Patterned Roller Fabrication for OLED Microlens Arrays

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

The challenge in enhancing light outcoupling from organic light-emitting devices (OLEDs) lies in the difficulty and expense of fabricating microlens arrays, as many photons are trapped due to waveguiding mechanisms, and conventional patterning techniques are not well-suited for creating patterns on flexible or curved surfaces.

Innovation Solution

A patterned roller is created using a two-step mold process, where a negative pattern is etched into a flat surface, followed by forming a positive pattern on a second mold, and then transferring this pattern to a roller, which is used to imprint microlenses onto a substrate, allowing for efficient and cost-effective fabrication of microlens arrays directly on OLED surfaces.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If conventional patterning techniques are used to create microlens arrays, then light outcoupling can be enhanced, but the fabrication process becomes difficult and expensive

Engineering Contradiction:

Improvelight outcoupling efficiencyVSAvoidfabrication difficulty and cost

Core Design Contradiction:

Loss of energyVSEase of manufacture

Solution Approach 1:

The patent applies preliminary action by first creating a master mold with the desired microlens pattern, then using this mold to create multiple replicas. This preliminary pattern creation simplifies subsequent manufacturing steps, as the complex patterning is done once in the master mold rather than repeatedly on each substrate, thereby reducing overall fabrication difficulty and cost while maintaining light outcoupling enhancement

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent uses copying by creating replica molds from a master mold, and then using these replicas to pattern multiple substrates. This copying approach allows the complex microlens pattern to be reproduced efficiently across many substrates without repeating the difficult master pattern creation process, reducing both fabrication difficulty and cost per unit while preserving the optical performance

Inventive Principle:

Principle #26Copying

2Adaptability or versatility

If microlens arrays are fabricated on flexible or curved surfaces, then adaptability to different OLED configurations is improved, but conventional patterning techniques become unsuitable

Engineering Contradiction:

Improvecompatibility with flexible and curved surfacesVSAvoidpatterning suitability

Core Design Contradiction:

Adaptability or versatilityVSEase of manufacture

Solution Approach 1:

The patent employs flexible shells and thin films by using elastomeric replica molds that can conform to flexible and curved substrates. The elastomeric material allows the mold to adapt to different surface geometries, enabling microlens array fabrication on both rigid and flexible OLED configurations while maintaining pattern fidelity, thus achieving both adaptability and ease of manufacture

Inventive Principle:

Principle #30Flexible shells and thin films

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 method enables the precise and cost-effective production of microlens arrays on OLED substrates, significantly improving light outcoupling efficiency by up to 2 times, while maintaining pattern resolution and avoiding distortions, thus enhancing the performance of OLEDs.

Implementation Method 1

forming a first mold having a negative pattern by etching pits in a flat mold surface with an etching process

Methodology Applied

Scientific EffectEtching:

Implementation Method 2

pouring a first curable material into the first mold, curing the first curable material

Methodology Applied

Scientific EffectCuring:

Implementation Method 3

coating a roller with a layer of a second curable material, pre-curing the second curable material to provide a viscous but not hardened surface

Methodology Applied

Scientific EffectPre-curing:

Implementation Method 4

rolling the roller over the second mold to create the negative pattern in the second curable material

Methodology Applied

Scientific EffectRolling transfer:

Implementation Method 5

A substrate is coated with the third curable material. The patterned roller is rolled over the third curable material to transfer the pattern to the third curable material. The third curable material may then be cured.

Methodology Applied

Scientific EffectCuring:

Data Source

PatentUS8257793B2Roll to roll fabrication of microlens arrays for low cost light outcoupling from OLEDs

Publication Date: 2012.09.04 THE RGT UNIV OF MICHIGAN

AI summary

A patterned roller, and a method of making the patterned roller, is provided. A patterned roller may be made by first forming a first mold having a negative pattern by etching pits in a flat mold surface with an etching process. Then, a second mold is formed having a positive pattern, by pouring a first curable material into the first mold, curing the first curable material, and removing the first curable material from the first mold. Then the patterned roller having the negative pattern is formed by coating a roller with a layer of a second curable material, pre-curing the second curable material to provide a viscous but not hardened surface, and rolling the roller over the second mold to create the negative pattern in the second curable material. The second curable material is then cured. Any of the curable materials may be coated after curing, preferably with metal, to reduce sticking in subsequent steps. The patterned roller may be used to create a pattern of microlenses in a third curable material. A substrate is coated with the third curable material. The patterned roller is rolled over the third curable material to transfer the pattern to the third curable material. The third curable material may then be cured.