Solution-Processed Metal Oxide Buffer Layers for Organic Electronics

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Solution Overview

Problem

Current metal oxide buffer layers for organic electronics, particularly ZnO and AZO, face challenges in large-area manufacturing due to the need for high-vacuum thermal evaporation and compatibility issues with silver electrodes in inverted architectures, leading to insufficient contact and damage to active layers.

Innovation Solution

Development of metal oxide nanoparticle-based buffer layers coated with dispersants, such as phosphate esters, that can be solution-processed at ambient pressure, eliminating the need for post-treatment annealing and allowing direct contact with silver electrodes without additional self-assembled monolayers.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If thermal evaporation under high vacuum is used to manufacture metal oxide buffer layers, then the buffer layers can be formed with good quality, but the manufacturing cost increases and large-area production becomes difficult

Engineering Contradiction:
Improvebuffer layer qualityVSAvoidmanufacturing cost and scalability
Core Design Contradiction:
Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The patent replaces the mechanical vacuum evaporation system with a solution-processing system. Instead of using thermal evaporation under high vacuum to deposit metal oxide layers, the invention uses solution-processed metal oxide nanoparticles that can be applied via low-cost, large-area techniques such as spin-coating, dip-coating, or spray-coating at ambient pressure, thereby eliminating the need for expensive vacuum equipment while maintaining buffer layer quality

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the physical and chemical parameters of the metal oxide material from bulk or evaporated forms to nanoparticle suspensions in solution. This parameter change allows the material to be processed from solid-vapor deposition to liquid-phase application, enabling low-cost, large-area manufacturing while preserving the functional properties of the buffer layer

Inventive Principle:
Principle #35Parameter changes

2Ease of manufacture

If unmodified metal oxide nanoparticles are used in solution-processed buffer layers, then the manufacturing cost decreases, but the active organic layer is damaged during deposition

Engineering Contradiction:
Improvemanufacturing costVSAvoiddamage to active organic layer
Core Design Contradiction:
Ease of manufactureVSObject-affected harmful factors

Solution Approach 1:

The patent introduces an intermediary substance - a shell or coating on the metal oxide nanoparticles - that acts as a protective barrier between the nanoparticles and the active organic layer. This shell prevents direct harmful interactions while allowing the nanoparticles to maintain their function, thus enabling low-cost solution processing without damaging the organic layer

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent creates composite nanoparticles consisting of a metal oxide core surrounded by a protective shell or coated with compatible organic materials. This composite structure combines the beneficial electrical properties of metal oxides with the protective and compatible characteristics of organic coatings, preventing damage to the active layer during solution processing

Inventive Principle:
Principle #40Composite materials

3Ease of manufacture

If sol-gel technique is used to produce buffer layers, then the buffer layers can be deposited by solution processing, but additional post-treatment annealing at high temperature is required

Engineering Contradiction:
Improvesolution processing capabilityVSAvoidnumber of processing steps
Core Design Contradiction:
Ease of manufactureVSDevice complexity

Solution Approach 1:

The patent performs preliminary action by pre-synthesizing metal oxide nanoparticles with desired crystalline structures and surface properties before deposition. These pre-prepared nanoparticles require no or minimal post-deposition annealing, thereby reducing the number of processing steps compared to sol-gel methods that require high-temperature treatment to form the oxide structure after deposition

Inventive Principle:
Principle #10Preliminary action

4Reliability

If additional self-assembled monolayers are deposited on metal oxide buffer layers to improve contact with silver electrodes, then the electrical contact improves, but the device complexity and manufacturing difficulty increase

Engineering Contradiction:
Improveelectrical contact qualityVSAvoidnumber of additional layers and processing steps
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent applies local quality by modifying only the surface of the metal oxide nanoparticles with specific coatings or functional groups that enhance compatibility with silver electrodes. This localized surface modification improves electrical contact without requiring additional bulk layers or complex multi-step processes, thereby maintaining device simplicity while achieving reliable contact

Inventive Principle:
Principle #3Local quality

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-processed buffer layers demonstrate improved device performance with enhanced compatibility and stability, enabling efficient and cost-effective large-area manufacturing of organic electronics without the need for additional processing steps or damage to active layers.

Implementation Method 1

metal oxide nanoparticle-based buffer layers coated with dispersants, such as phosphate esters, that can be solution-processed at ambient pressure

Methodology Applied
Scientific EffectDispersion: Dispersion (of waves)

Implementation Method 2

The coating liquid is a suspension of unmodified ZnO nanoparticles in 1-butanol. This suspension was applied on organic layers without damaging them

Methodology Applied
Scientific EffectSuspension: Suspension

Implementation Method 3

a temperature post-treatment

Methodology Applied
Scientific EffectAnnealing: Annealing

Data Source

PatentEP3080849B1Electronic devices comprising solution-processable metal oxide buffer layers
Publication Date: 2018.09.05 AVANTAMA AG
  • EP3080849B1 patent drawingFigure 1~3
  • EP3080849B1 patent drawingFigure 4~5
  • EP3080849B1 patent drawing

AI summary

The present invention relates to the field of electronic devices, such as organic electronics, wherein said device comprises a substrate and a multitude of layers, wherein at least one of said layers is a buffer layer, wherein said buffer layer comprises metal oxide nanoparticles coated with dispersant as described in the specification. The invention further provides for intermediate goods and materials suitable for manufacturing such electronic devices, to specific manufacturing methods and to specific uses.