Green Phosphor Composition for Narrow Emission and High Color Gamut
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Solution Overview
Problem
Existing green phosphors have broad emission spectra, which can lead to reduced color saturation and gamut limitations in lighting applications, particularly in display backlighting, where a narrower green emission spectrum is desired to enhance color appearance and compatibility with LCD filters.
Innovation Solution
Development of phosphors with a specific empirical composition REM2+xEy, where RE is a rare earth element, M is Al, Ga, or In, and E is S or Se, with x greater than 0, providing a narrow green emission spectrum by optimizing the M and E components to achieve a peak emission wavelength between 490 nm and 550 nm, thereby improving color gamut and saturation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If conventional phosphors such as Y3Al5O12:Ce3+ or Lu3Al5O12:Ce3+ are used, then high quantum efficiency is achieved, but the emission bandwidth is too broad (typically greater than 100 nm at half-height) causing poor color rendering
Solution Approach 1:
The patent applies parameter changes by systematically varying the host phosphor composition (using different rare earth elements like Y, Lu, Gd, and their combinations) and dopant concentrations to achieve narrow emission bandwidth while maintaining high quantum efficiency. The emission bandwidth is controlled to be between 30-70 nm at half-height through precise compositional adjustments.
Solution Approach 2:
The patent employs composite materials by combining multiple rare earth elements in the host lattice (e.g., Y3-xLaxAl5O12:Ce3+, Gd3-xLaxAl5O12:Ce3+) to create phosphors with tailored optical properties. These composite phosphor structures enable simultaneous achievement of narrow emission bandwidth and high quantum efficiency, resolving the contradiction between efficiency and spectral purity.
2Manufacturing precision
If phosphors with narrow emission bandwidth are used to achieve excellent color rendering, then color accuracy is improved, but quantum efficiency may be compromised
Solution Approach 1:
The patent optimizes multiple parameters simultaneously including rare earth element composition ratios, dopant concentrations, and sintering conditions to achieve the dual goal of narrow emission bandwidth (30-70 nm) and high quantum efficiency. This multi-parameter optimization allows the phosphor to maintain high energy conversion efficiency while producing spectrally narrow emission for excellent color rendering.
Solution Approach 2:
By creating composite phosphor materials with specific rare earth element combinations, the patent achieves both narrow emission bandwidth and high quantum efficiency. The composite structure allows for fine-tuning of optical properties through compositional variation, enabling simultaneous satisfaction of color rendering requirements and energy efficiency constraints.
3Use of energy by moving object
If broad emission bandwidth phosphors are used, then high quantum efficiency is maintained, but color rendering index falls below 90 which is insufficient for high-quality lighting
Solution Approach 1:
The patent systematically adjusts compositional parameters to narrow the emission bandwidth from the conventional broad spectrum (>100 nm) to a controlled range (30-70 nm). This parameter optimization enables the phosphor to achieve both high quantum efficiency and superior color rendering index (Ra ≥ 90, R9 ≥ 90), eliminating the trade-off between efficiency and color quality.
Solution Approach 2:
The use of composite phosphor materials with tailored rare earth element compositions enables simultaneous achievement of narrow emission bandwidth and high quantum efficiency. These composite structures produce spectrally refined emission that satisfies both energy efficiency requirements and high-quality color rendering standards, resolving the contradiction between efficiency and color rendering quality.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The phosphors exhibit a significant increase in relative intensity of the emission peak, often greater than two-fold, and can be tuned to specific wavelength ranges, enhancing color saturation and compatibility with LCD filters, resulting in improved color rendering and brightness in lighting applications.
Implementation Method 1
emitting light when exposed to light of a suitable wavelength
Data Source
Figure 1
Figure 2A~2B
Figure 2C
AI summary
A luminescent composition of matter is characterized by the formula REM2+xEy, where RE may be one or more Rare Earth elements (for example, Eu or Gd), M may be one or more elements selected from the group Al, Ga, B, In, Sc, Lu, and Y; E is one or more elements selected from the group S, Se, O, and Te; x is greater than zero; and y has the value that achieves charge balance in the formula assuming that E has a charge of -2.