Cationic Polythiophenes in Organic Solvents
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Solution Overview
Problem
Existing polythiophene-based conductive polymers face limitations in solubility and conductivity when used in organic aprotic solvents, requiring expensive re-dispersion processes and showing limited conductivity, which restricts their application in various electronic components.
Innovation Solution
A composition comprising cationic polythiophenes with specific monomer units and organic compounds carrying inorganic acid groups, dispersed in a wide range of solvents, including aprotic ones, achieving high conductivity and transparency, and can be easily blended with inert polymers like polyacrylates to achieve low sheet resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If block-copolymer counter-ions are used to render PEDOT soluble in organic aprotic solvents, then solubility in organic solvents is improved, but the dispersion becomes unstable when solvents such as PGMEA or ethanol are added
Solution Approach 1:
The patent changes the chemical structure parameters of the counter-ion from block-copolymer to small molecule sulfonic acid compounds (molecular weight <1000 g/mol). This parameter change enables the PEDOT complex to be soluble in organic aprotic solvents while maintaining dispersion stability, as the small molecule counter-ions do not dominate solubility parameters and allow flexible solvent compatibility.
2Adaptability or versatility
If re-dispersing process is used to replace water with organic solvents, then solubility in organic solvents is improved, but the process becomes expensive and complex
Solution Approach 1:
The patent applies preliminary action by incorporating the organic-soluble small molecule counter-ion into the PEDOT complex during the initial synthesis stage. This eliminates the need for subsequent re-dispersing processes to replace water with organic solvents, as the complex is directly prepared in organic solvent compatibility from the start, reducing both process steps and costs.
3Adaptability or versatility
If coupling through metal-organic compounds is used to prepare regioregular copolymers, then dispersibility in solvents is improved, but the conductivity is limited and application is restricted
Solution Approach 1:
The patent extracts the metal-organic coupling step and replaces it with direct oxidative polymerization using organic compounds as counter-ions. This eliminates the metal-mediated coupling that limits conductivity while maintaining solvent dispersibility through the small molecule counter-ion approach, enabling both high conductivity and broad solvent compatibility.
4Reliability
If PEDOT is used as polymer complex with polystyrene-sulfonic acid dispersed in water, then conductivity is improved, but solubility in organic aprotic solvents is limited
Solution Approach 1:
The patent changes the counter-ion parameter from polystyrene-sulfonic acid (large polymer) to small molecule sulfonic acids (molecular weight <1000 g/mol). This parameter change maintains the ionic conductivity mechanism while enabling solubility in organic aprotic solvents, as the small molecule counter-ions provide appropriate solubility characteristics without compromising electrical conductivity.
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 enables the preparation of highly conductive and transparent conductive layers with low sheet resistance, suitable for various electronic components, such as organic light-emitting diodes and solar cells, while simplifying the process by reducing the number of steps required.
Implementation Method 1
oxidatively polymerizing the thiophene monomers for the formation a polythiophene, preferably for the formation of a cationic polythiophene
Implementation Method 2
at least one organic compound carrying one or two inorganic acid group(s), preferably one or two sulfonic acid group(s)
Data Source
AI summary
The present invention relates to a composition comprisingi) at least one polythiophene comprising monomer units of structure (Ia) or (Ib)in which *, X, Z, R, and R1-R6 are as defined herein;ii) at least one organic compound carrying one or two inorganic acid group(s), preferably one or two sulfonic acid group(s), one or two sulfuric acid group(s), one or two phosphonic acid group(s) or one or two phosphoric acid group(s), or a salt of said organic compound, wherein the molecular weight of the organic compound or the salt thereof is less than 1,000 g/mol; andiii) at least one organic solvent. A method of preparing such compounds is also provided.