最新刊期

摘要：The piecewise linear current density recursive convolution (PLCDRC) finite-different time-domain (FDTD) method for magnetized plasmas was applied to study the characteristic of defect mode for one dimension magnetized plasma photonic crystals with a defect layer under the isothermal hypothesis. The electromagnetic propagation process of a Gaussian pulse through a magnetized plasma photonic crystal was investigated. The transmission coefficients through magnetized plasma photonic crystals were calculated, the effects of plasma temperature and density on characteristics of defect modes for magnetized plasma photonic crystals were analyzed with them. The results illustrated that the different defect modes can be obtained by changing plasma temperature and density.  

摘要：By using the method of optical transfer maxtrix, the optical transmission properties of compound photonic crystal with two symmetrical defect layer at the two ports were studied. The investigation results showed that two resonance transmittance peaks exist in the band gap in dual-period photonic crystal ² structure. The resonance transmittance peaks will shift with the small changes of the dielectric constants of photonic crystal induced by a control light. The more the dielectric constants change, the more resonance transmittance peaks shift, leading to high-efficiency dual channeled optical switches being realized. Each resonance transmission peak can split into N-1 different transmission peaks in the ^<em>N structure photonic crystal. We can gain appropriate multiple channel filters and optical switches by adjusting N.  

摘要：Tokuda-modified linear-combination operator method and the unitary transformation method were used to study the properties of the weakly-coupling polaron, considering the influence of Rashba effect, which is brought by the spin-orbit(SO) interaction, in an semiconductor triangular quantum well(TQW). Numerical calculation on the GaAs TQW, as the example, is performed. The expressions for the effective mass of the polaron as a function of the velocity, the coupling constant and the electron area density were derived. Numerical results showed that the total effective mass of the polaron is composed of two parts. The interactions between the orbit and the spin with different direction have different effects on the effective mass of the polaron.  

摘要：Based on the mechanism of injection, transport and recombination of the charge carriers, a model was developed to calculate the delay time of electroluminescence (EL) from bilayer organic light-emitting diodes. The relations of the recombination delay time versus the applied voltage and injection barrier or internal interfacial barrier or the thickness of organic layer were revealed. The optimal thickness of inserted LiF in bilayer organic light-emitting devices was calculated. The results shown that:(1) the EL delay time is dominated by recombination process at lower applied voltage and transport process at higher applied voltage; (2) when δ_e/δ_h＜2, metal/organic (M/O) interface is ohmic contact, when δ_e/δ_h＞2, M/O becomes contact limited; (3) when the potential of internal interface barrier exceeds 0.3 eV, the effect of H' _h on t_rec becomes very weak and t_rec is fundamentally governed by the applied voltage or other factors; (4) when increasing L_h/L, t_rec has a rising trend at low voltage. When the applied voltage exceeds a threshold value, t_rec does not change with L_h/L; (5)considering OLEDs with LiF/Ag cathode on different applied voltage, when L_d≈3.1 nm, both of the recombination time and the electroluminescent delay time are the shortest.  

摘要：In this report, devices using red phosphorescence dye Ir (piq)₂(acac) as dopant and CBP as host are fabricated. The structure of the device is ITO/CuPC(1 nm)/Ir (piq)₂(acac) ∶ CBP(25 nm)/BCP (10 nm)/Alq₃(35 nm)/LiF(1 nm)/Al(100 nm). Comparing with 4 kinds of different dopant concentration, the luminescence characteristics of the devices were investigated.All of the films are fabricated by thermal deposition way onto a precleaned ITO-coated glass substrate (sheet resistance 50 Ω/□) at a background pressure <2×10^{- 4} Pa. The deposition appartus is OLED high vacuum thermal evaporation coating system. The thickness of the deposited films is monitored by FTM-V film thickness monitor. The electroluminescence (EL) spectra, the photoluminescence (PL) spectra, voltage versus current and emission CIE coordinates of the devices were measured by a OLEDs testing system, comprosing of a 2400 Sourcemeter (Keithley) and a grating spectrometer of Omni-λ300 series which is produced by Zolix of Beijing. All the measurements are carried out at room temperature. Change the doping concentration in the host material, when the doping mol fraction reaches 8%, the emission color coordinates of the device are very close to the standard red, and its color purity is more than 98%.When driven at 16 V, the emission CIE coordinates of the device are (x=0.67, y=0.32) , the color purity is 99.74%, which basically meet the needs of red light-emitting requirements in the full color display.  

