Core/Shell Semiconductor Nanoparticles With Uniform Size Distribution
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Solution Overview
Problem
Current methods struggle to produce nanosized semiconductor particles with uniform particle size distribution, which is essential for achieving superior optical properties and enhanced emission efficiency in core/shell structures.
Innovation Solution
The development of nanosized semiconductor particles with a core/shell structure, where the coefficient of variation of core and shell particle size distributions is controlled to be within 30%, optimizing optical characteristics and ensuring uniform light-emission color through precise control of reaction conditions and shell thickness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If nanosized semiconductor particles are produced to achieve quantum size effects, then emission characteristics are improved, but particle size distribution becomes wide leading to reduced emission efficiency
Solution Approach 1:
The synthesis process is divided into two separate stages: first forming core particles with controlled size distribution, then forming the shell layer around them. This segmentation allows independent optimization of core size uniformity and shell thickness, achieving narrow overall particle size distribution while maintaining quantum size effects for superior emission characteristics
Solution Approach 2:
The core particles are pre-formed with controlled size distribution before shell formation begins. By establishing the core size distribution first (with coefficient of variation ≤30%), the subsequent shell formation process can uniformly coat all cores, ensuring both quantum size effects are achieved and particle size distribution remains narrow
2Use of energy by moving object
If core particle size is decreased to nanoscale to increase band gap energy, then quantum size effect is enhanced, but emission efficiency decreases due to wide size distribution
Solution Approach 1:
The core particles are given uniform nanoscale dimensions (coefficient of variation ≤30%) to ensure consistent quantum size effects and band gap energy across all particles. This local uniformity in size allows each particle to exhibit predictable optical properties, maximizing emission efficiency while maintaining enhanced band gap energy
Solution Approach 2:
A core/shell composite structure is created where the nanosized core provides quantum size effects and enhanced band gap energy, while the shell layer protects the core and contributes to overall particle stability. This composite approach allows the core to be optimized for quantum effects while the shell compensates for any surface defects that would reduce emission efficiency
3Illumination intensity
If shell layer is added to cover nanoparticle surface to enhance emission intensity, then emission efficiency improves, but particle size uniformity becomes difficult to control
Solution Approach 1:
The particle formation is segmented into core formation followed by shell formation. By controlling each stage independently—first achieving uniform core sizes, then adding uniform shell thickness—the final particle size distribution remains narrow (coefficient of variation ≤30%) while still benefiting from the emission intensity enhancement provided by the shell layer
Solution Approach 2:
The core particles are prepared with controlled size distribution before shell formation. This preliminary establishment of size uniformity ensures that when the shell is subsequently formed, all particles receive comparable coating thickness, maintaining particle size uniformity while achieving the emission intensity enhancement from the shell structure
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 high-luminescent materials with stable light-emission, increased packing density, and improved quantum yield, making them suitable for high-density light-emitting devices and applications like flat panel displays.
Implementation Method 1
nano-sized particles having a particle size smaller than the wavelength of an electron (ca. 10 nm), on which the influence of size finiteness on the movement of electrons increases as a quantum size effect
Implementation Method 2
the emission intensity can be enhanced by covering the Nanoparticles with a shelling material exhibiting a band gap greater than the band gap corresponding to the emission wavelength of the Nanoparticles
Data Source
AI summary
Nanosized semiconductor particles of a core/shell structure is disclosed, wherein the particles each comprise a core and a shell and exhibit an average particle size of not more than 100 nm and a coefficient of variation in core size distribution of not more than 30%.