Nitride Phosphor Composition for High-Temperature LED Efficiency
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Solution Overview
Problem
Current phosphors, such as oxide-based and garnet-based phosphors, face degradation in luminous intensity at high temperatures and have low luminous efficiency in long wavelength bands, limiting their suitability for high-brightness white light emission in LED applications.
Innovation Solution
A phosphor with the formula EuxMyL3−x−ySi6−zAlzN11−(z+y+z)O(z+y+z) is developed, where L is La, Y, or Gd, and M is Ca, Sr, or Ba, with partial substitution of Eu2+, offering improved high temperature characteristics and luminous efficiency in long wavelength bands.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If oxide-based phosphors are used, then manufacturing ease is improved, but luminous intensity degrades at high temperatures above 400 nm
Solution Approach 1:
The patent changes the chemical composition parameters by introducing nitride-based materials with specific stoichiometry (La3Si6N11) and doping elements (Ce, Eu, Mn) to achieve both ease of manufacture and high luminous intensity at high temperatures. The compositional formula EuxMyL3-x-ySi6-zAlzN11-(z+y+z)O(z+y+z) represents optimized parameter changes that resolve the contradiction.
Solution Approach 2:
The patent creates a composite phosphor material combining multiple elements (La, Si, N, Ce, Eu, Mn, Ca, Sr, Ba) in a specific ratio to achieve superior performance. This composite approach allows the material to maintain both manufacturing ease and high luminous intensity by leveraging the advantageous properties of each component element.
2Use of energy by moving object
If garnet-based phosphors (YAG) are used, then excitation efficiency is improved, but luminous efficiency degrades at high temperature
Solution Approach 1:
The patent modifies the phosphor composition by changing from traditional YAG garnet structure to a nitride-based La3Si6N11 structure with specific doping concentrations. This parameter change in material composition enables the phosphor to maintain high excitation efficiency while improving thermal stability and luminous efficiency at elevated temperatures.
Solution Approach 2:
The patent applies local quality by introducing specific dopant elements (Ce, Eu, Mn) at controlled concentrations within the phosphor matrix to enhance specific properties. The doping strategy targets specific local regions within the crystal structure to improve both excitation efficiency and high-temperature performance simultaneously.
3Reliability
If LSN phosphors are used, then high temperature characteristics are improved, but luminous efficiency decreases in wavelength band of 550 nm or more
Solution Approach 1:
The patent introduces specific dopant elements (Mn, Eu, Ce) at optimized concentrations to enhance the emission properties in the long wavelength region. By locally modifying the phosphor composition with these elements, the patent improves luminous efficiency at wavelengths of 550 nm or more while preserving the high temperature characteristics of the LSN base material.
Solution Approach 2:
The patent creates a composite phosphor system combining the high-temperature stable LSN base material with additional dopant elements (Mn, Eu, Ce, Ca, Sr, Ba) to enhance long wavelength emission. This composite approach allows simultaneous achievement of high temperature characteristics and improved luminous efficiency in the 550 nm+ wavelength band.
4Illumination intensity
If blue light LED is used as excitation source, then white light emission is achieved, but luminous efficiency degrades in phosphor layer at high temperature
Solution Approach 1:
The patent optimizes the phosphor composition parameters by introducing multiple dopant elements with specific concentrations to enhance thermal stability. The compositional formula EuxMyL3-x-ySi6-zAlzN11-(z+y+z)O(z+y+z) represents parameter changes that enable the phosphor to maintain high luminous efficiency when excited by blue light at elevated temperatures.
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 new phosphor exhibits enhanced luminous efficiency and narrow emission bandwidth, maintaining high efficiency in yellow and orange bands, enabling improved color rendering and brightness in light emitting devices, particularly in white LED applications.
Implementation Method 1
a phosphor converting a wavelength of the light emitted from the LED into visible light
Data Source
AI summary
A phosphor is represented by a general Formula: EuxMyL3−x−ySi6−zAlzN11−(z+y+z)O(z+y+z) and satisfies 0.00001≦x≦2.9999, 0.0001≦y≦2.99999 and 0≦z≦6.0. L is at least one element selected from La, Y, Gd and Lu. M is at least one element selected from Ca, Sr, Ba and Mn.