摘要：A series of Sr_1-yEu_ySi₂O_2-zN_2+2z/3 phosphors were synthesized by the high-temperature solid-state reaction and characterized systematically.The X-ray powder diffraction analysis confirms the formation of a solid solution of Sr_1-yEu_ySi₂O_2-zN_2+2z/3 phosphor for Eu concentration from 0 to 0.2. The photoluminescence properties show that the phosphors can be efficiently excited by UV-visible light from 250 to 500 nm and exhibit intense tunable yellowish green light due to Eu concentration. The relationship among the lowest 5d absorption bands, Stocks shifts, the centroid shifts and splitting of Eu²⁺ levels was studied in details. The temperature dependent emission spectra in the temperature range of 77~450 K show that they have a high thermal quenching temperature above 450 K. The LED based on UV/blue chip and Sr_1-yEu_ySi₂O_2-zN_2+2z/3 phosphors were encapsulated firstly, which show intense green, white and lower UV light emission. Their luminescent properties agree well with these phosphors. The luminous efficiency of the fabricated LED can reach 19 lm/W and the white LED can be obtained from the phosphors fabricated with blue chip based on different gel concentration. These results indicate that Sr_1-yEu_ySi₂O_2-zN_2+2z/3 phosphors are promising candidates for solid-state lighting LED.  

摘要：The luminescence of a single phase material LiCa₃MgV₃O₁₂ : Eu³⁺ are reported and discussed as a potential phosphor excited by UV-LED. The photoluminescence spectra show two bands with peaks at 530 nm and 610 nm, which are attributed to (VO₄)^3- and Eu³⁺ ,respectively. By mixing the colors of the two bans, the (x,y) coordinates vary systematically due to the different Eu³⁺ concentration. When the mol fraction of Eu³⁺ is 0.01, the (x,y) coordinate is (0.33,0.34). This single phosphor is capable of converting the ultraviolet emission of a UV-LED into white light-emitting.  

摘要：Calcium magnesium chlorosilicate doped with Eu²⁺ can be used as a kind of green phosphor for white-light LED because of its effective excitation under NUV light source and bright green emission. However, according to the current research, the relative brightness of this green phosphor had to be improved. In this paper, calcium magnesium chlorosilicate green phosphors, doped with Eu²⁺ or co-doped with Eu²⁺ and Dy³⁺, were synthesized by high-temperature solid-state reaction in reducing atmosphere. The luminescent properties of these phosphors, as well as the interaction mechanism between Dy³⁺ and Eu²⁺, were investigated. The significant enhancement of Ca₈Mg(SiO₄)₄Cl₂ ∶ Eu²⁺ green emission was obtained by co-doping with Dy³⁺, and the 505 nm emission intensity of Eu²⁺ is increased by 12% with an optimum Dy³⁺ content of 0.02. Funthermore, the concentration quenching process was also discovered, and the luminescent intensity of Ca₈Mg (SiO₄)₄Cl₂ ∶ Eu²⁺, Dy²⁺ phosphor decreases with further increasing the concentration of Dy³⁺. In this paper, It is suggested to be an energy transfer process between Dy³⁺ and Eu²⁺ on the basis of spectral characteristics of Dy³⁺ and Eu²⁺. On account of the relatively low intensity of Dy³⁺ 4f-4f emission, the energy transfer could be radiation reabsorption process. On the other hand, the energy transfer mechanism might be ascribed to resonant transfer process, for the radiative lifetime of the 4f-4f forbidden electric-dipole transition of Dy³⁺ is much longer than that of the 5d-4f transitions of Eu²⁺. Thus, the most likely energy transfer mechanism between Dy³⁺ and Eu²⁺ can be attributed to nonradiative cross relaxation process.  

摘要：LiCaBO₃ : Sm³⁺ phosphor was synthesized by solid state reaction and its luminescent properties were studied. The emission spectrum consists of three major orange-red emission bands at 561, 602 and 651 nm, which correspond to the ⁴G_5/2→⁶H_5/2, ⁴G_5/2→⁶H_7/2 and ⁴G_5/2→⁶H_9/2 typical transitions of Sm³⁺ , respectively. The excitation spectrum for the strongest emission (602 nm) extends in 320~420 nm, which indicated that this phosphor can be effectively excited by near-ultraviolet light-emitting diodes. The influences of Sm³⁺ concentration (x) on the emission intensity of LiCa_1-xBO₃ : xSm³⁺ phosphors were also investigated. The results showed that the intensity increases with increasing Sm³⁺ concentration, then decreases, and reaches the maximal value at 3% Sm³⁺. And the concentration self-quenching mechanism is the d-d interaction according to Dexter theory. The emission intensity of LiCaBO₃ : Sm³⁺ can be enhanced by doping charge compensator Li⁺ , Na⁺ , K⁺.  

