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151.
Norikazu Nakayama Satoru Kijima Satoshi Itoh Toyoharu Ohata Akira Ishibashi Yoshifumi Mori 《Optical Review》1995,2(3):167-170
Green light-emitting diodes (LEDs) were fabricated employing a ZnCdSe/ZnSSe triple quantum-well (TQW) active region surrounded by ZnMgSSe cladding layers grown on an n-type (100) GaAs substrate by molecular beam epitaxy (MBE). A 3.5 mW pure green emission was observed for the surface-emitting LED device at a peak wavelength of 513.3 nm (2.415 eV) with a spectral half-width of 11.7 nm (55 meV) under a 20 mA (4.6 V) direct current at room temperature (25°C). These correspond to an external quantum efficiency of 7.2%, a power conversion efficiency of 3.8%, a luminous current efficiency of 66 lm/A, and a luminous efficiency of 14 lm/W. 相似文献
152.
Eunjae Jeong Sun Hee Kim In Hwan Jung Yangjun Xia Kwanghee Lee Hongsuk Suh Hong‐Ku Shim Han Young Woo 《Journal of polymer science. Part A, Polymer chemistry》2009,47(14):3467-3479
An indenofluorene‐based copolymer containing blue‐, green‐, and red light‐emitting moieties was synthesized by Suzuki polymerization and examined for application in white organic light‐emitting diodes (WOLEDs). Tetraoctylindenofluorene (IF), 2,1,3‐benzothiadiazole (BT), and 4,7‐bis(2‐thienyl)‐2,1,3‐benzothiadiazole (DBT) derivatives were used as the blue‐, green‐, and red‐light emitting structures, respectively. The number‐average molecular weight of the polymer was determined to be 25,900 g/mol with a polydispersity index of 2.02. The polymer was thermally stable (Td = ~398 °C) and quite soluble in common organic solvents, forming an optical‐quality film by spin casting. The EL characteristics were fine‐tuned from the single copolymer through incomplete fluorescence energy transfer by adjusting the composition of the red/green/blue units in the copolymer. The EL device using the indenofluorene‐based copolymer containing 0.01 mol % BT and 0.02 mol % DBT units ( PIF‐BT01‐DBT02 ) showed a maximum brightness of 4088 cd/m2 at 8 V and a maximum current efficiency of 0.36 cd/A with Commission Internationale de L'Eclairage (CIE) coordinates of (0.34, 0.32). The EL emission of PIF‐BT01‐DBT02 was stable with respect to changes in voltage. The color emitted was dependent on the thickness of the active polymer layer; layer (~60 nm) too thin was unsuitable for realizing WOLED via energy transfer. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 3467–3479, 2009 相似文献
153.
Bar‐Yuan Hsieh Yun Chen 《Journal of polymer science. Part A, Polymer chemistry》2008,46(11):3703-3713
Copolyfluorenes ( PFR1 and PFR2 ), chemically doped with 0.1 and 0.025 mol % 2,5‐dihexyloxy‐1,4‐bis(2‐thienyl‐2‐cyanovinyl)benzene (MR chromophere) were synthesized by the Suzuki coupling reaction. The PFR s were used to fabricate white‐light‐emitting devices through incomplete energy transfer. Because of the low content of the MR chromophore, the optical, thermal, and electrochemical properties of the PFR s were almost identical to those of polyfluorene, except for their photoluminescent (PL) and electroluminescent (EL) properties. The copolymer films showed PL peaks at about 428 and 570 nm originating from fluorene segments and MR chromophores, respectively. Compared with the model compound ( MR ), the polymer chains extended the conjugation length of the MR chromophores and exhibited a 20–48 nm red‐shift in the emission band. In addition, the lower LUMO level of the MR (?3.27 eV) was expected to improve the electron injection. The EL devices [ITO/PEDOT:PSS/ PFR s/Ca (50 nm)/Al (100 nm)] showed a broad emission band, covering the entire visible region, with chromaticity coordinates of (0.36, 0.35) and (0.32, 0.30) for PFR1 and PFR2 devices, respectively. The emission color of the PFR2 device was very similar to that of a pure white light (0.33, 0.33); and the maximal brightness and current efficiency were 3011 cd/m2 and 1.98 cd/A, respectively, which surpass those found for polyfluorene devices (1005 cd/m2, 0.28 cd/A). A). © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 3703–3713, 2008 相似文献
154.
V. L. Ginzburg 《Journal of statistical physics》1969,1(1):3-24
The paper aims to elucidate the current status of the problem concerning the existence and observation of superfluid and superconducting states in the universe, that is, under cosmic conditions. Following an introduction, the paper discusses Bose-Einstein condensation, superfluidity, and superconductivity; possibilities for the occurrence of superfluidity and superconductivity under cosmic conditions; superconductivity of dense, degenerate electron plasma (large planets, white dwarfs); superfluidity and superconductivity in neutron stars; and finally superfluidity in a cosmological neutrino “sea.” 相似文献
155.
156.
Caishi Wang Zhiyuan Huang Xiangjun Wang 《Proceedings of the American Mathematical Society》2005,133(3):891-898
Let be the canonical framework of white noise analysis over the Gel'fand triple and be the space of continuous linear operators from to . Let be a self-adjoint operator in with spectral representation . In this paper, it is proved that under appropriate conditions upon , there exists a unique linear mapping such that for each . The mapping is then naturally used to define as , where is the Dirac -function. Finally, properties of the mapping are investigated and several results are obtained.
157.
掺杂聚合物蓝光发光二极管 总被引:3,自引:0,他引:3
报道了用有机染料TPB(1,l,4,4-四苯基丁二烯)分散到PVK(聚乙烯基咔唑)中的掺杂聚合物作有源层制作的蓝光发光二极管及其发光特性。聚合物发光层用旋转涂敷的方法制备,用透明导电材料ITO(铟锡氧化物)、金属Al作为正负电极。器件正向偏压为13V时,可以看到蓝光发射,峰值波长为455nm,注入电流为50mA/cm2时,亮度为44cd/m2。 相似文献
158.
159.
采用高温固相法合成了白光LED用Ca8Mg(SiO4)4Cl2:Eu和Ca8Mg(SiO4)4Cl2:Eu,Dy绿色发光粉。研究发现:共掺Dy可以明显地提高Ca8Mg(SiO4)4Cl2:Eu发光粉的发光性能,表明Dy3+和Eu2+之间存在着能量传递过程。当Dy3+的最佳掺杂摩尔分数为0.02时,发光粉505nm处绿光发射的强度约提高12%。通过对Dy3+和Eu2+光谱特性的分析,Dy3+和Eu2+之间的能量传递机制可归因于无辐射交叉弛豫。 相似文献
160.
采用凝胶-燃烧法合成了Ca3Sc2Si3O12 ∶Ce绿色LED用荧光粉,用X射线粉末衍射(XRD)、扫描电镜(SEM)、荧光光谱仪等对合成产物进行了分析和表征.结果表明:通过添加H3BO3做助熔剂,制得的荧光粉晶相纯正,颗粒形貌均呈现为较规则的类球形,而且所得荧光粉的粒径均小于1 μm.发射光谱呈现为一宽带,发射主峰位于505 nm,该宽峰对应于Ce3+关键词:
白光LED
荧光粉
3Sc2Si3O12 ∶Ce')" href="#">Ca3Sc2Si3O12 ∶Ce
发光 相似文献