Quantum Dot Layer Epitaxial Shell Growth for Charge Injection
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Solution Overview
Problem
There is a need to improve the luminous efficiency in light-emitting devices that incorporate a quantum dot layer.
Innovation Solution
A method for manufacturing a light-emitting device involves forming a quantum dot layer by applying a solution containing quantum dots, a ligand, and an inorganic precursor on a substrate, followed by temperature raising to melt the ligand and vaporize the solvent, then lowering the temperature to allow epitaxial growth of an inorganic shell around the existing shell, with the ligand present around the resulting structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a quantum dot layer is formed by simple application and drying, then the manufacturing process is simple, but the luminous efficiency is insufficient due to electron exudation and poor charge injection
Solution Approach 1:
The patent applies preliminary action by forming the quantum dot layer with pre-coated shells and ligands before final assembly. The quantum dots are prepared with core/shell structures and surface ligands in advance, then assembled into the light-emitting layer where they automatically form optimal configurations for charge injection and electron confinement, achieving high luminous efficiency without complex post-processing
Solution Approach 2:
The patent employs composite materials by creating a multi-component quantum dot structure consisting of a semiconductor core, intermediate shell layer, and outer shell layer, with organic ligands coordinating the surfaces. This composite structure provides both the simplicity of solution processing and the high luminous efficiency through controlled electron confinement and charge injection at each interface
2Device complexity
If the quantum dot structure is simplified to core-only, then the manufacturing is easier, but electron exudation increases and luminous efficiency decreases
Solution Approach 1:
The patent applies segmentation by dividing the quantum dot into distinct functional segments: a core region for light emission, an intermediate shell layer for electron confinement, and an outer shell layer for stability. Each segment performs a specific function, with the shell layers creating potential barriers that prevent electron exudation while maintaining manufacturability through solution-based processing
Solution Approach 2:
The patent implements local quality by assigning different material compositions and properties to different regions of the quantum dot. The core uses specific semiconductor materials for optimal light emission, while the shell layers use materials with appropriate band offsets for electron confinement. The surface ligands provide localized chemical coordination, creating optimal conditions for charge injection at specific interfaces without requiring complex overall restructuring
3Loss of energy
If shell thickness is increased to improve electron confinement, then luminous efficiency improves, but manufacturing precision requirements increase
Solution Approach 1:
The patent applies parameter changes by optimizing the shell thickness to specific ranges (first shell: 0.5-5 nm, second shell: 1-10 nm) that provide sufficient electron confinement while remaining compatible with solution-based manufacturing techniques. These parameter ranges balance the need for electron confinement with the practical limitations of controlling thin film deposition from solution, avoiding the need for ultra-precise atomic-layer control
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
This method enhances the luminous efficiency of the light-emitting device by improving charge injection and reducing electron exudation, resulting in improved light emission efficiency.
Implementation Method 1
raising a temperature until the ligand melts and the first solvent vaporizes
Implementation Method 2
raising a temperature until the ligand melts and the first solvent vaporizes
Implementation Method 3
epitaxially growing the first inorganic precursor around the first shell by first light irradiation
Data Source
AI summary
A method for manufacturing a light-emitting device includes forming the quantum dot layer, wherein the forming the quantum dot layer includes performing first application of applying, on a position overlapping with the substrate, a first solution including quantum dots, a ligand, a first inorganic precursor, and a first solvent, the quantum dots each including a core and a first shell coating the core, the ligand coordinating with each of the quantum dots, performing temperature raising of raising a temperature until the ligand melts and the first solvent vaporizes after the performing first application, performing first temperature lowering of lowering a temperature to a melting point of the ligand or lower after the performing temperature raising, and performing first light irradiation of epitaxially growing the first inorganic precursor around the first shell by first light irradiation after the performing first temperature lowering to form a second shell coating the first shell.