Organic Layer for Light-Emitting Element Hole Transport and Electron Blocking

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Solution Overview

Problem

Conventional organic electroluminescence elements face challenges in achieving high light-emission efficiency and long lifetime due to inadequate electron-blocking by the hole transport layer, which degrades with increased current density, leading to deterioration of the organic layers.

Innovation Solution

A light-emitting element with an organic layer that combines hole-transporting and electron-blocking properties, using amine-based and acene-based materials to efficiently transport holes and block electrons, thereby preventing electron accumulation and deterioration, even at high current densities.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If a conventional hole transport layer is used to enhance hole-injecting and hole-transporting properties, then hole transport efficiency is improved, but electron-blocking capability deteriorates under high current density

Engineering Contradiction:

Improvehole transport efficiencyVSAvoidelectron-blocking capability

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent combines hole-transporting and electron-blocking functions into a single organic layer. This layer simultaneously transports holes from the anode to the light-emitting layer and blocks electrons from the light-emitting layer, eliminating the need for separate functional layers and resolving the contradiction between hole transport efficiency and electron-blocking capability under high current density

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The organic layer is designed to perform multiple functions: it serves as both a hole transport layer and an electron blocking layer. This multi-functional design allows the layer to maintain effective electron-blocking capability while ensuring efficient hole transport, even when operated at high current densities

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Illumination intensity

If current density is increased to achieve high luminance, then light emission performance is improved, but organic layer deterioration accelerates

Engineering Contradiction:

ImproveluminanceVSAvoidelement lifetime

Core Design Contradiction:

Illumination intensityVSDuration of action of stationary object

Solution Approach 1:

The patent converts the harmful effect of high current density into a beneficial outcome. By designing the organic layer with dual functionality, the layer can handle high current densities without deterioration. The electron-blocking capability prevents electron accumulation and damage, while the hole-transporting efficiency ensures proper charge balance, enabling high luminance operation with extended element lifetime

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

3Reliability

If hole transport layer energy levels are adjusted to enhance electron-blocking effect, then electron confinement is improved, but hole transport capability is reduced

Engineering Contradiction:

Improveelectron-blocking effectVSAvoidhole transport capability

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The patent optimizes the energy level parameters of the organic layer to achieve both effective electron-blocking and efficient hole transport. By carefully selecting materials with appropriate HOMO and LUMO levels, the layer creates an energy barrier that blocks electrons while maintaining good hole transport capability, resolving the contradiction between electron confinement and hole transport

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 and extends the lifetime of the light-emitting element by effectively confining electrons and holes within the light-emitting layer, maintaining performance under high current densities.

Implementation Method 1

the organic layer has a first function of transporting holes and thus can efficiently transport the holes to the light-emitting layer from the anode

Methodology Applied

Scientific EffectHole transport: Conduction (electrical)

Implementation Method 2

the organic layer has a second function of preventing electrons from staying in the organic layer... since the organic layer has the second function of preventing electrons infiltrating from the light-emitting layer from staying in the organic layer

Methodology Applied

Scientific EffectElectron blocking: Electrical Resistance

Implementation Method 3

The electrons and the holes recombine in the light-emitting layer thereby generating an exciton. When the exciton returns to the ground state, a corresponding amount of energy is emitted as light

Methodology Applied

Scientific EffectElectroluminescence: Electroluminescence

Data Source

PatentUS8835943B2Light-emitting element, light-emitting device, display device, and electronic apparatus

Publication Date: 2014.09.16 SHIHENG CREATION LTD

AI summary

A light-emitting element includes: an anode; a cathode; a light-emitting layer which is provided between the anode and the cathode and emits light as the anode and the cathode are electrically connected to each other; and an organic layer which is provided between the anode and the light-emitting layer to come in contact with both layers. The organic layer has a first function of transporting holes and a second function of preventing electrons infiltrating from the light-emitting layer from staying in the organic layer.