High-Power LED Phosphor Thermal Stability
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Solution Overview
Problem
High power LED light emitting devices face issues with temperature-induced luminescence intensity decrease and color shift due to the imbalance between the LED chip and phosphor luminescence, leading to reduced luminance and inefficient heat dissipation.
Innovation Solution
A light emitting device with a phosphor layer containing a specific composition (Mg1-x,AEx)a(Ge1-y,Sny)bOcHAd:zMn, where AE is Ca or Sr, HA is F or Cl, and certain elemental ratios, which maintains high luminescence efficiency even at elevated temperatures, combined with a heat-dissipating supporting member like aluminum nitride or copper, to manage thermal resistance and prevent excessive temperature rise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If high power LED light emitting devices are used to increase luminance, then the luminance is improved, but the temperature in the vicinity of the LED chip increases
Solution Approach 1:
The patent uses a phosphor with specific compositional parameters (Mg1-x,AEx)a(Ge1-y,Sny)bOcHAd:zMn where AE is Ca or Sr, HA is F or Cl, and specific ranges for a, b, c, d, x, y, z values) that maintains stable luminescence properties at elevated temperatures. This parameter optimization allows the phosphor to resist temperature-induced luminescence intensity decrease, resolving the contradiction between high luminance and temperature control.
2Illumination intensity
If the temperature increases, then the luminance is improved initially, but the luminescence intensity of the phosphor decreases
Solution Approach 1:
The patent optimizes the phosphor composition parameters (a, b, c, d, x, y, z within specific ranges) to achieve stable luminescence intensity across a wide temperature range. The specific stoichiometric ratios and elemental substitutions in the Mg-AE-Ge-Sn-O-HA phosphor system prevent temperature-induced luminescence degradation, maintaining reliability while allowing initial luminance improvement.
Solution Approach 2:
The patent employs a composite phosphor material system combining multiple elements (Mg, AE, Ge, Sn, O, HA, and Mn) in specific proportions. This composite structure creates a stable crystal lattice that resists thermal degradation, preventing luminescence intensity decrease even when temperature increases occur during operation.
3Illumination intensity
If the luminescence intensity of phosphor decreases, then the luminance is improved temporarily, but the color shift occurs
Solution Approach 1:
The patent carefully controls the compositional parameters of the phosphor (specific ranges for a, b, c, d, x, y, z) to ensure that the emission spectrum remains stable across temperature variations. This parameter optimization prevents color shift by maintaining the balance between LED chip emission and phosphor luminescence intensity even when temperature changes occur during operation.
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 solution ensures high luminescence efficiency and minimal color shift at temperatures from 100° C to 200° C, enhancing the performance of high power LED light emitting devices by maintaining efficient light emission and heat dissipation.
Implementation Method 1
a phosphor layer which contains a phosphor represented by general formula (A), absorbs the light emitted from the light emitting element and emits light
Implementation Method 2
a heat-dissipating supporting member like aluminum nitride or copper, to manage thermal resistance and prevent excessive temperature rise
Data Source
AI summary
There is provided a light emitting device which includes a light emitting element having a main emission peak in the wavelength region of greater than 420 nm and equal to or less than 500 nm, and a phosphor layer formed on the light emitting element. The light emitting element of this light emitting device has a junction temperature of from 100° C. to 200° C. at the time of continuous driving. Furthermore, the phosphor layer contains a phosphor represented by the following general formula (A), which absorbs the light emitted from the light emitting element and thereby emits light having a main emission peak in the wavelength region of equal to or greater than 650 nm and equal to or less than 665 nm:(Mg1-x,AEx)a(Ge1-y,Sny)bOcHAd:zMn (A)wherein AE represents at least one or more elements selected from the group consisting of Ca or Sr;HA represents at least one or more elements selected from the group consisting of F or Cl;2.54≦a≦4.40,0.80≦b≦1.10,3.85≦c≦7.00,0≦d≦2.00,0≦x≦0.05,0≦y≦0.10, and0<z≦0.03.