Low-Reflectance Electrode for Organic Electronic Devices

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Solution Overview

Problem

Organic electronic devices, such as OLEDs, face challenges with high reflectivity due to shiny metal electrodes, which degrade contrast ratio and viewing quality, and require the use of polarizers that add weight, cost, and reduce efficiency.

Innovation Solution

An organic electronic device architecture featuring a light-transmitting anode or cathode combined with a low-reflectance electrode and an electron transport layer thicker than 50 nm, comprising an electron transport material and an n-dopant, reduces reflectivity and maintains high efficiency for all primary colors.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a shiny metal electrode is used, then electrical conductivity is improved, but reflectivity increases degrading contrast ratio and viewing quality

Engineering Contradiction:

Improveelectrical conductivityVSAvoidreflectivity

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent introduces an electron transport layer as an intermediary between the metal electrode and the photoactive layer. This layer mediates the conflict by providing electrical conductivity while reducing reflectivity, allowing both functions to coexist without direct interaction between the metal electrode and the light-emitting components.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The electrode structure is transformed from a simple metal layer into a composite structure consisting of multiple layers including the electron transport layer with specific thickness (greater than 50 nm) and composition. This composite approach combines the electrical conductivity of metal with the optical properties of organic electron transport materials to achieve both low reflectivity and high conductivity.

Inventive Principle:

Principle #40Composite materials

2Object-affected harmful factors

If a polarizer is added to reduce reflectivity, then viewing quality is improved, but device weight, cost, and efficiency are degraded

Engineering Contradiction:

ImprovereflectivityVSAvoiddevice structure

Core Design Contradiction:

Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The patent extracts the polarizer component from the device structure entirely. Instead of adding a polarizer to manage reflectivity, the invention modifies the electrode itself to be inherently low-reflectance, eliminating the need for the polarizer and all its associated drawbacks in weight, cost, and efficiency loss.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent converts the harmful reflectivity of metal electrodes into a benefit by using the electron transport layer to absorb excess light and reduce reflections. The very layer that transports electrons also serves to manage optical properties, turning a potential problem into a solution.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

3Productivity

If electron transport layer thickness is reduced, then device efficiency is improved, but sensitivity to thickness variations increases

Engineering Contradiction:

Improvedevice efficiencyVSAvoidthickness control

Core Design Contradiction:

ProductivityVSManufacturing precision

Solution Approach 1:

The patent changes the critical parameter from a thin electron transport layer to a thicker layer (greater than 50 nm). This parameter change fundamentally alters the system's sensitivity characteristics, making the device efficiency less sensitive to small variations in thickness while maintaining high performance.

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

The solution significantly reduces reflectivity, maintains high device efficiency, lowers dark current, and reduces sensitivity to electron transport layer thickness variations, eliminating the need for polarizers and improving viewing quality.

Implementation Method 1

an electron transport layer comprising an electron transport material and an n-dopant, the layer having a thickness greater than 50 nm... significantly reduces reflectivity

Methodology Applied

Scientific EffectLight absorption: Absorption (EM radiation)

Implementation Method 2

an electron transport layer comprising an electron transport material and an n-dopant

Methodology Applied

Scientific Effectn-doping: Dopants

Data Source

PatentUS8643000B2Organic electronic device with low-reflectance electrode

Publication Date: 2014.02.04 LG CHEM LTD

AI summary

There is provided an organic electronic device including an anode; a hole injection layer; a hole transport layer; a photoactive layer including a plurality of first subpixels, a plurality of second subpixels and a plurality of third subpixels; an electron transport layer including an electron transport material and an n-dopant, the layer having a thickness greater than 50 nm; and a cathode. One of the anode and cathode is light-transmitting and the other has low-reflectance.