Precise Simulation of Spectrum for Green Emitting Phosphors Pumped by a Blue LED Die

• Published in: IEEE photonics journal Vol. 6; no. 4; pp. 1 - 10
• Main Authors: Tsung-Hsun Yang, Ching-Yi Chen, Yu-Yu Chang, Glorieux, Benoit, Yi-Neng Peng, He-Xiang Chen, Te-Yuan Chung, Tsung-Xiang Lee, Ching-Cherng Sun
• Format: Journal Article
• Language: English
• Published: Piscataway IEEE 01.08.2014; The Institute of Electrical and Electronics Engineers, Inc. (IEEE); Institute of Electrical and Electronics Engineers (IEEE)
• Subjects: Absorption; Adjustment; Chemical Sciences; Chromaticity; Computer simulation; Emittance; Green products; Light emitting diodes; Material chemistry; Mathematical models; Optical device fabrication; Optical pumping; Phosphors; Scattering; Spectra; optical design and fabrication; illumination; Light-emitting diodes; non-imaging optical systems; illumination design
• ISSN: 1943-0655; 1943-0647
• DOI: 10.1109/JPHOT.2014.2341012

This paper proposes an effective approach for spectrum shaping in the optical modeling of phosphor-converted white light-emitting diodes (LEDs) in which overlapping of the absorption and emission spectra of the phosphor are considered. The spectrum shaping method was applied to explore the wavelength-dependent absorption effect and reabsorption by the green phosphor. The experimental results indicated that the adjustment factor for blue light can enable the blue light spectrum to fit well with the measured spectrum. The adjustment factor was linearly related to the transmission ratio of the blue light. The blue light emitted by the blue die and the green light emitted by the phosphor were simulated and predicted in an accurate way as compared with the experimental measurements. The enhanced accuracy in assessing the spectra resulted in enhanced precision of chromaticities. In the experiments, the color differences were one order smaller in CIE 1931 chromaticity (Δx, Δy) than in models without spectrum shaping and were almost imperceptible to the human eye. The novel optical modeling of green phosphor pumped by a blue die facilitates the application of these materials in high-color rendering in white LEDs and projection displays.