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An optimal spectral model for phosphor‐converted white light‐emitting diodes used in the mesopic vision
Author(s) -
Zheng Zishan,
Wang Le,
Zhang Hong,
Zhou Tianliang,
Zheng Peng,
Liang Pei
Publication year - 2019
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/jace.15894
Subject(s) - phosphor , mesopic vision , color rendering index , light emitting diode , optoelectronics , materials science , diode , optics , photopic vision , physics , retina
Abstract White light‐emitting diodes ( WLED s) for road lighting are required to have both the high scotopic to photopic ratio ( S/P ) and color rendering index ( CRI ). However, there is a trade‐off between S/P and CRI , and WLED s commonly having the S/P of 1.68‐2.38 usually exhibit a low CRI . In this work, to provide a best solution to the trade‐off problem we proposed an optimal spectral model for the phosphor‐converted WLED s (pc‐ WLED s) aiming to figure out the optimal phosphor combination. The Monte Carlo Algorithms combined with the Genetic Algorithm were adopted to obtain the optimization of CRI and S/P by varying the spectral power distributions of WLED s through adjusting the spectral parameters. Considering the spectral requirements of pc‐ WLED s based on the mesopic vision, we chose CaAlSiN 3 :Eu 2+ and Y 3 (Ga,Al) 5 O 12 :Ce 3+ as the red‐ and green‐emitting phosphors to prepare WLED s with both high S/P and CRI , respectively. The simulation based on the optimal spectral model led to an optimal pc‐ WLED with a high S/P of 2.0‐2.14, Ra > 80 and correlated color temperature ( CCT ) of 4000‐5000 K, which matches very well with the experimental results of S/P = 2.064, Ra = 93.9, and CCT = 4981 K for the two‐phosphor converted WLED s. It implies that the optimal spectral model would be used effectively for the spectral design and phosphor selection for WLED s.