最新刊期
卷 36 ， 期 4 ， 2015
- 摘要：Eu2+ doped Sr2Si5N8 red phosphors with different Eu2+ concentration were synthesized by high-temperature solid state method. The crystal structure, morphology, luminescence and thermal quenching properties were investigated in detail. X-ray diffraction (XRD) patterns show that a pure phase of Sr2Si5N8 phosphor with high crystallinity has been obtained. Photoluminescence (PL) spectra results indicate that there are two different luminescence centers when Eu2+ ions substitute Sr2+ sites. Thermal stability data show that the thermal quenching property is largely dependent on Eu2+ concentration. The changes of relative intensity ratio and fluorescence lifetime were examined for the two-peak emission in Sr2Si5N8:Eu2+. The results reveal that Eu2+ distribution changes with varying Eu2+ concentration, which should be the mainly mechanism of the thermal quenching behavior for Eu2+ doped Sr2Si5N8 phosphors at low dopant levels.关键词：Sr2Si5N8;phosphor;thermal quenching;fluorescence lifetime153|115|0更新时间：2020-08-12
- 摘要：The red phosphor K2ZnSiO4:Eu3+ which could be effectively excited by ultraviolet and blue light was synthesized by high temperature solid state reaction, and its luminescent characteristics were also investigated. The principal crystalline phase of the samples is K2ZnSiO4. The excitation spectra of the sample consist of O2-→Eu3+ charge transitions (200-350 nm) and Eu3+ ion excitation peak (350-500 nm). The maximum peak appears at 396 nm and the second peak appears at 466 nm. The phosphor presents several emission peaks under 396 nm and 466 nm excitation, which correspond to the 5D0→7FJ(J= 0, 1, 2, 3, 4)transition of Eu3+, respectively, and the strongest emission is located at 619 nm. The luminescent intensity increases with the increasing of Eu3+ content. The concentration quenching does not occur. The CIE coordinates of K2ZnSiO4:Eu3+ are very close to the NTSC standard.关键词：phosphor;red;Eu3+ doping;high temperature solid state reaction114|86|2更新时间：2020-08-12
- 摘要：utilizing cubic NaYF4 nanoparticles as cores,we synthesized hydrophobic core-shell α-NaYF4/β-NaLuF4:20%Yb,1%Tm upconversion nanoparticles under a mild solvothermal condition. The core-shell nanoparticles were characterized by X-ray diffraction, transmission electron microscopy, Fourier transform infrared spectrometer and fluorescence spectrometer.The measurement results showed that α-NaYF4 cores were about 10-15 nm, and average size of α-NaYF4/β-NaLuF4:20%Yb, 1%Tm upconversion nanoparticles was about 20 nm. Both the core and core-shell nanoparticles possessed narrow size distributions. The core-shell nanoparticles showed stronger luminescence intensity than those of cubic NaLuF4:20%Yb,1%Tm with similar size. The detection results showed that this kind of hydrophobic core-shell α-NaYF4/β-NaLuF4:20%Yb,1%Tm nanoparticle has a higher potential value in biomedical applications.关键词：upconversion luminescence;rare-earth doped nanoparticles;core-shell nanoparticles;hydrophobic surface125|142|1更新时间：2020-08-12
- 摘要：TiO2/p+-Si and TiO2:B/p+-Si heterostructures were formed by sputtering TiO2 films and boron-doped TiO2 (TiO2:B) films on heavily boron-doped silicon (p+-Si) substrates, respectively, followed by annealing at 600 ℃ in O2 ambient. In contrast with the TiO2/p+-Si heterostructured devices, the TiO2:B/p+-Si counterpart exhibits markedly enhanced electroluminescence (EL). It is derived that the doped B atoms in TiO2:B films enter into the interstitial sites of TiO2 lattice after annealing at high temperature, which introduces excess oxygen vacancies. The increase of the concentration of oxygen vacancies due to B-doping leads to the enhancement of EL from the TiO2:B/p+-Si heterostructured devices because oxygen vacancies are the light-emitting centers of the TiO2/p+-Si heterostructured devices.关键词：TiO2 films;boron-doping;heterostructure;electroluminescence96|74|0更新时间：2020-08-12
