Conductive Polymer Composite for Transparent Electrodes
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Solution Overview
Problem
Polythiophene-based conductive polymers using PSS as a dopant face issues with transparency, film formability, and surface roughness due to high hydrophilicity and aggregation, leading to poor performance in organic EL devices and conductive films.
Innovation Solution
A conductive polymer composite comprising a π-conjugated polymer and a dopant polymer with a specific repeating unit structure, which improves filterability, film formability, and affinity to organic solvents and substrates, enhancing the conductivity and transparency of the formed films.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If polythiophene using PSS as a dopant is used to form conductive films, then conductivity is improved, but transparency is worsened due to absorption in the blue region around 500 nm
Solution Approach 1:
The patent changes the chemical structure parameters of the dopant polymer by introducing fluorinated groups and adjusting the sulfonic acid content. This modifies the optical properties of the conductive polymer composite, reducing absorption in the visible region while maintaining conductivity through optimized doping efficiency.
Solution Approach 2:
The patent creates a composite material system combining polythiophene with a specifically designed fluorinated dopant polymer. This composite approach allows independent optimization of conductivity (through doping) and transparency (through fluorinated group modification), resolving the trade-off between these two properties.
2Adaptability or versatility
If polythiophene using PSS as a dopant is used, then hydrophilicity is improved, but moisture resistance is worsened leading to shortened device lifetime
Solution Approach 1:
The patent reduces the excessive hydrophilicity of PSS by introducing fluorinated groups with lower polarity and adjusting the sulfonic acid content to 5-20 mol%. This parameter optimization maintains sufficient water dispersibility while reducing moisture absorption, thereby improving device lifetime through better moisture resistance.
Solution Approach 2:
The patent converts the harmful excessive hydrophilicity of PSS into a beneficial property by controlled modification. The fluorinated dopant polymer provides optimal hydrophilicity that enables water dispersibility for processing while preventing excessive moisture uptake that would degrade device performance, thus transforming a drawback into an advantage.
3Reliability
If polythiophene using PSS as a dopant is used, then doping efficiency is improved, but film formability and surface flatness are worsened due to large particle size
Solution Approach 1:
The patent optimizes the molecular weight and structure of the dopant polymer, and adjusts the doping ratio parameters. This results in smaller particle size of the conductive polymer composite while maintaining high doping efficiency, enabling better film formability and surface flatness for high-quality conductive films.
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 composite enables the formation of conductive films with good filterability, high transparency, and flatness, improving the durability and conductivity of the films, making them suitable for use as transparent electrode layers.
Implementation Method 1
In a polymer having a conjugated double bond (a π-conjugated polymer), the polymer itself does not show conductivity, but conductivity is exhibited by doping an appropriate anion molecule and it becomes a conductive polymer material
Implementation Method 2
a conductive polymer composition formed by a conductive polymer which contains a π-conjugated polymer formed by a repeating unit selected from thiophene, selenophene, tellorophene, pyrrole, aniline, and a polycyclic aromatic compound
Implementation Method 3
it has been shown that it becomes an aqueous dispersion of a conductive polymer by combining water, a precursor monomer of the π-conjugated polymer, a fluorinated acid polymer, and an oxidizing agent
Data Source
AI summary
An object of the present invention is to provide a conductive polymer composite which has good filterability and good film forming property by spin coating and, when a film is formed, can form a conductive film having high transparency and good flatness property. It is provided a conductive polymer composite comprising (A) a π-conjugated polymer, and (B) a dopant polymer containing a repeating unit “a” represented by the following general formula (1), and having a weight average molecular weight in the range of 1,000 to 500,000:wherein, R1, Z1, Rf1, and “a” are as defined in the specification.