摘要：Alkaline earth silicate Ca₂MgSi₂O₇ : Eu²⁺ phosphors were prepared under a reducing atmosphere by solid-state reaction using CaCl₂ as flux medium and starting materials. Samples sintered under different CaCO₃ concentration, different temperatures and different time were obtained. The effect of these conditions on the structure was studied by X-ray diffraction (XRD). The synthetic conditions were optimized at the molar ratio of starting materials CaCO₃ : Mg(OH)₂ : SiO₂ : CaCl₂ equal to 1.5 : 1 : 2 : 2.4, sintering temperature 900 ℃ and sintering time 3 h. The photoluminescence (PL) spectra of the as-prepared phosphor powders were measured. The results indicated that the Ca₂MgSi₂O₇ : Eu²⁺ phosphor can be effectively excited by the light in the wavelength range of 360~480 nm and emission spectrum shows a broad green emission band centered at 529 nm with a bright green emission. And it is possible to determine the distribution of this broad emission band in the spectrum associated with transition from the 4f5d level of Eu²⁺ ion which only replaces the Ca²⁺ ion site with a coordinate number of eight. Furthermore, the broad green emission band is asymmetric as a result of the re-absorption of the blue light by the green-emission light. The Ca₂MgSi₂O₇ ∶ Eu²⁺ phosphors were also synthesized at 1 200 ℃ for 4 h in a reducing atmosphere using H₃BO₃ as flux medium and CaCO₃,Mg(OH)₂,SiO₂ as starting materials. Comparing the high temperature and low temperature methods, we found that their exitaton spectrum profiles are different, and the emission intensity of Ca₂MgSi₂O₇ ∶ xEu²⁺ (x=0.01, 0.02, 0.03, 0.04, 0.07) phosphor prepared at 900 ℃ is higher than that of powders prepared at 1 200 ℃.

  

摘要：Y₂O₂S : Eu,Si,M(M=Mg, Ca, Sr, Ba) long lasting red luminescence phosphors were synthesized by solid state reaction and analyzed by means of XRD, photoluminescence (PL), thermo luminescence, etc. The results indicate that the strongest emission of both emission spectrum and afterglow spectrum peaks at around 627.0 nm, which is assigned to electric dipole ⁵D₀→⁷F₂ transition of Eu³⁺ , which behaves excellent afterglow property. The doping of alkaline earth ions improves the PL intensity and the afterglow property of the Y₂O₂S : Eu,Si,M(M=Mg,Ca,Sr,Ba) phosphors. Of all, the Mg-doped sample shows the best property, the next one is the Ba-doped material.

  

摘要：YVO₄ : Eu³⁺ was successfully synthesized by hydrothermal method, and was further thermally treated at 400~800 ℃, respectively. Their crystal structure, SEM(scanning electron microscope)images and luminescence properties were obtained in room temperature. XRD showed that YVO₄ : Eu³⁺ was formed with good single phase, and when the temperature changes in 400~800 ℃, the crystallinity is higher and higher, and the crystal grain become bigger and bigger than untreated sample. SEM images also indicated the grain of the sample after treatment is bigger than that of YVO₄ : Eu³⁺ before treatment. In the UV range, the excitation band is composed of a broad band with the maximum at about 260 nm and a sharp band with the maximum at about 395 nm. The peak of 260 nm is assigned to the overlap of VO^3-₄ ion and O^2-→Eu³⁺ charge transfer band absorption; the peak at 395 nm is due to ⁷F₀→⁵L₆ transition of Eu³⁺. In the VUV range, the excitation band was composed of a strong broad band at about 156 nm and a broad band at about 200 nm. The peak of 156 nm could be assigned to the absorption band of host, and the peak of 200 nm is assigned to the charge transfer band of O^2-→Y³⁺. After 200 nm, the shape of absorption spetrum is similar to the UV excitation spectra. under 254 nm excitation, the YVO₄ ∶ Eu³⁺ phosphor exhibits the well-known Eu³⁺ emission, which makes up of several sharp lines of Eu³⁺, namely the ⁵D₀→⁷F₁, ⁵D₀→⁷F₂, ⁵D₀→⁷F₄ transitions, respectively,the dominated emission peak is ⁵D₀→⁷F₂ at 619 nm under 147 nm excitation, their emission spectra are consistent with that under 254 nm excitation. With the temperature increasing in 400~800 ℃, the emission intensity of samples is improved because of the higher crystallinity, bigger grain, and removing of OH^- and VO^3-₄ which can quench the luminescence. Under 254 nm and 147 nm excitation, the emission intensity of the sample thermally treated at 800 ℃ is improved 90% and 95% comparing with the untreated sample, respectively. It was indicated that 800 ℃ is the best thermal treatment temperature.  

