OLED Cathode Segmentation for Voltage Drop Reduction

Solution Overview

Problem

Organic light-emitting display devices face issues with uneven image quality and increased power consumption due to voltage drops in cathode electrodes, particularly as the size of the display increases, affecting the top-emission type more significantly.

Innovation Solution

The design incorporates auxiliary electrodes formed of the same material as scanning lines, which overlap with pixel electrodes and contact the cathode electrodes through contact holes, functioning as auxiliary wiring to minimize voltage drops and reduce power consumption by narrowing the driving voltage margin of OLEDs.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If cathode electrodes are made thick and low-resistance to minimize voltage drop, then voltage uniformity improves, but light transmission decreases

Engineering Contradiction:

Improvevoltage uniformityVSAvoidlight transmission

Core Design Contradiction:

ReliabilityVSIllumination intensity

Solution Approach 1:

The cathode electrode system is segmented into two parts: a thin transparent cathode electrode for light transmission and a separate auxiliary cathode electrode for voltage compensation. This segmentation allows each electrode to fulfill its specific function without compromise - the thin electrode maintains light transmission while the auxiliary electrode provides the necessary current capacity for voltage uniformity.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The auxiliary cathode electrode acts as an intermediary element that compensates for voltage drops in the main cathode electrode. By being connected to the same pixel electrode through a contact hole, it provides additional current pathways that balance the voltage distribution across the display, indirectly solving the voltage uniformity problem without affecting the optical properties of the main cathode electrode.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Area of stationary object

If display device size increases, then display area improves, but voltage drop in cathode electrodes increases

Engineering Contradiction:

Improvedisplay areaVSAvoidvoltage uniformity

Core Design Contradiction:

Area of stationary objectVSReliability

Solution Approach 1:

The cathode electrode system is segmented into two parts: a thin transparent cathode electrode for light transmission and a separate auxiliary cathode electrode for voltage compensation. This segmentation allows each electrode to fulfill its specific function without compromise - the thin electrode maintains light transmission while the auxiliary electrode provides the necessary current capacity for voltage uniformity.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The auxiliary cathode electrode is strategically positioned and dimensioned to provide localized current compensation where needed. By adjusting the size, shape, and position of the auxiliary electrode, the design optimizes voltage uniformity in specific regions of the display, allowing large display areas to maintain consistent voltage distribution across different zones.

Inventive Principle:

Principle #3Local quality

3Illumination intensity

If cathode electrodes are made thin and transparent to increase light transmission, then light transmission improves, but voltage drop increases

Engineering Contradiction:

Improvelight transmissionVSAvoidvoltage uniformity

Core Design Contradiction:

Illumination intensityVSReliability

Solution Approach 1:

The cathode electrode system is segmented into two parts: a thin transparent cathode electrode for light transmission and a separate auxiliary cathode electrode for voltage compensation. This segmentation allows each electrode to fulfill its specific function without compromise - the thin electrode maintains light transmission while the auxiliary electrode provides the necessary current capacity for voltage uniformity.

Inventive Principle:

Principle #1Segmentation

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 the evenness of brightness and reduces power consumption by minimizing voltage drops in cathode electrodes, thereby improving the overall performance and efficiency of the organic light-emitting display device.

Implementation Method 1

Light is emitted by energy that is generated when an exciton drops from an excitation state to a ground state within an organic emissive layer

Methodology Applied

Scientific EffectElectroluminescence: Electroluminescence

Implementation Method 2

a capacitor which includes first capacitor electrodes disposed on the same layer as the scanning lines, second capacitor electrodes disposed on the same layer as the gate electrode, and third capacitor electrodes disposed on the same layer as the source and drain electrodes

Methodology Applied

Scientific EffectCapacitance: Capacitance

Data Source

PatentUS9196667B2Organic light-emitting display with vertically stacked capacitor and capacitive feedback

Publication Date: 2015.11.24 SAMSUNG DISPLAY CO LTD

AI summary

An organic light-emitting display device includes a first electrode disposed on a substrate; a plurality of insulating layers which are sequentially disposed on the first electrode, and on which a contact hole for exposing a part of a surface of the first electrode is formed; and an organic light-emitting diode which includes a pixel electrode disposed on the plurality of insulating layers, a second electrode facing the pixel electrode and contacting the first electrode through the contact hole, and an organic emissive layer disposed between the pixel electrode and the second electrode.