Poly(3-alkynylthiophene) TFTs for Flexible Electronics

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Solution Overview

Problem

Conventional semiconductor materials for thin film transistors are unstable when exposed to air, leading to oxidative doping and poor performance characteristics, such as low current on/off ratios and rapid degradation, which increases manufacturing costs and limits their use in flexible and large-area devices.

Innovation Solution

The use of poly(3-alkynylthiophene) as a semiconductor material in thin film transistors, which is stable against oxidative doping and can be processed using solution-based methods, providing enhanced mechanical durability and structural flexibility, and is suitable for use on plastic substrates.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional semiconductor materials are used in thin film transistors, then high field effect mobility can be achieved, but the materials become unstable when exposed to air and undergo oxidative doping

Engineering Contradiction:
Improvestability against oxidative dopingVSAvoidoxidative doping by ambient oxygen
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent employs solution-based processing methods that allow the semiconductor material to be deposited and encapsulated in ambient conditions, effectively creating an inert environment during fabrication. The material is processed from solution rather than requiring vacuum deposition, eliminating exposure to oxidative conditions during manufacturing.

Inventive Principle:
Principle #39Inert atmosphere (Inert environment)

Solution Approach 2:

The patent uses a polymer semiconductor material that can be processed as a solution and deposited in a single step, replacing expensive and time-consuming vacuum deposition processes. The solution-based approach allows for low-cost fabrication without requiring complex vacuum equipment or inert atmosphere chambers.

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

2Manufacturing precision

If vacuum deposition methods are used to process semiconductor materials, then thin films can be formed, but the manufacturing cost increases and production efficiency decreases

Engineering Contradiction:
Improvethin film formation qualityVSAvoidmanufacturing cost and complexity
Core Design Contradiction:
Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The patent replaces the mechanical vacuum deposition system with a chemical solution-based deposition method. Instead of physically depositing material from the vapor phase under vacuum, the semiconductor is delivered dissolved in a solvent that is then evaporated or processed to leave the active material, simplifying the manufacturing apparatus.

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

Solution Approach 2:

The patent changes the physical state and delivery mechanism of the semiconductor material from solid vapor phase (requiring vacuum) to liquid solution phase (processable in ambient conditions). This parameter change enables low-cost spin-coating or dip-coating methods to replace expensive vacuum deposition equipment.

Inventive Principle:
Principle #35Parameter changes

3Ease of manufacture

If regioregular polythiophenes are selected as semiconductor layer, then solution processability is improved, but the materials remain sensitive to air and unstable when exposed to oxygen

Engineering Contradiction:
Improvesolution processabilityVSAvoidstability in ambient conditions
Core Design Contradiction:
Ease of manufactureVSReliability

Solution Approach 1:

The patent uses a polymer semiconductor material that combines the solution processability of polythiophenes with enhanced oxidative stability through its specific molecular structure. The material maintains the beneficial processing characteristics of conjugated polymers while resisting degradation from ambient oxygen exposure.

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The patent achieves stability by designing the semiconductor material with specific local structural characteristics that resist oxidative doping. The material's molecular structure includes features that protect against oxygen attack while maintaining solution processability, allowing selective optimization of different properties within the same material.

Inventive Principle:
Principle #3Local quality

4Strength

If flexible plastic substrates are used, then mechanical durability and structural flexibility are enhanced, but device fabrication complexity increases

Engineering Contradiction:
Improvemechanical durabilityVSAvoidfabrication process complexity
Core Design Contradiction:
StrengthVSDevice complexity

Solution Approach 1:

The patent uses a universal solution-based deposition method that works equally well on rigid and flexible substrates. The same processing technique can fabricate devices on plastic, glass, or metal, eliminating the need for specialized fabrication procedures for flexible substrates and reducing overall process complexity.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Data Source

PatentEP1843409B1Organic thin film transistor comprising a poly(ethynylthiophene)
Publication Date: 2015.05.13 XEROX CORP
  • EP1843409B1 patent drawingFigure 1~2
  • EP1843409B1 patent drawingFigure 3~4
  • EP1843409B1 patent drawing

AI summary

AN ELECTRONIC DEVICE COMPRISING A SEMICONDUCTIVE MATERIAL OF FORMULA (I) WHEREIN R IS A SUITABLE HYDROCARBON OR A HETEROATOM CONTAINING GROUP; AND N REPRESENTS THE NUMBER OF REPEATING UNITS.