We fabricated a phosphor-conversion white light emitting diode (LED) using an InGaN chip that emits 400 nm near-ultraviolet (n-UV) light and phosphors that emit in the blue and yellow region. When the white LED was operated at a forward-bias current of 20 mA at room temperature (RT), the color temperature (Tcp), average color rendering (Ra), operating voltage (Vf) and luminous efficacy (ηL) were estimated to be 5800 K, 85.3, 3.2 V, and 26.1 lm/W, respectively. With increasing forward-bias current, the luminous flux increased almost linearly and was estimated to be 5.0 lm at 60 mA. The Commission Internationale de l'Eclairage (CIE) chromaticity coordinates obtained from the measured spectra remained almost constant during the forward-bias current increase from 0.5 mA to 60 mA.

Phosphor-Conversion White Light Emitting Diode Using InGaN Near-Ultraviolet Chip : Semiconductors

Cr3+-Doped Broadband NIR Garnet Phosphor with Enhanced Luminescence and its Application in NIR Spectroscopy

Recent advances in near-infrared emitting lanthanide-doped nanoconstructs : mechanism, design and application for bioimaging

Physical, thermal, structural and optical properties of Dy3+ doped lithium alumino-borate glasses for bright W-LED

Single-phase cool white-light emitting BaNb2O6:Dy3+ phosphors have been synthesized via a conventional solid-state reaction method and characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM) observations and spectrofluorophotometric measurements. XRD and Rietveld structural refinement studies confirm that all the samples exhibit pure orthorhombic structure [space group – C2221(20)]. SEM observations reveal the dense particle packaging with irregular morphology in a micron range. The as-prepared phosphors exhibit blue (482 nm) and yellow (574 nm) emissions under 349, 364, 386 and 399 nm excitations corresponding to 4F9/2 → 6HJ (J = 15/2, 13/2) transitions of Dy3+ ions. The energy transfer mechanism between Dy3+ ions has been studied in detail and the luminescence decay lifetime for the 4F9/2 level was found to be around 146.07 μs for the optimized phosphor composition. The calculated Commission Internationale de L'Eclairage (CIE) chromaticity coordinates for the optimized phosphor are (x = 0.322, y = 0.339), which are close to the National Television Standard Committee (NTSC) (x = 0.310, y = 0.316) coordinates. The values of CIE chromaticity coordinates and correlated color temperature (CCT) of 5907 K endorse cool white-light emission from the phosphor. The study reveals that BaNb2O6:Dy3+ phosphor could be a potential candidate for near ultra-violet (NUV) excited white-LED applications.

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A.S. Rao

Papers

White light emission and color tunability of dysprosium doped barium silicate glasses

Photoluminescence and energy transfer studies of Dy 3+ ions doped lithium lead alumino borate glasses for w-LED and laser applications

Spectroscopic studies of Sm 3+ ions activated lithium lead alumino borate glasses for visible luminescent device applications

Spectroscopic studies of Pr3+ doped lithium lead alumino borate glasses for visible reddish orange luminescent device applications

Red light emitting BaNb2O6:Eu3+ phosphor for solid state lighting applications