Conductive Polymer Composite with Fluorinated Sulfo Dopant
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Solution Overview
Problem
Conductive polymer composites based on polythiophene with polystyrene sulfonic acid as a dopant face issues with transparency, filterability, and film-formability due to high hydrophilicity, leading to defects and reduced lifespan in organic electroluminescent devices and poor performance as transparent electrodes.
Innovation Solution
A conductive polymer composite comprising a π-conjugated polymer and a dopant polymer with a repeating unit containing an α-fluorinated sulfo group, which improves transparency, stability, and film-formability by spin coating, forming a conductive film with high conductivity and flatness on both organic and inorganic substrates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If polystyrene sulfonic acid (PSS) is used as a dopant for polythiophene, then conductivity and water dispersibility are improved, but hydrophilicity increases causing poor affinity to organic substrates and film-formability
Solution Approach 1:
The patent modifies the dopant polymer structure by introducing fluorinated groups and adjusting the ratio of sulfonic acid groups to change the hydrophilicity parameter. This allows the material to maintain sufficient conductivity while reducing excessive hydrophilicity that caused poor film-formability on organic substrates
Solution Approach 2:
The patent creates a composite conductive polymer material combining polythiophene with a specifically designed dopant polymer containing fluorinated sulfo groups. This composite structure achieves balanced properties: the polythiophene provides conductivity while the modified dopant polymer provides appropriate hydrophobicity for organic substrate compatibility
2Quantity of substance
If PSS is used as dopant, then water dispersibility is enhanced, but water remains in the film causing moisture absorption and device degradation
Solution Approach 1:
The patent changes the hydrophilicity parameter of the dopant polymer by introducing fluorinated groups, which have lower surface energy and reduced water affinity compared to standard PSS. This modification allows the material to maintain processability while reducing water retention and moisture absorption in the final film
3Reliability
If solid concentration or film thickness is increased to achieve required conductivity, then conductivity is improved, but transmittance of the film is affected
Solution Approach 1:
The patent modifies the optical properties by changing the chemical structure of the dopant polymer. The fluorinated sulfo group structure alters the absorption spectrum and reduces visible light absorption, allowing the film to achieve required conductivity at lower solid concentrations while maintaining high transmittance
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 achieves excellent filterability, film-formability, and transparency, enhancing the durability and conductivity of the conductive film, suitable for use as a transparent electrode layer with improved resistance to heat and light.
Implementation Method 1
A polymer having a conjugated double bond (i.e. n-conjugated polymer) does not show a conductivity by itself; however, if an appropriate anionic molecule is doped therein, it can express an conductivity
Implementation Method 2
improves transparency, stability, and film-formability by spin coating, forming a conductive film with high conductivity and flatness
Data Source
AI summary
The present invention provides a conductive polymer composite including a π-conjugated polymer and a dopant polymer which contains a repeating unit “a” represented by the following general formula (1) and has a weight-average molecular weight in the range of 1,000 to 500,000,wherein R1 represents a hydrogen atom or a methyl group; R2 represents a single bond, an ester group, or a linear, branched, or cyclic hydrocarbon group having 1 to 12 carbon atoms and optionally containing either or both of an ether group and an ester group; Z represents a single bond, a phenylene group, a naphthylene group, an ether group, or an ester group; and “a” is a number satisfying 0<a≦1.0. There can be provided a conductive polymer composite that has excellent filterability and film-formability by spin coating, and also can form a conductive film having high transparency and flatness when the film is formed from the composite.