- 摘要：The luminescence intensity of initial fullerene is very low because of its high molecular symmetry. The key point to enhance the luminescence intensity of fullerene is to lower the molecular symmetry of fullerene, which could make the forbidden bands transition allowed. Herein, C60 nano/microcrystals were synthesized by the evaporation of C60 saturated solution in m-xylene, 1,2,3-trichlorobenzene, 1,2,4-trichlorobenzene, and 1,3,5-trichlorobenzene. The structures of C60 nanocrystals were controlled and their PL intensities were also highly enhanced by the introduction of different solvent.关键词：fullerene;photoluminescence;organic solvent;doping;nanocrystal105|94|0更新时间：2020-08-12
- 摘要：Transparent bulk glass ceramics of 4.5ZnO-5.5Al2O3-90SiO2 (ZAS) and single doped ZAS:RE3+ (RE=Eu, Tb, Ce) were synthesized by sol-gel method. X-ray diffraction (XRD), transmission electron microscopy (TEM) and photoluminescence (PL) spectra were employed to study the influence of doping rare-earth ions concentration on the structure and luminescence properties of ZAS glass-ceramics. XRD results show that ZAS:RE3+ (RE=Eu, Tb, Ce) glass ceramics heat-treated at 900 ℃ consist of ZnAl2O4 phase with average grain size of 30 nm and amorphous SiO2. TEM results show that ZnAl2O4 were precipitated from ZAS system when heat-treated at 900 ℃, and doping ions have not changed the original structure. PL spectra indicate that ZAS:Eu3+ emits intense 611 nm red light originating from 5D0→7F2 transition of Eu3+ ions, ZAS:Tb3+ shows 541 nm green emission attributed to 5D4→7F5 transition of Tb3+ ions, and ZAS:Ce3+ gives 381 nm blue light corresponding to the 5d to 4f transition of Ce3+ ions. Furthermore, the concentration quenching phenomena are observed while the single doping mole fraction of Eu3+, Tb3+ and Ce3+ was 20%, 20% and 3%, respectively. The excellent Commission International de I'Eclairage (CIE) chromaticity coordinates of ZAS:RE3+ (RE=Eu, Tb, Ce) glass-ceramics indicate that they are good candidates for the application of white LEDs.关键词：ZAS glass ceramics;sol-gel method;rare-earth ions doped;luminescence properties108|85|0更新时间：2020-08-12
- 摘要：The nucleation and epitaxial films of ZnO on Si substrates were investigated by metal-organic chemical vapor deposition (MOCVD). As is known to all, the morphology and crystalline quality of ZnO are determined by both the nucleation and epitaxy process. In this paper, the effect of temperature on the growth of ZnO films by MOCVD was investigated in terms of these two processes separately. It is found that the temperature has a great influence on the nucleation process and the following epitaxial growth. Because high temperature has suppression on the lateral growth of ZnO nanorods, the diameters of nanorods don't increase with the ZnO nucleus. As a result, the ZnO nanorods with the largest diameter and lowest density were obtained at 560 ℃. In addition, the crystalline quality of ZnO thin films was further improved by modifying nucleation temperature.关键词：ZnO;MOCVD;nucleation;epitaxial films117|118|2更新时间：2020-08-12
- 摘要：Using reduced oxide graphene (RGO) as precursor, the monodispersed spherical graphene quantum dots (GQDs) with uniform size were prepared by one-step hydrothermal method. The morphology, structure and optical properties of the samples were characterized by TEM, AFM, FTIR, UV-visible spectroscopy and photoluminescence spectra. The GQDs that contain many oxygen functional groups on their surface show a strong absorption band at UV region, and a very strong, narrow and excitation-independent emission peak. When Mn2+ ions were added into the GQDs solution, the fluorescence significantly quenched with the concentration of Mn2+. The calibration curve is linear over the range of 0-400 μmol/L. The result indicates that GQDs can serve as a fluorescent sensing platform for Mn2+ detection.关键词：GQDs;one-step hydrothermal method;photoluminescence;Mn2+ detection142|96|4更新时间：2020-08-12
