Nanorod Light Emitting Device Quantum Dot Density
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Solution Overview
Problem
Conventional light emitting devices with quantum dots have low light emission efficiency due to low quantum dot density and uneven distribution, which limits the effectiveness of Förster Resonance Energy Transfer (FRET) from Multiple Quantum Well (MQW) structures.
Innovation Solution
A light emitting device with nanorods and quantum dots arranged in a three-dimensional configuration, where quantum dots are disposed between the nanorods to increase their density and proximity to the MQW, enhancing FRET and light emission efficiency, and allowing for adjustable emission wavelengths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If quantum dots are arranged in a mono-layer on the film surface, then the structure is simple, but the quantum dot density is low and light emission efficiency cannot be increased
Solution Approach 1:
The patent transitions from a two-dimensional mono-layer arrangement to a three-dimensional configuration by positioning quantum dots in the space between vertically arranged nanorods. This spatial dimensionality change increases the effective density of quantum dots near the MQW structure without significantly complicating the overall device architecture, thereby resolving the contradiction between structural simplicity and light emission efficiency.
Solution Approach 2:
The patent utilizes the porous or void space between nanorods to position quantum dots, effectively using the three-dimensional space that would otherwise be empty. This approach increases quantum dot density by utilizing available space efficiently while maintaining a relatively simple nanorod-based structural framework.
2Manufacturing precision
If reverse epitaxial growth is carried out to improve film quality, then the film quality is improved, but the light emission efficiency enhancement from FRET is considerably decreased
Solution Approach 1:
The patent circumvents the limitation of reverse epitaxial growth by moving the quantum dots from a two-dimensional surface position to a three-dimensional position between nanorods. This spatial repositioning allows quantum dots to be closer to the MQW structure in the vertical dimension, compensating for the reduced FRET effect caused by reverse epitaxial growth and maintaining high light emission efficiency despite the manufacturing process changes.
3Ease of manufacture
If quantum dots are distributed sparsely on the film surface, then the manufacturing process is simple, but the density of quantum dots for FRET is low
Solution Approach 1:
The patent utilizes the porous space between nanorods to distribute quantum dots throughout a three-dimensional volume rather than spreading them sparsely across a two-dimensional surface. This approach dramatically increases the effective quantum dot density available for FRET interactions while maintaining manufacturing simplicity, as the quantum dots are positioned in pre-formed spaces between the nanorod structure.
Solution Approach 2:
By transitioning from surface-level two-dimensional distribution to three-dimensional distribution between nanorods, the patent increases quantum dot density without proportionally increasing manufacturing complexity. The vertical spacing between nanorods provides additional dimensional space for quantum dot placement, effectively multiplying the available positions for quantum dots.
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 increased quantum dot density and proximity to the MQW structure enhance light emission efficiency, reduce heat generation, and enable the production of visible light, including white light, by effectively transferring energy from the MQW to quantum dots.
Implementation Method 1
the phenomenon of transferring energy that is generated from a Multiple Quantum Well (MQW) to quantum dots through Förster Resonance Energy Transfer (FRET) can be increased
Implementation Method 2
Quantum dots generate fluorescent light in a narrow wavelength range, and the light thus generated is stronger than that generated by typical fluorescent materials
Data Source
AI summary
A light emitting device includes a metal backing layer, a reflective electrode layer disposed on the metal backing layer, and a plurality of nanorods disposed on the reflective electrode layer. Each nanorod includes a p-semiconductor layer, an active layer, and an n-semiconductor layer, which are sequentially stacked on the reflective electrode layer. The light emitting device further includes an anti-reflection electrode layer disposed on the nanorods, and quantum dots disposed between the nanorods. The method includes sequentially growing the n-semiconductor layer, the active layer, and the p-semiconductor layer on a substrate; forming the nanorods by etching the p-semiconductor layer using a mask pattern; sequentially forming the reflective electrode layer and the metal backing layer on the p-semiconductor layer and then removing the substrate; disposing quantum dots between the nanorods; and forming the anti-reflection electrode layer on the nanorods.