Abstract
This paper successfully establishes an optical model with dual green/red phosphor layers based on the original single-phosphor model. Since the re-absorption effect of double-layer phosphors causes spectral distortion, the model must introduce a correction mechanism for spectral re-absorption. Through the LED packaging experiment, simulation, and verification of the double-layer phosphors, we can effectively predict the ratios required for the two phosphors under different color temperatures and confirm this model's high precision and accuracy. In the future, this model can be used to analyze further the optical performance of white LEDs with different dual-layer phosphor packaging types.
Highlights
I N THE field of LED solid-state lighting, many methods to generate the white light have been realized, and they have both pros and cons, including (1) Using red, green, blue LEDs and mix them directly; (2) using the blue LED to excite the yellow phosphor; (3) using the blue LED to excite the green and red phosphor and (4) using the UV LED to excite the phosphor of three colors or more at the same time [1]–[4]
When a white LED uses the red and green phosphors simultaneously, the green light radiated by the green phosphor will be re-absorbed and converted to the red light by the red phosphor according to the absorption spectrum of the green phosphor
We find that when the blue light excites the red phosphor sheet first, the ratio of the excitement of the red phosphor by the backward green light generated by the green phosphor sheet is lower, and its relative βg is small
Summary
I N THE field of LED solid-state lighting, many methods to generate the white light have been realized, and they have both pros and cons, including (1) Using red, green, blue LEDs and mix them directly; (2) using the blue LED to excite the yellow phosphor; (3) using the blue LED to excite the green and red phosphor and (4) using the UV LED to excite the phosphor of three colors (red, green and blue) or more at the same time [1]–[4]. Some use phosphors of the same color to increase their packaging efficiency, while others use different colors to improve their CRI These studies have confirmed that the dual-layer phosphor structure has significant benefits in enhancing the light quality of white LEDs. when modeling dual-layer phosphors with different colors, if the complex interaction between the two phosphors is not considered, the prediction from its phosphor model will cause doubts. As the LED package’s shape changes, the phosphor’s re-absorption effect will differ For these difficulties, we will have further discussion on the scattering behavior and re-absorption between different phosphors by establishing the dual-phosphor model. The model itself can predict the optical performances of various packaging types to improve the disadvantage that a new experiment is required for different packages This will help reduce manufacturing costs and allows a more in-depth analysis of the white LEDs with the model
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