- 摘要：By using liquid exfoliation method with sonication in appropriate stripping solvent, ultrasonic time, ultrasonic power, MoS2 hybrid-nanosheets suspension with different lateral dimension and uniform dispersion nanosheets were obtained. Under 360 nm excitation, the suspension shows both the luminescence properties of monolayer MoS2 and small MoS2 nanoparticles. The strongest peak of the sample is centered at 512 nm, and shows obvious blue-shifted compared with that of monolayers MoS2 exfoliated by the micromechanically cleavage method. The blue-shifted luminescence is mainly caused by the strong quantum confinement effect of the MoS2 hybrid nanosheets which produced in horizontal dimension as well.关键词：MoS2;hybrid-nanosheets;quantum confinement effect;photoluminescence110|170|0更新时间：2020-08-12
- 摘要：Red-emitting phosphors La2Mo2O9:Eu3+ and La2Mo2O9:Eu3+,W6+ were synthesized by the conventional solid state method. The structure and luminescent properties of these phosphors were investigated. The results indicate that these phosphors are of single phases with cubic crystal structure. La2Mo2O9:Eu3+ and La2Mo2O9:Eu3+,W6+ can be efficiently excited by near ultraviolet light, and the strongest excitation peak is at 395 nm. The emission intensity of La2Mo2O9:Eu3+ can be enhanced by introducing W6+ ions. La1.40Eu0.60Mo1.84O9:0.16W6+ exhibites the strongest red emission, which is about 1.23 times than that of La1.40Mo2O9:0.60Eu3+. The red light emitting diode (LED) was fabricated by coating InGaN chip (~395 nm emission) with the phosphor La1.40Eu0.60Mo1.84O9:0.16W6+, and red bright light could be observed from the LED. Hence La1.40Eu0.60Mo1.84O9:0.16W6+ maybe find application on near-UV InGaN-based white LEDs.关键词：red phosphor;LED;luminescent properties;La2Mo2O9107|92|1更新时间：2020-08-12
- 摘要：SnS thin films were prepared on glass substrates by RF magnetron sputtering technique. The crystalline structure, composition, surface morphology, film thickness, transmittance and reflectance of the films were characterized by XRD, EDS, AFM, FE-SEM and UV-Vis-NIR spectroscopy, respectively. The results show that the increase of thin film thickness helps to improve the crystalline quality and component ratio of the film, and the grain sizes and particle sizes increase with the increasing of the film thickness. The refractive index of the sample increases with the increasing of film thickness in the wavelength range from 1 500 to 2 500 nm. The samples have strong absorption in the visible light region with the absorption coefficients of 105 cm-1 order. The energy bandgap (Eg) of the film with thickness of 1 042 nm is 1.57 eV, closes to the best optical bandgap of the solar cell materials(1.5 eV).关键词：SnS thin film;RF magnetron sputtering;film thickness;crystalline structure;optical properties115|155|4更新时间：2020-08-12
- 摘要：The bulk heterojunction organic solar cells based on compositional blend of P3HT and PCBM were fabricated, the relationships among the carrier recombination loss, device manufacturing conditions and interface trap density were studied by changing the spin velocity and spin coating time to control the solvent evaporation time in the mixed film. The results show that the evaporation time of active composite film directly influences the photoelectric performance of organic solar cell. The device that the solvent evaporates faster can produce stronger trap-assisted recombination, it's interface trap density is larger, and the slope of the open circuit voltage versus the logarithm of the light intensity is greater. A numerical relationship among the manufacturing processing conditions, recombination loss mechanism, interface trap density and the device optoelectronic characteristics has been established in this paper, which can offer good guidance to improve the performance of polymer solar cells.关键词：solvent evaporation time;recombination loss;trap density137|121|1更新时间：2020-08-12