摘要：Upconversion luminescence is one of the most efficient progress for the generation of visible radiation by near-infrared (NIR) excitation. A lot of studying works indicated, that, under 980 nm excitation, Yb³⁺/Er³⁺ and Yb³⁺/Tm³⁺ co-doped NaYF₄ materials are well-known because of the highest upconversion efficiency so far. Due to the feature of NIR excitation, frequency upconversion materials would have wide and potential application in light emitting displays, multiplexed biological labeling, short-wavelength lasers and so on. In general, the manipulating color is implemented by changing the intensities of red, green and blue, respectively. The method is complex and expensive. For frequency upconversion red, green and blue lights can be emitted at same time by only one pump NIR laser and the proportions of red/green and red/blue are variable with the pump power. So, the simple color design can be obtained based on the upconversion luminescence. This paper specially discussed a feasible approach to modulate the output color based on the upconversion materials. In this paper the upconversion phosphors NaYF₄ : Yb³⁺ , Er³⁺ were prepared by co-precipitation progress. XRD patterns of the samples showed that the annealing process at 400~600 ℃ induced transformation from the cubic to the hexagonal phase that benefits the upconversion emission. A strong absorption peak near 970 nm was observed, which is due to the transition from ground state ²F_2/7 to excited state ²F_2/5 of Yb³⁺. Upconversion luminescence of red, green and blue was obtained under the excitation of 980 nm diode in NaYF₄ ∶ Yb³⁺ , Er³⁺. However, the blue light is too weak to observe. Green and red emissions centered at 521, 539 and 659 nm, correspond to the transitions ²H_11/2→⁴I_15/2, ⁴S_3/2→⁴I_15/2 and ⁴F_9/2→⁴I_15/2 of Er³⁺, respectively. The rate equation was built for this upconversion system. From the rate equations the two photons process is obtained for the green and red luminescence under low pump power. The experimental slope agrees with the results from the rate equations. A liner relationship between the pump power and the equivalent wavelength was obtained. The luminescent color can be continuously modulated in a broad wavelength region by changing the pump power. The equivalent wavelength region is also variable with the dopant concentration of Yb³⁺. In this work, the range is near 40 nm from 588 nm to 624 nm for 10%Yb³⁺. When dopant concentration of Yb³⁺ increases, the wavelength region shifts to blue. This study offers an approach for quantitatively modulating the emission color. This method is simple and easy to operate. It has a potential industrial application in light-emitting displays, anti-counterfeiting techniques, and so on.  

摘要：Different content of Mn²⁺ doped Zn₂SiO₄ green phosphors were prepared by sol-gel method under the dopants of boron ions.The photoluminescent properties and structure of the samples were studied by fluorescence spectroscopy and X-ray diffraction, respectively. Results showed that, after annealed at 900 ℃ in reducing atmosphere, the sample exhibits a clear green color and the best doping mol fraction is 2%. A strong concentration quenching effect is presented when the concentration of x_Mn²⁺ ＞2%, the possible luminescence mechanism of the samples was also analyzed in this paper.  

摘要：A vertical-external-cavity surface-emitting 920 nm semiconductor laser (OP-VECSEL) with active region of In_0.09Ga_0.91As quantum well (QW) system pumped by 808 nm laser diode module was constructed and optimized. By the finite element method, self-consistent solutions of electronic and optical equations of the semiconductor laser were realized and the characteristic parameters of OP-VECSEL were calculated. The performances of the especial mode in device, the threshold and the optical-optical conversion efficiency were analyzed by dealing with different structure parameters,including number of QWs (1, 2 and 3) in one period, QW depth, width and component of barrier and dimension of the non-absorption layer. The best structure of the laser was chosen.  

