Conductive Polymer Composition for OLED Hole-Injection Layers
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Solution Overview
Problem
Conductive polymer-based hole-injection layers in OLEDs, particularly those using PEDOT/PSS dispersions, face issues with solubility in water-immiscible solvents and have insufficient efficiency and lifetime, leading to rapid luminance decrease in OLEDs.
Innovation Solution
A composition comprising a cationic conductive polymer, a fluorinated compound, and a copolymeric anion with ionic and non-ionic repeating units, which is free of water and optimized for use in non-aqueous solvent systems to enhance the performance and longevity of OLEDs and solar cells.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If aqueous PEDOT/PSS dispersions are used to produce hole-injection layers in OLEDs, then the layers can be easily formed, but the efficiency and lifetime of OLEDs are insufficient and luminance decreases quickly
Solution Approach 1:
The patent changes the solvent parameter from aqueous to water-immiscible organic solvent, and modifies the polyanion structure to include both hydrophobic and hydrophilic segments. This allows the composition to be processed in organic solvents while maintaining the necessary polyelectrolyte complex formation, thereby improving OLED lifetime and efficiency without sacrificing ease of manufacture
Solution Approach 2:
The patent uses a composite polyanion structure combining hydrophobic segments (for solubility in water-immiscible solvents) and hydrophilic segments (for complex formation with cationic conductive polymer). This composite structure enables the material to function effectively in organic solvent systems while maintaining the polyelectrolyte complex necessary for hole-injection layer formation
2Ease of manufacture
If PSS is used as the polyanion, then the complex can be easily formed with cationic polythiophenes, but the polyanion is soluble in water and water-miscible organic solvents, not in water-immiscible organic solvents
Solution Approach 1:
The patent changes the chemical structure parameter of the polyanion by introducing hydrophobic segments alongside hydrophilic segments. This structural modification enables the polyanion to be soluble in water-immiscible organic solvents while retaining its ability to form complexes with cationic conductive polymers through the hydrophilic segments
Solution Approach 2:
The patent applies local quality by having different segments of the polyanion chain serve different functions: hydrophobic segments provide solubility in water-immiscible solvents, while hydrophilic segments provide complex formation capability with cationic polymers. This local differentiation resolves the contradiction between solubility and complex formation
3Productivity
If water-immiscible organic solvents are used for dispersing conductive polymers, then the solvents can be easily removed by evaporation and good film-forming properties are achieved, but traditional PEDOT/PSS dispersions are not compatible with these solvent systems
Solution Approach 1:
The patent changes the solvent parameter from water-miscible to water-immiscible organic solvent, and simultaneously modifies the polyanion parameter to include hydrophobic segments. This enables the composition to be dispersed in water-immiscible solvents, allowing easy solvent removal by evaporation and good film formation, while maintaining compatibility through the amphiphilic polyanion structure
Solution Approach 2:
The amphiphilic polyanion acts as an intermediary that bridges the cationic conductive polymer and the water-immiscible organic solvent. The hydrophobic segments interact with the organic solvent while the hydrophilic segments interact with the polymer, enabling dispersion and compatibility between otherwise incompatible components
Data Source
AI summary
The present invention relates to a composition comprising:a) at least one organic solvent;b) at least one conductive polymer, preferably a cationic polymer;c) at least one fluorinated compound;d) at least one polymeric anion, wherein the at least one polymeric anion is a copolymer comprising ionic and non-ionic repeating units.The present invention also relates to a layered structure comprising the composition, to a process for the production of the composition, to a process for the production of the layered structure and to devices comprising the layered structure as well as to the use of the composition in devices to achieve a prolongation of lifetime.