The influence of the iodine vapour pressure on the mechanisms of XeI^＊ formation is investigated in Xe/I2 mixture by dielectric barrier discharge. The iodine vapour pressure is measured as a function of the ultraviol...The influence of the iodine vapour pressure on the mechanisms of XeI^＊ formation is investigated in Xe/I2 mixture by dielectric barrier discharge. The iodine vapour pressure is measured as a function of the ultraviolet （UV） intensity of XeI^＊ emission at 253 nm, and found that the UV intensity reaches a maximum at 0.9 Torr of iodine at a xenon pressure of 300 Torr, then decreases slowly with the iodine pressure larger than 0.9 Torr. The discharge mode transforms from a hybrid discharge at a xenon pressure of 760 Torr with 1.0 Torr of iodine to a diffuse mode at 10 Torr of iodine. These results are quite different from those of other rare-gas halogen excimers and indicate a different mechanism of XeI^＊ formation from those of other rare-gas halogen excimers.展开更多
We investigated the formation of exciplex and electroluminescent absorption in ultraviolet organic light-emitting diodes（UV OLEDs） using different heterojunction structures.It is found that an energy barrier of over...We investigated the formation of exciplex and electroluminescent absorption in ultraviolet organic light-emitting diodes（UV OLEDs） using different heterojunction structures.It is found that an energy barrier of over 0.3 eV between the emissive layer（EML） and adjacent transport layer facilitates exciplex formation.The electron blocking layer effectively confines electrons in the EML,which contributes to pure UV emission and enhances efficiency.The change in EML thickness generates tunable UV emission from 376 nm to 406 nm.In addition,the UV emission excites low-energy organic function layers and produces photoluminescent emission.In UV OLED,avoiding the exciplex formation and averting light absorption can effectively improve the purity and efficiency.A maximum external quantum efficiency of 1.2%with a UV emission peak of 376 nm is realized.展开更多
YPO4 phosphors single-doped with Sb3+ or Gd3+ and co-doped with Sb3+ and Gd3+were prepared by a solid-state reaction method. The phase purity, morphology, photoluminescence excitation and emission properties of the pr...YPO4 phosphors single-doped with Sb3+ or Gd3+ and co-doped with Sb3+ and Gd3+were prepared by a solid-state reaction method. The phase purity, morphology, photoluminescence excitation and emission properties of the prepared phosphors were inves-tigated. The results showed that Sb3+ could sensitize Gd3+ in the co-doped phosphors which made the phosphors excitable by short-wave ultraviolet (UV) at a wavelength between 220 and 260 nm. Under 253.7 nm excitation, the co-doped phosphors Y1–x–yPO4: Sb3+x,Gd3+yshowed strong emission of Gd3+ at a wavelength of 312 nm whose intensity changed with the doping concentrations of Gd3+ and Sb3+. The optimized Y0.77PO4:Sb3+0.07,Gd3+0.16 phosphor showed an intensity comparable to commercial LaPO4:Ce phosphor (UVB-315), making it a potential candidate for mercury low-pressure discharge narrow-band UV-B emitting lamps.展开更多
We investigated the effects of Si-layer-thickness ratios on ultraviolet (UV) peak intensities of Si/ SiO2 multilayered films produced by alternately stacking several-nanometer-thick Si and SiO2 layers using radio-freq...We investigated the effects of Si-layer-thickness ratios on ultraviolet (UV) peak intensities of Si/ SiO2 multilayered films produced by alternately stacking several-nanometer-thick Si and SiO2 layers using radio-frequency sputtering for the first time. The Si-layer-thickness ratio of the Si/SiO2 film is a very important parameter for enhancing the peak intensity because the ratio is concerned with the size of Si nanocrystals in the film, which might affect the intensity of the UV light emission from the film. We prepared seven samples with various estimated Si-layer-thickness ratios, and measured the photoluminescence spectra of the samples after annealing at 1150°C, 1200°C, or 1250°C for 25 min. From our experiments, we estimate that the proper Si-layer-thickness ratio to obtain the strongest UV peaks from the Si/SiO2 multilayered films is around 0.29. Such a UV-lightemitting thin film is expected to be used in future higher-density optical-disk systems.展开更多
文摘The influence of the iodine vapour pressure on the mechanisms of XeI^＊ formation is investigated in Xe/I2 mixture by dielectric barrier discharge. The iodine vapour pressure is measured as a function of the ultraviolet （UV） intensity of XeI^＊ emission at 253 nm, and found that the UV intensity reaches a maximum at 0.9 Torr of iodine at a xenon pressure of 300 Torr, then decreases slowly with the iodine pressure larger than 0.9 Torr. The discharge mode transforms from a hybrid discharge at a xenon pressure of 760 Torr with 1.0 Torr of iodine to a diffuse mode at 10 Torr of iodine. These results are quite different from those of other rare-gas halogen excimers and indicate a different mechanism of XeI^＊ formation from those of other rare-gas halogen excimers.
