Silicon Core-Shell Nanoparticles for Higher Electroluminescence
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Solution Overview
Problem
Existing nanoparticle electroluminescence devices face challenges in achieving high luminescence efficiency due to defects such as dangling bonds and vacancies on the surface of silicon fine particles, which affect light emission characteristics.
Innovation Solution
A nanoparticle electroluminescence device with a core/shell structure, where the core is made of silicon and the shell is formed of silicon oxide or silicon nitride, is used to improve interface and luminescence characteristics, preventing defects and enhancing light emission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If silicon fine particles are used as emitting layer material, then light emission in visible area can be obtained, but luminescence efficiency is reduced due to surface defects such as dangling bonds and vacancies
Solution Approach 1:
The patent employs a core-shell composite structure where silicon nanoparticles (core) are coated with silicon oxide or silicon nitride shells. This composite structure allows the silicon core to provide visible light emission through quantum confinement effects while the shell layer passivates surface defects, thereby simultaneously achieving light emission and high luminescence efficiency.
Solution Approach 2:
The shell layer acts as an intermediary between the silicon core and the external environment. It passivates surface defects on the silicon nanoparticles, preventing non-radiative recombination at defect sites while allowing the silicon core to maintain its light-emitting properties. This intermediary layer resolves the contradiction by protecting the core from surface defect-induced efficiency losses.
2Length of moving object
If nanoparticle size is decreased to increase energy bandgap, then light wavelength can be shortened, but surface defects become more prominent affecting luminescence characteristics
Solution Approach 1:
By creating a core-shell composite structure, the patent enables the use of very small silicon nanoparticles (2-10 nm) to achieve short wavelength emission through quantum confinement, while the shell layer compensates for the increased surface-to-volume ratio by providing comprehensive surface passivation, thus maintaining luminescence characteristics despite reduced particle size.
Solution Approach 2:
The shell layer provides localized quality enhancement at the nanoparticle surface. While the core maintains uniform small size for quantum confinement effects, the shell locally modifies the surface properties by passivating defects, creating a spatial differentiation where the core provides size-dependent optical properties and the shell provides surface protection.
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 core/shell structure effectively stabilizes the silicon core, improving luminescence efficiency and light emission, resulting in a device with enhanced performance.
Implementation Method 1
a shell formed of silicon oxide or silicon nitride on the surface of the core
Implementation Method 2
Electroluminescence (EL) devices are devices which emit light by electrical excitation. When electric energy is supplied to electrons in a low energy level and the electrons move to a higher energy level when the electric energy is cut off, the electrons return to the low energy level and light of predetermined wavelength may be generated.
Implementation Method 3
light having a variety of wavelengths, that is, light from a total visible area and a blue color to an ultraviolet-ray area can be easily produced due to an increase in an energy bandgap and a quantization effect as the size of the nanoparticles decreases
Data Source
AI summary
The nanoparticle electroluminescence device includes: a front electrode formed of a transparent conductive material; a rear electrode formed of a conductive material; and an emitting layer interposed between the front electrode and the rear electrode and comprising a plurality of nanoparticles having a core/shell structure comprising a core formed of silicon and a shell formed of silicon oxide or silicon nitride on the surface of the core.