Fluorinated Dopant Polymer Composite for Organic EL Film Uniformity
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conductive polymer composites with sulfonic acid-based dopants face issues such as high residual moisture, surface roughness, and poor coatability on hydrophobic substrates, leading to decreased device performance and durability in organic EL devices due to uncontrolled H+ generation and acidity.
Innovation Solution
A conductive polymer composite incorporating a π-conjugated polymer with a dopant polymer containing a non-doping fluorinated unit, which reduces H+ generation and improves filterability and film formability, forming a conductive film with high transparency and flatness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If PSS (polystyrenesulfonic acid) is used as a dopant for π-conjugated polymer, then doping efficiency is improved and dispersibility in water is enhanced, but residual moisture in the film increases and device lifetime is shortened
Solution Approach 1:
The patent changes the chemical structure parameters of the dopant polymer by introducing fluorinated alkyl groups with specific chain lengths (C1-C20) and configurations (linear, branched, cyclic). This structural modification reduces the hydrophilicity of PSS while maintaining its doping efficiency, thereby decreasing residual moisture in the film without compromising the primary function.
Solution Approach 2:
The patent creates a composite dopant structure by combining fluorinated alkyl groups with the sulfonic acid functional groups in the polymer chain. This composite approach integrates the hydrophobic properties of fluorinated groups with the dopant functionality of sulfonic acid groups, achieving both efficient doping and reduced moisture retention.
2Ease of operation
If PSS is used as a dopant, then dispersibility in water is improved, but coatability on hydrophobic substrates deteriorates and surface roughness increases
Solution Approach 1:
The patent modifies the surface energy parameters of the dopant polymer by incorporating fluorinated alkyl groups, which have low surface energy and high hydrophobicity. This parameter change enables the dopant to maintain water dispersibility while simultaneously improving compatibility with hydrophobic substrates, thereby enhancing coatability and reducing surface roughness.
3Reliability
If sulfonic acid-based dopant is used, then conductivity is improved, but H+ generation increases and acidity becomes uncontrolled, leading to decreased device performance
Solution Approach 1:
The patent changes the pKa parameter of the dopant system by introducing fluorinated alkyl groups, which are electron-withdrawing groups. This electronic effect modifies the acid strength of the sulfonic acid groups, reducing H+ generation while maintaining the conductivity necessary for device operation. The fluorinated groups effectively tune the acidity parameter to an optimal range.
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 efficiently removes residual moisture, enhances film uniformity and conductivity, and suppresses H+ diffusion, improving the durability and performance of organic EL devices by reducing acidity and improving affinity to hydrophobic substrates.
Implementation Method 1
A polymer having a conjugated double bond (a π-conjugated polymer) does not show conductivity by itself, but becomes a conductive polymer material by doping with an appropriate anion molecule which causes electron or hole to move.
Implementation Method 2
doping with an appropriate anion molecule which causes electron or hole to move
Implementation Method 3
After device formation and sealing, the moisture volatizes and fills the device... When this material is used for a film (thin film) constituting, for example, an organic EL, the moisture remaining in the film and moisture absorbed from the external atmosphere in the manufacturing process till sealing volatize or permeate an adjacent layer
Implementation Method 4
As the method for forming the film, for example, coating with a spin coater or the like, bar coating, dipping, comma coating, spray coating, roll coating, screen printing, flexographic printing, gravure printing, or ink-jet printing may be employed for the coating, followed by a heat treatment with a hot air circulation furnace, hot plate, or the like
Implementation Method 5
a sulfonic acid-based anion has most frequently been used as the anion molecule (a dopant). This is because the sulfonic acid, which is a strong acid, interacts efficiently with the π-conjugated polymer
Data Source
AI summary
Provided are a conductive polymer composite and composition which: improve water volatilization efficiency during film formation by incorporating a novel non-doping fluorinated unit in a dopant polymer; also reduce H+ generation by using the non-doping fluorinated unit in place of an acid unit generating extra acids; have good filterability and film formability; and are capable of forming a film having high transparency and good flatness when the film is formed. The conductive polymer composite is a composite containing: (A) a π-conjugated polymer; and (B) a dopant polymer which is a copolymer containing a repeating unit “a” shown by the following general formula (1) and at least one repeating unit “b” selected from repeating units shown by the following general formulae (2-1) to (2-7).