InP Core-Shell Nanoparticle Aggregates for Narrow Red Emission
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional InP-based semiconductor nanoparticles face challenges in achieving both high quantum yield and a narrow full width at half maximum, with improvements in one property often leading to a degradation in the other, making it difficult to meet market requirements.
Innovation Solution
A core/shell type semiconductor nanoparticle aggregate with specific parameters for peak wavelength, full width at half maximum, and standard deviations of the emission spectrum, including a core of In and P and a shell with one or more layers, optimized to achieve a high quantum yield and narrow full width at half maximum, with the semiconductor nanoparticles comprising In, P, Zn, Se, and halogen in specific molar ratios.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If InP-based semiconductor nanoparticles are used to replace Cd-based nanoparticles, then environmental safety is improved, but quantum yield decreases and emission wavelength control becomes difficult
Solution Approach 1:
The patent employs a core-shell composite structure where the core is made of InP-based semiconductor nanoparticles and the shell consists of ZnSe and ZnS layers. This composite structure allows the InP core to provide environmentally safe, cadmium-free light emission while the ZnSe/ZnS shell enhances the quantum yield by passivating surface defects and reducing non-radiative recombination. The shell also protects the core from oxidation and degradation, thereby improving overall reliability without compromising environmental safety.
2Manufacturing precision
If the particle diameter of semiconductor nanoparticles is varied to control emission wavelength, then wavelength control is achieved, but the full width at half maximum increases causing color mixing
Solution Approach 1:
The patent utilizes parameter changes in the shell thickness and composition to control the emission properties. By precisely controlling the thickness of the ZnSe and ZnS shell layers, the patent achieves narrow full width at half maximum while maintaining desired emission wavelengths. The shell parameters are optimized to confine the excitons within the core region, reducing the sensitivity to particle size variations and thereby narrowing the emission spectrum without sacrificing wavelength control capability.
3Reliability
If attempts are made to improve quantum yield of InP-based nanoparticles, then quantum yield increases, but full width at half maximum widens
Solution Approach 1:
The patent implements a nested multi-layer shell structure where an inner ZnSe layer is surrounded by an outer ZnS layer. This nested configuration allows the inner ZnSe layer to provide strong exciton confinement and high quantum yield, while the outer ZnS layer with its wider bandgap further passivates surface states and reduces non-radiative recombination pathways. The synergistic effect of the nested shell structure achieves high quantum yield without the trade-off of widened emission spectrum, as each layer contributes differently to the overall optical properties.
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 semiconductor nanoparticle aggregate achieves a high quantum yield of 80% or more and a narrow full width at half maximum, satisfying the required properties for wavelength conversion applications.
Implementation Method 1
Excitons formed in the semiconductor particles by means such as photoexcitation and charge injection emit photons having energy depending on the band gap by recombination. Therefore, the emission wavelength can be controlled by adjusting the crystal size of the semiconductor nanoparticles
Implementation Method 2
Such semiconductor nanoparticles are microscopic particles that may exhibit a quantum confinement effect and the width of the band gap varies depending on the size of the nanoparticles
Data Source
AI summary
A semiconductor nanoparticle aggregate that is an aggregate of core/shell type semiconductor nanoparticles including a core including In and P and a shell having one or more layers, in which a peak wavelength of an emission spectrum of the semiconductor nanoparticle aggregate is from 605 nm to 655 nm and a full width at half maximum of the emission spectrum is 43 nm or less. For each semiconductor nanoparticle, (1) an average value of a full width at half maximum of an emission spectrum is 28 nm or less, (2) a standard deviation of a peak wavelength of the emission spectrum is 10 nm or more and 30 nm or less, and (3) a standard deviation of the full width at half maximum of the emission spectrum is 12 nm or less.