Inclined Insulation Structures for OLED Light Extraction

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Solution Overview

Problem

Conventional organic light emitting display devices suffer from reduced light efficiency due to total reflection of light between the anode and cathode, and additional optical resonance structures lead to poor side visibility due to color shift phenomena.

Innovation Solution

Formation of inclined structures on insulation layers with specific inclination angles using a method involving the creation of recesses on insulation films and a reflow process, preventing total light reflection and eliminating the need for additional optical resonance structures.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If conventional flat insulation layers are used in OLED devices, then the device configuration remains simple, but light efficiency is reduced due to total reflection between electrodes

Engineering Contradiction:

Improvelight efficiencyVSAvoidinsulation layer structure

Core Design Contradiction:

Loss of energyVSDevice complexity

Solution Approach 1:

The patent applies curvature by forming inclined surfaces on the insulation layer instead of using flat surfaces. The inclined structure has sidewalls that are inclined relative to the substrate, creating non-planar surfaces that alter light reflection angles and prevent total internal reflection between electrodes, thereby improving light efficiency without adding complex optical resonance structures

Inventive Principle:

Principle #14Spheroidality (Curvature)

Solution Approach 2:

The inclined structure introduces asymmetry in the insulation layer configuration. The sidewalls are inclined at specific angles (e.g., 45 degrees) relative to the substrate, creating an asymmetric geometry that disrupts the symmetric reflection path of light between electrodes, preventing total reflection and improving outcoupling efficiency

Inventive Principle:

Principle #4Asymmetry

2Loss of energy

If optical resonance structures are added to improve light efficiency, then light extraction is enhanced, but side visibility deteriorates due to color shift phenomena

Engineering Contradiction:

Improvelight efficiencyVSAvoidside visibility

Core Design Contradiction:

Loss of energyVSIllumination intensity

Solution Approach 1:

The patent extracts and eliminates the need for separate optical resonance structures by integrating the light extraction function directly into the insulation layer through inclined surfaces. This removes the source of color shift phenomena while maintaining improved light efficiency, as the inclined geometry provides extraction enhancement without the resonant cavity effects that cause viewing angle-dependent color shifts

Inventive Principle:

Principle #2Taking out (Extraction)

3Loss of energy

If inclined structures with large inclination angles are formed, then light efficiency improves significantly, but manufacturing precision requirements increase

Engineering Contradiction:

Improvelight efficiencyVSAvoidinclination angle control

Core Design Contradiction:

Loss of energyVSManufacturing precision

Solution Approach 1:

The patent optimizes the inclination angle parameter to balance light efficiency improvement with manufacturing feasibility. Specific inclination angles (e.g., 45 degrees) are selected as optimal values that provide significant light extraction enhancement while remaining achievable with standard semiconductor fabrication processes, avoiding excessively steep angles that would be difficult to manufacture

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

Significantly enhances light efficiency by over 30% while maintaining a simplified configuration, improving luminance, contrast, and viewing angle without color shift issues.

Implementation Method 1

The inclined structure may be formed from the first and the second recesses by performing a reflow process on the first and the second insulation films

Methodology Applied

Scientific EffectReflow process: Melting

Data Source

PatentUS9029838B2Methods of forming inclined structures on insulation layers, organic light emitting display devices and methods of manufacturing organic light emitting display devices

Publication Date: 2015.05.12 SAMSUNG DISPLAY CO LTD

AI summary

An organic light emitting display device comprises a first substrate, an insulation layer having an inclined structure, a first electrode, a pixel defining layer defining a luminescent region and a non-luminescent region, an organic light emitting structure, a second electrode and a second substrate. Lateral portions of the first electrode, the second electrode and/or the pixel defining layer may have an inclination angle for preventing a total reflection of light generated from the organic light emitting structure, so that the organic light emitting display device may ensure a light efficiency substantially larger than that of the conventional organic light emitting display device by about at least 30 percent.