LED Encapsulating Composition Light Scattering Particle Size Optimization
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Solution Overview
Problem
Conventional encapsulating compositions for light emitting devices suffer from low light extraction efficiency due to refractive index mismatch between LED chips and encapsulating materials, and high costs associated with rare metal phosphor particles, which also reduce brightness when light scattering particles are used.
Innovation Solution
An encapsulating composition comprising a transparent thermosetting resin with light scattering particles of 190-450 nm average size and phosphor particles of 5-20 μm average size, optimized in weight ratio, to enhance light extraction and maintain brightness while reducing phosphor particle amounts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If phosphor particles are used to convert light wavelength, then white light is produced, but the cost increases due to rare metal materials
Solution Approach 1:
The patent replaces expensive rare metal phosphor particles with inexpensive fluorescent pigment particles that can be mass-produced through chemical synthesis. These pigment particles, while having shorter persistence than phosphors, provide sufficient fluorescence for LED applications at a fraction of the cost, directly addressing the cost issue while maintaining light quality conversion
2Quantity of substance
If light scattering particles are added to increase light-phosphor collisions, then phosphor particle amount can be decreased, but the brightness of the light emitting device decreases
Solution Approach 1:
The patent extracts the light scattering function from traditional phosphor particles by introducing separate dedicated light scattering particles (such as TiO2, SiO2, or ZrO2) with specific size ranges (0.1-10 μm). This separation allows the phosphor particles to focus on wavelength conversion while the scattering particles handle light diffusion, preventing brightness loss while enabling reduced phosphor content
3Illumination intensity
If there is refractive index mismatch between LED chip and encapsulating composition, then light extraction efficiency is limited to 30%, but increasing refractive index requires adding organic and/or inorganic materials
Solution Approach 1:
The patent creates a composite encapsulating composition that combines transparent resin base material with suspended particles serving multiple functions: light scattering particles (TiO2, SiO2, ZrO2) for diffusion, fluorescent pigment particles for wavelength conversion, and optionally refractive index matching particles. This composite structure achieves high light extraction efficiency (exceeding 30%) by addressing refractive index mismatch through the scattering and fluorescence mechanisms while maintaining relative composition simplicity
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 composition significantly improves brightness and maintains light quality by controlling particle sizes and ratios, achieving superior light emitting device performance with reduced phosphor particle usage.
Implementation Method 1
a plurality of light scattering particles distributed throughout the transparent resin and having an average particle size ranging from 190 nm to 450 nm
Implementation Method 2
The photoluminescent material absorbs a portion of light emitted by the LED chip of the light emitting device and re-emits light with a different wavelength
Data Source
AI summary
An encapsulating composition for a light emitting device includes a transparent resin, a plurality of light scattering particles distributed throughout the transparent resin and having an average particle size ranging from 190 nm to 450 nm, and a plurality of phosphor particles distributed throughout the transparent resin. A light emitting device includes the encapsulating composition and a light emitting diode that is encapsulated by the encapsulating composition.