Curved Filling Pattern for OLED Light Extraction

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Solution Overview

Problem

Current organic light-emitting display devices face challenges in preventing color mixture between sub-pixels, which affects brightness and color gamut, and have limitations in light extraction efficiency.

Innovation Solution

A display device design featuring a first substrate with light-emitting elements, a second substrate, and a filling layer with a specific filling pattern that includes curve portions to scatter light, reducing color mixture and enhancing light extraction efficiency by optimizing the refractive index difference between the filling pattern and the substrates.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If a conventional flat filling layer is used between substrates, then the structure is simple and easy to manufacture, but light extraction efficiency is limited and color mixture between sub-pixels occurs

Engineering Contradiction:
Improveease of manufactureVSAvoidlight extraction efficiency
Core Design Contradiction:
Ease of manufactureVSReliability

Solution Approach 1:

The filling layer incorporates convex portions and concave portions (curved surface structures) instead of a flat surface. The convex portions protrude upward and concave portions protrude downward, creating curved interfaces that scatter light in multiple directions. This curvature increases the optical path length and enhances light extraction efficiency while preventing color mixture between adjacent sub-pixels through effective light scattering.

Inventive Principle:
Principle #14Spheroidality (Curvature)

2Device complexity

If the filling layer has uniform refractive index throughout, then the material composition is simple, but light scattering effect is insufficient to prevent color mixture

Engineering Contradiction:
Improvedevice complexityVSAvoidcolor mixture prevention
Core Design Contradiction:
Device complexityVSReliability

Solution Approach 1:

The filling layer employs different refractive index regions: a first filling material with refractive index n1 in convex portions, a second filling material with refractive index n2 in concave portions, and a third filling material with refractive index n3 in flat portions. This local variation in refractive index creates multiple optical interfaces that enhance light scattering effects, effectively preventing color mixture between sub-pixels while maintaining manageable device complexity.

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 improves brightness and color gamut by minimizing color mixture and increases light extraction efficiency, leading to better performance in organic light-emitting display devices.

Implementation Method 1

at least a part of the light incident on the filling pattern is to be scattered at the curve portion of the first pattern part

Methodology Applied
Scientific EffectLight scattering: Scattering

Implementation Method 2

a refractive index of the filling material is smaller than a refractive index of the filling pattern

Methodology Applied
Scientific EffectRefraction: Refraction

Implementation Method 3

at least a part of the light scattered at the curve portion is to be incident on the second substrate

Methodology Applied
Scientific EffectReflection: Reflection

Data Source

PatentEP3690971B1Display device
Publication Date: 2023.06.28 SAMSUNG DISPLAY CO LTD
  • EP3690971B1 patent drawingFigure 1
  • EP3690971B1 patent drawingFigure 2
  • EP3690971B1 patent drawingFigure 3

AI summary

A display device comprises a first substrate comprising at least one light-emitting element; a second substrate facing the first substrate, wherein light emitted from the light-emitting element is to be incident on the second substrate; and a filling layer between the first substrate and the second substrate, wherein the filling layer comprises a filling pattern comprising a first pattern part on the first substrate and having a curve portion formed in at least a part thereof.