Organic Semiconductor Thin Film Coating Method
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Solution Overview
Problem
Existing methods for manufacturing organic semiconductor thin films face challenges in forming large-area, uniform films with directional crystal structures due to issues with inkjet droplet landing lag, solvent solubility, and the need for specific substrate storage regions, leading to low productivity and difficulty in mass production.
Innovation Solution
A method involving the preparation of a first coating liquid with a high-affinity solvent and a second coating liquid with a low-affinity solvent, applied in an overlapping manner on a substrate, where the second coating liquid contacts the first during application, allowing for continuous multilayer coating and drying after precipitation, optimizing solubility ratios and contact angles to achieve uniform crystal growth.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Extent of automation
If inkjet droplets are used to apply coating liquids, then the manufacturing process can be automated, but time lag occurs in landing of each liquid droplet leading to multiple mixing portions and loss of crystal growth directionality
Solution Approach 1:
The patent replaces the inkjet mechanical droplet ejection system with a slot die coating system that uses continuous liquid flow. The slot die apparatus applies coating liquids continuously across the substrate width without the intermittent droplet deposition, eliminating the time lag problem while maintaining automation through controlled liquid delivery mechanisms.
2Productivity
If liquid droplet size is increased to reduce number of droplets, then processing time decreases, but peripheral portion dries more easily than central portion causing aggregation and loss of uniformity
Solution Approach 1:
The patent segments the coating process into two separate coating liquids applied in sequence: first coating liquid (good solvent) and second coating liquid (poor solvent). This segmentation allows each liquid to perform its specific function - the first provides uniform wetting and dissolution, the second triggers controlled precipitation - avoiding the drying gradient problem of single large droplets while maintaining high productivity through continuous application.
3Manufacturing precision
If substrate storage regions are formed to enable continuous crystal growth, then large-area uniform films can be produced, but device complexity increases due to need for specific region formation
Solution Approach 1:
The patent implements continuous coating by applying the first and second coating liquids in continuous streams across the substrate without interrupting to form discrete storage regions. The liquids flow continuously and overlap to create a continuous coating zone, enabling uninterrupted crystal growth across large areas while simplifying the process by eliminating the need to pre-form or locate specific storage regions on the substrate.
4Manufacturing precision
If high concentration of organic semiconductor is used in coating liquid, then film thickness can be controlled better, but solubility decreases making it difficult to control drying and form uniform crystals
Solution Approach 1:
The patent changes the solvent parameter by using a two-solvent system instead of a single solvent. The first coating liquid uses a good solvent to achieve high solubility and homogeneous dissolution at high semiconductor concentration, while the second coating liquid uses a poor solvent to trigger precipitation. This parameter change allows maintaining high concentration without sacrificing solubility or uniformity.
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 approach enables the continuous formation of large-area, high-uniformity organic semiconductor thin films with directional crystal structures, enhancing productivity and facilitating various shapes, thereby overcoming previous limitations in film formation and mass production.
Implementation Method 1
it has been found that when production is performed in an atmosphere whose relative humidity is within a specific range, high-quality organic semiconductor thin films in which molecules are oriented in a specific direction can be obtained by utilizing self-assembly of the molecules
Implementation Method 2
high-quality organic semiconductor thin films in which molecules are oriented in a specific direction can be obtained by utilizing self-assembly of the molecules through non-covalent interactions
Implementation Method 3
when a specific amount of water is introduced into an atmosphere during production of an organic semiconductor thin film, high-quality organic semiconductor thin films in which molecules are oriented in a specific direction can be obtained by utilizing self-assembly of the molecules
Data Source
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AI summary
Provided is a method for manufacturing an organic semiconductor thin film which can continuously form an organic semiconductor thin film having a large area and high uniformity, and can easily correspond to various shapes. The method includes a preparation step of preparing a first coating liquid in which an organic semiconductor is dissolved in a first organic solvent and a second coating liquid containing a second organic solvent having a lower affinity for the organic semiconductor than that of the first organic solvent, a coating step of applying the first coating liquid and the second coating liquid on a substrate in an overlapping manner in a direction perpendicular to a surface of the substrate, the second coating liquid being applied on a substrate side, and a drying step of drying a coating film of the first coating liquid and the second coating liquid applied on the substrate in the coating step after the organic semiconductor is precipitated from the coating film. In the coating step, the second coating liquid is in contact with the first coating liquid during a period from jetting of the second coating liquid to application of the second coating liquid on the substrate.