OLED Display Refractive Index Gradient for Lateral Light Extraction

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Solution Overview

Problem

Organic light emitting displays suffer from reduced light output efficiency due to lateral light emission, leading to increased power consumption and reduced lifespan of the organic light emitting elements.

Innovation Solution

A display device design incorporating a subpixel structure with a first and second total reflection layer and a planarization layer, where the refractive index of the planarization layer is greater than that of the second total reflection layer, and the second total reflection layer's refractive index is greater than the first, to refract and reflect lateral light emissions towards the upward direction.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Illumination intensity

If organic light emitting displays are used, then viewing angle and contrast ratio are improved, but light output efficiency deteriorates due to lateral light emission

Engineering Contradiction:

Improveviewing angle and contrast ratioVSAvoidlight output efficiency

Core Design Contradiction:

Illumination intensityVSLoss of energy

Solution Approach 1:

The patent converts the harmful lateral light emission into beneficial upward-directed light by introducing total reflection layers with specific refractive indices. The first total reflection layer (refractive index 1.5-1.7) and second total reflection layer (refractive index 1.7-1.9) work together to reflect lateral light at the planarization layer interface, transforming energy loss into useful light output in the upward direction.

Inventive Principle:

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

Solution Approach 2:

The patent changes the refractive index parameter of the planarization layer to be greater than both total reflection layers, creating the optical conditions necessary for total internal reflection. This parameter change enables the conversion of lateral light into upward light, improving both light output efficiency and maintaining the viewing angle and contrast ratio benefits of OLED displays.

Inventive Principle:

Principle #35Parameter changes

2Use of energy by stationary object

If lateral light emission occurs, then power consumption increases, but light output efficiency decreases

Engineering Contradiction:

Improvepower consumptionVSAvoidlight output efficiency

Core Design Contradiction:

Use of energy by stationary objectVSLoss of energy

Solution Approach 1:

The patent transforms the energy-wasting lateral light emission into useful upward light through total internal reflection at the planarization layer interface. By using total reflection layers with refractive indices of 1.5-1.7 and 1.7-1.9 respectively, the system converts what would be lost lateral light into beneficial upward light output, simultaneously improving light output efficiency and reducing power consumption.

Inventive Principle:

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

Solution Approach 2:

The patent modifies the refractive index parameter of the planarization layer to exceed that of the total reflection layers, creating the optical conditions for total internal reflection. This parameter optimization ensures that lateral light is efficiently redirected upward, reducing energy loss and power consumption while maintaining display performance.

Inventive Principle:

Principle #35Parameter changes

3Loss of energy

If lateral light emission occurs, then light output efficiency decreases, but lifespan of organic light emitting elements is reduced

Engineering Contradiction:

Improvelight output efficiencyVSAvoidlifespan of organic light emitting elements

Core Design Contradiction:

Loss of energyVSDuration of action of stationary object

Solution Approach 1:

The patent converts harmful lateral light emission into beneficial upward light through total internal reflection at the planarization layer interface. By implementing total reflection layers with refractive indices of 1.5-1.7 and 1.7-1.9, the system redirects lateral light that would otherwise cause element degradation and reduce lifespan, thereby improving both light output efficiency and extending the lifespan of organic light emitting elements.

Inventive Principle:

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

Solution Approach 2:

The patent optimizes the refractive index parameter of the planarization layer to be greater than the total reflection layers, enabling total internal reflection. This parameter change redirects lateral light into upward light, reducing energy loss and minimizing degradation of the organic light emitting elements, thus extending their operational lifespan.

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 design enhances light output efficiency, prolongs the life of organic light emitting elements, and reduces power consumption by effectively redirecting lateral light emissions.

Implementation Method 1

A refractive index of the planarization layer is greater than a refractive index of the second total reflection layer

Methodology Applied

Scientific EffectRefraction: Refraction

Implementation Method 2

a first total reflection layer overlapping the pixel defining layer, a second total reflection layer disposed on the first total reflection layer

Methodology Applied

Scientific EffectTotal internal reflection: Total Internal Reflection

Data Source

PatentUS20220077256A1Display device

Publication Date: 2022.03.10 SAMSUNG DISPLAY CO LTD

AI summary

A display device includes a subpixel which including a first electrode, a light emitting layer, and a second electrode. The display device further includes a pixel defining layer defining the subpixel, a first total reflection layer overlapping the pixel defining layer, a second total reflection layer disposed on the first total reflection layer, and a planarization layer disposed on the second total reflection layer. A refractive index of the planarization layer is greater than a refractive index of the second total reflection layer, and the refractive index of the second total reflection layer is greater than a refractive index of the first total reflection layer.