Quantum Dot Light-Emitting Device With Gradient Shell Thickness

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Solution Overview

Problem

Existing quantum dot light-emitting devices exhibit poor efficiency under general use luminance (300-1000 cd/m2), with current solutions failing to effectively address this issue.

Innovation Solution

A quantum dot light-emitting device structure featuring multiple quantum dot light-emitting layers with core-shell quantum dots, where the thickness of outermost shell layers increases sequentially from the anode to the cathode, optimizing hole and electron injection balance by varying shell layer thicknesses.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If a single quantum dot light-emitting layer is used to achieve simple device structure, then the device complexity is reduced, but the efficiency under general use luminance deteriorates

Engineering Contradiction:

Improvelight-emitting layer structureVSAvoidefficiency under general use luminance

Core Design Contradiction:

Device complexityVSProductivity

Solution Approach 1:

The light-emitting layer is segmented into multiple quantum dot light-emitting layers (first quantum dot light-emitting layer to Nth quantum dot light-emitting layer) with different shell layer thicknesses. Each layer contains core-shell quantum dots where the outermost shell layer thickness increases sequentially from the first layer to the Nth layer. This segmentation allows different layers to optimize for different carrier injection requirements, thereby improving overall device efficiency under general use luminance while maintaining a systematic structure.

Inventive Principle:

Principle #1Segmentation

2Ease of manufacture

If uniform shell layer thickness is used across all quantum dot layers, then the manufacturing process is simplified, but the carrier injection balance deteriorates

Engineering Contradiction:

Improvequantum dot layer fabricationVSAvoidcarrier injection balance

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

Different quantum dot light-emitting layers are assigned different local qualities in terms of shell layer thickness. The first quantum dot light-emitting layer has the thinnest outermost shell layer to facilitate hole injection, while subsequent layers have progressively thicker shell layers. This local differentiation optimizes carrier injection balance for each layer's specific position and function, improving overall device reliability without requiring complex manufacturing processes.

Inventive Principle:

Principle #3Local quality

3Reliability

If thick shell layers are used in all quantum dot layers to reduce injection barriers, then the carrier injection is improved, but the energy level alignment deteriorates

Engineering Contradiction:

Improveinjection barrier reductionVSAvoidenergy level alignment

Core Design Contradiction:

ReliabilityVSStability of the object's composition

Solution Approach 1:

The shell layer thickness is made dynamic rather than static, varying sequentially across different quantum dot light-emitting layers. The outermost shell layer thickness increases from the first layer to the Nth layer, creating a gradient structure. This dynamic variation allows each layer to have optimized thickness for its specific energy level requirements and injection barrier needs, achieving both improved carrier injection and proper energy level alignment throughout the device.

Inventive Principle:

Principle #15Dynamics

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

Improves efficiency under general use luminance and prolongs device lifetime by facilitating balanced carrier injection and reducing injection barriers.

Implementation Method 1

Colloidal quantum dots (CQDs) have proven to be excellent semiconductor materials for photovoltaic devices and applications, such as quantum dot light-emitting diodes (QLED), photodetectors, and photovoltaics, because of their tunable band gap by quantum size effects.

Methodology Applied

Scientific EffectQuantum size effects:

Implementation Method 2

quantum dot light-emitting diodes (QLED)

Methodology Applied

Scientific EffectElectroluminescence: Electroluminescence

Data Source

PatentUS20240284695A1Quantum dot light-emitting device, manufacturing method therefor, and display apparatus

Publication Date: 2024.08.22 TCL TECHNOLOGY GROUP CORPORATION

AI summary

Disclosed is a quantum dot light-emitting device, a manufacturing method thereof, and a display apparatus. There are at least two light-emitting layers, each of the light-emitting layers includes a core-shell quantum dot, the core-shell quantum dot includes a core and at least one shell layer coated on a surface of the core, thicknesses of respective outermost shell layers of the core-shell quantum dots of the quantum dot light-emitting layers become sequentially increased in a direction from an anode to a cathode.