The influence of phosphor sedimentation on the white LEDs with different structure chip

Lee, Kwang-Cheol; Kim, Deok Gi; Kim, Sang-Mook; Oh, Hwa-Sub; Baek, Jong Hyeob

doi:10.1117/12.905827

Cited by 9 publications

(5 citation statements)

References 2 publications

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“…The larger the concentration gradient is, the lower the LEE is. This trend was also reported by Lee et al 7 by experiments.…”

Section: Study On Phosphor Sedimentation Based On Multi-layer Modelsupporting

confidence: 89%

“…In the LED packaging industry, phosphor sedimentation is a serious problem, which may cause decay of luminous efficiency, color non-homogeneity, etc. [7][8][9] As far as we know, there are few studies referring to phosphor sedimentation. Lee et al 7 investigated the influence of phosphor sedimentation on the luminous efficacy of white LEDs by changing the chip structures.…”

Section: Introductionmentioning

confidence: 99%

“…[7][8][9] As far as we know, there are few studies referring to phosphor sedimentation. Lee et al 7 investigated the influence of phosphor sedimentation on the luminous efficacy of white LEDs by changing the chip structures. Sommer et al 8 simulated the phosphor sedimentation in LEDs by the commercial software package ASAP and found that the color temperature and flux-output are highly sensitive to the variations of phosphor distribution.…”

Section: Introductionmentioning

confidence: 99%

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Study on phosphor sedimentation effect in white light-emitting diode packages by modeling multi-layer phosphors with the modified Kubelka-Munk theory

Qiu

Wang

Zou

et al. 2013

Journal of Applied Physics

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In this study, we studied the phosphor sedimentation effect in white phosphor-converted light-emitting diode packages by modeling the multi-layer phosphors with gradient concentrations. The essence of phosphor sedimentation can attribute to the variation of phosphor concentrations. By modifying the Kubelka-Munk theory, we built a multi-layer phosphor model with considering the light scattering, light absorption, and light conversion process simultaneously. With a brief review of Kubelka-Munk theory, multi-layer phosphors were modeled on the basis of single-layer phosphor model. The phosphor sedimentation effect was characterized by modeling multi-layer phosphors with gradient concentrations, whereas keeping the total amount of phosphors at the same level. It is found from the five calculation cases that phosphor sedimentation will cause the drop of light extraction efficiency (LEE) by 13.04%. Furthermore, the phosphor layer with inverse-gradient concentrations will enhance the LEE 16.56%. To figure out the reasons, the light losses were calculated, and it is proved that the light loss is enhanced when phosphor sedimentation happens. V

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“…The larger the concentration gradient is, the lower the LEE is. This trend was also reported by Lee et al 7 by experiments.…”

Section: Study On Phosphor Sedimentation Based On Multi-layer Modelsupporting

confidence: 89%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Study on phosphor sedimentation effect in white light-emitting diode packages by modeling multi-layer phosphors with the modified Kubelka-Munk theory

Qiu

Wang

Zou

et al. 2013

Journal of Applied Physics

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“…increasing the encapsulant viscosity and using small phosphor particles [13]. However, using high-viscosity encapsulation makes the process difficult and time-consuming resulting in low manufacturing efficiency.…”

Section: Introductionmentioning

confidence: 99%

Performance Enhancement of White LEDs Through Phosphor/Silicone Composite Particles

Lei

Zheng

Liu

et al. 2015

IEEE Photon. Technol. Lett.

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“…They found that LED optical performances, such as the color temperature and the flux output, are highly dependent on phosphor distribution. Lee et al [6] investigated the influence of phosphor sedimentation on the white LEDs with different structure chips, and found that phosphor sedimentation cause 20% difference in the luminous efficiency of white LEDs. Hu et al [7] established a multi-layer phosphor model by assuming the concentration gradient of phosphor, which was applied to study the effect of phosphor sedimentation on the light extraction efficiency.…”

Section: Introductionmentioning

confidence: 99%

Modeling on phosphor sedimentation phenomenon during curing process of high power LED packaging

Wang

Zheng

et al. 2014

J Sol State Light

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In the LED packaging, the phosphor particles are usually mixed with silicone matrix material, and then dispensed onto the LED chips directly. Since the density of the phosphor particle is bigger than that of the silicone, the phosphor particles may settle in the silicone matrix because of the gravity during dispensing and curing processes. In this paper, a model was developed to investigate the phosphor sedimentation phenomenon in silicone during isothermal curing according to the Stokes' law, and the size distribution of phosphor particles and the viscosity-time function of silicone during curing were built for the model. We compared the modeling results with the experimental results and found that the model can well simulate the sedimentation phenomenon. The modeling results show that the sedimentation velocity is inversely proportional to the viscosity of silicone and proportional to the size of phosphor particle. Phosphor particles sedimentation lasts for about 5 minutes during isothermal curing at 85°C, and the big particles accumulate in the bottom of the sample.

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The influence of phosphor sedimentation on the white LEDs with different structure chip

Cited by 9 publications

References 2 publications

Study on phosphor sedimentation effect in white light-emitting diode packages by modeling multi-layer phosphors with the modified Kubelka-Munk theory

Study on phosphor sedimentation effect in white light-emitting diode packages by modeling multi-layer phosphors with the modified Kubelka-Munk theory

Performance Enhancement of White LEDs Through Phosphor/Silicone Composite Particles

Modeling on phosphor sedimentation phenomenon during curing process of high power LED packaging

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