Current Optics and Photonics

Optical Society of Korea (한국광학회)
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Red-emitting α-SrO·3B2O3:Sm2+ Phosphor for WLED Lamps: Novel Lighting Properties with Two-layer Remote Phosphor Package

  • Tin, Phu Tran (Faculty of Electronics Technology, Industrial University of Ho Chi Minh City) ;
  • Nguyen, Nhan K.H. (Faculty of Electrical and Electronics Engineering, Ton Duc Thang University) ;
  • Tran, Minh Q.H. (Faculty of Electrical and Electronics Engineering, Ton Duc Thang University) ;
  • Lee, Hsiao-Yi (Department of Electrical Engineering, National Kaohsiung University of Applied Sciences)
  • Received : 2017.01.22
  • Accepted : 2017.06.28
  • Published : 2017.08.25
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Abstract

This paper investigates a method to improve the lighting performance of white light-emitting diodes (WLEDs), which are packaged using two separate remote phosphor layers, a yellow-emitting YAG:Ce phosphor layer and a red-emitting ${\alpha}-SrO{\cdot}3B_2O_3:Sm^{2+}$ phosphor layer. The thicknesses of these two layers are $800{\mu}m$ and $200{\mu}m$, respectively. Both of them are examined in conditions where the average correlated color temperatures (CCT) are 7700 K and 8500 K. For this two-layer model, the concentration of red phosphor is varied from 2% to 30% in the upper layer, while in the lower layer the yellow phosphor concentration is kept at 15%. It was found interestingly that the lighting properties such as color rendering index (CRI) and luminous flux are enhanced significantly, while the color uniformity is maintained in a relatively close range to the one of one-layer configuration (measured at the same correlated color temperature). Besides, the transmitted and reflected light of each phosphor layer are revised by combining Kubelka-Munk and Mie-Lorenz theories. Through analysis, it is demonstrated that the packaging configuration of two-layer remote phosphor that employs red-emitting ${\alpha}-SrO{\cdot}3B_2O_3:Sm^{2+}$ phosphor particles provides a practical solution for general WLEDs lighting.

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References

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