Porous Phosphor Converter Structure for Reflective Light Extraction
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Solution Overview
Problem
The use of glue interfaces between phosphor and reflective layers in LED devices leads to thermal and reflectivity issues, reducing light efficiency.
Innovation Solution
A phosphor converter structure with two layers of differing porosity, where the denser and smoother layer is metallized, enhancing light extraction and reducing reflectivity loss at the reflector-phosphor interface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a glue interface is used between phosphor and reflective layer, then adherence is achieved, but thermal conductivity deteriorates and reflectivity is reduced
Solution Approach 1:
The patent removes the glue interface layer between the phosphor layer and reflective layer, replacing it with a direct interface. This extraction of the harmful intermediate layer eliminates the thermal and optical barriers that glue creates, thereby improving thermal conductivity and reflectivity while maintaining adherence through direct material contact.
Solution Approach 2:
The patent introduces an intermediary porous layer with controlled porosity (30-70%) between the phosphor and reflective layer. This porous structure acts as a mediator that provides mechanical adherence while maintaining thermal and optical pathways, solving the contradiction between needing glue for adherence and avoiding it for thermal/optical performance.
2Productivity
If phosphor concentration in phosphor layer is increased, then light conversion efficiency is improved, but light extraction deteriorates
Solution Approach 1:
The patent applies local quality by creating a porous layer with spatially varying porosity (30-70%) adjacent to the phosphor layer. This localized porous structure provides light extraction pathways in specific regions without reducing the overall phosphor concentration, thereby maintaining high light conversion efficiency while improving light extraction through the porous network.
Solution Approach 2:
The patent introduces a porous layer with controlled porosity (30-70%) between the phosphor and reflective layers. This porous material structure provides multiple light extraction pathways and reduces total internal reflection, enabling high phosphor concentration to be maintained while improving light extraction efficiency through the porous network structure.
3Illumination intensity
If porous layer is added to improve light extraction, then light extraction is enhanced, but device complexity increases
Solution Approach 1:
The patent merges the porous layer with either the phosphor layer or reflective layer to form an integrated structure. This consolidation approach reduces device complexity by eliminating separate components and interfaces, while the porous functionality is incorporated directly into existing layers, maintaining light extraction enhancement without proportionally increasing structural complexity.
Solution Approach 2:
The porous layer serves multiple functions simultaneously: it provides light extraction pathways, maintains mechanical adherence between layers, and facilitates thermal management. This multi-functionality reduces the need for additional separate components, thereby enhancing light extraction without proportionally increasing device complexity.
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
Improves thermal conductivity and maintains high reflectivity, resulting in enhanced light efficiency and performance of LED devices.
Implementation Method 1
The porosity enhances light extraction
Implementation Method 2
the smoother surface decreases a loss of reflectivity at the reflector-phosphor interface
Implementation Method 3
LEDs may be combined with one or more wavelength converting materials (generally referred to herein as 'phosphors') that absorb light emitted by the LED and in response emit light of a longer wavelength
Implementation Method 4
The layer of the converter structure that is denser and having a smoother surface may be the one that is metallized
Data Source
AI summary
This specification discloses a converter element and light emitting devices including the converter element. The converter element is monolithic with at least two layers, where one layer is more porous than the other layer. The converter element may be integrated with a reflector layer, such as by metallization. The layer of the converter structure that is denser and having a smoother surface may be the one that is metallized, while the more porous layer is closer to the laser. The porosity enhances light extraction while the smoother surface decreases a loss of reflectivity at the reflector-phosphor interface. The converter element may be used in a laser based light emitting device.