- 摘要：Polymer solar cells based on blends of poly(3-hexylthiophene) (P3HT) and [6, 6]-phenyl-C61-butyric acid methyl ester (PCBM) were fabricated by solvent annealing under different environmental pressures. The performance of the solar cells were tested by X-ray diffraction (XRD), atomic force microscopy (AFM) images and absorption spectra. By increasing the environmental pressure of solvent annealing, the optical absorption of the active layer was enhanced, the crystallinity of the active layer and the phase segregation of P3HT and PCBM were improved, which facilitated photogenerated exciton dissociation and charge-carrier transport. The power conversion efficiency of the polymer solar cell fabricated by solvent annealing under 2.0 MPa is 3.69%, which is 29% higher than that of the one fabricated under atmosphere pressure.关键词：polymer solar cells;environmental pressure;solvent annealing under high pressure107|266|1更新时间：2020-08-12
- 摘要：In order to improve the short-circuit current of the polymer solar cells, water-soluble silver nanoparticles (40 nm) were used to attach on ZnO film which acted as electron transport layer of the device with the structure of ITO/ZnO/AgNPs/P3HT:PC[60]BM/MoO3/Ag. The resonance absorption peak of localized surface plasmon resonance (LSPR) of Ag NPs appears at 410 nm and the full width at half maximum (FWHM) is 60 nm. Compared to traditional devices, the short-circuit current of the experiment device increases about 20.2%, and the power conversion efficiency increases about 17.2%.关键词：Ag NPs;localized surface plasmon resonance;P3HT:PC[60]BM152|164|1更新时间：2020-08-12
- 摘要：In order to analysize the angle dependence of the microcavity organic light emitting device(MOLED), both simulation research using transmission matrix method and experiment were carried out, based on microcavity principles and relative formations. The structure of the device was designed as Glass/DBR/ITO(58 nm)/NPB(46 nm)/DPVBi(20 nm)/Alq3(56 nm)/LiF(1 nm)/Al(150 nm). The experimental electro-luminescence (EL) spectrum shows that the luminescence peaks blue shift and weaken down with the increasing of the detection angle. Comparing with the simulated reflection spectrum under different detection angle, it is found that the transmission peaks of the reflection spectrum correspond to the EL peaks. Further simulation analysis shows that the two reflection mirrors in the microcavity tend to have different reflection rate and different reflection phase change for S and P polarization light under different detection angle. Meanwhile, the optical thickness of the organic layer in the microcavity also changes under different emitting angle, which induces a change in the effective length of the microcavity. The reasons above all lead to the changes of the EL spectrum.关键词：organic light emitting device (OLED);microcavity;angle dependence153|269|5更新时间：2020-08-12
- 摘要：The transfer matrix method and the orthogonal analysis method were used to calculate the optimum film thickness of MoO3/Ag/MoO3 as a transparent anode. In order to validate the accuracy of simulation calculation, MoO3/Ag/MoO3 transparent anodes with different thickness of MoO3 and Ag films were fabricated. Then, the top emitting OLEDs with structure of Al/LiF/tris(8-hydroxyquinolinato)aluminum(Alq3)/N,N'-bis-(1-naphthyl)-N,N'- biphenyl-1,1'-biphenyl-4,4'-diamine(NPB)/MoO3/Ag/MoO3 were fabricated to further verify the accuracy of the simulation calculation used in device fabrication. When the electrode thickness is MoO3 (10 nm)/Ag (10 nm)/MoO3 (25 nm), the device reaches the most optimal performance. The maximum transmittance is 88.256% at 532 nm. And the maximum luminance and luminous efficiency are 20 076 cd/m2 and 4.03 cd/A, which are improved by 18.5% and 56% compared with the reference device, respectively. The results demonstrate a practical way to fabricate highly efficient top emitting OLEDs.关键词：TOLED;simulation calculation;MoO3;transmittance132|71|3更新时间：2020-08-12
