White Light-Emitting Diodes With High Color Rendering Index and Tunable Color Temperature Fabricated Using Separated Phosphor Layer Structure

Chiang, Chung-Hao; Gong, Syuan-Jhih; Zhan, Ting-Shi; Cheng, Kuo-Ching; Chu, Sheng−Yuan

doi:10.1109/led.2016.2576498

Cited by 20 publications

(6 citation statements)

References 13 publications

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“…The modeling process of three WLED models, including the conformal, in-cup, and remote phosphor packages, is performed with the LightTools simulation software and the Monte Carlo method [21]. The phosphor sheets covering the LED chip's surface are simulated with a flat silicon thin film.…”

Section: Structure Of Pc-wledsmentioning

confidence: 99%

CaO:Tb<sup>3+ </sup> green-emitting phosphor for white light-emitted diode-phosphor applications: the improvement of light output intensity

Tung,

Nguyen Thi

2024

Bulletin EEI

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The use of CaO:Tb3+ with light green emission on for improvement of both luminescent output and chromatic fidelity of the white light emitted from a light-emitting diode (LED). The CaO:Tb3+ is combined with the yellow-emitting phosphor of YAG:Ce3+ to provide sufficient colored spectral proportion for the white light generation, enhancing the color performance. The phosphor combination is utilized for the three most applied LED structures: conformal, in-cup, and remote phosphor structures. The changes in optical properties of these three LEDs are monitored with adjustments in the proportion of CaO:Tb3+. The higher proportion of the green phosphor results in higher scattering efficiency in all structures, offering better color coordination and stronger luminous flux. The color quality scale is somehow reduced when CaO:Tb3+ concentration is more than a certain level. Therefore, depending on the phosphor configuration of the white light-emitting diode (WLED), the concentration of CaO:Tb3+ should be modified to achieve a good color rendition with improved color consistency and luminous properties.

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Section: Structure Of Pc-wledsmentioning

confidence: 99%

CaO:Tb<sup>3+ </sup> green-emitting phosphor for white light-emitted diode-phosphor applications: the improvement of light output intensity

Tung,

Nguyen Thi

2024

Bulletin EEI

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“…Conventionally, the color performance of WLEDs is evaluated from two aspects: the emitting color from the WLED and the releasing color of objects exposed under the WLED. Theoretically, the former is characterized by correlated color temperature (CCT), and the latter is characterized by color rendering property, in which the concept of general color rendering index (Ra) is conventionally adopted for evaluation by the International Commission on Illumination [4]. CCT expresses a warm or cold feeling when we observe the light beam, while Ra reveals the ability of a light source to express the real color of an object.…”

Section: Introductionmentioning

confidence: 99%

An Investigation on CCT and Ra Optimization for Trichromatic White LEDs Using a Dual-Weight-Coefficient-Based Algorithm

Xiao

et al. 2022

Micromachines

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Spectral optimization is applied as an effective tool in designing solid-state lighting devices. Optimization speed, however, has been seldomly discussed in previous reports as regards designing an algorithm for white light-emitting diodes (WLEDs). In this study, we propose a method for trichromatic WLEDs to obtain the optimal Ra under target correlated color temperatures (CCTs). Blue-, yellow-, and red-color monochromatic spectra, produced by the GaN LED chip, YAG:Ce3+ phosphors, and CdSe/ZnSe quantum dots, respectively, are adopted to synthesize white light. To improve the effectiveness of our method, the concept of dual weight coefficients is proposed, to maintain a numerical gap between the proposed floating CCT and the target CCT. This gap can effectively guarantee that Ra and CCT ultimately move toward the targeting value simultaneously. Mechanisms of interaction between CCT, Ra, and dual-weight coefficients are investigated and discussed in detail. Particularly, a fitting curve is drawn to reveal the linear relationship between weight coefficients and target CCTs. This finding effectively maintains the accuracy and accelerates the optimization process in comparison with other methods with global searching ability. As an example, we only use 29 iterations to achieve the highest Ra of 96.1 under the target CCT of 4000 K. It is hoped that this study facilitates technology development in illumination-related areas such as residential intelligent lighting and smart planting LED systems.

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“…Phosphor-converted (pc) white solid-state lighting has an inevitable role in our life with emission close to standard white light because of extraordinary foreseen advantages over the conventional lamps. Out of all the methods to generate white light, the method involving ultraviolet (UV) excitation of phosphors is found to be most suitable from technological and physical point of view for maintaining stable colour rendering index (CRI) and high luminous efficacy (luminous efficacy of radiation (LER)) over time along and uniform excitation for every visible band [1]. Additionally, to resolve the energy crisis and to address the environmental concerns, rare-earth-free solid-state lighting is also in demand with different types of nanostructures [2][3][4][5][6][7].…”

Section: Introductionmentioning

confidence: 99%

GaN phosphors converted white light‐emitting diodes for high luminous efficacy and improved thermal stability

Kumar

et al. 2020

IET Optoelectronics

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White Light-Emitting Diodes With High Color Rendering Index and Tunable Color Temperature Fabricated Using Separated Phosphor Layer Structure

Cited by 20 publications

References 13 publications

CaO:Tb<sup>3+ </sup> green-emitting phosphor for white light-emitted diode-phosphor applications: the improvement of light output intensity

CaO:Tb<sup>3+ </sup> green-emitting phosphor for white light-emitted diode-phosphor applications: the improvement of light output intensity

An Investigation on CCT and Ra Optimization for Trichromatic White LEDs Using a Dual-Weight-Coefficient-Based Algorithm

GaN phosphors converted white light‐emitting diodes for high luminous efficacy and improved thermal stability

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