Quantum Dot Light-Emitting Element Electron Balance

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Solution Overview

Problem

The light-emitting element with quantum dots exhibits suboptimal light emission efficiency due to excessive electron injection, which disrupts the electron-hole balance, leading to reduced external quantum efficiency and potential degradation of organic materials in the hole transport layer.

Innovation Solution

A light-emitting element is designed with a quantum dot layer comprising a first intrinsic or impurity quantum dot layer and a second quantum dot layer, where the second quantum dot layer acts as an electron accumulating layer to confine electrons and maintain electron-hole balance, preventing excessive electron injection and promoting radiative recombination.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If non-light-emitting quantum dots are used to reduce electron mobility and function as a barrier, then light emission efficiency is improved, but electron-hole balance is disrupted and excessive electron injection occurs

Engineering Contradiction:

Improvelight emission efficiencyVSAvoidelectron-hole balance

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The quantum dot layer is segmented into multiple sub-layers: a first quantum dot sub-layer containing both light-emitting and non-light-emitting quantum dots, and a second quantum dot sub-layer containing only non-light-emitting quantum dots. This segmentation allows different regions to perform different functions - the first sub-layer generates light through electron-hole recombination while the second sub-layer acts as an electron barrier, collectively achieving both high light emission efficiency and proper electron-hole balance.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different regions of the quantum dot layer are assigned different compositions and properties. The first quantum dot sub-layer has a mixed composition of light-emitting and non-light-emitting quantum dots to enable both light generation and electron control. The second quantum dot sub-layer has a specialized composition of non-light-emitting quantum dots to provide electron barrier functionality. This local differentiation allows each region to optimize its specific function without compromising the overall device performance.

Inventive Principle:

Principle #3Local quality

2Illumination intensity

If electrons are excessively injected into quantum dots, then light emission intensity increases, but external quantum efficiency decreases and organic materials degrade

Engineering Contradiction:

Improvelight emission intensityVSAvoidexternal quantum efficiency

Core Design Contradiction:

Illumination intensityVSLoss of energy

Solution Approach 1:

The second quantum dot sub-layer acts as an electron barrier that provides feedback control on electron injection into the first quantum dot sub-layer. By regulating the electron flow based on the electron-hole balance in the light-emitting quantum dots, the system prevents excessive electron injection that would lead to non-radiative recombination and energy loss, while maintaining sufficient electron density for high light emission intensity.

Inventive Principle:

Principle #23Feedback

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 enhances light emission efficiency by maintaining electron-hole balance, reducing electron overflow into the hole transport layer, and improving the reliability and longevity of the light-emitting elements by minimizing non-radiative recombination and material degradation.

Implementation Method 1

a second quantum dot layer comprising a plurality of second quantum dots, the second quantum dots having a different material composition or different particle size from the first quantum dots

Methodology Applied

Scientific EffectQuantum confinement:

Implementation Method 2

electrons and holes injected into the quantum dots are recombined so that the quantum dots emit light

Methodology Applied

Scientific EffectRadiative recombination:

Data Source

PatentUS20240008299A1Light-emitting element

Publication Date: 2024.01.04 SHARP KK

AI summary

A light-emitting element includes: a first electrode; a second electrode; and a quantum dot layer disposed between the first electrode and the second electrode. The quantum dot layer includes: a first quantum dot that is either an intrinsic quantum dot or an impurity quantum dot; and a second quantum dot disposed between the second electrode and the first quantum dot. The second quantum dot is either the intrinsic quantum dot or the impurity quantum dot other than the first quantum dot.