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Structural and optical properties of highly thermally active Gd2Zr2O7:Dy3+ phosphors for lighting applications
摘要： Near white light emitting (Gd2?2x Dy2x Zr2O7) (2x = 0.01, 0.02, 0.04, 0.06, 0.08) phosphors have been synthesized by the facile hydrothermal method. To examine the structural and optical properties, the prepared phosphors were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), photoluminescence spectroscopy (PL) and UV–Vis diffuse reflectance spectroscopy. The XRD results confirm the defect fluorite structure of the prepared phosphors having cubic crystal system with space group Fm3m and incorporation of Dy3+ ions does not modify host lattice crystal structure. The photoluminescence properties have been well studied in respect of excitation spectra, emission spectra and decay kinetics. The PL emission spectra of the sample under 351 nm UV excitation exhibits two intense peaks around 484 nm and 580 nm which are attributed to the transitions 4F9/2–6H15/2 and 4F9/2–6H13/2, respectively of Dy3+ ion. The emission intensity goes on increasing until Dy3+ doping concentration reaches at 2 mol% and intensity decreases thereafter on higher concentration. The average life times are found to decrease with the increase of Dy3+ concentration. Photometric studies such as CIE color coordinate, CCT and Color purity facilitate that the reported phosphors can generate near white light emission. Temperature dependent PL spectral measurement reveals that the emission intensity as well as the life time gradually increases with temperature. Thus, the affirmative experimental result indicates that the Dy3+ ions doped Gd2Zr2O7 phosphors can be used as active near white lighting emitting phosphor materials.
关键词： white light emitting diode,Gd2Zr2O7:Dy3+,photoluminescence,phosphors,hydrothermal method
更新于2025-09-04 15:30:14
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Electronic structure of the polymer-cathode interface of an organic electroluminescent device investigated using operando hard x-ray photoelectron spectroscopy
摘要： The electronic structure of a polymer-cathode interface of an operating organic light-emitting diode (OLED) was directly investigated using hard X-ray photoelectron spectroscopy (HAXPES). The potential distribution pro?le of the light-emitting copolymer layer as a function of the depth under the Al/Ba cathode layer in the OLED depended on the bias voltage. We found that band bending occurred in the copolymer of 9,9-dioctyl?uorene (50%) and N-(4-(2-butyl)-phenyl)diphenylamine (F8-PFB) layer near the cathode at 0 V bias, while a linear potential distribution formed in the F8-PFB when a bias voltage was applied to the OLED. Direct observation of the built-in potential and that band bending formed in the F8-PFB layer in the operating OLED suggested that charges moved in the F8-PFB layer before electron injection from the cathode.
关键词： polymer-cathode interface,band bending,organic light-emitting diode,electronic structure,hard X-ray photoelectron spectroscopy
更新于2025-09-04 15:30:14
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Influence of Light Emitting Diode on Bone Marrow and Healing of Dermatome Wounds
摘要： The irradiation of large surfaces or whole body with light emitting diode LED λ-470 nm and λ-940 nm (LED shower) causes structural changes in bone marrow and stimulates healing of experimental dermatome wounds. The increase of migration of the bone marrow cells in derma and epithelial layers of skin indicates that LED-shower intensifies intercellular interactions and cells migration between tissues.
关键词： Bone marrow,Dermatome wounds,Light emitting diode irradiation,Morphology
更新于2025-09-04 15:30:14
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Light Emitting Diodes Based on Inorganic Composite Halide Perovskites
摘要： CsPbBr3 is a promising type of light-emitting halide perovskite with inorganic composition and desirable thermal stability. The luminescence efficiency of pristine CsPbBr3 thin films, however, appears to be limited. In this work, light emitting diodes based on CsPbBr3|Cs4PbBr6 composites are demonstrated. Both quantum efficiency and emission brightness are improved significantly compared with similar devices constructed using pure CsPbBr3. The high brightness can be attributed to the enhanced radiative recombination from CsPbBr3 crystallites confined in the Cs4PbBr6 host matrix. The unfavorable charge transport property of Cs4PbBr6 can be circumvented by optimizing the ratio between the host and the guest components and the total thickness of the composite thin films. The inorganic composition of the emitting layer also leads to improved device stability under the condition of continuous operation.
关键词： stability,conductivity,composite perovskite,light emitting diode,Cs4PbBr6
更新于2025-09-04 15:30:14
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[IEEE 2018 1st International Cognitive Cities Conference (IC3) - Okinawa, Japan (2018.8.7-2018.8.9)] 2018 1st International Cognitive Cities Conference (IC3) - A Novel Image Analysis of Light Emitting Diode Array Biostimulation Applied on Microcirculation
摘要： A novel development platform of the specific microcirculation analysis was proposed in this study. This study was to observe the effect of the blood microcirculation with LED stimulation. The experiment involved the light emitting diode array (LEDA), the designed control board and the image processing algorithm on the platform. LEDA (six LEDs, wavelength 660 nm, operating frequency 8 - 15 Hz) was used to stimulate the palm of the subject, and then, the microcirculation images were analyzed by the image processing algorithm. The blood velocity on the ring finger was increased after LEDA stimulation, and it was approximately 1.7 times compared with and without the light stimulation. Thus, LEDA stimulation on the palm enhanced the microcirculation. Also, a specific platform of LEDA system with microcirculation measurement was developed in this study.
关键词： image processing algorithm,microcirculation,light emitting diode array
更新于2025-09-04 15:30:14