Ligand-Modified Quantum Dot Composition for Carrier Transfer

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Solution Overview

Problem

Existing quantum dot light emitting diodes (QD-LEDs face challenges with quantum dot material stability and solubility due to the use of short-chain ligands, which reduce preservation and increase coagulation, while long-chain ligands lead to low carrier transfer efficiency.

Innovation Solution

A quantum dot composition with a ligand modifier having a structural formula of segment A-segment B, where segment A is adsorbed on the quantum dot and segment B is a long molecular chain that can be cleaved under heating or illumination, improving solubility and stability, and allowing for dense stacking of quantum dots to enhance carrier transfer performance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If short-chain ligands are used on quantum dot surface, then carrier transfer efficiency is improved, but solubility and stability deteriorate leading to coagulation

Engineering Contradiction:
Improvecarrier transfer efficiencyVSAvoidsolubility and stability
Core Design Contradiction:
ProductivityVSStability of the object's composition

Solution Approach 1:

The ligand is divided into two functional segments: segment A (short-chain) that binds to quantum dot surface and segment B (long-chain) that provides solubility and stability. This segmentation allows each part to fulfill its specific function without compromising the other, resolving the contradiction between carrier transfer efficiency and solubility/stability.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Different parts of the ligand have different properties: segment A has short-chain characteristics for efficient carrier transfer, while segment B has long-chain characteristics for enhanced solubility and stability. This local differentiation of properties allows the single ligand molecule to simultaneously address both requirements of the quantum dot system.

Inventive Principle:
Principle #3Local quality

2Stability of the object's composition

If long-chain ligands are used on quantum dot surface, then solubility and stability are improved, but carrier transfer efficiency deteriorates

Engineering Contradiction:
Improvesolubility and stabilityVSAvoidcarrier transfer efficiency
Core Design Contradiction:
Stability of the object's compositionVSProductivity

Solution Approach 1:

The ligand is segmented into segment A (short-chain) for carrier transfer and segment B (long-chain) for solubility/stability. By separating these functions into different segments, the patent achieves both high solubility/stability and efficient carrier transfer, eliminating the need to choose one over the other.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The ligand exhibits local quality differentiation where segment A provides short-chain benefits for carrier transfer efficiency while segment B provides long-chain benefits for solubility and stability. This localized functional distribution resolves the contradiction by allowing both properties to coexist in the same ligand structure.

Inventive Principle:
Principle #3Local quality

3Productivity

If short-chain ligands are used, then carrier transfer is enhanced, but preservation and anti-coagulation performance deteriorate

Engineering Contradiction:
Improvecarrier transfer efficiencyVSAvoidpreservation and anti-coagulation
Core Design Contradiction:
ProductivityVSReliability

Solution Approach 1:

The ligand is segmented such that segment A handles carrier transfer while segment B handles preservation and anti-coagulation. This functional segmentation allows the system to maintain both high carrier transfer efficiency and reliable preservation performance without compromise.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Different segments of the ligand have specialized local qualities: segment A is optimized for carrier transfer efficiency while segment B is optimized for preservation and anti-coagulation properties. This local quality differentiation enables simultaneous achievement of both performance requirements.

Inventive Principle:
Principle #3Local quality

4Reliability

If long-chain ligands are used, then preservation and solubility are improved, but carrier transfer efficiency and device performance deteriorate

Engineering Contradiction:
Improvepreservation and solubilityVSAvoidcarrier transfer efficiency
Core Design Contradiction:
ReliabilityVSProductivity

Solution Approach 1:

The ligand is divided into segment A (short-chain) for carrier transfer and segment B (long-chain) for preservation and solubility. This segmentation enables the system to achieve both reliable preservation/solubility and efficient carrier transfer, eliminating the trade-off between these properties.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The ligand exhibits local quality differentiation where segment A provides short-chain benefits for carrier transfer efficiency while segment B provides long-chain benefits for preservation and solubility. This localized functional distribution resolves the contradiction by allowing both properties to coexist.

Inventive Principle:
Principle #3Local quality

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 quantum dot composition achieves improved solubility and stability as a solution or ink, with segment B cleavage enhancing carrier transfer efficiency by forming a densely packed quantum dot layer, thereby improving the performance of QD-LEDs.

Implementation Method 1

segment B is a long molecular chain which can be cleaved under heating or illumination

Methodology Applied
Scientific EffectPhotocleavage: Photodissociation

Implementation Method 2

segment B is a long molecular chain which can be cleaved under heating or illumination

Methodology Applied
Scientific EffectThermal decomposition: Pyrolysis

Implementation Method 3

segment A is adsorbed on the quantum dot

Methodology Applied
Scientific EffectAdsorption: Adsorption

Implementation Method 4

segment A includes any one or more selected from a group comprising an amino group, sulfhydryl, hydroxyl, a polyamino group, polysulfhydryl, polyhydroxyl, phosphorus, phosphorusoxy, organophosphorus, and thioether

Methodology Applied
Scientific EffectChemical bonding: Chemical Bonding

Implementation Method 5

After the quantum dot composition is formed on a substrate, heating or illumination is performed to cleave segment B of the ligand modifier

Methodology Applied
Scientific EffectEvaporation: Evaporation

Implementation Method 6

forming a densely packed quantum dot layer

Methodology Applied
Scientific EffectSelf-assembly: Self-Assembly

Data Source

PatentEP3656832B1Ligand-modified quantum dot composition, ligand-modified quantum dot layer, preparation method therefor, and quantum dot light-emitting diode
Publication Date: 2023.06.21 BOE TECHNOLOGY GROUP CO LTD
  • EP3656832B1 patent drawingFigure 1~4
  • EP3656832B1 patent drawingFigure 5~7
  • EP3656832B1 patent drawingFigure 8

AI summary

A ligand-modified quantum dot composition, a ligand-modified quantum dot layer, preparation methods thereof, and a quantum dot light emitting diode are provided. Segment B of the ligand modifier in the ligand-modified quantum dot composition is a chain-cleavable segment, that is, segment B is a longer molecular chain, so that the material has good solubility and stability, thus the ligand-modified quantum dot composition is present in the form of a solution or ink, etc. Segment B itself is not very stable and may be cleaved under certain conditions. In specific applications, the group in segment B may be cleaved by heating or illumination, so that the ligand modifier becomes a short molecular chain ligand, thereby making the quantum dots densely stack and improving the carrier transfer performance.