最新刊期
卷 33 ， 期 2 ， 2012
- 摘要：The fluorescence emission of rare earth doped nanocrystal depends on the optical active ion and its matrix structure. For a given system, it can be adjusted either by changing the characteristics of the particle or by improving the environmental conditions around the particle. The characteristics of the particle can be modified by adjusting the content and structure of the matrix crystal, codopant ion and its concentration, morphology and size of the particle, surface modification as well as the introduction of enhancement through metallic surfaces. The environmental change could refer to the environmental temperature and the excitation of the system. In current paper, possible factors that influence the fluorescence emission as well as frequently used techniques for controlling the fluorescence properties are reviewed briefly. Changes in local symmetry and interactions of optically active ion with neighbored ions, which are mainly induced by adjusting the crystal structure and codoping process, are discussed intensively.关键词：rare earth ions;nanocrystal;fluorescence emission127|202|2更新时间：2020-08-12
- 摘要：Er3+ doped NaYF4 up-conversion luminescence material was successfully prepared by hydrothermal method. The X-ray diffraction (XRD) indicates that when the reaction temperature is 180 ℃ or 200 ℃, the crystal structure is a mixture of hexagon and quadrangle, when the reaction temperature is 220 ℃, the crystal shows a hexagon phase structure. The scanning electron microscopy (SEM) and transmission electron microscopy (TEM) results indicate that the crystal grain has a hexagon structure, and possesses an average size of about 100 nm with a uniform distribution. The fluorescence spectra show that under the exciting wavelength of 500 nm, the sample emits ultraviolet light. It can be concluded from the energy level diagram that the ground state 4I15/2 electrons of Er3+ will first transmit to 2H11/2 and 4S3/2 levels, and then give out the 310 nm and 340 nm ultraviolet light through the energy transmit up-conversion (ETU) process, respectively. Considering the up-conversion emission mechanism, both the 310 nm and 340 nm up-conversion peaks can be characterized as biphotonic processes. The research results demonstrate that the Er3+ doped NaYF4 exhibites an ultraviolet up-conversion light emitting property;and it has a promising way in biomedical imaging, photocatalytic reaction and biomark process, etc.关键词：NaYF4∶Er3+;ultraviolet upconversion emissions;hydrothermal synthesis137|136|5更新时间：2020-08-12
- 摘要：ZnO nanorods arrays were prepared by cathodic electrochemical deposition method,in which ITO-coated glass substrate were used as a cathode. The electrolyte consisted of an aqueous solution of Zn(NO3)2·6H2O with the concentration of 0.01 mol·L-1 and KCl supporting electrolyte with the concentration of 0.1 mol·L-1 were used for the depositing. The influences of depostion potential and buffer layer on the preferred orientation and density of the ZnO nanorods were investigated by scanning electron microscope (SEM) and X-ray diffraction (XRD). A significant variation of density and orientation of ZnO nanorod arrays were obtained by changing the deposition time of buffer layer. Pre-deposition ZnO buffer layer relieved the lattice mismatch between ZnO and ITO substrate, and also provided the nuclei centers for the ZnO nanorods. SEM and XRD data showed that ZnO nanorods with the highest density and best c-axis orientation can be achieved by pre-depositing a buffer layer at applied potential of -1.10 V and last for 60 s.关键词：electrodeposition;ZnO nanorod;controlled density;buffer layer83|336|1更新时间：2020-08-12
- 摘要：Water soluble NaYF4∶20%Yb3+,2%Er3+ upconversion nanoparticles were prepared in ionic liquid. The obtained samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and luminescence spectra. The morphology and crystal structure could be well controlled by adjusting the fluoride concentration. Based on the experimental date, the high fluoride concentration was in favor of the formation of hexagonal phase. The products could be dissolved in water and the solution exhibit bright green luminescence under the excitation of 980 nm laser.关键词：NaYF4;ionic liquid;fluoride concentration;rare earth;upconversion111|141|1更新时间：2020-08-12
