Composite Electrode for Top-Emission OLED Voltage Drop

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Solution Overview

Problem

In organic electroluminescence (EL) display units, particularly top emission types, the high resistance of the upper electrode leads to voltage drops and variations in light emission luminance due to the limited aperture ratio and the need for precise processing of auxiliary power supply lines, which is challenging for large-scale production and high definition panels.

Innovation Solution

A display unit configuration with a conductive layer in the counter substrate, including an inorganic light-shielding layer and a low-resistance layer, electrically connected to the upper electrode through pillars, allowing for improved power supply and reduced voltage drops, while using a color filter layer to enhance light blocking and conductivity without the need for precise alignment.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Illumination intensity

If a transparent conductive film is used for the upper electrode in a top emission type organic EL display unit, then light extraction is improved, but the electrode has high resistance causing IR drop and voltage variations

Engineering Contradiction:

Improvelight extractionVSAvoidvoltage stability

Core Design Contradiction:

Illumination intensityVSReliability

Solution Approach 1:

The patent combines the transparent conductive film (upper electrode) with a reflective layer to form a composite electrode structure. This merged structure allows the transparent conductive film to maintain its light extraction function while the reflective layer provides additional electrical conductivity pathways, reducing overall resistance and IR drop in the electrode system.

Inventive Principle:

Principle #5Merging (Combining)

2Illumination intensity

If the upper electrode is made thinner to improve transparency, then light extraction is enhanced, but resistance increases causing greater voltage drop

Engineering Contradiction:

ImprovetransparencyVSAvoidelectrical conductivity

Core Design Contradiction:

Illumination intensityVSReliability

Solution Approach 1:

The patent employs a composite electrode structure consisting of a transparent conductive film combined with a reflective layer. This composite material approach allows the thin transparent conductive film to maintain its optical transparency while the integrated reflective layer compensates for the increased electrical resistance, providing a dual-function material system that addresses both transparency and conductivity requirements.

Inventive Principle:

Principle #40Composite materials

3Reliability

If an auxiliary power supply line is added to reduce voltage drop, then voltage stability is improved, but manufacturing complexity increases due to precise alignment requirements

Engineering Contradiction:

Improvevoltage stabilityVSAvoidalignment precision

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent extracts the power supply function from the traditional single-electrode configuration and implements it through the integrated reflective layer in the composite electrode structure. By incorporating electrical connection portions directly into the reflective layer pattern, the design eliminates the need for separate auxiliary power supply lines, thereby maintaining voltage stability while significantly simplifying the manufacturing process and reducing alignment complexity.

Inventive Principle:

Principle #2Taking out (Extraction)

4Area of stationary object

If a common light-emitting layer is used for all pixels, then aperture ratio is improved, but precise processing of auxiliary electrodes becomes necessary

Engineering Contradiction:

Improveaperture ratioVSAvoidelectrode patterning

Core Design Contradiction:

Area of stationary objectVSManufacturing precision

Solution Approach 1:

The patent implements a universal electrode pattern design where the reflective layer serves multiple functions simultaneously: it provides electrical conductivity, acts as a light reflector to enhance aperture ratio, and incorporates integrated electrical connection portions for power supply. This multi-functional universal pattern eliminates the need for separate auxiliary electrode processing, thereby maintaining high aperture ratio while significantly reducing manufacturing precision requirements.

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

This configuration effectively reduces variations in light emission luminance and improves display quality by minimizing voltage drops and enabling precise patterning, suitable for large-scale and high-definition panels.

Implementation Method 1

an organic electroluminescence display unit displaying an image with use of an organic EL effect

Methodology Applied

Scientific EffectElectroluminescence: Electroluminescence

Implementation Method 2

a conductive layer in the counter substrate, including an inorganic light-shielding layer

Methodology Applied

Scientific EffectLight absorption: Absorption (EM radiation)

Data Source

PatentUS9425241B2Organic electroluminescence display unit, method of manufacturing organic electroluminescence display unit, and color filter substrate

Publication Date: 2016.08.23 MAGNOLIA BLUE CORP

AI summary

A display device includes a first electrode, an organic layer including a light emitting region, and a second electrode. The display device also includes a conductive layer electrically connected to the second electrode and including an opening corresponding to the light emitting region.