Ink-jet Printing Ink Electron Transport Layer OLED
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Solution Overview
Problem
The high cost of vacuum thermal evaporation methods for preparing OLED devices and the difficulty in achieving a full-solution-process OLED due to mutual solubility issues between ink layers in ink-jet printing processes limit the commercialization of OLEDs.
Innovation Solution
A method for preparing ink-jet printing ink for the electron transport layer using an ionic conjugated polyelectrolyte dispersed in a solvent, with adjustments to viscosity and surface tension modifiers to meet ink-jet printing requirements, avoiding solubility issues with adjacent layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If vacuum thermal evaporation method is used to prepare electron transport layer and cathode, then device performance is improved, but production cost increases significantly
Solution Approach 1:
The patent changes the preparation method from vacuum thermal evaporation to ink-jet printing, and selects specific ink-jet printable materials (conductive polymers, metal complexes) that can be deposited via solution processing. This parameter change enables solution-based fabrication while maintaining acceptable device performance, thereby reducing production costs.
2Ease of manufacture
If ink-jet printing method is used to prepare electron transport layer, then production cost is reduced, but mutual solubility between adjacent ink layers occurs causing manufacturing difficulties
Solution Approach 1:
The patent introduces a barrier layer between the electron transport layer and adjacent organic layers. This barrier layer acts as an intermediary that prevents mutual solubility and diffusion between layers, ensuring layer stability while enabling ink-jet printing fabrication.
Solution Approach 2:
The patent selects specific materials (conductive polymers, metal complexes) and adjusts their molecular weight, solubility parameters, and glass transition temperature to ensure they can be printed via ink-jet while maintaining layer stability and preventing mutual solubility with adjacent layers.
3Ease of manufacture
If ionic conjugated polyelectrolyte is dispersed in solvent to create ink-jet printing ink, then full-solution OLED device can be achieved, but ink viscosity and surface tension require precise adjustment
Solution Approach 1:
The patent adjusts key ink parameters including viscosity (1-100 cP), surface tension (20-40 mN/m), and solvent composition to optimize ink-jet printing performance. Specific solvents and their ratios are selected to achieve the required rheological properties for successful ink-jet fabrication.
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
This method enables the production of a full-solution OLED device by ensuring the ink-jet printing ink meets manufacturing requirements, preventing solubility issues and reducing production costs, thus facilitating the commercialization of OLEDs.
Implementation Method 1
dispersing the ionic conjugated polyelectrolyte in the solvent to obtain a polyelectrolyte solution
Implementation Method 2
The ink-jet printing method uses a plurality of nozzles to drop the ink of the functional material into a predetermined pixel area
Implementation Method 3
then a desired film is obtained by drying
Data Source
AI summary
An ink-jet printing ink of an electron transport layer and its preparing method are provided. The method of the disclosure adopts an ionic conjugated polyelectrolyte as a solute and alcohol compounds as a solvent. By adjusting the proportion of each component, viscosity and surface tension to obtain an ink-jet printing ink of the electron transport layer. The ink-jet printing ink meets the manufacturing requirements and is able to be produced by ink-jet printing process. Simultaneously, it avoids a mutually soluble phenomenon occurred between the electron transport layer and the adjacent structural layers during the preparation of the OLED, which is favorable for the production of a full-solution OLED device. According to the above method, the disclosure satisfies the manufacturing requirements of the ink-jet printing and realizes the ink-jet printing type of the electron transport layer, and is favorable for the production of a full-solution OLED device.