A white light-emitting diode (0.33, 0.33) is fabricated using perovskite quantum dot/silica composites. It is shown to have greatly improved stability.

White light-emitting diodes ͑LEDs͒ were fabricated by associating an InGaN-based blue LED chip with highly luminescent phosphors, Y 3 Al 5 O 12 :Ce 3+ ͑YAG:Ce͒ and CaSiAlN 3 :Eu 2+ . The thermal stability of these phosphors, depending weakly on the composition and the activator concentration, remains high over a wide range of temperatures ͑25-300°C͒. When a mixture of YAG:Ce and CaSiAlN 3 :Eu 2+ was coated on a blue LED, the resultant white LED had a high luminous efficiency of L = 68 lm/W, a high color rendering index of Ra = 93, and a color temperature of T C = 3007 K ͑at 50 mA͒. Additionally, the color coordinates, Ra and T C , of the white LED tend to remain constant against an appreciable variation in applied current.Global warming is worsening on account of the consumption of fossil fuels, which produce CO 2 gas, 1 and the fact that a large amount of energy is required for illumination, including both industrial and residential lighting. Accordingly, white light-emitting diodes ͑WLEDs͒ represent a potential next-generation illumination source, as they have very favorable properties, such as high energy efficiency, low power consumption, reliability, and environmental protection. [2][3][4][5] Phosphors are important materials in lighting and have been extensively investigated. 6 The most universal WLED employs a 450-470 nm blue-emitting chip that is coated with a yellow phosphor, Y 3 Al 5 O 12 :Ce ͑Ce-doped yttrium alumina garnet, YAG:Ce͒. The color rendering property of YAG:Ce-based WLEDs is poor owing to a red deficiency of the phosphor YAG:Ce. This problem has attracted the attention of numerous researchers, who have sought to improve the color rendering property of phosphor-converted ͑pc͒ WLEDs. Jang et al. 7 enhanced the color rendering property of the YAG:Ce phosphor by adding Pr and Tb as a coactivator, at the expense of reducing luminous efficiency by energy transfer and increasing the cost of manufacture. Wu et al. 8 reported on a blue light-emitting diode ͑LED͒ that was precoated with green/red phosphors; its luminous efficiency was low and the red-emitting phosphor reached luminescence saturation as the applied current was increased. In addition, Kimura et al. 9 also used a multicomponent oxynitride and nitride phosphors mixture, pumped with blue light to produce an extrahigh color rendering white light, producing the drawbacks of complex blending operations and a decrease in the device efficiency. Such as that of inorganic phosphors, the color rendering property of quantum-dot-assisted YAG:Ce-based WLEDs was excellent, as revealed by the work of Ziegler et al. 10 on InP/ZnS nanocrystals as converter materials.In this study, oxide-and nitride-based highly luminescent phosphors, such as yellow-emitting YAG:Ce and red-emitting CaSiAlN 3 :Eu 2+ , respectively, are adopted. A mixture of YAG:Ce and CaSiAlN 3 :Eu 2+ was excited using a blue LED, and the WLED thus comprised a high luminous efficiency, high color rendering index, and Commission International del'Eclairage ͑CIE͒ chromaticity coordinates th...

Quantum dot white light-emitting diodes (QD-WLEDs) were fabricated from green- and red-emitting AgInS2/ZnS core/shell QDs coated on GaN LEDs. Their electroluminescence (EL) spectra were measured at different currents, ranging from 50 mA to 400 mA, and showed good color stability. The modulation bandwidth of previously prepared QD-WLEDs was confirmed to be much wider than that of YAG:Ce phosphor-based WLEDs. These results indicate that the AgInS2/ZnS core/shell QDs are good color-converting materials for WLEDs and they are capable in visible light communication (VLC).