Quantum Dot Light Emitting Diode With Hole Transporting Layer

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Solution Overview

Problem

In quantum dot light emitting diodes (QLEDs), the exciton recombination region is typically formed in the hole transporting layer rather than the quantum dot light emitting layer due to the low hole mobility of organic materials used in the hole injection and transporting layers, leading to reduced luminous efficiency.

Innovation Solution

A QLED structure is developed with a light emitting layer comprising a first quantum dot layer having a hole transporting property and a second quantum dot layer having an electron transporting property, where the quantum dots are surface-coordinated with specific ligands to enhance hole and electron transport, ensuring exciton recombination occurs within the quantum dot layers.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If organic materials are used in the hole injection and transporting layers, then the device structure is simple and ease of manufacture is improved, but hole mobility is low causing exciton recombination to occur in the wrong layer

Engineering Contradiction:

Improveease of manufactureVSAvoidluminous efficiency

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The patent changes the material parameters by replacing organic hole transporting materials with inorganic semiconductor materials (such as CuInS2, CuSe, CuS, ZnO, ZnSe, ZnS, GaN, InN, or their composite materials) that have significantly higher hole mobility. This parameter change resolves the contradiction by maintaining ease of manufacture through solution processing while achieving the required hole mobility for proper exciton recombination in the quantum dot layer.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent employs composite material structures where inorganic semiconductor materials are used in the hole injection and transporting layers. These composite materials combine the advantages of solution processability with high carrier mobility, resolving the contradiction between ease of manufacture and luminous efficiency by enabling proper charge transport while maintaining fabrication simplicity.

Inventive Principle:

Principle #40Composite materials

2Ease of manufacture

If organic materials are used in the hole transporting layer, then ease of manufacture is improved, but exciton recombination occurs in the hole transporting layer instead of the quantum dot light emitting layer

Engineering Contradiction:

Improveease of manufactureVSAvoidexciton recombination location precision

Core Design Contradiction:

Ease of manufactureVSManufacturing precision

Solution Approach 1:

The patent changes the hole mobility parameter by using inorganic semiconductor materials with significantly higher hole mobility compared to organic materials. This ensures that holes can efficiently reach the quantum dot layer for recombination, achieving precise control over exciton recombination location while maintaining ease of manufacture through solution processing methods.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent substitutes organic molecular materials with inorganic semiconductor materials, replacing the mechanical/molecular transport mechanism with a more efficient electronic transport mechanism. This substitution enables precise control of exciton recombination location in the quantum dot layer while maintaining solution processability.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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 configuration improves the luminous efficiency of QLEDs by ensuring exciton recombination in the quantum dot layers, thereby enhancing light emission performance.

Implementation Method 1

the ligand in the ligand alkyl chain includes at least one of a mercapto group, a polymercapto group, an amino group, a polyamino group, and a phosphorusoxy group

Methodology Applied

Scientific EffectSurface coordination:

Implementation Method 2

Under the action of an electric field, holes and electrons perform migration of the carriers in their respective transport layers, and combine into excitons in the quantum dot light emitting layer to emit light

Methodology Applied

Scientific EffectElectroluminescence: Electroluminescence

Data Source

PatentUS11171300B2Quantum dot light emitting diode, method for fabricating the same, and display device

Publication Date: 2021.11.09 BOE TECHNOLOGY GROUP CO LTD

AI summary

A quantum dot light emitting diode includes: a light emitting layer, the light emitting layer including a first quantum dot layer and a second quantum dot layer which are stacked; the first quantum dot layer including a first quantum dot having a hole transporting property; and the second quantum dot layer including a second quantum dot having an electron transporting property. The first quantum dot layer having hole transporting property and the second quantum dot layer having electron transporting property are stacked. The first quantum dot layer and the second quantum dot layer not only form a quantum dot light emitting layer, but also transport holes and electrons respectively, thereby causing excitons to be recombined in the first quantum dot layer and/or the second quantum dot layer, or near the interface of the first quantum dot layer and the second quantum dot layer.