The Impacts of Red-Emitting SrwFxByOz:Eu2+,Sm2+ Phosphor on Color Quality of Dual-Layer Phosphor Geometry

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 Sr_wF_xB_yO_z:Eu²⁺,Sm²⁺ on the yellow phosphorus layer YAG:Ce³⁺. The results show that Sr_wF_xB_yO_z:Eu²⁺,Sm²⁺  brings great benefits to increasing CRI and CQS. Specifically, the greater the concentration of Sr_wF_xB_yO_z:Eu²⁺,Sm²⁺ has, the higher CRI and CQS get. However, the declining trend of luminous flux occurs when the Sr_wF_xB_yO_z: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.

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