最新刊期
卷 35 ， 期 2 ， 2014
- 摘要：Oxyfluoride glass ceramics with different Er3+/Yb3+ concentration were prepared by the melt-quenching method. The up- and down-conversion emissions were measured under 980 nm laser excitation. It is found that the intensities of up- and down-conversion emissions can be adjusted by changing the Er3+ doping concentration. The energy transfer model of up- and down-conversion emission is proposed, which clarifies the previous disagreements about up- and down-conversion energy transfer processes. The results will be used in controlling luminescent processes at different application fields.关键词：up-conversion;down-conversion;Er3+/Yb3+;glass ceramics;energy transfer117|171|1更新时间：2020-08-12
- 摘要：Graphene quantum dots (GQDs) were prepared by hydrothermal approach. ZnO@ Graphene quantum dots(ZnO@ GQDs) core/shell quantum dots were synthesized by in-situ polymerization. The morphology, structure and the optical properties of the samples were characterized by TEM, HR-TEM, XRD, UV-Vis and PL, respectively. The results show that ZnO@ GQDs core/shell quantum dots are spherical and good dispersible with a uniform particle size of ～7 nm. The GQDs shell was coated on the surface of ZnO QDs and formed the ZnO@ GQDs core/shell structure QDs. The blue shift and higher intensity of core/shell QDs compared with the pure ZnO QDs were observed in PL spectra, which suggested the introduction of the GQDs induced a synergistic luminescence effect. This novel material may be a potential candidate for LED display device.关键词：zinc oxide quantum dots;graphene quantum dots;ZnO@ graphene quantum dots with core-shell structure;synergistic luminescence effect121|36|2更新时间：2020-08-12
- 摘要：Reduced graphene oxide (rGO) films with different reduction degrees (C/O ratios) were prepared on FTO by electrochemical deposition method. rGO prepared from GO electrolyte, A-rGO prepared from electrolyte after alkali treatment, and B-rGO prepared from electrolyte after NaBH4 treatment, respectively. XRD, XPS, SEM and UV-Vis analysis were adopted to analyze the chemical structure and morphology of the films. The photoelectric properties of the films under visible light were studied. The results show that B-rGO film has the highest C/O ratio (8.1) and the lowest band gap (0.54 eV) among the three films, and its conduction band is almost closed to the FTO's. Under visible light illuminating, the films all generate cathodic photocurrent, and the photocurrent density increases with the increasing of C/O ratio. The photocurrent density of B-rGO (1 μA·cm-2) is the largest in the three films. In our work, we provide a feasible method to control the photoelectric property of rGO films by controlling their C/O ratios.关键词：reduced graphene oxide;photoelectric property;reduction degree;energy band structure90|267|4更新时间：2020-08-12
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Effects of Different Volume Ratio of Diglycol to Water on The Crystalline Phase of β-NaYF4：Yb3+,Er3+
摘要：NaYF4:20%Yb3+,2%Er3+crystal has been prepared via a simple hydrothermal route at different volume ratio of diglycol to water. X-ray diffraction (XRD), field emission-scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), and photoluminescence (PL) spectra were used to characterize and analysis the samples. FE-SEM images show that the samples have a smaller size with the increase of volume ratio of diglycol to water and finally can reach nanoscale. XRD results have proven that the volume ratios of diglycol to water have an effect on crystalline phase, and α-NaYF4 phase begins to appear in the products when volume ratio of diglycol to water reaches to 30/10 mL. The forming mechanism is proved to be correct and get a simulation diagram of the relationship between phase transition time and volume ratio of diglycol to water. TEM images indicate that the samples belong to the polycrystalline and have good crystallinity. Under the excitation of 980 nm semiconductor laser, β-NaYF4 crystal can emit bright blue/red upconversion luminescence.