Research challenges to ultra‐efficient inorganic solid‐state lighting

Phillips, Julia M.; Coltrin, Michael E.; Crawford, Mary H.; Fischer, Arthur J.; Krames, Michael R.; Mueller‐Mach, Regina; Mueller, Gerd; Ohno, Yoshi; Rohwer, Lauren E. S.; Simmons, J. A.; Tsao, Jeffrey Y.

doi:10.1002/lpor.200710019

Cited by 378 publications

(280 citation statements)

References 96 publications

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“…[34], fluorescent tube (3937K) [35], YAG+blue chips [36]; higher than that of tungsten lamp (2836 K) [35]; and especially very close to the ideal CCT value of warm white light (3000 K) [8]. Besides, the CCT values are much lower than many other Dy 3+ doped compounds, such as some fluoride, tungstate, borate, and silicate [20][21][22][23][24][25][26].…”

Section: Cie Coordinates and Cct Valuesmentioning

confidence: 94%

“…Usually, WLEDs can be generally categorized as warm WLEDs (<4000 K) and cool WLEDs (≥4000 K) [6,7]. A rating of 3000 K is considered a more ideal CCT value for warm WLEDs with higher luminous efficacy of radiation and more energy efficiency [8]. Compared with the cool WLEDs, warm WLEDs have lower CCT and are closer to sunlight color, which is beneficial for keeping natural circadian rhythms in humans and offering more visibility.…”

Section: Introductionmentioning

confidence: 99%

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Crystal Growth and Luminescence Properties of Dy3+ and Ge4+ Co-Doped Bi4Si3O12 Single Crystals for High Power Warm White LED

et al. 2017

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Φ1 inch Dy 3+ and Ge 4+ co-doped bismuth silicate (Bi 4 Si 3 O 12 , BSO) single crystals with the length of 80-100 mm were successfully grown by Bridgman method. They are transparent, free of cracks and inclusions. The white residual at the top parts of BSO crystals disappears with co-doping 1 mol% Dy 3+ and more than 3 mol% Ge 4+ . The FWHM values of X-ray rocking curves shows 1%Dy,3%Ge:BSO crystal possesses high crystallization quality. The intrinsic emission peak of BSO and the characteristic emission peaks of Dy 3+ ions are weakened with increasing the doping concentration of Ge 4+ . 1 mol% Dy 3+ and 3 mol% Ge 4+ are the optimal concentrations due to high crystallization quality and moderate emission intensity. The CIE coordinates and CCT values shift towards warmer white light region with increased Ge 4+ co-doping. The CCT values are close to the ideal value of 3000 K for warm white light when 1%Dy,3%Ge:BSO crystal is excited by various UV light. Increasing the temperature from 298 K to 573 K leads the luminescence lifetime to decrease from 659 µs to 645 µs. More than 95% and 80% photoluminescence intensity at room temperature is still retained at 423 K and 573 K respectively. Dy,Ge:BSO crystals are potential candidates for fabricating high power warm WLEDs.

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Section: Cie Coordinates and Cct Valuesmentioning

confidence: 94%

Section: Introductionmentioning

confidence: 99%

Crystal Growth and Luminescence Properties of Dy3+ and Ge4+ Co-Doped Bi4Si3O12 Single Crystals for High Power Warm White LED

et al. 2017

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“…These shortcomings inhibit the wider penetration of these RAGB multipackage white LEDs in lighting applications. 36,37 Abbreviations: CAF, circadian action factor; CCT, correlated color temperature; CER, the circadian efficacy of radiation; CQS, color quality scale; CRI, color rendering index; CW, cool-white; FL, fluorescent lamp; HPS, high-pressure sodium; LE, luminous efficacy; LPS, low-pressure sodium; LER, luminous efficacy of radiation; MH, metal-halide; MSI, melatonin suppression index; pc-LED, phosphor-converted LED; WW, warm-white. Healthy, natural, efficient and tunable lighting JH Oh et al 6…”

Section: Optical Properties Of Long-wavelength Pass Dichroic Filter (mentioning

confidence: 99%

Healthy, natural, efficient and tunable lighting: four-package white LEDs for optimizing the circadian effect, color quality and vision performance

2014

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To date, most current reports on the development and optimization of artificial lighting sources have focused on the energy performance levels and limited color qualities of white light-emitting diodes (LEDs). However, these properties are insufficient in terms of representing all performance levels required when adjusting white LEDs for healthy and smart lighting. Here, we introduce essential and advanced figures of merit pertaining to circadian performance as well as vision performance and color quality. We compare all possible properties of commercialized artificial lighting, daylight and four-package white LEDs which consist of long-wavelength pass dichroic filter (LPDF)-capped, phosphor-converted red, amber and green LEDs (pc-LEDs) and a blue LED. We show that these tunable four-package white LEDs produce a tunable circadian effect for melatonin suppression/secretion, a high color quality for color perception/reproduction, high efficiency for energy savings and tunable figures of merit for the smart LED lighting market.

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“…6 This decrease in device efficiency may be due to intrinsic strain-related factors such as a large thermodynamic miscibility gap and a lack of lattice-matched substrates. 2,7 These factors complicate the growth of single-crystalline, high indium composition InGaN with a low density of defects.…”

Section: Introductionmentioning

confidence: 99%

Effect of Thermal Annealing in Ammonia on the Properties of InGaN Nanowires with Different Indium Concentrations

et al. 2013

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The utility of an annealing procedure in ammonia ambient is investigated for improving the optical characteristics of In x Ga 1-x N nanowires (0.07≤x≤0.42) grown on c-Al 2 O 3 using a halide chemical vapor deposition method. Morphological studies using scanning electron microscopy confirm that the nanowire morphology is retained after annealing in ammonia at temperatures up to 800 °C. However, significant indium etching and composition inhomogeneities are observed for higher indium composition nanowires (x = 0.28, 0.42), as measured by energy-dispersive x-ray spectroscopy and Z-contrast scanning transmission electron microscopy. Structural analysis, using x-ray diffraction and high-resolution transmission electron microscopy, indicate that this is a result of the greater thermal instability of higher indium composition nanowires. The effect of these structural changes on the optical quality of InGaN nanowires is examined using steadystate and time-resolved photoluminescence measurements. Annealing in ammonia enhances the integrated photoluminescence intensity of In x Ga 1-x N nanowires by up to a factor of 4.11±0.03 ( for x = 0.42) by increasing the rate of radiative recombination. Fitting of photoluminescence decay curves to a Kohlrausch stretched exponential indicates that this increase is directly related to a larger distribution of recombination rates from composition inhomogeneities caused by annealing. The results demonstrate 2 the role of thermal instability on the improved optical properties of InGaN nanowires annealed in ammonia.

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Research challenges to ultra‐efficient inorganic solid‐state lighting

Cited by 378 publications

References 96 publications

Crystal Growth and Luminescence Properties of Dy3+ and Ge4+ Co-Doped Bi4Si3O12 Single Crystals for High Power Warm White LED

Crystal Growth and Luminescence Properties of Dy3+ and Ge4+ Co-Doped Bi4Si3O12 Single Crystals for High Power Warm White LED

Healthy, natural, efficient and tunable lighting: four-package white LEDs for optimizing the circadian effect, color quality and vision performance

Effect of Thermal Annealing in Ammonia on the Properties of InGaN Nanowires with Different Indium Concentrations

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