- 摘要：Benzoic acid (BA) ligand was bonded on the side chains of polysulfone (PS) via a polymer reaction and obtained aryl carboxylic acid-functionalized polysulfone PSBA. The secondary complex PS-(BA)3-Tb(Ⅲ), the ternary complexes PS-(BA)1-Tb(Ⅲ)-(Phen)2 and PS-(BA)1-Tb(Ⅲ)-(Phen)3 were prepared by the coordination of Tb(Ⅲ) ion and PSBA using PSBA as a macromolecular ligand and phenanthroline (Phen) as a smaller ligand. The chemical structures of the complexes were characterized by FTIR and UV absorption spectra, and their florescence emission characters were investigated. The investigation results show that both the secondary complex and ternary complexes formed by using PSBA as a macromolecular ligand can emit the strong characteristic fluorescence of Tb(Ⅲ) ion, which indicate the BA bonded on the side chains of PSBA can effectively sensitize the fluorescence emission of Tb(Ⅲ) ion. In comparison with the secondary complex PS-(BA)3-Tb(Ⅲ), the ternary complexes with Phen as the second ligand have higher florescence emission intensity.关键词：polystyrene;benzoic acid;Tb(Ⅲ) ion;polymer-rare earth complex;sensibilization122|222|4更新时间：2020-08-12
- 摘要：Two simple methods, including acid treatment and cathode reduction treatment, are employed to treat porous silicon material for improving the luminescence properties of porous silicon material and obtaining good results. The results show that cathode reduction can significantly improve the stability of porous silicon and acid treatment can effectively improve the luminous intensity. When both of these two methods are adopted, cathode reduction prior to acid treatment can obtain a better result than opposite process.关键词：porous silicon;acid treatment;cathode reduction treatment93|108|0更新时间：2020-08-12
- 摘要：Y2SiO5∶Eu and Y2SiO5∶Tb nanopowders were prepared by sol-gel method. The structure, morphology and luminescent properties were analyzed by X-ray diffraction, scanning electron microscopy and so on. The luminescent properties of Eu3+ and Tb3+ doped yttrium silicate nanopowders with different concentration were investigated. The main emission peak of obtained Y2SiO5∶Eu nanopowders is at 612 nm excited by UV light, ascribed to the transition of5D0→7F2 of Eu3+. The main emission peak of Y2SiO5∶Tb nanopowders is at 540 nm, ascribed to the transition of5D4→7F5 of Tb3+.关键词：yttrium silicate;nanopowders;luminescent properties107|107|0更新时间：2020-08-12
- 摘要：The fluorescent carbon nanoparticles were synthesized by electrochemistry etching graphite electrode using the ethylene diamine tetraacetic acid disodium salt solution as the electrolyte. The properties of the light absorption and fluorescence emission of carbon nanoparticles were obtained by electrochemistry etching and were characterized by UV-Vis absorption and fluorescence spectrophotometers. The crystal characterizations and compositions of the obtained carbon nanoparticles were investigated by employing the transmission electron microscope and energy disperse spectroscopy. The results show that carbon nanoparticles with several nanometers are dispersive and exhibit the strong absorption at 325 nm and the bright blue light emission. The effects of the electrolytic solutions and concentrations on the light emissions from carbon nanoparticles were also studied. Finally, the origin of the light emission from carbon nanoparticles obtained by electrochemistry etching was proposed.关键词：fluorescence;carbon nanoparticles;electrochemistry95|202|3更新时间：2020-08-12
- 摘要：A novel red phosphor Ca2Li2BiV3O12∶Eu3+ was synthesized by solid-state method and characterized by X-ray diffraction (XRD) and fluorescence spectrophotometer. The influence of synthesis temperature and the concentration of Eu3+ ions, on phase compositions and luminescent properties were systematically investigated. The results show that the Ca2Li2BiV3O12∶Eu3+ phosphor with high purity and crystallinity can be obtained at 650~700 ℃. The excitation band of the phosphor prepared covers 200~400 nm, the emission spectra are described by the well-known 5D0 →7FJ(J=1, 2, 3, 4) emission lines of the Eu3+ ions, the sample prepared with the Eu3+ mole fraction of 14% has the highest emission intensity. This phosphor shows a strong red emission centered at 612 nm under near-UV light and may be applied for white light-emitting diodes.关键词：Ca2Li2BiV3O12∶Eu3+;red phosphor material;solid-state method;energy transfer107|84|3更新时间：2020-08-12
