OLED Hydrophobic Patterning for Pixel Confinement

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Solution Overview

Problem

Existing OLED manufacturing techniques face challenges in forming uniform organic emitting layers within pixel regions, leading to issues with high contrast images and increased costs due to the need for large masks and excessive materials, especially as OLED device sizes grow.

Innovation Solution

The implementation of a hydrophobic pattern on a hole transport layer with distinct conductivity patterns in pixel and non-pixel regions, using fluorine-based or organosilane-based materials, to confine the emitting layer and enhance luminescence characteristics, allowing for improved resolution and contrast.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If conventional printing or patterning processes are used to form the organic emitting layer, then the layer can be deposited, but uniformity within pixel regions is poor and material usage is excessive

Engineering Contradiction:

Improveuniformity of organic emitting layerVSAvoidmaterial usage

Core Design Contradiction:

Manufacturing precisionVSLoss of substance

Solution Approach 1:

The device is divided into pixel regions and non-pixel regions with distinct functional requirements. The hole transport layer is segmented into first patterns (conductive) in pixel regions and second patterns (insulating) in non-pixel regions, enabling precise control of material deposition and reducing waste

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different regions of the hole transport layer are given different electrical conductivity properties through selective patterning. The first patterns in pixel regions maintain high conductivity for proper device operation, while the second patterns in non-pixel regions have reduced conductivity to prevent unwanted material deposition and improve uniformity

Inventive Principle:

Principle #3Local quality

2Ease of manufacture

If masks are used for patterning processes, then layer formation is possible, but mask fabrication becomes difficult and costs increase with larger device sizes

Engineering Contradiction:

Improvepatterning process feasibilityVSAvoidmask fabrication complexity

Core Design Contradiction:

Ease of manufactureVSDevice complexity

Solution Approach 1:

The hydrophobic patterns are formed in advance on the hole transport layer before depositing the organic emitting layer. This preliminary patterning creates a surface energy gradient that guides subsequent material deposition without requiring complex masks during the emission layer formation process

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The hydrophobic pattern acts as an intermediary layer between the hole transport layer and the organic emitting layer. It mediates the deposition process by providing selective adhesion properties that direct material flow into pixel regions while preventing deposition in non-pixel regions, eliminating the need for physical masks

Inventive Principle:

Principle #24Intermediary (Mediator)

3Manufacturing precision

If the organic emitting layer is not precisely confined to pixel regions, then manufacturing is simpler, but resolution and contrast of displayed images deteriorate

Engineering Contradiction:

Improveconfinement of emitting layerVSAvoidmanufacturing simplicity

Core Design Contradiction:

Manufacturing precisionVSProductivity

Solution Approach 1:

The surface energy parameters of the hole transport layer are changed spatially through the hydrophobic patterning process. By creating regions with different surface energies (hydrophilic pixel regions vs. hydrophobic non-pixel regions), the organic emitting layer is directed to deposit only where needed, achieving precise confinement through physical-chemical parameter gradients rather than mechanical constraints

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

This approach enables precise formation of the organic emitting layer within pixel regions, enhancing luminescence characteristics and reducing material usage, thereby improving the OLED device's resolution and contrast while minimizing manufacturing costs.

Implementation Method 1

a hydrophobic pattern disposed on the hole transport layer in the second region

Methodology Applied

Scientific EffectHydrophobic effect: Hydrophobe

Implementation Method 2

The second pattern includes the hole transport material and a cross-linked or polymerized photosensitive material

Methodology Applied

Scientific EffectPhoto-polymerization: Photopolymerisation

Data Source

PatentEP2535956B1Organic Light Emitting Structures, Methods of Forming Organic Light Emitting Structures, Organic Light Emitting Display Devices and Methods of Manufacturing Organic Light Emitting Display Devices

Publication Date: 2017.10.11 SAMSUNG DISPLAY CO LTD

Figure 1~2A
Figure 2B~2C
Figure 2D~3

AI summary

An organic light emitting display device includes a hole transport layer (HTL) having a first region and a second region, an emitting layer (EML) disposed on the hole transport layer in the first region, a hydrophobic pattern disposed on the hole transport layer in the second region and an electron transport layer (ETL) disposed on the hydrophobic pattern and the emitting layer.