OLED Border Electrode Absorbs Leakage Current

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Solution Overview

Problem

Display devices using self-luminous elements, such as OLEDs, face issues with carrier leakage current between adjacent pixels, leading to unintended light emission and reduced image resolution and color reproducibility, especially as pixel size decreases.

Innovation Solution

A display device design that includes a bank and border electrode structure to absorb carriers in the border area between pixels, preventing leakage current and maintaining image quality by applying a specific potential to the border electrode.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If the auxiliary layer is formed continuously throughout the image display area, then carrier injection efficiency is improved, but carrier leakage current between adjacent pixels increases

Engineering Contradiction:

Improvecarrier injection efficiencyVSAvoidleakage current between pixels

Core Design Contradiction:

Use of energy by moving objectVSObject-generated harmful factors

Solution Approach 1:

The patent divides the continuous auxiliary layer into pixel-specific segments by introducing pixel electrodes that extend into the auxiliary layer. This segmentation creates electrical isolation between adjacent pixels, preventing carrier leakage while maintaining efficient carrier injection within each pixel through the same auxiliary layer structure.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent applies different electrical properties to different regions by extending pixel electrodes into the auxiliary layer. The auxiliary layer maintains its continuous structure for efficient carrier injection, while the extended pixel electrodes create localized electrical boundaries that prevent carrier leakage into adjacent pixels, achieving both efficiency and isolation.

Inventive Principle:

Principle #3Local quality

2Manufacturing precision

If pixel size is decreased for higher definition, then display resolution is improved, but carrier leakage current between pixels becomes more pronounced

Engineering Contradiction:

Improvedisplay resolutionVSAvoidcarrier leakage current

Core Design Contradiction:

Manufacturing precisionVSObject-generated harmful factors

Solution Approach 1:

The extended pixel electrodes segment the continuous auxiliary layer into electrically isolated pixel regions. This segmentation allows pixels to be placed closer together for higher definition displays while the electrode extensions maintain electrical boundaries that prevent carrier leakage between the smaller, closer pixels.

Inventive Principle:

Principle #1Segmentation

3Ease of manufacture

If the auxiliary layer spreads over multiple pixels, then manufacturing simplicity is improved, but color reproducibility deteriorates due to leakage current

Engineering Contradiction:

Improvemanufacturing simplicityVSAvoidcolor reproducibility

Core Design Contradiction:

Ease of manufactureVSManufacturing precision

Solution Approach 1:

The patent maintains the simple continuous formation of the auxiliary layer for manufacturing ease, while extending pixel electrodes into this layer to create electrical segmentation. This allows the auxiliary layer to be manufactured as a single continuous component while the electrode extensions prevent color contamination by blocking carrier leakage between pixels of different luminescent colors.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The auxiliary layer maintains uniform properties across the entire display area for manufacturing simplicity, while the extended pixel electrodes introduce localized electrical boundaries. These boundaries preserve color purity by preventing carriers from leaking into adjacent pixels with different luminescent colors, achieving both manufacturing ease and color accuracy.

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

The solution effectively prevents carrier leakage between pixels, enhancing image resolution and color purity by ensuring accurate light emission from individual pixels without cross-color interference.

Implementation Method 1

When a potential enough to draw the carriers in the border area of the light-emitting element layer is applied to the border electrode, the border electrode absorbs the carriers

Methodology Applied

Scientific EffectCarrier absorption: Absorption (physical)

Implementation Method 2

a light-emitting layer for emitting light in response to injection of carriers

Methodology Applied

Scientific EffectElectroluminescence: Electroluminescence

Data Source

PatentUS9461100B2Display device

Publication Date: 2016.10.04 MAGNOLIA WHITE CORP

AI summary

A display device, in which self-luminous elements are arranged, prevents a leakage current through a common layer, included in the self-luminous elements and disposed throughout its image display area, from causing adjacent pixels to emit unintended light. An organic EL display device has a bank and a light-emitting element layer. The bank is formed on a substrate and is positioned in the border between first and second pixels adjacent to each other. The light-emitting element layer is deposed to spread over the first pixel, the second pixel, and the bank. A first electrode and a second electrode are formed on both sides of the light-emitting element layer and inject electric charges to the light-emitting element layer. A third electrode is formed in contact with the light-emitting element layer in an area overlapping with the bank 106 and absorbs the leakage current.