- 摘要：A novel ancillary ligand (2-(1-hydroxy-naphthyl)-benzothiozolato) (HNBT) and the corresponding red emitting phosphorescent iridium(Ⅲ) complex, Ir(ppy)2(NBT) with 2-phenylphridine(ppy) as first ligand are designed and synthesized. Saturated red-emitting electrophosphorescent devices using Ir(ppy)2(NBT) as emission center are fabricated. The thermal, photophysical, and electroluminescent properties of Ir(ppy)2(NBT) are investigated in detail. It is noteworthy that the emission spectrum shape of complex Ir(ppy)2(NBT) is similar to Gauss, which has only one emission peak centralized 614 nm with a full-width at half-maximum of 65 nm. The optimized device exhibits a maximum brightness of 6 400 cd/m2 and the peak current efficiency is 4.53 cd/A.关键词：electrophosphorescence;iridium complex;red-emitting;organic-light-emitting146|178|3更新时间：2020-08-12
- 摘要：Core-shell structure ZnSe/ZnS nanocrystal(NCs) with size of about 4 nm was synthesized in aqueous solution, Good cubic crystal with zinc-blend structure of ZnSe/ZnS NCs was confirmed by using X-ray diffraction(XRD) and transmission electron microscopy(TEM) technology. A surfactant was replaced of ZnSe/ZnS NCs to transfer from aqueous solution to organic solution, which have been great dispersed in organic polymer. Organic light emitting devices were fabricated using a thin film which was spin-coated the MEH-PPV and ZnSe/ZnS NCs mixer solution under the quality ratio of 1∶0.5 as the emitting layer. The electroluminescence(EL) diodes with single-layer structure of ITO/poly [2-methoxy-5-(2'-ethyl hexyloxy-p-phenylenevinylene)](MEH-PPV)∶ZnSe/ZnS(50 nm)/Al and a multilayer structure of ITO/poly(ethylene- dioxythio phene)∶poly(styrenesulfonate)(PEDOT∶PSS)(70 nm)/MEH-PPV∶ZnSe(ZnS)(50 nm)/bathocuproine(BCP)(15 nm)/tris-(8-hydroxylquinoline)-aluminum(Alq3)(12 nm)/LiF(0.5 nm)/Al were fabricated, respectively. The clearly blue shift of the emissive peak in the multilayer device was measured with the increasing of applied voltage, but there is not the changing of the emissive peak in the single-layer device. Under the effect of applied voltage and the hole blocking layer BCP, EL of multilayer device may be from MEH-PPV and ZnSe/ZnS NCs.关键词：ZnSe/ZnS;nanocrystal;MEH-PPV;electroluminescence123|119|4更新时间：2020-08-12
- 摘要：Phosphor-converted white organic light emitting diodes (pc-WOLEDs) are fabricated by combining blue OLED with red Sr2Si5N8∶Eu2+ phosphor spin coated color conversion layer (CCL). The pc-WOLED shows maximum luminous efficiency of 22.1 cd/A, maximum power efficiency of 11.26 lm/W, external quantum efficiency of 10.2% and CIE coordinates of (0.32, 0.34). Moreover, the output spectral and CIE coordinates of the pc-WOLED have a small shift in different driving current density, which demonstrate good color stability.关键词：phosphor-converted white organic light-emitting diodes (pc-WOLEDs);red emitting phosphor;color conversion layers.202|109|1更新时间：2020-08-12
- 摘要：The cavitation of a liposome microbubble dynamics in drug release was studied. The main objective of this work was to investigate the role by the mechanical index (MI) in the 300 kHz and 1MHz ultrasound. Several simulations indicated that bubble radius changes quickly from maximal value to zero by the driving frequency. Drug release was more efficient at 300 kHz compared to 1 MHz when MI was greater than 0.4. When the MI was less than 0.4, drug release was more efficient at 1 MHz compared to 300 kHz. The results demonstrate that ultrasound has a potential in enhancing drug release from liposome.关键词：cavitation;drug release of liposome;microbubble dynamics101|159|1更新时间：2020-08-12
