Investigation on Modulation Speed of Photon-Recycling White Light-Emitting Diodes With Vertical-Conduction Structure

Chen, Fu-Bang; Chi, Kai-Lun; Yen, W.M.; Sheu, Jinn-Kong; Lee, Ming-Lun; Shi, Jin‐Wei

doi:10.1109/jlt.2018.2890331

Cited by 14 publications

(16 citation statements)

References 16 publications

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“…This assumption can be valid because the lateral dimension of a large-area vertical LED chip can be as large as 1 mm whereas the vertical dimension is only several μms. Several groups have also presented μ-LED structures with vertical or flip-chip structures for efficient heat dissipation through a small chip area [2], [7], [15], [23]- [25]. However, side-wall emissions cannot be neglected for the simulation of μ-LED structures.…”

Section: Introductionmentioning

confidence: 99%

Light Extraction Efficiency of GaN-Based Micro-Scale Light-Emitting Diodes Investigated Using Finite-Difference Time-Domain Simulation

2020

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We conducted a systematic investigation of the light extraction efficiency (LEE) of GaN-based vertical micro-scale light-emitting diode (μ-LED) structures using threedimensional finite-difference time-domain (FDTD) simulations. The LEE of μ-LED structures was found to have a strong dependence on structural parameters such as the shape of the chip cross section, chip dimension, and p-GaN thickness. The LEE of a μ-LED with a circular cross section was lower than that of a μ-LED with a square cross section by 5∼10% owing to the coupling of light with high-quality-factor whispering gallery modes. The LEE of a μ-LED structure decreased as the chip dimension increased, which could be attributed to the increased portion of trapped light inside the LED chip and increased light absorption in the GaN with an increasing chip dimension. In addition, the LEE varied significantly with the thickness of the p-GaN layer, which could be explained by the strong dependence of the angular distribution of the emission pattern on the p-GaN thickness. The FDTD simulation method presented in this study is expected to be advantageously employed in designing μ-LED structures with high LEE.

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Section: Introductionmentioning

confidence: 99%

Light Extraction Efficiency of GaN-Based Micro-Scale Light-Emitting Diodes Investigated Using Finite-Difference Time-Domain Simulation

2020

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“…The calculation in this part will contribute greatly to the significant enhancement in WLED performance. In particular, the transmitted blue light and the converted yellow light in a single-layer remote structure in which the phosphor layer is 2h thick are computed by [23][24][25]:…”

Section: Computation and Discussionmentioning

confidence: 99%

Application of BaY2F8:Er3+,Yb3+ and Mg8Ge2O11F2:Mn4+ in improving the lighting quality of phosphor-in-glass based white light-emitting diodes with the dual-convex design

Dang

That

2021

IJECE

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<span>Although the luminous of the remote phosphor structure tends to be better than that of the in-cup or conformal phosphor structures, the poor light quality prevents this lighting method from being widely used. It is recognized through experiments that the two-layer remote phosphorus structure should be used to improve color rendering index (CRI) and color quality ratio (CQS) for WLEDs. In the experiments, WLED structures containing green BaY2F8:Er3+,Yb3+ or red Mg8Ge2O11F2:Mn4+ phosphor on the yellow YAG:Ce3+ phosphor were performed at 8500 K.. After that, Mg8Ge2O11F2:Mn4+ and BaY2F8:Er3+,Yb3+ concentrations in each WLED structure is adjusted until chromatic performance reached the finest quality. As a result, Mg8Ge2O11F2:Mn4+is proved to bring great benefits to the increase of CRI and CQS. Specifically, the greater the concentration of Mg8Ge2O11F2:Mn4+, the better CRI and CQS because of the additional red-light material from this phosphor. The other phosphor material, green BaY2F8:Er3+,Yb3+ phosphor, is beneficial for the expansion of luminous flux. However, if the concentration of Mg8Ge2O11F2:Mn4+ or BaY2F8:Er3+,Yb3+ is over the limit, the decrease in lumen output and chromatic quality will occur. While doing the experiment, Mie-scattering theory and the Beer’s law are great tools to verify the accuracy of results. The results of this article can serve the purpose of improving WLEDs fabrication to produce higher quality product.</span>

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“…Based on the Mie theory [23][24][25][26][27][28][29][30][31][32][33][34][35], the scattering coefficient μsca are computed to verify the optical properties of phosphor compounding. The relationship among the scattering coefficient (SC), the wavelength, and diameter of SrBaSiO4:Eu 2+ particles is expressed in the formula below:…”

Section: Computation and Discussionmentioning

confidence: 99%

“…Based on the LightTools 8.5.0 software and Monte Carlo method [30][31][32], the prototype simulation of MCW-LEDs is conducted through two main periods with a flat silicone layer. Setting up and manufacturing the framework and lighting characteristics of MCW-LED at first, then the influences of phosphor compounding with different SrBaSiO4:Eu 2+ concentration is analyzed based on the performance of MCW-LED with different phosphor geometries.…”

Section: Construction Of Mc-wledsmentioning

confidence: 99%

SrBaSiO4:Eu2+ phosphor: a novel application for improving the luminous flux and color quality of multi-chip white LED lamps

Loan¹,

Anh²

2020

IJECE

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This paper described in detail the chromatic homogeneity and luminous flux influences in producing better quality white LED devices with various phosphor layers (MCW-LEDs). The method is to let Eu2+-activated strontium–barium silicate (SrBaSiO4:Eu2+) mixed with their phosphor compounding, which results in notable impact on lighting performance. The increase in concentration of yellow-green-emitting SrBaSiO4:Eu2+ phosphor also promotes the color performance and lumen output of WLED devices at high correlated color temperature around 8500K. This is the first time this approach is applied and it results can be utilized for better understanding of optical properties interaction with phosphor materials. Although SrBaSiO4:Eu2+ receives many positive responses, we still need to limit it concentration for high SrBaSiO4:Eu2+ concentration is detrimental to CQS. The appropriate choice of concentration and size of SrBaSiO4:Eu2+ is the principal factor to decide the performance of MCW-LEDs.

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Investigation on Modulation Speed of Photon-Recycling White Light-Emitting Diodes With Vertical-Conduction Structure

Cited by 14 publications

References 16 publications

Light Extraction Efficiency of GaN-Based Micro-Scale Light-Emitting Diodes Investigated Using Finite-Difference Time-Domain Simulation

Light Extraction Efficiency of GaN-Based Micro-Scale Light-Emitting Diodes Investigated Using Finite-Difference Time-Domain Simulation

Application of BaY2F8:Er3+,Yb3+ and Mg8Ge2O11F2:Mn4+ in improving the lighting quality of phosphor-in-glass based white light-emitting diodes with the dual-convex design

SrBaSiO4:Eu2+ phosphor: a novel application for improving the luminous flux and color quality of multi-chip white LED lamps

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