Light-emitting device with dielectric-coated core particles
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Solution Overview
Problem
Conventional light-emitting devices face challenges in achieving high light extraction efficiency due to the degradation of metal reflectors like silver (Ag) and the inefficiencies in forming dielectric multilayer films around light-emitting elements, which can lead to reduced reflectivity and heat dissipation.
Innovation Solution
The use of dielectric multilayer films covering core particles arranged around light-emitting elements to reflect light efficiently, with the dielectric multilayer films being formed of materials like SiO2, TiO2, and Nb2O5, and the core particles being made of materials with good heat dissipation properties such as Cu, Ag, and Al, allowing for flexible and efficient light reflection even on irregular surfaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a metal coating (e.g., Ag) is applied in the cavity to increase reflectance, then light extraction efficiency is improved, but the metal may be discolored due to sulfurization resulting in decreased reflectivity
Solution Approach 1:
The invention uses a composite structure consisting of a metal core particle (e.g., Ag, Al, or Cu) covered with a dielectric multilayer film. This composite design combines the high reflectance of metal with the chemical stability and protective properties of dielectric materials, preventing sulfurization while maintaining optical performance
Solution Approach 2:
The dielectric multilayer film acts as an intermediary protective layer between the metal core and the external environment. This intermediate layer prevents direct contact between the metal and sulfur-containing substances, thereby preventing sulfurization while still allowing the metal to function as an effective reflector
2Illumination intensity
If a dielectric multilayer film is formed around the light-emitting element to reflect light, then reflectivity is improved, but heat dissipation may be reduced
Solution Approach 1:
The invention segments the reflective structure into discrete core particles rather than forming a continuous film. This segmentation creates voids and interfaces that facilitate heat dissipation pathways while maintaining sufficient reflective surface area, thus balancing optical performance with thermal management
Solution Approach 2:
The dielectric multilayer film is applied selectively to cover only the surface of the metal core particles, creating localized reflective zones. This localized approach maintains heat dissipation pathways in other regions while providing sufficient light reflection where needed, avoiding the heat trapping effect of a complete continuous film
3Illumination intensity
If a continuous dielectric multilayer film is formed in the cavity, then light extraction efficiency is improved, but manufacturing complexity increases due to difficulty in forming films on irregular surfaces
Solution Approach 1:
The invention divides the continuous film requirement into discrete core particles that can be independently manufactured and then assembled. This segmentation allows each particle to be formed using standard techniques without the need for complex conformal coating processes on irregular cavity surfaces
Solution Approach 2:
The invention extracts the reflective function from the cavity wall and relocates it to discrete core particles that can be positioned within the cavity. This extraction allows the use of simpler particle fabrication methods rather than requiring complex in-situ film deposition on the cavity surfaces
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 enhances light extraction efficiency, improves heat dissipation, and allows for flexible reflection layer formation on complex surfaces, reducing color non-uniformity and enhancing the color mixture effect in light-emitting devices.
Implementation Method 1
The dielectric multilayer film covers the core and has a thickness to reflect a wavelength of the light emitted by the light-emitting element
Implementation Method 2
a coating of a metal may be applied in the cavity of the package made of a resin material to increase the reflectance... use of a dielectric multilayer film (e.g., distributed Bragg reflector: DBR) for the coating in the cavity
Implementation Method 3
the core particles being made of materials with good heat dissipation properties such as Cu, Ag, and Al
Data Source
AI summary
A light-emitting device includes a base, a light-emitting element, and reflecting elements. The light-emitting element is mounted on the base. The reflecting elements are arranged around the light-emitting element to reflect light emitted by the light-emitting element. Each of the reflecting elements includes a core and a dielectric multilayer film. The dielectric multilayer film covers the core and has a thickness to reflect a wavelength of the light emitted by the light-emitting element.