Abstract
When the features of remote phosphor structure are compared with these of conformal phosphor or in-cup phosphor, it is recognized that it is more outstanding than the rest about luminous flux but the quality of color tends to be worse. Through that we have grasped these disadvantages and find out many studies in order to improve the color of the remote phosphor structure. In this study, we propose a dual-layer remote phosphor structure that could improve the color rendering index (CRI) and color quality scale (CQS) for WLEDs. In this study, three similar WLEDs structures but having different color temperatures including 5600 K, 6600 K and 7700K are applied. The principal idea is putting a red phosphoric layer SrwFxByOz:Eu2+,Sm2+ on the yellow phosphorus layer YAG:Ce3+. The results show that SrwFxByOz:Eu2+,Sm2+ brings great benefits to increasing CRI and CQS. Specifically, the greater the concentration of SrwFxByOz:Eu2+,Sm2+ has, the higher CRI and CQS get. However, the declining trend of luminous flux occurs when the SrwFxByOz:Eu2+,Sm2+ concentration exceeds the level. This can be demonstrated through the results of the study and be explained by the Mie dispersion theory and the Lambert-Beer law. The results of this article are important in making WLEDs of higher color quality. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Highlights
WnoLuEs DEs, caScryw,FCxBolyoOrzQ:Euua2l+it,ySmSc2a+l,e.Lumimore outstanding than the others in term of luminous ux but its color quality is a drawback that needs to improve
The results show that SrwFxByOz:Eu2+, Sm2+ brings great benets to increase color rendering index (CRI) and color quality scale (CQS)
The most common approach for white light generation is to combine the blue light with yellow c 2017 Journal of Advanced Engineering and Computation (JAEC)
Summary
WnoLuEs DEs, caScryw,FCxBolyoOrzQ:Euua2l+it,ySmSc2a+l,e.Lumimore outstanding than the others in term of luminous ux but its color quality is a drawback that needs to improve. The luminous ux has a tendency of dropping when the SrwFxByOz:Eu2+, Sm2+ concentration increases excessively This can be demonstrated and explained based on the Mie phor converted white light emitting diodes (pcWLEDs) is a remarkable turning point in the lighting market, making it deserve to become the fourth potential generation light source used to replace the conventional one [1]. There are several common phosphor coating methods which are researched and selected carefully to so that the research can put the best results such as dispensing coating and conformal coating These structures do not provide high luminous ux due to the degradation in light conversion of phosphor material caused by yellow emitting phosphor directly contacts with the LED chip, leading to the temperature increase at the junction of the LED and phosphor layer. Remote phosphor with dual layer package is proposed to improve the light output of LEDs
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