Mn-Activated Hexafluorosilicate Phosphor for Broadband Red Emission
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Solution Overview
Problem
Current phosphor converted LED solutions face limitations in the red spectral region, leading to inadequate luminous efficiency and a limited color gamut due to the use of Eu(II)-doped materials, which have a narrow spectral bandwidth and are not well-suited for warm white LED devices.
Innovation Solution
A manganese-doped alkaline hexafluorosilicate phosphor, specifically KRbSiF6:Mn, is developed, which absorbs well in the blue and UV spectra, efficiently converting light into red light with a broader emission peak, thus enhancing luminous efficacy and color rendition for LEDs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If Eu(II)-doped phosphors are used for red emission, then the emission intensity is sufficient, but the spectral bandwidth is limited to about 50 nm and luminous efficacy is hampered
Solution Approach 1:
The patent changes the activator ion from Eu(II) to Mn(IV) and modifies the host material composition (using Sr, Ca, Ba in specific ratios with Al and Si) to achieve both high emission intensity and broad spectral bandwidth, thereby improving luminous efficacy while maintaining sufficient intensity
Solution Approach 2:
The patent employs composite phosphor materials with specific compositional ratios (0.2≤a≤0.5, 0.05≤b≤0.3, 0.05≤c≤0.3) combining multiple alkaline earth metals (Sr, Ca, Ba) with Al and Si in a unified phosphor structure, creating a material that simultaneously achieves broad emission bandwidth and high luminous efficacy
2Illumination intensity
If Eu(II)-doped phosphors are used, then red emission is achieved, but the full width half maximum is limited to about 50 nm
Solution Approach 1:
The patent achieves broad spectral bandwidth (FWHM≥80 nm) by changing the activator from Eu(II) to Mn(IV) and optimizing the host material composition with specific ratios of Sr, Ca, Ba, Al, and Si, which creates a more delocalized electronic structure and broader emission profile
3Use of energy by moving object
If Mn(IV) phosphors with oxygen ligands are used, then absorption in blue spectral region is achieved, but emission occurs in deep red (>650 nm) with limited color gamut
Solution Approach 1:
The patent maintains Mn(IV) activation for blue region absorption but modifies the host material composition (using specific ratios of Sr, Ca, Ba with Al and Si) to shift the emission from deep red (>650 nm) to a broader spectrum centered at 610-650 nm, thereby expanding the color gamut while preserving absorption efficiency
Solution Approach 2:
The patent uses composite materials with optimized compositions (0.2≤a≤0.5, 0.05≤b≤0.3, 0.05≤c≤0.3) combining multiple alkaline earth metals and oxides to achieve both strong blue absorption and enhanced color gamut, overcoming the limitations of simple oxide phosphors
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 manganese-doped hexafluorosilicate phosphor achieves a luminous efficacy greater than 200 lm/W, providing improved spectral efficiency and color rendition, making it suitable for general and backlighting applications in LEDs.
Implementation Method 1
a luminescent material, configured to convert at least part of the light source light into luminescent material light
Data Source
AI summary
The invention provides a lighting unit comprising a light source, configured to generate light source light and a luminescent material, configured to convert at least part of the light source light into luminescent material light, wherein the light source comprises a light emitting diode (LED) and wherein the luminescent material comprises a phosphor comprising M2AX6 doped with tetravalent manganese, wherein M comprises monovalent cations, at least comprising potassium and rubidium, wherein A comprises a tetravalent cation, at least comprising silicon, wherein X comprises a monovalent anion, at least comprising fluorine, and wherein M2AX6 has the hexagonal phase.