摘要：In this paper, a method strictly controlling the width of pump stripe in the measurement of variable stripe length (VSL) method is present. For the gain measurements, we deal samples with lithography and sputtering, so that three different wide stripes, 2.6, 6.2 and 10.5 μm, are exposed separately on three samples, besides the rest parts are covered by 100 nm thick aluminum coating to strictly control the width of the pump stripe. We specially noticed that the pump stripes exposed are all along the same crystal orientation, in order to avoid the influence of different crystal orientation on optical gain. Using the VSL method, we studied the optical gain and saturation semiconductor laser with different pump stripe width. The gain spectra were discussed for three different pump stripe widths of 2.6, 6.2 and 10.5 μm, respectively. An increase of the modal gain and the decrease of saturation length with increasing stripe width were observed for most wavelengths on the amplified spontaneous emission spectrum through our experiments. The phenomenon that the gain changes with the pump stripe width could be due to the carrier diffusion. The carrier diffusions impact on different width pump stripe was discussed by theoretical calculation. The conclusion indicated that diffusion leads to lower non-equilibrium carrier concentration in a narrower pump stripe, and the modal gain decreases. To obtain effective optical gain and the long saturation length, experiments in many papers suggested making the pump stripe as narrow as possible, but this approach did not take the impact of diffusion into account. Our experiments showed that the diffusion can not be ignored when the stripe is narrow. Based on our experiments and calculation, pump stripe width is an important parameter related to the optical gain in VSL. We can choose an appropriate width of the pump stripe according to the needs when measuring the optical gain and its spectrum through the variable stripe length method.  

摘要：Influence of Indium doping on acceptor activation energy in p-type Al_xGa_1-xN was presented. The p-type Al_xGa_1-xN epilayers were grown on AlN/sapphire templates by metal organic chemical vapor deposition (MOCVD). TMIn flow rate is varied as 0, 40, 80 and 120 sccm while keeping other growth conditions changeless. X-ray diffraction (XRD) was used to determine the crystalline quality and Al composition in Al_xGa_1-xN epilayers. At room temperature, the resistivity of p-type Al_0.43Ga_0.57N epilayer grown In doping is in order of 10⁴ Ω·cm, but that grown without In is above 1×10⁶ Ω·cm. Variable temperature Hall-effect measurements were employed to determine the acceptor activation energy in p-type Al_0.43Ga_0.57N epilayers. It was seen that the acceptor activation energy decreases significantly with the introduction of In. The minimum of 259 meV is obtained at TMIn flow rate of 80 sccm. It was suggested that acceptor-donor-acceptor (A-D-A) complexes could be formed in p-type Al_0.43Ga_0.57N epilayers. The formation of A-D-A complexes would decrease the acceptor activation energy in p-type Al_0.43Ga_0.57N epilayers due to lower activation energy for A-D-A complexes. In order to verify the influence of the In-ambient on acceptor activation energy, the ultraviolet light-emitting diodes (UV-LEDs) were fabricated. It was seen that there are a lower turn-on voltage and a lower diode series resistance for the UV-LEDs fabricated with p-type Al_0.43Ga_0.57N grown under In-doping, compared with that without In-ambient.  

摘要：Using the high power light-emitting diode(LED) made by the method of chip-on-board (COB) packaging, this article compared and analyzed the temperature variation discipline on the different thermal radiators. We investigated the relationship between the different thermal equilibrium temperature and photo-electric parameter, such as luminous flux, electrical parameters, and so on. The results shown that when the LED illumination system is turned on, the temperature of the radiator rises rapidly, and keeps in a certain value after a period of time. In this process, the luminous flux, the forward voltage, power and luminous efficiency presents the downward trend. These parameters fluctuate around the equilibrium value. For high-power white light LED illumination systems, luminous flux, forward voltage and luminous efficiency keeps good linear relationship with radiator temperature, respectively. The results also showed that, with the rising of reverse saturation current, the radiator temperature rapidly rises. By linear fitting, luminous flux temperature coefficient, vol-tage temperature coefficient and luminous efficiency temperature coefficient were calculated.Finally, the relation formula of temperature and luminous flux was proposed. By measuring the radiator temperature, the luminous flux can be calculated. It can be used as a kind of calculation methods of luminous flux. High-power white LED lighting system should be reasonable design to improve its thermal dissipation capacity. Reducing equilibrium temperature of high-power LED-lighting system is an effective method to improve performance of the system.  

