Conductive Polymer Electrode for LCDs via Solution Coating
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Solution Overview
Problem
Existing transparent electrode materials for LCDs, such as ITO and IZO, require costly vacuum deposition processes and have poor light transparency, while alternative materials like conductive polymers suffer from increasing surface resistance over time.
Innovation Solution
A conductive composition comprising a conductive polymer, a dopant, a solvent with a carbonyl group, and a silane coupling agent, which includes specific weight percentages of these components, is used to form a ground electrode with improved coating uniformity, low surface resistance, and high light transparency and surface hardness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If ITO or IZO is used as ground electrode material, then electric resistance and surface hardness are excellent, but vacuum deposit process is required and light transparency is poor
Solution Approach 1:
The patent replaces the mechanical vacuum deposition process with a solution-based coating method. The conductive polymer composition is applied through conventional coating techniques, eliminating the need for vacuum equipment and complex deposition processes while achieving comparable or superior electrical properties.
Solution Approach 2:
The patent changes the material state from solid sputtered films (ITO/IZO) to solution-processable conductive polymer compositions. By adjusting composition parameters (polymer type, dopant concentration, solvent selection) and processing parameters (coating method, drying conditions), the patent achieves low surface resistance without vacuum deposition.
2Reliability
If ITO or IZO is used as ground electrode material, then electric resistance is excellent, but light transparency is poor
Solution Approach 1:
The patent uses composite conductive polymer materials combining conjugated polymers with specific dopants. This composite structure provides both electrical conductivity and optical transparency, overcoming the limitation of ITO/IZO which block light while providing conductivity.
Solution Approach 2:
The patent optimizes the composition parameters including polymer molecular weight, dopant ratio, and solvent selection to achieve a balance between electrical conductivity and optical transparency. By controlling these parameters, the ground electrode achieves low surface resistance while maintaining high light transmission.
3Illumination intensity
If conductive polymer is used as ground electrode material, then light transparency is good, but surface resistance increases according to use time
Solution Approach 1:
The patent introduces silane coupling agents as intermediaries between the conductive polymer and the substrate. This intermediary layer enhances adhesion and prevents polymer degradation over time, maintaining stable surface resistance while preserving light transparency.
Solution Approach 2:
The patent incorporates antioxidants and stabilizers in the conductive polymer composition to prevent degradation before it occurs. This beforehand cushioning approach ensures long-term stability of surface resistance by preventing oxidation and environmental degradation of the polymer.
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 achieves superior coating uniformity, low surface resistance, and high light transparency and surface hardness, particularly demonstrating reliability over 500 hours, suitable for various LCD modes like IPS and FFS.
Implementation Method 1
a silane coupling agent, and a solvent having a carbonyl group in the molecule
Implementation Method 2
a conductive polymer; a dopant
Implementation Method 3
a solvent having a carbonyl group in the molecule
Data Source
AI summary
The present invention relates to a conductive composition for forming a back electrode of a liquid crystal device, and a formation method of a back electrode using the same. The conductive composition enables the supply of a back electrode having excellent coating uniformity, low surface resistance, high transmittance and surface hardness, and particularly excellent reliability of 500 hours.