OLED Dissociation Layer for Carrier Imbalance and Exciton Quenching

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Solution Overview

Problem

The mobility imbalance of holes and electrons in OLED light emitting devices leads to carrier injection imbalance and exciton accumulation at interfaces, affecting device performance and lifetime.

Innovation Solution

Incorporating a dissociation layer between the light emitting layer and the anode or cathode, which dissociates excitons into holes and electrons under an external electric field, adjusting the number of carriers injected and preventing exciton accumulation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If a light emitting layer is used in OLED device, then light emission function is achieved, but carrier injection imbalance occurs due to different hole and electron mobility

Engineering Contradiction:
Improvelight emission efficiencyVSAvoiddevice performance stability
Core Design Contradiction:
Use of energy by moving objectVSReliability

Solution Approach 1:

An exciton separation layer is introduced as an intermediary between the light emitting layer and the electrode. This layer mediates the interaction between carriers and excitons by selectively separating electrons and holes, allowing one type of carrier to pass through while blocking the other, thereby preventing carrier accumulation and improving device reliability without compromising light emission efficiency

Inventive Principle:
Principle #24Intermediary (Mediator)

2Power

If excitons are formed at the interface between light emitting layer and electrode, then recombination occurs, but exciton accumulation causes quenching of OLED

Engineering Contradiction:
Improverecombination rateVSAvoidOLED quenching
Core Design Contradiction:
PowerVSObject-affected harmful factors

Solution Approach 1:

The exciton separation layer acts as a mediator that prevents direct contact between excitons and the electrode interface. By selectively transporting one type of carrier away from the interface while blocking the other, the layer prevents exciton accumulation and subsequent quenching, while still allowing efficient recombination to occur in the bulk of the light emitting layer

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The exciton separation layer extracts one type of carrier (either electrons or holes) from the recombination process at the interface by selective transport. This removes the excess carrier that would otherwise accumulate and cause exciton buildup, thereby eliminating the harmful quenching effect while maintaining overall recombination efficiency

Inventive Principle:
Principle #2Taking out (Extraction)

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 solution addresses carrier injection imbalance and prevents OLED quenching, thereby enhancing device performance and extending its lifetime by ensuring balanced carrier injection and reducing exciton accumulation.

Implementation Method 1

Incorporating a dissociation layer between the light emitting layer and the anode or cathode, which dissociates excitons into holes and electrons under an external electric field

Methodology Applied
Scientific EffectElectron-hole dissociation in excitons under electric field: Electric Field

Implementation Method 2

An organic light emitting diode (simply referred to as OLED) is an organic thin-film electroluminescent device

Methodology Applied
Scientific EffectElectroluminescence: Electroluminescence

Data Source

PatentEP3220438B1OLED light-emitting device and preparing method therefor, and display apparatus
Publication Date: 2021.04.28 BOE TECHNOLOGY GROUP CO LTD
  • EP3220438B1 patent drawingFigure 1~3
  • EP3220438B1 patent drawingFigure 4~6
  • EP3220438B1 patent drawingFigure 7~9

AI summary

The present invention provides an OLED light emitting device and the production method thereof and a display apparatus, relates to the field of display technology, and ameliorates the problems in the prior art, such as carrier injection imbalance and organic light emitting diode quench caused by the accumulation of excitons at the interface. The OLED light emitting device comprises a base substrate, and an anode, a cathode, and a light emitting layer located between the anode and the cathode, which are provided on the base substrate, and the OLED display device further comprises a dissociation layer for dissociating excitons which arrive at the dissociation layer into holes and electrons; wherein the dissociation layer is provided between the light emitting layer and the anode in the case where the electron mobility is greater than the hole mobility; and the dissociation layer is provided between the light emitting layer and the cathode in the case where the hole mobility is greater than the electron mobility. The present invention is applicable in an OLED light emitting device, a display apparatus comprising the OLED light emitting device, and the production thereof.