Quantum Dot Light Emitting Element with Perovskite Coating

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Solution Overview

Problem

Current light-emitting elements with quantum dots experience reduced efficiency due to ligand desorption causing surface defects, trapping carriers and converting electric energy into heat, and high quantum-dot dispersibility hindering carrier injection, leading to low light emission efficiency and increased driving voltage.

Innovation Solution

A light-emitting element with a quantum dot core or core-shell structure containing a zinc element, covered by a perovskite compound with a halogen element, improving stability and emission efficiency by stabilizing the quantum dot surface and enhancing carrier injection.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If ligand is used to cover quantum dot surface, then quantum dot dispersibility is improved, but light emission efficiency deteriorates due to ligand desorption causing surface defects

Engineering Contradiction:

Improvequantum dot dispersibilityVSAvoidlight emission efficiency

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The patent applies preliminary action by forming a perovskite compound layer on the quantum dot surface before the ligand can desorb. This perovskite compound (containing halogen elements) is deposited in advance to create a stable surface structure that prevents future ligand desorption and surface defect formation, thereby maintaining both dispersibility and light emission efficiency over time.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent uses composite materials by combining quantum dots with perovskite compounds to create a hybrid structure. The perovskite compound layer (containing halogen elements like iodine, bromine, or chlorine) forms a composite with the quantum dot surface, providing both stable dispersion and high light emission efficiency by preventing surface defects while maintaining quantum dot properties.

Inventive Principle:

Principle #40Composite materials

2Adaptability or versatility

If quantum dot dispersibility is increased, then carrier injection is hindered, but this raises driving voltage

Engineering Contradiction:

Improvequantum dot dispersibilityVSAvoiddriving voltage

Core Design Contradiction:

Adaptability or versatilityVSUse of energy by moving object

Solution Approach 1:

The perovskite compound acts as an intermediary layer between the quantum dots and the charge transport materials. This intermediary perovskite compound (containing halogen elements) facilitates carrier injection by providing appropriate energy level alignment and improving interfacial contact, thereby enabling high dispersibility without increasing driving voltage.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Reliability

If lead sulfide quantum dot is used, then photoelectric conversion is achieved, but visible light emission is impossible due to narrow band gap

Engineering Contradiction:

Improvephotoelectric conversion capabilityVSAvoidvisible light emission

Core Design Contradiction:

ReliabilityVSIllumination intensity

Solution Approach 1:

The patent applies parameter changes by modifying the band gap parameter of the quantum dot material. Instead of using lead sulfide with a narrow band gap, the patent uses quantum dots with wider band gap materials (such as CdSe, CdTe, ZnSe, or their core-shell structures) that can emit visible light while maintaining photoelectric conversion capabilities. The perovskite compound coating further optimizes the optical and electrical properties.

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 solution enhances light emission efficiency, reduces driving voltage, and improves the endurance of the light-emitting element by stabilizing the quantum dot surface and optimizing carrier injection, resulting in improved visible light emission.

Implementation Method 1

a perovskite compound covering the quantum dot, wherein the surface of the core or the shell includes a semiconductor or an insulator containing a zinc element, and the perovskite compound contains a halogen element

Methodology Applied

Scientific EffectSurface stabilization: Adsorption

Implementation Method 2

light-emitting element includes a light-emitting layer that contains, as a material, a quantum dot covered with an organic compound called a ligand

Methodology Applied

Scientific EffectElectroluminescence: Electroluminescence

Data Source

PatentUS20230313029A1Light emitting element, quantum dot-containing composition, and light emitting element manufacturing method

Publication Date: 2023.10.05 SHARP KK

AI summary

A light-emitting element includes a light-emitting layer including the following: a quantum dot including a core and a shell covering the core; and a perovskite compound covering the quantum dot, wherein the shell includes a semiconductor or an insulator containing a zinc element, and the perovskite compound contains a halogen element.