Quantum Dot Intermediate Layer for Carrier Extraction
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Solution Overview
Problem
Optoelectric devices, such as solar cells, face inefficiencies in carrier extraction due to the core/shell structure's bandgap differences, which hinder light-emission efficiency in light-emitting devices and optoelectric performance.
Innovation Solution
An optoelectric device is designed with a quantum dot core and an intermediate layer on its surface, embedded in a semiconductor matrix, where the intermediate's energy band levels are optimized to enhance carrier extraction efficiency, and the coverage ratio of the intermediate layer is controlled to improve optoelectric performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a core/shell structure is used in quantum dots for light-emitting devices, then light-emission efficiency is improved, but carrier extraction efficiency deteriorates when applied to optoelectric devices like solar cells
Solution Approach 1:
The patent segments the quantum dot structure by providing only a partial shell covering a portion of the quantum dot core surface, rather than a complete core/shell structure. This segmentation allows different regions to serve different functions: the covered region provides stability and controlled emission, while the exposed region enables efficient carrier extraction, thus resolving the contradiction between light-emission efficiency and carrier extraction efficiency
Solution Approach 2:
The patent applies local quality by creating non-uniform shell coverage on the quantum dot core surface. The shell is present in some regions and absent in others, allowing each region to have optimized properties for its specific function. This local differentiation enables simultaneous optimization of both light-emission characteristics and carrier extraction performance
2Illumination intensity
If the bandgap of the shell is greater than that of the core in core/shell structure, then light-emission characteristics are enhanced, but the efficiency of extraction of carriers generated in the core to the outside deteriorates
Solution Approach 1:
The patent extracts or removes the shell material from certain regions of the quantum dot core surface. By taking out the shell in partial regions, carriers can be extracted directly from the core to the outside without being blocked by the shell's larger bandgap, thus maintaining high carrier extraction efficiency while preserving the core's light-emission characteristics in the covered regions
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 proposed structure significantly enhances carrier extraction efficiency, leading to improved optoelectric performance and increased responsivity compared to core quantum dot structures, with a 3.9 times average increase in responsivity and faster decay rates indicating higher efficiency.
Implementation Method 1
the optoelectric device is configured to convert light energy incident upon the optoelectric device to electrical energy
Implementation Method 2
A quantum dot (QD) is a nanocrystal made of a semiconductor material having a diameter of about 10 nm or less and having a quantum confinement effect
Data Source
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AI summary
An optoelectric device includes a quantum dot core and an intermediate provided on at least a part of a surface of the quantum dot core, thereby converting light energy incident upon the optoelectric device to electrical energy.