Phosphor Composition for Stable LED Color Rendering
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current conversion LEDs for general lighting and backlighting face issues with wavelength fluctuations in semiconductor chips, leading to inconsistent color rendering and efficiency, particularly due to the use of phosphors like yttrium aluminum garnet and β-SiAlON, which have limited color space and efficiency, and quantum dots that are unstable and contain harmful elements.
Innovation Solution
A lighting device utilizing a phosphor with a specific molecular formula that includes elements such as Eu, Ce, and Yb as activators, which provides stable and efficient conversion of primary radiation into secondary radiation with narrowband emission, allowing for precise control of peak wavelength and full width at half maximum, thereby improving color rendering and efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional phosphors like yttrium aluminum garnet or β-SiAlON are used, then the conversion LED can be manufactured with existing processes, but the color space coverage is limited and efficiency is reduced
Solution Approach 1:
The patent changes the chemical composition parameters of the phosphor material by incorporating rare earth elements (Eu, Ce, Yb) into a garnet structure, adjusting the emission characteristics to achieve narrowband emission with improved color space coverage while maintaining compatibility with existing manufacturing processes
Solution Approach 2:
The patent creates a composite phosphor material combining multiple rare earth elements (Eu, Ce, Yb) within a garnet host structure, leveraging the complementary properties of each element to achieve both narrowband emission and high efficiency in existing LED conversion processes
2Device complexity
If blue-emitting semiconductor chips are used, then the device structure is simplified, but wavelength fluctuations occur leading to inconsistent color rendering
Solution Approach 1:
The patent develops a phosphor formulation with specific compositional parameters that provide stable emission characteristics across varying excitation wavelengths, compensating for semiconductor chip wavelength fluctuations and maintaining consistent color rendering while working with standard blue LED chips
Solution Approach 2:
The patent uses the specially designed phosphor material as an intermediary that decouples the semiconductor chip's wavelength variations from the final emitted light, absorbing the blue primary radiation and re-emitting at stable wavelengths that ensure consistent color output regardless of chip variations
3Manufacturing precision
If quantum dots are used for conversion, then narrowband emission is achieved, but stability is poor and harmful elements are present
Solution Approach 1:
The patent replaces unstable quantum dots with a more stable phosphor material that, while requiring precise compositional control, offers long-term reliability and does not contain harmful elements, sacrificing some quantum efficiency for overall system stability and environmental compliance
Solution Approach 2:
The patent converts the potential harm of using unstable quantum dots containing heavy metals into a benefit by developing a heavy-metal-free phosphor formulation that achieves comparable or superior stability while maintaining narrowband emission characteristics through careful rare earth element selection
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 phosphor enables stable and efficient conversion LEDs with improved color rendering and efficiency, suitable for both general lighting and backlighting applications, with the ability to adjust properties for specific color loci and applications, reducing the need for costly equipment and harmful materials.
Implementation Method 1
a phosphor configured at least partly to convert the electromagnetic primary radiation into an electromagnetic secondary radiation
Data Source
AI summary
A lighting device is specified. The lighting device comprises a phosphor having the general molecular formula(MA)a(MB)b(MC)c(MD)d(TA)e(TB)f(TC)g(TD)h(TE)i(TF)j(XA)k(XB)l(XC)m(XD)n:E.In this case, MA is selected from a group of monovalent metals, MB is selected from a group of divalent metals, MC is selected from a group of trivalent metals, MD is selected from a group of tetravalent metals, TA is selected from a group of monovalent metals, TB is selected from a group of divalent metals, TC is selected from a group of trivalent metals, TD is selected from a group of tetravalent metals, TE is selected from a group of pentavalent elements, TF is selected from a group of hexavalent elements, XA is selected from a group of elements which comprises halogens, XB is selected from a group of elements which comprises O, S and combinations thereof, XC=N and XD=C and E=Eu, Ce, Yb and/or Mn. The following furthermore hold true: a+b+c+d=t; e+f+g+h+i+j=u; k+l+m+n=v; a+2b+3c+4d+e+2f+3g+4h+5i+6j−k−2l−3m−4n=w; 0.8≤t≤1; −3.5≤u≤4; 3.5≤v≤4; (−0.2)≤w≤0.2 and 0≤m≤0.875 v and/or v≥1>0.125 v.