关键词：volume ratio of diglycol to water;αβ-NaYF4;particle size;up-conversion luminescence95|25|0更新时间：2020-08-12 - 摘要：Two new types of fluorene derivatives, 2,7-bis(3,5-bis(trifluoromethyl)phenyl)-9,9-diethyl fluorene (C33H22F12, Mr=646.51, compound 1) and 2,7-bis(4-fluorophenyl)-9,9-diethyl fluorene (C29H24F2, Mr=410.48, compound 2) were synthesized and characterized by elemental analysis, IR spectra and single-crystal X-ray diffraction. Compound 1 belonged to monoclinic crystal system, space group P21/c, and compound 2 was of triclinic with space group P-1. Their optoelectric properties were measured by UV-Vis absorption spectra and fluorescence spectra. The results show that compound 1 and 2 have low-energy absorption bands ranging from 350 nm to 400 nm in dichloromethane solution or solid film, which can be assigned to the π-π* charge transfer transitions. The optical band gaps (Eg) of 1 and 2 are estimated to be 3.31 eV and 3.30 eV, respectively. The title compounds exhibite strong blue photoluminescence under 330 nm excitation at room temperature. The fluorescence quantum yields in CH2Cl2 of compound 1 and 2 are 0.62 and 0.61, and solid-state lifetimes are 6.39 ns and 9.00 ns, respectively.关键词：fluorene-based derivatives;synthesis;crystal structure;film;spectroscopic properties111|200|3更新时间：2020-08-12
- 摘要：Multicolor fluorescence labeling techniques used in biological multiplex detection can achieve fast, real-time, simultaneous information for a large number of target bio-molecules. Using upconversion nanoparticles as multicolor fluorescent probes can effectively decrease the influence of auto-fluorescence from biological molecules on the fluorescence signal from the nanoparticles. In this paper, the core-shell structured upconversion nanoparticles were prepared by a facile solvothermal method using polyvinylpyrrolidone (PVP) as the surfactant. By co-doping sensitizer and activator ions in the cores and/or shells, the relative intensity of the emission peak was changed. The multicolor fluorescence was obtained from different nanoparticles with different color and intensity of the emission spectra. These nanoparticles were spherical and their sizes were about 30 nm. With the excitation of a 980 nm diode laser, those nanoparticles emitted bright upconversion luminescence from red to blue-violet.关键词：upconversion;multi-color fluorescence;rare earth nanoparticles;core-shell structures127|360|2更新时间：2020-08-12
- 摘要：A facile, environmentally friendly, low cost method was employed to synthesize perovskite-type LaAlO3 powders. The stoichiometric mixtures of La(OH)3/La2O3, and Al(OH)3 were activated by a hydrothermal treatment in teflon-lined stainless steel autoclave at 220℃ for 3 d, and then the precursors were quickly heated to 900℃ and reacted for 5 h to obtain LaAlO3. The obtained samples were characterized by X-ray diffraction (XRD) and photoluminescence (PL) spectra. XRD result shows that LaAlO3 crystal structure belongs to the rhombohedral system with the space group of R3c (No.167). PL results indicate the main emissions of LaAlO3：Eu3+ come from the magnetic dipole-dipole 5D0→7F1 transition and the electric dipole-dipole 5D0→7F2 transition. The ratio value of the intensity of Eu3+:5D0→7F2 transition to the intensity of Eu3+:5D0→7F1 transition increases with the increase of Eu3+ concentration. Host absorption of LaAlO3：Eu3+ in the VUV range is weaker than that of O2--Eu3+ charge transfer band in the UV range.关键词：LaAlO3：Eu3+;green chemical synthesis;XRD;luminescent properties108|78|0更新时间：2020-08-12
- 摘要：Diluted magnetic semiconductors Zn1-2xFexNixO with different consistency ratio (x=0,0.025, 0.05, 0.1) have been synthesized by hydrothermal method.The samples were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and X-ray energy dispersive spectrometry (XEDS), and the optical and magnetic properties of the products were investigated by Raman scattering spectra (Raman), photoluminescence spectra (PL) and vibrating sample magnetometer (VSM).The experiment results show that all samples synthesized by this method possess wurtzite structure with good crystallization, no other impurity phase appeared, and the morphology are nanorods and well dispersed. All the Fe2+ and Ni2+ successfully substituted for the lattice site of Zn2+ and generate single-phase Zn1-2xFexNixO, Raman spectra occurred red shift and the photoluminescence intensity were quenched due to the crystal defects and internal stress increase with iron and nickel co-doping. In addition, the obvious ferromagnetic was found in all samples at room temperature, and the saturation magnetization enhanced with the increase of iron and nickel doping content.关键词：co-doped ZnO;hydrothermal method;optical properties;ferromagnetism89|234|0更新时间：2020-08-12
