PbS Quantum Dot Semiconductor Film for Infrared Sensitivity
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Solution Overview
Problem
Current photodetector elements, such as silicon photodiodes and InGaAs-based materials, have limitations in sensitivity and cost-effectiveness for infrared light detection, and existing semiconductor quantum dot technologies require further improvement in external quantum efficiency.
Innovation Solution
A semiconductor film comprising an aggregate of metal-containing quantum dots, specifically PbS quantum dots, with a ligand coordinated to the dots, where the half width at half maximum of the exciton absorption peak is narrowed to enhance external quantum efficiency, achieved through a manufacturing method involving a PbS quantum dot dispersion liquid and ligand exchange process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a silicon photodiode is used as a photoelectric conversion layer, then the structure is simple and manufacturing is easy, but the sensitivity in the infrared region having a wavelength of 900 nm or more is low
Solution Approach 1:
The patent changes the material parameters by using PbS quantum dots with specific size distributions and ligand treatments to achieve high sensitivity in the infrared region while maintaining ease of manufacture through solution processing methods
Solution Approach 2:
The patent employs composite materials by combining PbS quantum dots with specific ligands (such as 3-mercaptopropionic acid and ZnI2) to create a photoelectric conversion layer that achieves both high infrared sensitivity and ease of manufacture
2Reliability
If InGaAs-based semiconductor material is used to achieve high quantum efficiency, then the external quantum efficiency is improved, but extremely high-cost processes such as epitaxial growth or substrate sticking are required
Solution Approach 1:
The patent uses a disposable substrate approach where a inexpensive substrate is used for quantum dot deposition, then the substrate is removed and the quantum dots are transferred to the final device, avoiding costly epitaxial growth and substrate sticking processes while maintaining high external quantum efficiency
Solution Approach 2:
The patent changes the manufacturing parameters by using solution-based quantum dot synthesis and deposition methods instead of high-cost epitaxial growth, achieving comparable external quantum efficiency through controlled quantum dot size distribution and ligand engineering
3Reliability
If the half width at half maximum of an exciton absorption peak is narrowed, then the external quantum efficiency with respect to light having a wavelength in the vicinity of the exciton absorption peak is improved, but the manufacturing precision requirements increase
Solution Approach 1:
The patent narrows the half width at half maximum of the exciton absorption peak by precisely controlling quantum dot size distribution and implementing specific ligand treatments, achieving high external quantum efficiency while managing manufacturing precision through solution processing
Solution Approach 2:
The patent performs preliminary ligand exchange treatments and quantum dot size sorting before final device assembly, narrowing the exciton absorption peak width in advance to ensure high external quantum efficiency without requiring extreme manufacturing precision in subsequent steps
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 film exhibits high external quantum efficiency for light in the infrared region, improving sensitivity and reducing surface defects, thereby enhancing the performance of photodetector elements and image sensors.
Implementation Method 1
a half width at half maximum of an exciton absorption peak in optical characteristics of the semiconductor film is 60 nm or less
Implementation Method 2
it is possible to improve the external quantum efficiency with respect to light having a wavelength in the vicinity of the exciton absorption peak
Data Source
AI summary
There is provided a semiconductor film including an aggregate of semiconductor quantum dots that contain a metal atom and a ligand that is coordinated to the semiconductor quantum dot, in which a half width at half maximum of an exciton absorption peak in optical characteristics of the semiconductor film is 60 nm or less. There are also provided a manufacturing method for a semiconductor film, a photodetector element, and an image sensor.