- 摘要：GaN-based LED films were grown on Si(111) substrate with different miscut angle from 0° to 0.9° by MOCVD. The miscut angles of Si(111) substrates were precisely measured by high resolution X-ray diffraction (HRXRD). The morphologies of the samples were characterized by atomic force microscopy (AFM). The GaN crystal quality and indium content of MQWs were analyzed by HRXRD. The optical properties of the samples were investigated by photoluminescence (PL). The results reveal that the miscut of Si(111) substrate has significant influence on the crystal quality, surface morphology and optical properties of GaN film. The optimal miscut angle of Si(111) substrate is within 0.5°. Beyond this range, the crystal quality, surface morphology and optical properties of GaN film will deteriorate drastically.关键词：Si substrate;miscut;GaN;MOCVD161|226|1更新时间：2020-08-12
- 摘要：Using 3-mercaptopropionic acid(MPA) as the stabilizer, ZnS:Mn quantum dots(QDs) were synthesized via water phase method, which could emit strong phosphorescence at room temperature. Bovine serum albumin (BSA) can effectively recover the defect on the surface of ZnS:Mn QDs, so the phosphorescence intensity of ZnS:Mn QDs can be enhanced after the conjugation between BSA and ZnS:Mn QDs. Ceftriaxone sodium can obviously quench the phosphorescence of ZnS:Mn QDs-BSA, and the quenched phosphorescence intensity amount (△P) is linearly proportional to the concentration of ceftriaxone sodium with the correlation coefficient R=0.99. The optimal condition of conjunction between ZnS:Mn QDs and BSA is as following: pH=7.4, reaction temperature of 37 ℃, response time of 40 min, BSA concentration of 80 mg·L-1, ZnS:Mn QDs concentration of 40 mg·L-1, respectively. As the phosphorescence probe, the synthesized ZnS:Mn QDs-BSA can detect ceftriaxone sodium effectively with the linear scope of 0－30 μmol·L-1, correlation coefficient R=0.99, inspection limit of 0.14 μmol·L-1, relative standard deviation of 1.63%, respectively.关键词：quantum dots;bovine serum albumin;phosphorescence probe;ceftriaxone115|87|1更新时间：2020-08-12
- 摘要：Ambipolar organic thin film transistors (OTFTs) based on copper hexadecafluorophthalocyanine (F16CuPc) and copper phthalocyanine (CuPc) with double heterojunction were fabricated. The carrier mobility was 4-5 times enhanced compared with that of double layer-architecture devices under the same process. The double heterojunction effect was attributed to the great enhancement which showed an effective way to promote the performance of ambipolar OTFTs. The double heterojunction architecture also provided another way to adjust the carrier threshold voltage and decrease the critical dependence of the film thicknesses in double layer architecture.关键词：OTFTs;double heterojunction;carrier mobility;threshold voltage136|193|1更新时间：2020-08-12
- 摘要：In this paper, we introduce the carbon dots (CDs) into transparent embryos of zebrafishes and study the fluorescent imaging and toxicology of CDs. With immerging oosperms and infants of zebrafishes into the aqueous solution of CDs for 1.5 h, the CDs go through the cell membrane and emerge inside of them. Then, from the morphological, we study the biological effects on the individual development and in vivo observe the supersession of zebrafishes. We demonstrate that CDs have no apparent toxicity on the growing development and do not induce the development abnormity of embryo. Furthermore, the CDs do not lead to the death of zebrafishes. We also find that CDs can enter into the zebrafisher rapidly and be expelled from the body within 48 h.关键词：zebrafishes;carbon dots;embryonic development;biotoxicity158|315|4更新时间：2020-08-12
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