- 摘要：Hydrothermal etching method was employed to fabricate four iron-passivated porous silicon (IP-Si) samples on two silicon wafers with different crystal orientations. The morphology of the samples was observed by scanning electron microscope (SEM), and no correlation between the porous structures and the crystal orientation was found. Under 300 nm excitation, the samples emitted strong orange light with a peak at ～618 nm and FWHM of ～132 nm. Furthermore, Fourier transform infrared spectroscopy was employed to characterize the chemical bonds on the surface of porous structures. Finally, the physical mechanism for the photoluminescence of IP-Si was interpreted by using the quantum confinement-luminescence center model, and the tiny difference in PL can be ascribed to the small inconsistency of non-bridging oxygen hole center distributed in IP-Si.关键词：porous silicon;iron passivated;photoluminescence;nonbridging oxygen hole center;hydrothermal etching89|149|1更新时间：2020-08-12
- 摘要：Er：YbGG nanopowder was prepared by sol-gel method. XRD, TG-DTA, SEM and spectra analysis were utilized to investigate the phase structure and spectrum properties of the powder. The experiment results indicate that the fine Er：YbGG nanopowder belongs to a cubic phase with a space group of Ia-3d and lattice parameter a=1.216 2 nm. Under 980 nm excitation, an intensive fluorescence emission peak appears near 1 533 nm in the emission spetrum of Er：YbGG nanopowder, and the high intensity of the emission is attributed to the energy transmission between Yb3+ and Er3+ ions.关键词：sol-gel method;Er：YbGG nanopowder;phase structure;fluorescence spectrum120|208|0更新时间：2020-08-12
- 摘要：Organic thin film transistors with different buffer layers were investigated. Electric measurements reveal that 4,7-diphenyl-1,10-phenanthroline is a better buffer layer material than lithium fluoride. In comparison with the device with no buffer layer, the device with 4,7-diphenyl-1,10-phenanthroline (3 nm) buffer layer obtains an enhanced mobility of 0.302 cm2·V-1·s-1, threshold voltage of-31.2 V and on/off current ratio of 6.2×102. The improvements of the device performance are attributed to the reduction of barrier height and the contact resistance at Au/pentacene interface.关键词：OTFT;pentacene;electric performance131|164|0更新时间：2020-08-12
- 摘要：The performances of polymer solar cells (PSCs) depend on processing conditions strongly. In order to increase the crystalline content of polymer and therefore improve the photovoltaic performance of devices, a combinative annealing process featured toluene vapor pretreatment and thermal annealing was introduced to the organic photovoltaic device fabrication, resulting in a high PCE up to 3.25% for P3HT： PCBM-based solar cells. The results of XRD and AFM further revealed that the improvement of JSC, VOC and FF were attributed to the improved P3HT crystallinity and chain ordering which facilitated photogenerated exciton dissociation and charge-carrier transport, compared with solvent or thermal annealed samples.关键词：solvent vapor annealing;thermal annealing;polymer solar cells99|167|0更新时间：2020-08-12
- 摘要：The surface morphology and the interface electronic states of Indium-tin-oxide (ITO)/Rubrene were investigated by atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS). The AFM results manifest that the Rubrene film deposited on ITO is very uniformity. The XPS results show that there are three main peaks in the C1s spectrum of the origin surface, which located at 282.50, 284.70, 289.30 eV, respectively. They are associated with C—Si, C O, C—C bonds. With the increasing of sputtering time, the peak corresponding to the aromatic C becomes intensely while the other peaks disappear rapidly. As the removing of the oxygen contamination on the surface, the O1s peak weakens firstly and then strengthens gradually. The O atoms mainly bond to C,and form O C, C—O—C and aldehyde group in the interface. The peaks of In3d and Sn3d strengthen slowly, and become stable near the interface of ITO/Rubrene. The peak of C1s, In3d and Sn3d moves toward lower binding energy, indicating an inter-diffusion system formed by the interaction of Rubrene film and ITO in the interface.关键词：XPS;Rubrene;chemical shift;interfacial state125|242|2更新时间：2020-08-12
- 摘要：51 V high voltage LED (HV LED) was designed and fabricated. Firstly, the HV LED was tested by large current attack, then the damage reason was analyzed. The key part's thermal parameters distribution model of HV LED was simulated by using finite element analysis software ANSYS, and the steady distribution of temperature was achieved. By analyzing the infrared thermal image, the reason of HV LED failure after large current attack was gotten. The core particle electrode burned at the connection part which was thin and narrow, so the resistance was large. It provided a good reference for the sequence design of more reliable HV LED. Meanwhile, the chips were packaged into white lamp with color temperature of 5 000 K and blue lamp, respectively. The thermal resistance of the white lamp was about 4℃/W higher than the blue lamp without phosphor coating, and it was also higher than the conventional 1 W LED. The deep groove structure and numerous interconnected electrode structure of HV LED may be the reason of the thermal performance of high voltage LED worse than the conventional 1 W LED.关键词：high voltage LED;thermal analysis;ANSYS;thermal resistance;deep groove structure115|131|1更新时间：2020-08-12
