LED Chip Filter Layer for Light Extraction Efficiency
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Solution Overview
Problem
Conventional light emitting diodes (LEDs) face efficiency limitations due to optical losses such as internal reflection and absorption, which prevent all generated light from escaping, resulting in reduced visible light emission.
Innovation Solution
The implementation of an LED chip structure comprising a light conversion layer and a filter layer, where the filter layer is transmissive to the initial wavelength and reflective to the converted wavelength, preventing internal losses and enhancing light extraction efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If conventional LED structure without filter layer is used, then device complexity is low, but light extraction efficiency is reduced due to internal reflection and absorption losses
Solution Approach 1:
A filter layer is introduced as an intermediary component between the LED active region and the external environment. This filter layer selectively transmits light of a first wavelength while reflecting light of a second wavelength, thereby preventing internal reflection and absorption losses for the transmitted wavelength and improving overall light extraction efficiency without fundamentally changing the LED's core structure
Solution Approach 2:
The LED structure is enhanced by incorporating a composite multi-layer configuration that includes the filter layer with specific optical properties. This composite structure combines the LED active region with the wavelength-selective filter layer, creating a system that optimizes light extraction for specific wavelengths while managing optical losses through material property differentiation
2Illumination intensity
If filter layer is added to improve light extraction efficiency, then visible light output increases, but manufacturing complexity increases
Solution Approach 1:
The filter layer is integrated into the LED fabrication process at an early stage, before final packaging and assembly. By incorporating the filter layer during the semiconductor manufacturing process itself, the additional component is added without requiring separate post-fabrication steps, thereby minimizing the increase in manufacturing complexity while achieving improved visible light output
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
This configuration increases the overall efficiency of the LED chip by minimizing absorption and reflection losses, allowing more converted light to escape and improving the visible light output.
Implementation Method 1
at least one light conversion layer on the LED layer capable of converting at least a portion of the light of a first wavelength to light of a second wavelength
Implementation Method 2
at least one filter layer therebetween that is transmissive to light of a first wavelength and reflective to light of a second wavelength. The filter layer(s) may prevent at least some of the light of a second wavelength from entering the LED layer(s) or any other underlying layers where it may be subject to various optical losses, such as total internal reflection and absorption
Data Source
AI summary
LED chips including an LED layer or layers capable of emitting light of a first wavelength, a light conversion layer on the LED capable of converting at least a portion of the light of a first wavelength to light of a second wavelength, and a filter layer therebetween that is transmissive to light of a first wavelength and reflective to light of a second wavelength. The filter layer may prevent at least some of the light of a second wavelength from entering the LED layer or layers, where it may be subject to various optical losses, such as internal reflection and absorption. LED chips may also include multiple filter and light conversion layers. Methods of fabrication are also disclosed.