OVJP Patterning of OLED Upper Electrodes
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Solution Overview
Problem
Existing techniques for patterning electrodes over organic thin films in electronic devices, such as photolithography, are problematic due to chemical incompatibility with standard photolithographic methods, necessitating the development of alternative methods for organic semiconductor materials.
Innovation Solution
A method involving directed stream printing technologies like organic vapor jet printing (OVJP) is used to pattern organic materials after initial photolithography steps, allowing for the formation of electronic devices without the need for further photolithography, enabling the creation of isolated upper electrodes and organic layers in OLED displays.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If photolithography is used to pattern electrodes over organic thin films, then standard fabrication processes can be applied, but chemical incompatibility with organic semiconductor materials occurs
Solution Approach 1:
The fabrication process is divided into two distinct stages: first, photolithography is used to pattern inorganic components (electrodes, interconnects) on the substrate; second, directed stream printing is used to pattern organic semiconductor materials. This segmentation allows each technique to be applied to materials it is chemically compatible with, resolving the contradiction between ease of manufacture and chemical compatibility.
Solution Approach 2:
Directed stream printing acts as an intermediary technique that bridges the gap between photolithography and organic material deposition. It enables precise patterning of organic semiconductors without direct chemical interaction with photolithographic reagents, thus maintaining both manufacturing efficiency and chemical compatibility.
2Reliability
If directed stream printing is used to pattern organic materials, then chemical incompatibility issues are avoided, but additional process steps are required
Solution Approach 1:
The patent combines photolithography and directed stream printing into a unified fabrication sequence where both techniques work synergistically. The photolithography step creates the inorganic framework, and the directed stream printing step adds the organic functional layers, merging the advantages of both methods while minimizing overall process complexity.
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 avoids the limitations of conventional photolithography, enabling cost-effective and high-resolution patterning of organic electronic materials, facilitating the production of efficient and reliable electronic devices like OLED displays without the complications associated with traditional photolithographic techniques.
Implementation Method 1
In this technique, organic molecules are sublimated into a hot, inert carrier gas and expanded through microscopic nozzles forming a highly collimated gas jet
Implementation Method 2
The gas jet impinges on a cooled substrate to form a well-defined thin film of organic molecules
Data Source
AI summary
A method for forming an electronic device such as a passive color OLED display. Bottom electrodes are patterned onto a substrate in rows. Raised posts formed by photoresist are patterned into columns oriented orthogonally to the bottom row electrodes. One or more organic layers, such as R, G, B organic emissive layers are patterned over the raised posts and bottom electrodes using organic vapor jet printing (OVJP). An upper electrode layer is applied over the entire device and forms electrically isolated columnar electrodes due to discontinuities in the upper electrode layer created by the raised columnar posts. This permits patterning of the upper electrodes over the organic layers without using photolithography. A device formed by this method is also described.