- 摘要：A photodetector was prepared by a heterojunction of p-type silicon and (perylene-3,4,9,10-tetracarboxylic acid dianhydride) PTCDA,with comb-shape Au thin film acting as electrode and light-incident window. The experiment results show that the thickness of PTCDA and Au film have a great influence on the photoresponsivity and the external quantum efficiency of the photosensitive diode. The light responsivity can reach the maximum value of 0.3 A/W when PTCDA thickness is 100 nm. Then, the devices with the optimized 100 nm PTCDA and different thickness of Au electrode were fabricated. The optimal light responsivity can reach 0.5 A/W with 20 nm Au thickness.关键词：organic/inorganic heterojunction;photodetector;PTCDA;thickness optimization77|144|0更新时间：2020-08-12
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Modeling Calculation for Field Enhancement Factor on A Carbon Nanotube Array with Parallel Back-grid
摘要：A model on the carbon nanotube array with parallel back-grid was proposed. The actual electric field at the top of carbon nanotubes and field enhancement factor were calculated analytically by using mirror image charge method based on the superposition principle of electric field. The effects of the geometrical parameters of the carbon nanotube device on the field enhancement factor were investigated. The calculation results show that the carbon nanotube array has the best density for field emission, the inter-tube distances are double height of carbon nanotubes and the electron emission ability of carbon nanotube near the edge of carbon nanotube array is larger than the carbon nanotube at the center of this array. The field enhancement factor increases with the width of back-grid, and decreases with the thickness and space of the back-grids.关键词：parallel back-grid;carbon nanotube array;field enhancement factor;floated sphere134|158|0更新时间：2020-08-12 - 摘要：The OLED devices with TBPe(2, 5, 8, 11-tetratertbutylperylene) doped (poly ) as luminescent layer were fabricated, and the effect of the doping ratio of TBPe to MEH-PPV on the device performance was investigated. The highest efficiency was obtained in the device with the structure of ITO/PEDOT：PSS/MEH-PPV/TBPe(0.5 nm)/Al. The luminous intensity increased by 325% compared with the standard device, the optimized doping ratio of TBPe：MEH-PPV was 30：100 in weight, and the luminous intensity of the device with the optimized TBPe doping ratio increased by 44% compared with no doping device. In order to enhance the electrons injection, the EIL (electron injection layer) of Alq3 and modified layer of Liq and LiF was employed. The brightness of OLED with multi-layer structure and modified layer of Liq and LiF could reach to 4 162 cd/m2 and 4 701 cd/m2, respectively. The EL wavelength of all the devices is 580 nm that is attributed to MEH-PPV, and the doping of TBPe plays a role of enhancer for the lumininescence of MEH-PPV. .关键词：MEH-PPV;organic electroluminescence device;TBPe;dopant concentrations91|118|0更新时间：2020-08-12
- 摘要：Europium fluoride (EuF3) was employed to modify the source and drain electrodes in CuPc based OFETs, in which they were fabricated by low work function metal Ag. The Influence of EuF3 with different thickness on devices was investigated. The contact resistance reduced from 23.65×105 Ω·cm to 3.86×105 Ω·cm as the thickness of EuF3 increased from 0 nm to 0.6 nm, which lead to an increased field-effect mobility from 1.5×10-3 cm2·V-1·s-1 to 4.65×10-3 cm2· V-1·s-1. The UPS results show that an interfacial dipole potential is formed between the silver electrodes and the organic semiconductor layer. It raises the surface work function of the source and drain electrodes and reduces the hole injection barrier, thus decreases the contact resistance and improves the hole injection efficiency.关键词：field effect transistors;europium fluoride;modified layer101|80|0更新时间：2020-08-12
