Gradient Fluorescent Layer for LED Reliability
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current white LED systems using inorganic fluorescent materials face challenges in achieving high red color rendering and light emission intensity due to poor adhesion and thermal issues between stacked fluorescent layers, leading to reduced reliability and efficiency.
Innovation Solution
A light-emitting device with a fluorescent layer comprising a matrix polymer, organic fluorescent material, and inorganic fluorescent material, where the concentration of inorganic fluorescent material decreases towards the uppermost surface and organic fluorescent material decreases towards the lowermost surface, enhancing adhesion and reducing thermal stress, while maintaining high light emission intensity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a stacked body with separated inorganic fluorescent layer and organic fluorescent layer is used, then local heating deterioration of organic fluorescent material is prevented, but separation occurs due to poor adhesion and difference in thermal expansion coefficient
Solution Approach 1:
The patent merges the inorganic fluorescent layer and organic fluorescent layer into a single integrated fluorescent layer with a concentration gradient structure. The inorganic fluorescent material concentration decreases from bottom to top while organic fluorescent material concentration increases from bottom to top, creating a seamless structure that eliminates adhesion problems between separate layers while maintaining the protective effect against local heating.
Solution Approach 2:
The patent applies local quality by creating a concentration gradient within the fluorescent layer. The inorganic fluorescent material is concentrated at the bottom near the light-emitting part where heat generation occurs, while organic fluorescent material is concentrated at the top. This spatial distribution optimizes both heat management and light emission properties at different locations within the same layer.
2Reliability
If a stacked body with separated inorganic fluorescent layer and organic fluorescent layer is used, then local heating deterioration of organic fluorescent material is prevented, but light extraction efficiency decreases due to difference in refractive index and interface state fluctuation
Solution Approach 1:
The patent eliminates the interface between separate inorganic and organic fluorescent layers by merging them into a single continuous layer. This removes the interface that causes light reflection and scattering due to refractive index differences, thereby improving light extraction efficiency while maintaining the protective function against local heating through the concentration gradient structure.
Solution Approach 2:
The concentration gradient structure distributes fluorescent materials locally optimized for their function: inorganic materials near the heat source for thermal stability and organic materials at the top for efficient light emission. This local optimization eliminates interface-related energy loss while maintaining functional benefits.
3Illumination intensity
If inorganic fluorescent material is added to achieve white light emission, then red color rendering is improved, but light emission intensity is insufficient
Solution Approach 1:
The patent uses local quality by concentrating inorganic fluorescent material at the bottom of the fluorescent layer where it can effectively convert light from the light-emitting part. Organic fluorescent material is concentrated at the top where it emits light more efficiently. This spatial separation optimizes both color rendering (from inorganic materials) and light emission intensity (from organic materials) without requiring uniform mixing.
Solution Approach 2:
The patent creates a composite fluorescent layer that combines inorganic and organic fluorescent materials in a concentration gradient structure. This composite structure leverages the advantages of both material types: inorganic materials provide stable color rendering including red components, while organic materials provide high light emission intensity, achieving both goals simultaneously.
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 reliability, efficiency, and color rendering by minimizing decomposition of organic fluorescent materials and optimizing light extraction, resulting in improved durability and brightness retention.
Implementation Method 1
a fluorescent layer comprising a matrix polymer, an organic fluorescent material, and an inorganic fluorescent material
Implementation Method 2
an organic fluorescent material... red light with high light emission intensity can be obtained
Implementation Method 3
due to difference in the refractive index, fluctuation of the interface state, or the like among a plurality of fluorescent layers, the light extraction efficiency may decrease
Implementation Method 4
a fluorescent layer comprising a matrix polymer, an organic fluorescent material, and an inorganic fluorescent material
Data Source
AI summary
A light-emitting device assured of high reliability, high efficiency and high color rendering, is provided. The light-emitting device includes a frame, an LED chip provided on the frame, and a fluorescent layer containing an inorganic fluorescent material and an organic fluorescent material and being provided on the LED chip. In the fluorescent layer, the concentration of the inorganic fluorescent material is decreased toward the top from the bottom of the fluorescent layer, and the concentration of the organic fluorescent material is decreased toward the bottom from the top of the fluorescent layer.