- 摘要：A hundred-watt level semiconductor laser air cooling system was analyzed by ANSYS finite element analysis software. The temperature distribution and air cooling system of this high-power semiconductor laser module were simulated and optimized. It provides the basis of the choice program for 100 W-class high-power semiconductor laser module air cooling technology, and the relative experiment has been verified.关键词：high-power semiconductor laser;thermal characteristic;ANSYS;temperature distribution135|339|3更新时间：2020-08-12
- 摘要：The performance of two DCM∶Alq3 based on red organic light-emitting diodes(OLEDs) were compared. In device A, ultrathin LiF was inserted between emitting layer and electron transporting layer, the other without inserting layer was named device B. As a result, device A showed a maximum EQE(external quantum efficiency) of 5.9%,which was obtained under the highest brightness 76 740 cd/m2 with current density of 487 mA/cm2. Correspondingly, the internal quantum efficiency of 40% was far exceeded the theoretical upper limit of 25% for fluorescent OLEDs. We attributed the unusual phenomenon to the manipulation of the charge transfer state mixing and the electrical field effect on the excitons.关键词：external quantum efficiency;organic fluorescence;organic light-emitting diodes104|137|0更新时间：2020-08-12
- 摘要：The polymer distributed feedback (DFB) laser based on conjugated polymer poly(2-methoxy-5-(2'-ethylhexyloxy)-1,4-phenylene vinylene) (MEH-PPV) is reported in this paper. A one-step fabrication approach of laser ablation by two interference beams is employed and a periodic grating can be directly recorded onto the polymer layer. MEH-PPV is spin-coated to form a 400-nm-thick film on the substrate. The ablation experiments used a frequency-tripled Nd∶YAG laser (Spectra-physics Company) with 3 nm pulse width, 10 ns pulse length, 10 Hz repetition rate and 355 nm wavelength. The polymer film was exposed by two beams which were split from the UV laser with beam size of ~6 mm in diameter. The grating depth was fixed at around 100 nm by adjusting the laser power. The grating recorded on the polymer film with different periods was obtained by adjusting the writing angle. The DFB laser with grating period of 370 nm shows a lasing threshold of 182 μJ·cm-2·pulse-1. The peak wavelength and the full width at the half maximum are 609 nm and 4.2 nm, respectively. The peak position is tuned over 18 nm by increasing the period from 360 nm to 390 nm.关键词：interference ablation;DFB lasers;lasing spectrum100|124|0更新时间：2020-08-12
- 摘要：ith the combination of optical activity of ZnO nanowires and the hole-transporting characteristics of polyaniline(PANI), a flexible light-emitting diode based on PANI /ZnO nanowire film was designed and prepared, and luminescence properties were discussed. By our simple polymer-assisted growth method, the ordered single-crystalline ZnO nanowires were uniformly distributed on flexible polyethylene terephthalate(PET)-based indium-tin-oxide-coated substrates.The array of ZnO nanowires grown on PET substrate was successfully embedded in a polyaniline thin film, through which a PANI/ZnO nanowire film and a hybrid device of organic-inorganic hetero-junction of ITO/(ZnO nanowires-PANI) were obtained. The photo- and electroluminescence results show that the hybrid device of organic-inorganic hetero-junction is of tunable electroluminescence and emits ultraviolet at relatively low turn-on voltage; surface capping with PANI on ZnO nanowires enhances ultraviolet emission and reduces defect-related emission at 450 nm of bare ZnO nanowire array, which is attributed to electron transitions from the extended state Zni to the valance band. The results also indicate that PANI/ZnO nanowire film has a great potential for application in flexible optoelectronic devices.关键词：flexible display;ZnO nanowire;light emitting device;polymer soft-template;electroluminescence99|206|2更新时间：2020-08-12
- 摘要：All-solution method is used to fabricate polymer light-emitting diodes(PLEDs). The electron injection buffer layer and the light-emitting polymer layer are obtained by spin coating. As for the top electrode, we use drop-casted highly conductive PEDOT∶PSS film as transparent anode layer to obtain a high device performance. The conductivity of 608.7 S/cm for the PEDOT∶PSS film is achieved by secondary doping. At the thickness of 240 nm, the sheet resistance of the polymer layer is 68 Ω/□, and at 1 micron, the sheet resistance of the film is less than 10 Ω/□. I-V characteristics of the devices show a threshold voltage of ~ 4 V under forward bias.关键词：polymer light-emitting;full-solution preparation;PEDOT∶PSS;polymer electrode100|120|1更新时间：2020-08-12