摘要：Conjugates of human IgG and CdSe/ZnS quantum dots (QDs) capped with an amphiphilic poly (acrylic acid) polymer modified with poly (ehylene glycol) amine were synthesized by a glutaraldehyde (Cho) cross-linking procedure. The IgG-QD assemblies form in this reaction, as evidenced by gel electrophoresis. The key function of QD bioconjugates is to fluoresce readily and remain stable in biological conditions in order to allow for efficient bioapplication. However, the photoluminescence (PL) properties of QDs are sensitive to their environment, so it is particular important to study the mechanisms of the PL change of QDs linked to biomolecules. The effect of cross-linking processes on the PL of QDs was studied by means of steady-state and time-resolved photoluminescence spectroscopy. Attachment of Cho on the surface of QDs results in a significant decrease of QD emission due to the increase of surface defects with Cho destroying the surface of QDs. Attachment of IgG on the surface of QDs results in a significant increase of QD-Cho emission, which is attributed to the conjugation of IgG to QD modifying the surface of CdSe/ZnS QDs.  

摘要：An individual ZnO self-organized microneedle was fabricated from ZnO and graphite powder by vapor-phase transport. The lattice phase, morphology and photoluminescence property of the sample were characterized by XRD,SEM and PL. respectively, the result indicated that this product is wurtzite ZnO microneedle with hexagonal cross-section and has similar UV spontaneous and stimulated emission property comparing with other kinds of linear ZnO microstructure. Furthermore, under excitation of a femtosecond pulse laser with 800 nm wavelength, the UV laser with narrow linewidth from the sample was observed.  

摘要：Stimulated emissions in a novel nanoneedle ZnO composite with two complex needle parts were investigated using the two-photon induced time-resolved photoluminescence pumped with the femtosecond pulse at the wavelength of 640 nm in room temperature. Comparing with the results of single-photon pumped, we observe three operation mechanisms of two-photon induced UV emission behaviors with the excitation power increasing:spontaneous emission of free-exciton, exciton-exciton(E-E) scattering and electron-hole-plasma (EHP) recombination. The threshold of two-photon excitation emission is 4.82 GW/cm²,which is far lower than that of mirconeedle ZnO reported recently and the other nanostructure of ZnO(TW/cm²).Our research results proved that the new ZnO nanoneedle structure with UV emission efficiently induced two-photon shows great potential applications in the two-photon induced nanolasers fields.  

摘要：Using a hydrothermal method, the single-crystalline ZnO nanowires with a hexagonal cone-shape were synthesized with zinc acetate and hexamethylenetetramine(HMT). The morphology of the hexagonal cone-shaped ZnO was investigated by selected area electron diffraction (SAED) and scanning electron microscopy (SEM) measurements. The photoluminescence (PL) spectrum of the synthesized ZnO nanowires shows a strong ultraviolet (UV) emission at 379 nm and some weak emission peaks at the visible wavelength region. In addition, the formation mechanism of the hexagonal cone-shaped ZnO is discussed.  

摘要：The spectral properties of different mass percentages of the porphyrin(5,10,15,20-tetra-p-tolyl-21H,23H-porphine, TTP) doped poly (MEH-PPV) were studied by UV-Vis absorption and fluorescent emission spectra in this paper. The absorption spectra of the blended systems as both films and chloroform solutions show the same behaviors. Meanwhile, the aggregation of polymer chains for MEH-PPV was found under the both cases and the absorption of TTP at 420 nm increase with increasing TTP in the blends. However, the emission spectra from the films are different from those in chloroform solutions. Frster energy transfer from MEH-PPV to TTP occurs in the films and chloroform solutions. Moreover, the splits of emission peak of MEH-PPV induced by energy transfer in chloroform solutions with high TTP doping levels are observed. The phenomenon is disappeared when the solution is diluted, indicating an enlarged distance between the energy donor and acceptor at that time. Furthermore, the rate of energy transfer was obtained at 1×10⁸ mg·mL^-1·s^-1.  