- 摘要：Evaluation of drought resistance during germination of maize is one of the basic problems that have not been solved in modern water-saving agriculture, while biological delayed luminescence technology may solve this problem. In order to explore the method of using delayed luminescence to evaluate drought resistance in maize germinating stage, the delayed luminescence of two maize varieties Wanrui No.168 and Yandan No.8 germinated in PEG-6000 solution with osmotic potential of-0.1 MPa and-0.3 MPa was measured. The results show that the integrated intensity of delayed luminescence of Wanrui No. 168 and Yandan No. 8 increase gradually with the germination process. Drought stress with osmotic potential of-0.1 MPa and-0.3 MPa inhibits the increase in integrated intensity of delayed luminescence of Wanrui No.168 and Yandan No.8, and the stronger the stress, the greater the difference of integrated intensity of delayed luminescence between two maize varieties. The relative change rate of delayed luminescence is defined as RDL. The study found that the change of RDL of Wanrui No. 168 and Yandan No. 8 was the same as the change of seed germination drought index and storage material transport rate under drought stress. It indicated that the size of RDL during germination under drought stress could be used to evaluate drought resistance of maize during seed germination.关键词：biological delayed luminescence;evaluation of drought resistance;maize germination;nondestructive testing99|136|6更新时间：2020-08-12
- 摘要：In traditional LED display screen, optical energy utilization rate and imaging filling ratio are very low. Based on the theory of non-imaging optics, a structure system and a design method are developed to improve optical energy utilization rate and imaging filling ratio of full-color LED display. Using compound parabolic concentrator (CPC), light diverging angle emitted from LED chips is transformed and compressed. Therefore, total reflection loss on external surface of display module can be avoided. Accordingly, optical energy utilization rate of display system is greatly improved. Based on uniform lighting principle of integrator-rod and light distribution principle of scattering, imaging filling ratio, pixel uniformity and primary color multiplexing area of LED display screen are improved. According to the above method, a P10 mm full-color LED display module is designed. Using LIGHTTOOLS software, the display module system is simulated and analyzed. The simulation results show that, optical energy utilization rate of system is higher than 70%, imaging filling ratio closes to 100%, uniformity of unit pixel area is better than 85%. The display module has the advantages of high energy utilization rate, high imaging filling ratio, uniform and soft showing, easy manufacturability.关键词：LED display screen;imaging filling ratio;optical energy utilization rate;non-imaging optics104|140|3更新时间：2020-08-12
- 摘要：CdSeTe quantum dots (QDs) were synthesized by the reaction of CdCl2·2.5H2O, Na2SeO3, Na2TeO3 and N2H4·H2O in water and in the presence of 3-mercaptopropionic acid (MPA) as stabilizer. Comparing with the CdTe QDs, the CdSeTe alloy QDs showed an obvious red-shifted emission with the color-tune capability to the near-infrared (NIR) wavelength. The fluorescence of the CdSeTe QDs could be quenched by Cu2+ ions. A simple and rapid method for Cu2+ ions determination was proposed using the NIR CdSeTe QDs as fluorescent probes. Under optimal conditions, the response was linearly proportional to the concentration of Cu2+ ions from 10 to 200 μg/L, the limit of detection was 1.13 μg/L. The developed method was successfully applied to the detection of trace Cu in real samples, and the results coincided with the ICP method.关键词：near-infrared-emitting quantum dots;copper ions;fluorescence quenching122|152|2更新时间：2020-08-12
- 摘要：Technology of surface enhanced Raman scattering (SERS) on substrate based on film of noble metal nanoparticles has many advantages of application and potentiality in molecular biology, immunoassay of medicine and organic molecules, etc. In this work, in order to research SERS, sodium citrate was employed as aggregation reagent to induce the aggregation of Ag nanoparticles modified by 4-mercaptobenzoic acid. And the "hot spots" resulted from the aggregation were used to enhance the SERS spectra. Strong SERS spectra of 4-mercaptobenzoic acid molecules were observed. In conclusion, "hot spots" of aggregation of Ag nanoparticles modified by 4-mercaptobenzoic acid in aqueous solution has highly effect of SERS.关键词：aggregation of silver nanoparticles;aqueous solution;hot spot;SERS spectra122|174|1更新时间：2020-08-12
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