- 摘要：Indium-Tin-Oxide(40 nm)/Ga-doped ZnO(140 nm)(ITO/GZO) and GZO(180 nm) films were deposited onto both glass substrates and p-GaN epitaxial layers by magnetron sputtering as transparent current spreading layer of GaN-based LEDs. After thermal annealing in air ambient conditions, the ITO/GZO films exhibite high transparency(~80%) in visible light and low resistivity(1.15×10-3 Ω·cm). The roughness of the ITO/GZO films is bigger than that of the GZO films which enhances the extraction of photons. The ITO interface modulation layer can reduce the contact barrier of GZO/p-GaN and improve the photoeletric performance of LEDs. GaN-based light-emitting diodes(LEDs) were also fabricated. With 20 mA injection current, it is found that the forward voltage are 6.8 V and 9.5 V, while the luminous intensity are 297 mcd and 245 mcd, respectively for the LEDs with ITO/GZO electrode and GZO electrode. Compared the LEDs with GZO electrodes, the luminous intensity of LEDs with ITO/GZO electrode increased by 20% at 20 mA forward current and increased by 50% at 35 mA forward current.关键词：LED devices;ITO/GZO complex films;GZO electrode136|61|3更新时间：2020-08-12
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Effect of Doping Concentration on The Peak Wavelength of Photoluminescence in Donor-acceptor Systems
摘要：Efficient donor-acceptor (DA) energy transfer material systems are considered to be the candidate for organic lasers. We developed a numerical model for the emission spectra of DA systems based on the theory of Förster energy transfer and stimulated emission. The model describes the essential emission spectrum features related on the acceptor concentration in theoretical DA system,in which the monomer wavelength of the photoluminescence increases none linearly with the acceptor concentration, and tends to reach the monomer emission wavelength of acceptor at high acceptor concentration.关键词：organic lasers;emission spectrum;acceptor concentration;donor-acceptor systems103|129|0更新时间：2020-08-12 - 摘要：Organic photovoltaic devices based on the bulk heterojunction of poly(3-hexylthiophene) and [6,6]-phenyl-C61 butyric acid methyl ester(P3HT∶PCBM) have been fabricated in this work. We have studied that the effects of LiF, as cathode buffer layer, on the performance of pre-annealed devices under various ambient pressure. The results indicate that the key role of ultrathin LiF layer is to increase the short circuit current and maintain the open circuit voltage, which can improve the power conversion efficiencies. Nevertheless, the performance of polymer solar cells are mainly determined by the morphology of active layer and the configuration of interface between electrode and blend layer, while the latter could be improved by cathode buffer layer.关键词：polymer solar cells;cathode buffer layer;annealing ambient pressure90|217|1更新时间：2020-08-12
- 摘要：Aluminum nitride (AlN) films were prepared successfully on sapphire and nitrided sapphire substrates by reactive DC magnetron sputtering. The effect of nitridation of sapphire substrate on the growth of AlN films was studied. The films were characterized by X-ray diffraction (XRD), atomic force microscopy (AFM) and optical absorption spectrum. XRD patterns of AlN films exhibited a strong preferential c-axis orientation,and nitridation of sapphire substrate could improve the crystal quality of AlN films and also decrease the residual stress of films. But AFM results revealed that the grain size distribution of films deposited on nitrided sapphire substrates was not more homogenous than that of films deposited on sapphire substrates, and optical absorption results also showed nitridation of sapphire substrate nearly had no effect on the optical behavior of AlN films.关键词：crystal structure;optical Absorption;surface morphology149|205|1更新时间：2020-08-12
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