摘要：A new complex Eu₂(bdb)₃ · 4H₂O was designed and synthesized. Its structure was characterized by elemental analysis, IR spectrum, FAB-Ms, the results shown that the complex has stranded dinuclear europimum (Ⅲ) structure with triple ligands. The complex emits bright red luminescence, correspending to ⁵D₀ →⁷F_<em>J (J=0~4) transitions of Eu³⁺ with the maximum peak at 614 nm under near UV irradiation. Monitored at 614nm, the strongest excitation wavelength is located at 370 nm, which well matched to the emission light of 370 nm InGaN chip. The fluorescence lifetime of the complex is 336 μs, the decay curve can be fit with a single exponential model, which is consistent with only one symmetric site for the Eu(Ⅲ) ion in the complex molecule. The thermogravimetric analysis curve for the complex shows the decomposition temperature of the complex is up to 230 ℃ and meets the requirement of fabrication of LED device. A red conversion light-emitting diode (LED) device was fabricated by coating complex onto 370 nm InGaN-based-LED chip. When the mass ratio of the europium complex to the silicone is 1 : 30, the CIE chromaticity coordinates of LED emission are x=0.635 3, y=0.334 0, the luminescence efficiency of device is 1.36 lm/W. The results indicate that complex Eu₂(bdb)₃ · 4H₂O can act as red component in the fabrication of white LED.  

摘要：The rare-earth complexes with aromatic carboxylic acids are a kind of good luminous materials because of the good light-emitting singleness, high luminous intensity and a high quantum efficiency. In recent years, more and more attention has been paid to the fluorescence properties of these complexes. The research showed that addition of the non-fluorescent rare-earth ions can enhance the fluorescence intensity of rare-earth complexes. The trimellitic acid, which has a variety of forms of coordination, is a good performance of the organic ligand. A lot of researches about the complexes of europium with trimellitic acid has been reported, however the study of europium-lanthanum complexes with trimellitic acid and 1,10-phenanthroline has been seldom reported. In this study, the series of solid complexes Eu_1-xLa_x(TLA)phen(x=0,0.1,0.2,0.3,0.4,0.5,0.6,0.7,0.8) were obtained by the trimellitic acid, 1,10-phennanthroline and mixed rare earth chloride of EuCl₃ and LaCl₃ in CH₃CH₂OH solution. These complexes were characterized by IR spectrum, TG-DTG and SEM. The IR spectrum showed that the oxygen atoms of carboxylate and the nitrogen atoms of phen coordinate with RE³⁺, and these complexes have similar structure. The TG-DTG analysis showed that these complexes are thermally stable. The fluorescence properties of these complexes were also studied. The results indicated that the complexes can emit intense characteristic fluorescence from europium ion. The fluorescence intensities of europium ions are sensitized by the doping of lanthanum ions and the intensity of fluorescence is the best when n(Eu³⁺) : n(La³⁺)=0.5 ∶ 0.5, at same time the position of the emission peak does not changed.  

摘要：In order to obtain multi-wavelength short pulse source with high-repetition frequency, supercontinuum (SC) spectrum generation in dispersion-shifted fiber (DSF) was experimentally investigated. In use of actively mode-locked Er-doped fiber laser as pump, supercontinuum with 40 nm width was obtained. And the experiment also demonstrated that the stability and power of the pump pulse are important factors for supercontinuum generation.  

摘要：The operation mechanism of exciton blocking layer (EBL) in organic photovoltaic (PV) cells was demonstrated, the EBL materials with higher electron-transporting ability were used such as bathocuproine (BCP), bathophenanthroline (Bphen),and so on. However, it was interestingly found that copper phthalocyanine (CuPc) widely used as donor of the PV cells also can be used as EBL materials and under thicknesses of larger than 10 nm the EBL property even is higher than that of traditional EBL consisting of BCP and Bphen, due to its stronger hole transporting ability from the cathode to the CuPc layer.  

摘要：In this paper, the LED electroluminescence response was analyzed, a simple but useful model of LED voltage pulse response was built. Based on this model, we studied the nonlinear error of LED brightness caused by the voltage-to-intensity response when driven with PWM, and then we conducted an experiment. The test result shows that the average nonlinear error between the LED intensity and the PWM duty is about 10%. At last, a method for gray value correction in LED display screen is suggested based on the LED voltage-to-intensity response model. It effectively reduces the PWM brightness error caused in the process of LED response, makes the LED electroluminescence change linearly along with the pixel gray value, and reduces the color aberration, and furthermore improves the display effect of LED display screen.