Quantum-confined-atom-based nanophosphors for solid state lighting

Taskar, N. R.; Bhargava, R. N.; Barone, Juanita; Chhabra, V.; Chabra, Vipin; Dorman, D.; Ekimov, A. I.; Herko, Samuel; Kulkarni, Bharati

doi:10.1117/12.515432

Cited by 24 publications

(23 citation statements)

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“…Past literature acknowledges that a significant portion of the light is backscattered by the phosphor and is lost within the LED due to absorption. 5,6 In 2003, we performed an optical ray-tracing study to understand how much of the light is trapped within an LED package for a remote-phosphor concept shown in Figure 4. 7 Figure 5 illustrates the results from the ray-tracing analysis.…”

Section: White Ledmentioning

confidence: 99%

Improved performance white LED

Narendran

2005

Fifth International Conference on Solid State Lighting

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This paper describes work leading to the development of a new packaging method for white LEDs, called scattered photon extraction (SPE). Previous work by our group showed that the traditional placement of the phosphor close to the die negatively affects the overall luminous efficacy and lumen maintenance of phosphor-converted white LEDs. The new SPE method enables higher luminous efficacy by placing the phosphor at a remote location from the die and by shaping the lens surrounding the die to extract a significant portion of the back-transferred light before it is absorbed by packaging components. Although the remote phosphor concept is not new, SPE is the first method to demonstrate efficient extraction of back-transferred light and show over 60 percent improvement in light output and efficacy compared to similar commercial white LEDs. At low currents, the prototype white LEDs based on the SPE technique showed over 80 lumens per watt. The SPE concept was tried on two types of commercial packages and both showed similar improvements. BACKGROUNDDisplacing traditional light sources with solid-state light sources is the dream of many researchers. Since the first demonstration of white light-emitting diodes (LEDs) in the mid-1990s, researchers have been striving to boost the performance of this technology so that its luminous efficacy far exceeds the commonly used incandescent light bulb and the linear fluorescent lamp. The luminous efficacies of these two traditional light source technologies are nominally around 15 lumens per watt and 85 lumens per watt, respectively. The luminous efficacy of presently available commercial white LED products is in the range of 40 lumens per watt. The target for solid-state light sources is to reach 150 lumens per watt by 2012. 1 For white LEDs to reach this target, improvements are needed in several areas, including the internal quantum efficiency, the light extraction efficiency, and the phosphor efficiency. The white LED luminous efficacy gains made during the past several years can be attributed mostly to improvements in internal quantum efficiency and light extraction efficiency from the chip. Although new phosphor blends have been used to improve color properties, they have not contributed much to the luminous efficacy gains. This may be mainly due to the fact that the commonly used YAG:Ce phosphor in white LEDs is very efficient, and most of the newer phosphor blends have added more energy in the red region of the spectrum, which is likely to lessen the efficacy. Even though the YAG:Ce phosphor is efficient, recently our group showed that the traditional phosphor placement method negatively impacts the overall efficacy of white LEDs. 2 The goal of this paper is to describe the work that led to this finding and to the development of a new phosphor placement method.

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Section: White Ledmentioning

confidence: 99%

Improved performance white LED

Narendran

2005

Fifth International Conference on Solid State Lighting

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“…Similar works were performed for light emitting diodes (LEDs) and thin-film electroluminescence (TFEL) devices. High light extraction efficiency could be obtained by surface texturing [12], surface roughing [13], a two-dimensional surface grating [14], inserting an in situ rough SiN x [15], and introducing a two-dimensional SiO 2 nanorod pattern into the glass substrate of a TFEL [16].…”

Section: Introductionmentioning

confidence: 99%

Luminescent properties of CaTiO3:Pr thin-film phosphor deposited on ZnO/ITO/glass substrate

Chung

Han

Song³

et al. 2005

Journal of Luminescence

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“…Commercial white solid state lighting typically uses a gallium nitride (GaN) semiconductor-based blue light emitting diode (LED), operating at wavelengths of λ = 450 nm -470 nm, that excites a yellow-emitting phosphor powder, such as cerium doped yttrium aluminum garnet (YAG:Ce), which is blended or encapsulated with epoxy on top of the LED die [1][2][3][4][5][6][7]. See Fig.…”

Section: Introductionmentioning

confidence: 99%

Solid state lighting using deoxyribonucleic acid-phosphor blend

2012

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Commercial white solid state lighting consists of a blue light emitting diodes (LEDs) that excites a yellow-emitting phosphor powder, which is encapsulated with epoxy on top of the LED die. In this paper, we present the results of replacing the epoxy, with a promising new material, a deoxyribonucleic acid (DNA)-based biopolymer. Using this DNA-biopolymer as the host, has shown the potential for improving both the brightness and color of the light output.

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Quantum-confined-atom-based nanophosphors for solid state lighting

Cited by 24 publications

References 0 publications

Improved performance white LED

Improved performance white LED

Luminescent properties of CaTiO3:Pr thin-film phosphor deposited on ZnO/ITO/glass substrate

Solid state lighting using deoxyribonucleic acid-phosphor blend

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