A2[MF6]:Mn4+ Phosphor Preferred Orientation for WLED Color Rendering
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Solution Overview
Problem
Current white light-emitting diodes (WLEDs) lack a red light-emitting phosphor that effectively increases the color rendering index, as traditional red light-emitting phosphors face challenges in luminous efficiency and heat resistance, necessitating a new phosphor with improved properties.
Innovation Solution
A phosphor with a preferred orientation, represented by the formula A2[MF6]:Mn4+, where A is Li, Na, K, Rb, Cs, or NH4, and M is Ge, Si, Sn, or Ti, is synthesized using a sol-gel reaction method with controlled temperature and surfactant addition to achieve high luminous efficiency and quantum output, allowing for red fluorescence and enhanced color rendering.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If traditional red light-emitting phosphors are used in WLEDs, then the red light spectrum is provided, but the luminous efficiency and heat resistance are insufficient
Solution Approach 1:
The patent changes the chemical composition parameters of the phosphor by incorporating fluorine atoms into the crystal structure (forming A2[MF6]:Mn4+ compounds), which fundamentally alters the thermal and luminescent properties. This compositional parameter change enables simultaneous achievement of high luminous efficiency and heat resistance that traditional phosphors cannot achieve
Solution Approach 2:
The patent creates composite phosphor materials by combining specific metal elements (M = Ge, Si, Sn, Ti, Zr) with alkali metal cations (A = Li, Na, K, Rb, Cs, NH4) and fluorine in a defined stoichiometric structure. This composite approach with Mn4+ doping produces a material that integrates multiple functional properties including high quantum efficiency and thermal stability
2Ease of manufacture
If YAG phosphor is used in WLEDs, then the manufacturing cost is low, but the red light spectrum is lacking and color rendering index is poor
Solution Approach 1:
The patent modifies the phosphor composition parameters by using abundant earth-element metals (Ge, Si, Sn, Ti, Zr) combined with fluorine and alkali metals, creating a new class of phosphors with different optical properties than YAG. This parameter change enables red light emission with improved color rendering while maintaining cost-effectiveness through the use of readily available materials
3Use of energy by moving object
If blue LED chips excite yellow light-emitting phosphor, then the luminous efficiency of white light is improved, but the red light spectrum remains insufficient
Solution Approach 1:
The patent changes the emission wavelength parameters of the phosphor by selecting specific metal fluorides (GeF6, SiF6, SnF6, TiF6, ZrF6) that, when doped with Mn4+, emit in the red region (600-680 nm). This parameter change allows the phosphor to be excited by blue LED chips while simultaneously providing the missing red light spectrum component
Solution Approach 2:
The patent creates a universal phosphor system where the A2[MF6]:Mn4+ structure can accommodate multiple metal elements and alkali metal cations, all of which can be excited by blue LED chips (430-480 nm) to produce red light. This multi-functionality allows the same phosphor structure to replace multiple different phosphors while maintaining high luminous efficiency and providing complete color rendering
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 resulting phosphor increases the color rendering index of WLEDs by emitting red light with peak wavelengths between 600-650 nm, avoiding absorption of yellow and green light, thus improving the overall lighting apparatus's color rendering capability.
Implementation Method 1
A phosphor with a preferred orientation, represented by the formula A2[MF6]:Mn4+, where A is Li, Na, K, Rb, Cs, or NH4, and M is Ge, Si, Sn, or Ti, is synthesized using a sol-gel reaction method with controlled temperature and surfactant addition to achieve high luminous efficiency and quantum output, allowing for red fluorescence and enhanced color rendering.
Data Source
AI summary
The present invention provides a phosphor with a preferred orientation represented by the following formula: A2[MF6]:Mn4+, wherein A is selected from a group consisting of Li, Na, K, Rb, Cs, and NH4, M is selected from a group consisting of Ge, Si, Sn, Ti, and Zr. The preferred orientation is a (001)/(011) preferred orientation. The present invention also provides a method for fabricating the above phosphor. The present invention further provides a light-emitting element package structure employing the same.