QLED Light-Emitting Device With Insulating Layers Among Quantum Dot Layers

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Solution Overview

Problem

Current QLED light-emitting devices face a technical problem of unbalanced transmission of electrons and holes due to a higher electron transmission rate compared to hole transmission rate, leading to electron accumulation and exciton quenching in the light-emitting functional layer.

Innovation Solution

Incorporating insulating layers made of polymethyl methacrylate material between quantum dot layers in the light-emitting layer, with varying thicknesses adjacent to the electron and hole injection layers to balance electron and hole transmission rates, where the thicknesses range from 3 nm to 8 nm, and reducing in sequence from the electron injection layer to the hole injection layer.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If a light-emitting layer consists of a plurality of quantum dot layers without insulating layers, then the device structure is simple and easy to manufacture, but electrons accumulate in the quantum dot layers causing exciton quenching and unbalanced transmission of electrons and holes

Engineering Contradiction:

Improveease of manufactureVSAvoidtransmission balance

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

An insulating layer is introduced as an intermediary between adjacent quantum dot layers. This insulating layer acts as a barrier to electron transmission while allowing hole transmission, thereby preventing electron accumulation and exciton quenching without significantly complicating the manufacturing process

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The insulating layer is selectively positioned between specific quantum dot layers where electron accumulation is most problematic. The thickness of the insulating layer varies at different positions (6-8 nm adjacent to electron injection layer, 3-5 nm adjacent to hole injection layer) to locally optimize electron blocking while maintaining overall device performance

Inventive Principle:

Principle #3Local quality

2Reliability

If insulating layers are disposed between every two adjacent quantum dot layers, then electron transmission is effectively blocked and transmission balance is improved, but the device structure becomes more complex

Engineering Contradiction:

Improvetransmission balanceVSAvoiddevice complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The light-emitting layer is segmented into multiple quantum dot layers with insulating layers strategically placed between them. This segmentation allows electron blocking at specific interfaces while maintaining continuous hole transport pathways, achieving transmission balance without requiring insulating layers throughout the entire structure

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The thickness parameter of the insulating layer is optimized to range from 3-8 nm, with specific variations at different positions. This parameter control allows effective electron blocking while minimizing the added structural complexity and maintaining reasonable manufacturing feasibility

Inventive Principle:

Principle #35Parameter changes

3Reliability

If thicknesses of insulating layers adjacent to electron injection layer are greater than those adjacent to hole injection layer, then electron blocking is enhanced, but manufacturing precision requirements increase

Engineering Contradiction:

Improveelectron blockingVSAvoidthickness control

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The insulating layer thickness is locally optimized: 6-8 nm adjacent to the electron injection layer for enhanced electron blocking, and 3-5 nm adjacent to the hole injection layer to maintain hole transport efficiency. This local quality variation addresses the electron accumulation problem while keeping manufacturing precision requirements within achievable limits

Inventive Principle:

Principle #3Local quality

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 effectively blocks electron transmission, improves the membrane quality of quantum dot layers, and balances electron and hole transmission rates, enhancing the luminous efficiency of QLEDs.

Implementation Method 1

insulating layers are disposed among the quantum dot layers adjacent to one side of the electron injection layer

Methodology Applied

Scientific EffectElectrical insulation: Electrical Resistance

Data Source

PatentUS11588126B2QLED light-emitting device and QLED display panel having insulating layer among quantum dot layer

Publication Date: 2023.02.21 TCL CHINA STAR OPTOELECTRONICS TECHNOLOGY CO LTD

AI summary

A QLED light-emitting device is provided, including a first electrode layer, an electron injection layer, an electron transport layer, a light-emitting layer, a hole transport layer, a hole injection layer, and a second electrode layer. Wherein, the light-emitting layer includes a plurality of quantum dot layers disposed in a stack, and insulating layers are disposed among the quantum dot layers adjacent to one side of the electron injection layer. Through disposing the insulating layers among the quantum dot layers adjacent to the one side of the electron injection layer, an electron transmission rate is reduced, thereby balancing the electron transmission rate and a hole transmission rate and improving luminous efficiency of QLEDs.