Patterned Priming Layer for OLED Ink Containment

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Solution Overview

Problem

Current methods for producing full-color OLEDs face challenges in preventing ink spreading and color mixing, leading to non-uniformity and reduced emissive area due to the need for containment structures and surface tension discontinuities, which hinder continuous coating and increase costs.

Innovation Solution

A process involving a fluorinated material as the first layer, treated with a priming layer of an aromatic amine compound and photoinitiator, exposed to radiation, and developed to create a patterned surface energy, allowing for patterned liquid deposition of a second layer without spreading.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If containment structures (pixel wells, banks) are used to prevent ink spreading, then color mixing is prevented, but the emissive area is reduced and thickness uniformity is compromised

Engineering Contradiction:

Improvecolor mixing preventionVSAvoidemissive area

Core Design Contradiction:

Manufacturing precisionVSArea of stationary object

Solution Approach 1:

A surfactant layer is introduced as an intermediary between the emissive ink and the containment structure. This surfactant layer modifies the surface tension at the interface, allowing the ink to be contained within the pixel region without requiring large physical containment structures, thereby preserving emissive area while preventing color mixing.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The surface tension parameter of the substrate is modified by applying a surfactant layer before depositing the emissive ink. This parameter change allows the ink to spread controllably within the desired pixel region without wetting the containment structures, eliminating the need for large containment structures and maximizing emissive area.

Inventive Principle:

Principle #35Parameter changes

2Manufacturing precision

If surface tension discontinuities are created to contain ink, then ink spreading is prevented, but all layers must be printed increasing device complexity and cost

Engineering Contradiction:

Improveink containmentVSAvoidnumber of printed layers

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The surfactant layer is applied in advance before the emissive ink deposition. This preliminary action creates the necessary surface tension conditions that will contain the subsequent ink layers, allowing continuous coating of remaining layers without requiring printed containment structures for each layer.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The surfactant layer serves multiple functions: it acts as a release agent for continuous coating, provides ink containment through surface tension modification, and enables precise patterning. This multi-functionality eliminates the need for separate containment structures and reduces the number of printed layers required.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Manufacturing precision

If containment structures are moved outside the emissive region, then thickness uniformity is improved, but the available emissive area is reduced

Engineering Contradiction:

Improvethickness uniformityVSAvoidemissive area

Core Design Contradiction:

Manufacturing precisionVSArea of stationary object

Solution Approach 1:

By changing the surface tension parameter through surfactant application, the ink is contained through chemical means rather than physical barriers. This allows the containment effect to occur at the molecular level without requiring macroscopic structures that would reduce emissive area, while still achieving uniform thickness through controlled wetting behavior.

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 process enables continuous coating of organic active layers, improving yield and reducing equipment costs while maintaining high-quality, full-color OLED performance by controlling the surface energy and containment of the second layer.

Implementation Method 1

exposing the priming layer patternwise with radiation having a wavelength greater than 300 nm, resulting in exposed areas and unexposed areas

Methodology Applied

Scientific EffectPhotopolymerization: Photopolymerisation

Implementation Method 2

forming the first layer comprising a fluorinated material and having a first surface energy

Methodology Applied

Scientific EffectSurface energy modification: Surface Tension

Data Source

PatentUS9293739B2Process and materials for making contained layers and devices made with same

Publication Date: 2016.03.22 LG CHEM LTD

AI summary

There is provided a process for forming a contained second layer over a first layer, including the steps:forming the first layer including a fluorinated material and having a first surface energy;treating the first layer with a priming layer;exposing the priming layer patternwise with radiation having a wavelength greater than 300 nm, resulting in exposed areas and unexposed areas;developing the priming layer to effectively remove the priming layer from the unexposed areas resulting in a first layer having a patterned priming layer, wherein the patterned priming layer has a second surface energy that is higher than the first surface energy; andforming the second layer by liquid deposition on the patterned priming layer on the first layer.The priming layer includes an aromatic amine compound and a photoinitiator.