OLED Electrode Resistance Matching for Luminance Uniformity

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Solution Overview

Problem

Conventional organic light-emitting devices (OLEDs) suffer from luminance non-uniformity due to high sheet resistance of transparent conducting oxides, leading to resistive losses and potential drops across the panel, which affects device performance and lifetime.

Innovation Solution

The solution involves matching the sheet resistances of the anode and cathode electrodes within a specific range (0.3 to 1.3 times the anode's sheet resistance) to achieve a uniform potential drop across the OLED, thereby improving luminance uniformity and fill factor.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If transparent conducting oxides with high sheet resistance are used in conventional OLEDs, then device fabrication is simplified, but luminance uniformity deteriorates due to resistive losses and potential drops across the panel

Engineering Contradiction:

Improvefabrication simplicityVSAvoidluminance uniformity

Core Design Contradiction:

Ease of manufactureVSManufacturing precision

Solution Approach 1:

The patent applies parameter changes by adjusting the sheet resistance of electrodes to specific ranges (anode: 10-100 Ω/□, cathode: 1-20 Ω/□) to optimize the balance between resistive losses and manufacturing feasibility, thereby improving luminance uniformity while maintaining ease of fabrication

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent employs composite electrode structures combining transparent conducting oxides with metal layers (e.g., ITO/Al, IZO/Ag) to achieve optimal electrical conductivity and luminance uniformity, resolving the contradiction between fabrication simplicity and manufacturing precision

Inventive Principle:

Principle #40Composite materials

2Manufacturing precision

If electrode sheet resistance is reduced to improve luminance uniformity, then resistive losses decrease, but device complexity increases due to additional layers or materials

Engineering Contradiction:

Improveluminance uniformityVSAvoidelectrode structure complexity

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent optimizes the thickness and material composition of electrode layers to achieve target sheet resistance values, balancing luminance uniformity improvement with structural simplicity by selecting appropriate material parameters and layer configurations

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 approach results in enhanced luminance uniformity, with a 10% or more increase in uniformity compared to conventional configurations, and maintains a high fill factor, while minimizing additional power loss.

Implementation Method 1

OLEDs make use of thin organic films that emit light when voltage is applied across the device

Methodology Applied

Scientific EffectElectroluminescence: Electroluminescence

Data Source

PatentUS10797258B2System and method for matching electrode resistances in OLED light panels

Publication Date: 2020.10.06 UNIVERSAL DISPLAY CORP

AI summary

Provided are an OLED device and a method of manufacturing the OLED device that may provide improved luminance uniformity. The disclosed OLED may have a first electrode that has a first sheet resistance Rs, and a second electrode that has a second sheet resistance, wherein the second sheet resistance may be in the range of 0.3 Rs-1.3 Rs. In addition, the disclosed OLED may have a plurality of equal potential difference between points on a first electrode and a second electrode. The equal potential difference may be provided by a gradient resistance formed on at least one of the electrodes.