Doped Graphene Transparent Electrode for Flexible Displays

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Solution Overview

Problem

Current transparent electrodes, such as those made from indium tin oxide (ITO), face challenges with high sheet resistance due to insufficient flexibility and reduced transmittance when doped with common dopants like nitric acid or gold (III) chloride, which also have stability issues when exposed to air.

Innovation Solution

A transparent electrode is developed using graphene doped with a p-dopant having a molecular weight of 120 or more, such as organic or inorganic acids, which maintains high transmittance and reduces sheet resistance without absorbing visible light, thereby improving stability and flexibility.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If common dopants like nitric acid or gold (III) chloride are used to reduce sheet resistance, then electrical properties are improved, but transmittance is reduced and stability when exposed to air deteriorates

Engineering Contradiction:

Improveelectrical propertiesVSAvoidtransmittance

Core Design Contradiction:

ReliabilityVSIllumination intensity

Solution Approach 1:

The patent changes the molecular weight parameter of the dopant to 120 or more, which fundamentally alters the doping mechanism. This parameter change enables reduced sheet resistance while maintaining high transmittance and improving air stability, resolving the technical contradiction between electrical properties and optical properties

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent uses composite doping by combining multiple dopants with molecular weights of 120 or more, or by sequential doping processes. This composite approach achieves synergistic effects that simultaneously improve electrical conductivity, maintain transmittance, and enhance stability when exposed to air

Inventive Principle:

Principle #40Composite materials

2Reliability

If common dopants like nitric acid or gold (III) chloride are used to reduce sheet resistance, then electrical properties are improved, but stability when exposed to air deteriorates

Engineering Contradiction:

Improveelectrical propertiesVSAvoidstability when exposed to air

Core Design Contradiction:

ReliabilityVSStability of the object's composition

Solution Approach 1:

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent replaces unstable, volatile dopants like nitric acid with more stable dopants having molecular weights of 120 or more. These alternative dopants provide lasting stability when exposed to air, eliminating the need for frequent re-doping and maintaining consistent electrical properties over time

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

3Reliability

If the number of layers of graphene is increased to reduce sheet resistance, then electrical properties are improved, but transmittance of visible light is reduced

Engineering Contradiction:

Improvesheet resistanceVSAvoidtransmittance of visible light

Core Design Contradiction:

ReliabilityVSIllumination intensity

Solution Approach 1:

The patent changes the dopant molecular weight parameter to 120 or more, which dramatically improves the doping efficiency. This enables achieving low sheet resistance with fewer graphene layers (1-5 layers), thereby maintaining high visible light transmittance while obtaining the required electrical conductivity

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent uses charge transfer doping to create charge carriers in graphene without adding physical mass or thickness. This copying approach to conductivity generation allows maintaining the thin, transparent structure while achieving the required electrical properties through electronic modification rather than structural thickening

Inventive Principle:

Principle #26Copying

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

The doped graphene transparent electrode achieves reduced sheet resistance with minimal transmittance variation, enhancing optical and electrical properties while maintaining stability when exposed to air, making it suitable for display devices and solar cells.

Implementation Method 1

sheet resistance may be reduced by increasing density of a carrier embodied by charge transfer between graphene and adsorbed dopants

Methodology Applied

Scientific EffectCharge transfer:

Implementation Method 2

Gold (III) chloride (AuCl3), which is also commonly used as a dopant, absorbs visible light by transition between d-orbitals contained in Au ions

Methodology Applied

Scientific Effectd-orbital transition: Absorption Spectroscopy

Data Source

PatentUS10177261B2Transparent electrode comprising doped graphene, process of preparing the same, and display device and solar cell comprising the electrode

Publication Date: 2019.01.08 SAMSUNG ELECTRONICS CO LTD

AI summary

A transparent electrode on at least one surface of a transparent substrate may include graphene doped with a p-dopant. The transparent electrode may be efficiently applied to a variety of display devices or solar cells.