Quantum Dot LED Composite Electron Transport Layer

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Solution Overview

Problem

Existing quantum dot light-emitting diodes (QLEDs) suffer from luminescence quenching due to surface defects in electron transport materials, leading to reduced luminous performance and device lifespan, primarily caused by photocatalytic effects of metal oxide materials.

Innovation Solution

A quantum dot light-emitting diode with a composite electron transport layer containing an electron transport material and an ultraviolet absorbing material, where the ultraviolet absorbing material passivates surface defects, preventing luminescence quenching and enhancing device performance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If metal oxide electron transport materials (such as zinc oxide, titanium dioxide) are used to achieve high carrier mobility and excellent electron transport properties, then electron injection and transport performance is improved, but surface defects and strong photocatalytic ability cause luminescence quenching and damage to organic ligands, reducing device lifespan

Engineering Contradiction:

Improveelectron transport performanceVSAvoidluminescence quenching and photocatalytic damage

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

An ultraviolet absorbing material is introduced as an intermediary layer between the metal oxide electron transport material and the quantum dot layer. This intermediary absorbs ultraviolet photons before they can reach the metal oxide, preventing photocatalytic reactions that would otherwise damage organic ligands on quantum dot surfaces and cause luminescence quenching, while allowing the metal oxide to maintain its electron transport function

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The strong photocatalytic ability of metal oxide materials, which normally causes harmful oxidation reactions, is converted into a beneficial effect by pairing it with an ultraviolet absorbing material. The ultraviolet absorbing material selectively absorbs the harmful ultraviolet radiation, allowing the metal oxide to function as an effective electron transport material without suffering from photocatalytic degradation, thus transforming the harmful photocatalytic property into a manageable characteristic

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

2Ease of manufacture

If nanoparticles of metal oxide or metal sulfide semiconductor are prepared using solution method to form thin film, then device fabrication is simplified, but a lot of defects exist on the surface and in the internal part, becoming recombination center of carriers and reducing luminous performance

Engineering Contradiction:

Improvefabrication simplicityVSAvoidluminous performance

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The ultraviolet absorbing material serves as a protective intermediary that prevents ultraviolet-induced damage to the nanoparticle structure and organic ligands. This allows the use of solution-method-prepared nanoparticles with their inherent defect structures, while the ultraviolet absorbing layer prevents further degradation that would create additional recombination centers and reduce luminous performance over time

Inventive Principle:

Principle #24Intermediary (Mediator)

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 use of a composite electron transport layer with ultraviolet absorbing material effectively passivates surface defects, improving the luminous performance and extending the lifespan of QLEDs by mitigating photocatalytic damage and luminescence quenching.

Implementation Method 1

a composite electron transport layer containing an electron transport material and an ultraviolet absorbing material

Methodology Applied

Scientific EffectAbsorption (EM radiation): Absorption (EM radiation)

Implementation Method 2

Functional groups in the ultraviolet absorbing material are combined with vacancies or dangling bonds on the surface of the electron transport material to passivate the surface defects

Methodology Applied

Scientific EffectSurface passivation:

Implementation Method 3

when these materials are irradiated with photons having an energy greater than the forbidden band width, electrons will transit from a valence band to a conduction band, thereby generating electron-hole pairs

Methodology Applied

Scientific EffectPhotocatalysis:

Implementation Method 4

electrons will transit from a valence band to a conduction band, thereby generating electron-hole pairs

Methodology Applied

Scientific EffectPhotoelectric effect: Photoelectric Effect

Implementation Method 5

quantum dot light-emitting diode (QLED) is an emerging display device, which adopts inorganic quantum dots having more stable performance as the light-emitting materials

Methodology Applied

Scientific EffectElectroluminescence: Electroluminescence

Data Source

PatentUS11485908B2Quantum dot light-emitting diode and method for fabricating the same

Publication Date: 2022.11.01 TCL TECHNOLOGY GROUP CORPORATION

AI summary

A quantum dot light-emitting diode and a method for fabricating the same. The quantum dot light-emitting diode, includes: an anode, a cathode, and a quantum dot light-emitting layer arranged between the anode and the cathode. A composite electron transport layer is arranged between the cathode and the quantum dot light-emitting layer, and the composite electron transport layer contains an electron transport material and an ultraviolet absorbing material.