Conductive Polymer Composition for Transparent Low-Moisture Films
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Solution Overview
Problem
Existing conductive polymer compositions used in organic electroluminescent devices face issues with moisture retention, aggregation, poor film formability, and surface roughness, leading to decreased device performance and durability.
Innovation Solution
A conductive polymer composition comprising a π-conjugated polymer, a dopant polymer with fluorinated acid units, and a water-soluble organic solvent, which enhances filterability, film formability, and transparency, allowing for droplet-coating methods like spray coating and inkjet printing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If PSS with high hydrophilicity is used as dopant, then dispersibility in water is improved, but moisture retention in film increases
Solution Approach 1:
The patent modifies the chemical structure of the dopant polymer by introducing fluorinated acid units (such as perfluoroalkyl groups) to change the hydrophilicity parameter. This reduces the excessive moisture retention while maintaining adequate dispersibility. The fluorinated units decrease the hydrophilic character of the dopant, thereby reducing moisture retention in the film without completely sacrificing dispersibility.
Solution Approach 2:
The patent creates a composite dopant structure combining fluorinated acid units with sulfonic acid groups. This composite approach allows balancing two opposing requirements: the sulfonic acid groups provide dispersibility, while the fluorinated units reduce moisture retention. The synergistic combination resolves the contradiction between these two properties.
2Object-affected harmful factors
If composite is dispersed in organic solvent, then moisture retention is reduced, but uniform dispersion becomes difficult
Solution Approach 1:
The patent changes the solvent system parameter by using a mixed solvent system comprising both water and organic solvent. This intermediate approach allows achieving uniform dispersion (better than pure organic solvent) while reducing moisture retention (better than pure water dispersion). The organic solvent component reduces overall moisture content, while the water component maintains dispersibility.
3Ease of manufacture
If H2O dispersion is used for coating, then film formation is achieved, but surface roughness and aggregation occur
Solution Approach 1:
The patent modifies the surface tension parameter of the dispersion by adjusting the solvent composition and dopant structure. The fluorinated acid units and organic solvent components work together to reduce surface tension, preventing aggregation and improving wetting. This results in smoother surfaces and better film formation without the roughness problems associated with pure water dispersions.
4Reliability
If PEDOT-PSS is used for high conductivity, then transparent electrode function is achieved, but light absorption increases and transmittance decreases
Solution Approach 1:
The patent applies local quality modification by introducing fluorinated acid units at specific positions in the dopant polymer structure. These localized fluorinated groups alter the electronic properties and optical characteristics of the conductive polymer complex. The fluorinated units modify the HOMO-LUMO energy levels, reducing visible light absorption while maintaining conductivity, thereby improving transmittance without sacrificing electrical performance.
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 composition forms a conductive film with high transparency, flatness, and low residual moisture, improving device performance and durability by reducing acid diffusion and surface defects.
Implementation Method 1
the surface tension and the contact angle are so low that leveling property on a substrate is imparted
Implementation Method 2
a polymer (B) shown by the following general formula (2)... wherein Rf1 represents a fluorine atom or a trifluoromethyl group
Data Source
AI summary
A conductive polymer composition containing: a composite containing a π-conjugated polymer (A) and a polymer (B) shown by the following general formula (2); H2O (D) for dispersing the composite; and a water-soluble organic solvent (C). This provides a composition which has favorable filterability and film formability, and which is capable of relieving acidity and forming a conductive film with high transparency. Moreover, since the H2O dispersion of the conductive polymer compound is mixed with an organic solvent, the surface tension and the contact angle are so low that leveling property on a substrate is imparted. The composition is usable in droplet-coating methods. Since an organic solvent having a higher boiling point than H2O is used as the organic solvent, the composition can avoid solid content precipitation around a nozzle and solid content precipitation due to drying between ejecting the liquid material from a nozzle tip and landing on a substrate.