Light Extraction Pattern Layout for Higher-Luminance OLED Displays

Solution Overview

Problem

Light-emitting display devices suffer from low light extraction efficiency due to total reflection at the interface between the light-emitting layer and electrodes or the substrate, leading to decreased luminance and increased power consumption.

Innovation Solution

A light-emitting display device with a substrate featuring pixels that include a light extraction pattern with concave portions and protruding portions, and a light-emitting layer with a non-emission area overlapping the top portion of the protruding portion between adjacent concave portions, designed to enhance light extraction efficiency by altering the light propagation path.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Illumination intensity

If a light-emitting layer is placed between two electrodes to emit light, then light emission function is achieved, but light extraction efficiency decreases due to total reflection at interfaces

Engineering Contradiction:

ImproveluminanceVSAvoidlight extraction efficiency

Core Design Contradiction:

Illumination intensityVSLoss of energy

Solution Approach 1:

The light-emitting layer is divided into multiple segments along the thickness direction, with non-emission layers positioned at specific depths. This segmentation creates multiple interfaces that redirect light paths, preventing total internal reflection and improving light extraction efficiency while maintaining luminance output.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent introduces a vertical dimension solution by stacking multiple light-emitting layers at different depths within the light-emitting unit. This three-dimensional arrangement allows light to be extracted through the substrate from different vertical positions, overcoming the two-dimensional limitation of conventional single-layer structures and significantly improving overall light extraction efficiency.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Power

If light is emitted from the light-emitting layer, then light output is achieved, but power consumption increases due to low extraction efficiency

Engineering Contradiction:

Improvepower consumptionVSAvoidlight extraction efficiency

Core Design Contradiction:

PowerVSLoss of energy

Solution Approach 1:

The light-emitting layer is divided into multiple segments along the thickness direction, with non-emission layers positioned at specific depths. This segmentation creates multiple interfaces that redirect light paths, preventing total internal reflection and improving light extraction efficiency while maintaining luminance output.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent converts the harmful effect of total internal reflection at interfaces into a beneficial light redirection mechanism. By strategically positioning non-emission layers, the interfaces that would normally trap light are transformed into light-extraction pathways, improving efficiency and reducing power consumption.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

3Device complexity

If a conventional light-emitting structure is used, then device simplicity is maintained, but light extraction efficiency is low

Engineering Contradiction:

Improvestructure complexityVSAvoidlight extraction efficiency

Core Design Contradiction:

Device complexityVSLoss of energy

Solution Approach 1:

The light-emitting layer is divided into multiple segments along the thickness direction, with non-emission layers positioned at specific depths. This segmentation creates multiple interfaces that redirect light paths, preventing total internal reflection and improving light extraction efficiency while maintaining luminance output.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The stacked light-emitting layer structure serves multiple functions simultaneously: it maintains the basic light emission function, improves light extraction efficiency through multiple interfaces, and enables color filtering functionality. This multi-functionality reduces the need for separate components, keeping the overall device structure relatively simple.

Inventive Principle:

Principle #6Universality (Multi-functionality)

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 significantly improves light extraction efficiency, enhancing luminance and reducing power consumption by effectively redirecting light emitted from the light-emitting layer towards the substrate, thereby increasing the external extraction efficiency.

Implementation Method 1

some light of light emitted from a light-emitting layer is not externally discharged, due to total reflection or the like, at an interface between the light-emitting layer and an electrode and/or an interface between the substrate and an air layer

Methodology Applied

Scientific EffectTotal internal reflection: Total Internal Reflection

Data Source

PatentUS12176382B2Light-emitting display device

Publication Date: 2024.12.24 LG DISPLAY CO LTD

AI summary

A light-emitting display device includes: a substrate, a plurality of pixels on the substrate, each pixel including an opening area, a light extraction pattern disposed in each opening area, the light extraction pattern including: a plurality of concave portions spaced apart from each other, and a protruding portion surrounding each of the plurality of concave portions, and a light-emitting device layer including: a light-emitting layer over the light extraction pattern, and a non-emission area overlapping a top portion of the protruding portion between the two adjacent concave portions.