Zinc Oxide Nanoparticle Electron Transport Layer for Electroluminescent Devices

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Solution Overview

Problem

Current light-emitting devices, particularly quantum dot-based electroluminescent devices, face challenges in achieving improved lifespan and electroluminescent characteristics while maintaining high light-emitting efficiency, often requiring harmful heavy metals like cadmium and experiencing reduced performance due to aluminum incorporation in zinc oxide nanoparticles.

Innovation Solution

An electroluminescent device is designed with a light-emitting layer comprising cadmium-free semiconductor nanoparticles and an electron transport layer made of zinc oxide nanoparticles containing magnesium and aluminum, optimized to enhance electroluminescence properties and extend device lifespan by controlling the composition and UV-Vis absorption characteristics.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If aluminum is incorporated in zinc oxide nanoparticles to improve electron transport, then electron mobility increases, but device lifespan decreases and electroluminescent characteristics deteriorate

Engineering Contradiction:

Improveelectron mobilityVSAvoiddevice lifespan

Core Design Contradiction:

SpeedVSDuration of action of stationary object

Solution Approach 1:

The patent optimizes the aluminum content parameter in zinc oxide nanoparticles to a specific range (0.5-30 mol%) to achieve the best balance between electron mobility and device lifespan. This parameter optimization resolves the contradiction by finding the optimal point where electron transport is sufficiently improved without causing excessive degradation of device longevity and electroluminescent properties.

Inventive Principle:

Principle #35Parameter changes

2Use of energy by moving object

If cadmium-containing quantum dots are used to achieve high light-emitting efficiency, then electroluminescent performance improves, but harmful heavy metal content increases

Engineering Contradiction:

Improvelight-emitting efficiencyVSAvoidharmful heavy metal content

Core Design Contradiction:

Use of energy by moving objectVSObject-generated harmful factors

Solution Approach 1:

The patent extracts and removes cadmium from the quantum dot composition, replacing it with cadmium-free alternative materials such as zinc chalcogenide nanoparticles. This extraction of the harmful element while maintaining the light-emitting function resolves the contradiction between high efficiency and environmental safety.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent employs composite material structures, such as core-shell quantum dots with zinc chalcogenide composition, to achieve high light-emitting efficiency without relying on cadmium. The composite structure maintains the desired optical properties while eliminating the harmful heavy metal content.

Inventive Principle:

Principle #40Composite materials

3Illumination intensity

If zinc oxide nanoparticle size is reduced to enhance UV-Vis absorption, then electroluminescence properties improve, but manufacturing precision requirements increase

Engineering Contradiction:

ImproveUV-Vis absorptionVSAvoidnanoparticle size control

Core Design Contradiction:

Illumination intensityVSManufacturing precision

Solution Approach 1:

The patent establishes a specific nanoparticle size parameter range (1-15 nm) for zinc oxide to optimize UV-Vis absorption while maintaining feasible manufacturing precision. This parameter definition resolves the contradiction by setting realistic boundaries that achieve the desired optical enhancement without imposing excessive manufacturing challenges.

Inventive Principle:

Principle #35Parameter changes

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 device achieves improved electroluminescent performance and extended lifespan with enhanced light-emitting efficiency and reduced current requirements, avoiding the use of harmful heavy metals and minimizing current leakage.

Implementation Method 1

The light emission from the semiconductor nanoparticle may occur when an electron in an excited state resulting from light excitation or an applied voltage moves from a conduction band to a valence band

Methodology Applied

Scientific EffectElectroluminescence: Electroluminescence

Implementation Method 2

optimized to enhance electroluminescence properties and extend device lifespan by controlling the composition and UV-Vis absorption characteristics

Methodology Applied

Scientific EffectUV-Vis absorption: Absorption (EM radiation)

Data Source

PatentUS20240224562A1Electroluminescent device, production method thereof, and display device including the same

Publication Date: 2024.07.04 SAMSUNG DISPLAY CO LTD

AI summary

Disclosed are an electroluminescent device including a first electrode and a second electrode spaced apart from each other; a light-emitting layer disposed between the first and second electrodes; and an electron transport layer between the light-emitting layer and the second electrode; a production method thereof; and a display device including the same. The light-emitting layer includes a semiconductor nanoparticle, the electron transport layer includes a zinc oxide nanoparticle having a size of 1 nm or more to 15 nm or less, and the zinc oxide nanoparticle further includes magnesium and aluminum, and an amount of aluminum in the zinc oxide nanoparticle is greater than or equal to about 0.5 mol % and less than or equal to about 30 mol % based on a total amount of zinc, magnesium, and aluminum.