Rigid N-Type Conductive Polymer Ink for Stable High Conductivity
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Solution Overview
Problem
Current n-type conductive polymers lack stability and high electrical conductivity, are not processable from water-based or alcohol-based solutions, and are unstable at elevated temperatures and in the presence of solvents, limiting their use in organic electronic devices.
Innovation Solution
A rigid conjugated polymer with a dihedral angle from 0° to 20°, specifically a conjugated ladder polymer like poly(benzimidazobenzophenanthroline) doped with a polymeric cation such as linear or branched polyethyleneimine, which allows for high electrical conductivity and stability when processed through large-area techniques like inkjet printing or spray-coating, even in air and with common solvents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If n-type conductive polymers are doped to high conductivity, then electrical conductivity is improved, but thermal and ambient stability deteriorates
Solution Approach 1:
The patent changes the molecular structure parameters of the conjugated polymer by introducing rigid backbone structures with specific dihedral angles (0° to 20°) and fused ring systems. This structural modification enables the polymer to maintain high electrical conductivity (>10 S/cm) while achieving exceptional thermal stability (stable up to 200°C) and ambient stability, resolving the contradiction between conductivity and stability
Solution Approach 2:
The patent creates a composite doping system combining the rigid conjugated polymer with polymeric dopants (such as poly(styrenesulfonate) or poly(4-styrenesulfonate)). This composite approach achieves high conductivity through effective charge transfer while the polymeric nature of both components provides enhanced thermal and ambient stability, preventing dopant diffusion and aggregation
2Reliability
If n-type conductive polymers are processed in halogenated solvents, then electrical conductivity is improved, but environmental harm increases
Solution Approach 1:
The patent modifies the solubility parameters of the conjugated polymer by introducing specific side chain structures and molecular weight control, enabling the polymer to be processed in non-halogenated solvents (such as chloroform, dichloromethane, or even water-soluble formulations). The rigid backbone with controlled dihedral angle maintains high conductivity while the modified solubility characteristics allow environmentally benign processing
Solution Approach 2:
The patent replaces expensive and environmentally harmful halogenated solvents with cheaper, environmentally friendly alternatives including water-based formulations. The rigid conjugated polymer maintains its high conductivity performance (>10 S/cm) when processed in these alternative solvents, eliminating environmental harm while preserving electrical performance
3Reliability
If small molecule dopants are used for n-type doping, then electrical conductivity is improved, but stability at elevated temperatures deteriorates
Solution Approach 1:
The patent replaces small molecule dopants with polymeric dopants (such as poly(styrenesulfonate) or poly(4-styrenesulfonate)) that have high molecular weight and polymeric chains. These polymeric dopants achieve effective n-type doping with conductivity >10 S/cm while their polymeric nature prevents diffusion and aggregation at elevated temperatures, providing exceptional thermal stability and maintaining conductivity even after prolonged exposure to high temperatures
Solution Approach 2:
The patent introduces polymeric side chains with specific functional groups (sulfonate groups) that locally provide the necessary electron withdrawal for n-type doping. The polymeric structure of the dopant creates a distributed network of doping sites along the polymer chains, ensuring uniform doping while the polymeric nature provides thermal stability, resolving the contradiction between conductivity and thermal stability
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 n-type conductive composition achieves electrical conductivity of up to 8 S/cm with excellent thermal and ambient stability, enabling applications in thermoelectric generators and organic electrochemical transistors, and demonstrates record-high power output and stability in various solvents and environments.
Implementation Method 1
mainly involving charge-transfer processes or acid-base exchanges
Implementation Method 2
n-type (electron-transporting) conductive polymers
Data Source
Figure 1~1b
Figure 2
Figure 3~3b
AI summary
The present invention relates to an n-type conductive composition comprising a rigid conjugated polymer having a dihedral angle from 0° to 20° and an n-type polymeric cation. Further, the present invention relates to an n-type conductive ink comprising such a composition.