基金supported by the National Natural Science Foundation of China(Grant Nos.61136003 and 61275041)the Guangxi Provincial Natural Science Foundation,China(Grant No.2012GXNSFBA053168)
文摘We investigated the formation of exciplex and electroluminescent absorption in ultraviolet organic light-emitting diodes（UV OLEDs） using different heterojunction structures.It is found that an energy barrier of over 0.3 eV between the emissive layer（EML） and adjacent transport layer facilitates exciplex formation.The electron blocking layer effectively confines electrons in the EML,which contributes to pure UV emission and enhances efficiency.The change in EML thickness generates tunable UV emission from 376 nm to 406 nm.In addition,the UV emission excites low-energy organic function layers and produces photoluminescent emission.In UV OLED,avoiding the exciplex formation and averting light absorption can effectively improve the purity and efficiency.A maximum external quantum efficiency of 1.2%with a UV emission peak of 376 nm is realized.
文摘YPO4 phosphors single-doped with Sb3+ or Gd3+ and co-doped with Sb3+ and Gd3+were prepared by a solid-state reaction method. The phase purity, morphology, photoluminescence excitation and emission properties of the prepared phosphors were inves-tigated. The results showed that Sb3+ could sensitize Gd3+ in the co-doped phosphors which made the phosphors excitable by short-wave ultraviolet (UV) at a wavelength between 220 and 260 nm. Under 253.7 nm excitation, the co-doped phosphors Y1–x–yPO4: Sb3+x,Gd3+yshowed strong emission of Gd3+ at a wavelength of 312 nm whose intensity changed with the doping concentrations of Gd3+ and Sb3+. The optimized Y0.77PO4:Sb3+0.07,Gd3+0.16 phosphor showed an intensity comparable to commercial LaPO4:Ce phosphor (UVB-315), making it a potential candidate for mercury low-pressure discharge narrow-band UV-B emitting lamps.
文摘We investigated the effects of Si-layer-thickness ratios on ultraviolet (UV) peak intensities of Si/ SiO2 multilayered films produced by alternately stacking several-nanometer-thick Si and SiO2 layers using radio-frequency sputtering for the first time. The Si-layer-thickness ratio of the Si/SiO2 film is a very important parameter for enhancing the peak intensity because the ratio is concerned with the size of Si nanocrystals in the film, which might affect the intensity of the UV light emission from the film. We prepared seven samples with various estimated Si-layer-thickness ratios, and measured the photoluminescence spectra of the samples after annealing at 1150°C, 1200°C, or 1250°C for 25 min. From our experiments, we estimate that the proper Si-layer-thickness ratio to obtain the strongest UV peaks from the Si/SiO2 multilayered films is around 0.29. Such a UV-lightemitting thin film is expected to be used in future higher-density optical-disk systems.
