Organic Refractive Layers for Front Brightness in OLEDs

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Solution Overview

Problem

Organic light emitting display devices suffer from low brightness in the front direction due to light emission in multiple directions, including lateral directions, which reduces light emitting efficiency.

Innovation Solution

A display device structure incorporating a first refractive layer, a second refractive layer with a higher refractive index, and a third refractive layer, where the second refractive layer has a grid shape and a first opening that overlaps the pixel opening, and the third refractive layer has a planarized surface, to totally reflect lateral light and direct it towards the front direction.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If light is emitted in multiple directions including lateral directions, then light emitting efficiency is improved, but brightness in the front direction decreases

Engineering Contradiction:

Improvelight emitting efficiencyVSAvoidbrightness in the front direction

Core Design Contradiction:

Loss of energyVSIllumination intensity

Solution Approach 1:

The patent converts the harmful lateral light emission (which causes energy loss and reduces front brightness) into a beneficial component by using the refractive layer to redirect it. The refractive layer with its specific refractive index and grid pattern captures lateral light and refracts it toward the front direction, transforming what was previously wasted light into useful illumination.

Inventive Principle:

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

Solution Approach 2:

The patent changes the optical parameters of the system by introducing a refractive layer with a specific refractive index (different from the emission layer and electrode). This parameter change enables control over light propagation directions, allowing lateral light to be redirected toward the front while maintaining overall light emitting efficiency.

Inventive Principle:

Principle #35Parameter changes

2Illumination intensity

If a refractive layer is added to redirect light, then brightness in the front direction is improved, but device complexity increases

Engineering Contradiction:

Improvebrightness in the front directionVSAvoidstructure complexity

Core Design Contradiction:

Illumination intensityVSDevice complexity

Solution Approach 1:

The refractive layer serves multiple functions simultaneously: it redirects lateral light toward the front direction, maintains structural integrity of the device, and can be integrated with existing electrode patterns. This multi-functionality reduces the need for additional separate components, thereby limiting the increase in device complexity.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The refractive layer is implemented as a thin film structure that can be deposited conformally on the electrode surface. This thin film approach minimizes the additional volume and structural complexity while still achieving the light redirection function effectively.

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 configuration enhances light emitting efficiency by ensuring that light emitted in lateral directions is totally reflected and directed towards the user, increasing brightness in the front direction.

Implementation Method 1

a third refractive layer on the second refractive layer, the third refractive layer having a second refractive index greater than a first refractive index of the second refractive layer

Methodology Applied

Scientific EffectTotal internal reflection: Total Internal Reflection

Implementation Method 2

the second refractive layer having a first refractive index and having a first opening that overlaps the pixel opening, and a third refractive layer on the second refractive layer, the third refractive layer having a second refractive index greater than a first refractive index of the second refractive layer

Methodology Applied

Scientific EffectRefraction: Refraction

Data Source

PatentUS11711942B2Display device

Publication Date: 2023.07.25 SAMSUNG DISPLAY CO LTD

AI summary

A display device may include a first electrode, a pixel defining layer disposed on the first electrode, the pixel defining layer having a pixel opening that exposes the first electrode, an emission layer disposed in the pixel opening and on the first electrode, a second electrode disposed on the emission layer, a first refractive layer disposed on the second electrode and being an organic refractive layer, a second refractive layer disposed on the first refractive layer and being an organic refractive layer, the second refractive layer having a first opening that overlaps the pixel opening, and a third refractive layer disposed on the second refractive layer, the third refractive layer having a second refractive index greater than a first refractive index of the second refractive layer.