fourier infrared spectrum(FT-IR), X-ray photoelectron spectroscopy(XPS), photoluminescence(PL) and UV-Vis spectroscopy(UV-Vis), and the energy band structure of various defects in ZnAl2O4 structure was calculated by means of the first-principle calculations. The experimental results show that Zn1-xCuxAl2O4 nanoparticles prepared by this method possess spinel structure. The XPS spectra demonstrate that the doped Cu2+ all occupy the tetrahedral sites for Zn0.9Cu0.10Al2O4 samples, the PL spectra show luminescence quenching occurs for Cu2+ doped samples, the UV-Vis result shows the new absorption peak appeared after Cu2+ doped, and the optical properties of the sample are explained by the first principle calculations.关键词：doped;ZnAl2O4;first-principle calculations;optical properties174|148|1更新时间：2020-08-12
Synthesis and Properties of Materials
- 摘要：In order to achieve an optical absorber working in the whole visible frequencies, we design a one-dimensional photonic crystal embedded by graphene layers. We study its propagation characteristic through the modified transfer matrix method. Through the parameter optimization and cascade structures, the structure can achieve the absorption rate 0.88 in the whole visible frequencies except for two special frequencies on normal incidence. The absorber is also found to be insensitive to the incidence angle.关键词：graphene;one-dimensional photonic crystal;absorption176|228|2更新时间：2020-08-12
- 摘要：Red-light external cavity semiconductor lasers are constructed by using reflective volume-Bragg-grating(VBG) as a feedback component, experimental research on the output characteristics of the device.The influence of the position of the VBG on the far field characteristics of the red-light external cavity semiconductor lasers is mainly studied. Results show that, reducing the distance between the VBG and the laser chip can improve the mode-locking effect, narrow the spectrum and improve the divergence angle of the slow-axis beam. Using a VBG with a diffraction efficiency of 20%, the output wavelength of the semiconductor lasers can be stably locked around 634 nm, the line width of the output spectral can be compressed to about 0.7 nm, and the output power can reach 1.06 W.关键词：laser;semiconductor laser;volume-Bragg-grating;spectrum175|289|3更新时间：2020-08-12
- 摘要：To realize photodetection ranging from UV to visible region with high responsivity and low cost, a novel broadband photodetector based on mixed-dimensional van der Waals (vdW) heterojunction comprising a two dimensional (2D) n-type InSe nanosheet and a p-type Se microwire is proposed. Benefiting from the high crystal micrometer-sized Se microwire and two dimensional InSe nanosheet, the device exhibits a high responsivity ranging from UV to visible region with a sharp cutoff at 700 nm. It is worth pointing out that the responsivity of the device could reach up to 108 mA/W at 460 nm at -5 V. The responsivity is 800% larger than that of pristine Se device. These investigations will broaden our fundamental knowledge of vdW heterostructures, which would open additional opportunities for fabricating low dimensional photodetectors with high performance.关键词：semiconductors;van der Waals heterojunction;photodetector;multilayer structure234|123|0更新时间：2020-08-12
- 摘要：In order to reduce far-field divergence angle of semiconductor laser along slow axis and improve slow axis beam quality, a new type of adiabatic package structure is proposed. With this structure, the strength of thermal lens effect of the laser chip can be reduced. We have simulated the lateral heat distribution of broad-area semiconductor laser chip with the new structure by ANSYS 18.0, the model is based on the law of heat conduction(Fourier's law).The beam quality of 808 nm In0.08Ga0.78Al0.14As/Al0.37GaAs broad-area semiconductor laser was experimentally investigated. Measurement is based on charge coupled device(CCD) image acquisition analysis method. The results show that the adiabatic package structure can reduce slow axis divergence angle by about 40%, and the slow axis divergence angle is more stable as the working currents change. Moreover, the corresponding beam parameter product (BPP) and beam quality factor M2 are also reduced by about 33% and 30%. The narrower the contact width between chip and heat sink is, the better the effect of the improvement will be. The introduction of the air gap in the adiabatic package leads to a deterioration of photoelectric characteristics. The output power P reduces by 14%, electro-optical conversion efficiency η reduces by 8.7%. Adiabatic package method has guiding significance to the improvement of the slow axis beam quality of 808 nm broad-area semiconductor lasers.关键词：slow axis divergence angle;thermal lens effect;adiabatic package202|227|1更新时间：2020-08-12
- 摘要：A narrow-strip single-longitudinal-mode semiconductor laser based on periodic anodes with a central wavelength of approximately 674 nm is demonstrated. The manufacturing process is simple, the periodic trenches and periodic electrode structures fabricated only using i-line lithography and conventional etching techniques, which ensures that the device operates under a gain coupling mechanism, thereby enabling the output of a single longitudinal mode laser. When the injection current is 85 mA and the test temperature is 18℃, the output power of the laser is 2.603 mW. When the injection current is 60 mA, the device maintains a single longitudinal mode operation at different test temperatures. When the room temperature is 16℃, the measured spectral linewidth of the device can reach 2.42 pm, and the side mode suppression ratio is 47 dB. Owing to the low-cost fabrication methods and good performances, our single-longitudinal-mode devices can be used for widespread practical applications.关键词：periodic electrode;single longitudinal mode laser;semiconductor laser142|241|0更新时间：2020-08-12
- 摘要：High threshold is the main obstacle to achieving direct electrically pumped polymer lasers. In this paper, high-performance blue light material, polyfluorene(PFO) is used as a laser gain medium. A planar optical microcavity with appropriate structure is designed based on cavity quantum electrodynamics principle. The self-absorption of active layer material is further reduced by lowing the thickness of polymer layer. Optical microcavity is constructed by DBRs with two different material system. The extra optical loss is cut down in the preparation process of top DBR, and the optical resonator with low loss and high Q value is finally obtained. An optically pumped low threshold polymer laser with a peak wavelength of 443 nm and a threshold of only 30 mW/cm2 is realized by effectively controlling the spontaneous emission and stimulated emission characteristics of PFO.关键词：optical pumping;threshold;optical microcavity;polymer laser;polyfluorene162|162|2更新时间：2020-08-12
Device Fabrication and Physics
- 摘要：Progesterone(PROG) is a common drug for treatment of threatened abortion in clinical practice, but its transport mechanism in human body is still unclear. Here, fluorescence spectrum, infrared spectrum, and molecular docking were employed to comprehensively analyze the mechanism underlying the interaction between PROG and bovine serum albumin (BSA). The results indicated that a stable PROG-BSA complex was formed and van der Waals forces played a major role in this binding process. The order of magnitude of the binding constants (Ka) was 1.423×104 L·mol-1 at normal body temperature of human. Solution experiments showed that the binding site for PROG was located at Sudlow site I of BSA, and the distance between PROG and BSA was obtained(r=1.63 nm) according to the Förster theory of non-radiative energy transfer. Infrared spectrum results revealed the changes in secondary structure of the protein upon interaction with PROG. The results of Ligplus+ highlighted the role of hydrogen bonds in the bind process whereas in well agreement with solution experiments. The data of spectrum and molecular docking experiments confirmed each other, which provided data support for revealing the transport and storage process of PROG in human body. This work will be helping us to understand the binding mode of PROG-BSA system and provide a new insight about the effect of PROG on human health.关键词：progesterone;bovine serum albumin;molecular docking;fluorescence spectrum;interaction220|231|5更新时间：2020-08-12
Luminescence Applications and Interdisciplinary Fields
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