Semiconductor Nanoparticle Microbeads for LED Encapsulation
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Solution Overview
Problem
Current methods for fabricating semiconductor nanoparticle-based light emitting devices face challenges such as agglomeration of quantum dots in LED encapsulants, reduced quantum efficiency, and poor color rendering due to instability and scattering, making it difficult to produce high-performance devices on a commercial scale.
Innovation Solution
Incorporating semiconductor nanoparticles into discrete polymeric microbeads, which are then embedded in a host LED encapsulation medium, allowing for controlled and reproducible color tuning and enhanced stability, thereby improving quantum efficiency and device performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If semiconductor nanoparticles are directly incorporated into LED encapsulants, then device fabrication is simplified, but quantum dots agglomerate and scatter causing reduced quantum efficiency and poor color rendering
Solution Approach 1:
The patent divides the encapsulant into discrete microbead units, each containing semiconductor nanoparticles. This segmentation prevents agglomeration by isolating nanoparticles within individual beads while maintaining ease of manufacture through simple mixing and curing processes.
Solution Approach 2:
The patent introduces microbeads as an intermediary carrier between the semiconductor nanoparticles and the LED encapsulant. The microbeads act as a protective medium that prevents direct contact and agglomeration of quantum dots while allowing optical properties to be maintained.
2Ease of manufacture
If semiconductor nanoparticles are directly incorporated into LED encapsulants, then fabrication process is simplified, but color rendering deteriorates due to scattering
Solution Approach 1:
By segmenting the encapsulant into microbeads, the patent eliminates scattering issues associated with direct nanoparticle incorporation. Each bead acts as a discrete optical element that maintains color purity while the overall fabrication process remains simple.
Solution Approach 2:
The patent applies local quality by ensuring each microbead contains uniformly dispersed semiconductor nanoparticles with controlled size and composition. This local control over nanoparticle properties within each bead ensures consistent color rendering across the entire device.
3Device complexity
If semiconductor nanoparticles are exposed to environmental factors, then device structure is simplified, but quantum yield decreases due to instability
Solution Approach 1:
The microbeads serve as a protective intermediary layer that shields semiconductor nanoparticles from environmental factors such as oxygen and moisture. This protective barrier maintains high quantum yield without requiring complex encapsulation structures.
Solution Approach 2:
The patent uses microbead shells as flexible protective enclosures for the semiconductor nanoparticles. These thin-film structures provide effective protection against environmental degradation while maintaining optical transparency and not significantly 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
This approach results in more robust and efficient light emitting devices with improved color rendering and extended lifetime, as the quantum dots within the beads are protected from environmental factors and maintain high quantum yield, simplifying the fabrication process and aligning with commercial production requirements.
Implementation Method 1
the light from the LED (the 'primary light') is absorbed by the phosphorescent material and then re-emitted at a different frequency (the 'secondary light'), i.e. the phosphorescent materials down convert the primary light to the secondary light
Implementation Method 2
because of quantum confinement effects the band gap gradually becomes larger as the size of the particle decreases. This effect is a consequence of the confinement of an 'electron in a box' giving rise to discrete energy levels similar to those observed in atoms and molecules
Implementation Method 3
One method to eliminate defects and dangling bonds on the inorganic surface of the quantum dot is to grow a second inorganic material, having a wider band-gap and small lattice mismatch to that of the core material epitaxially on the surface of the core particle
Data Source
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AI summary
The present invention relates to a formulation for use in the fabrication of a light emitting device said formulation comprising a population of semiconductor nanoparticles incorporated into a plurality of discrete microbeads comprised of an optically transparent medium, said nanoparticle-containing medium being embedded in a host light emitting diode encapsulation medium. A method of preparing such a formulation is described. There is further provided a light emitting device including a primary light source in optical communication with such a formulation and a method of fabricating the same.