OLED Sub-Pixel Inorganic Overhang Patterning Without Lift-Off
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Solution Overview
Problem
Current OLED pixel patterning processes restrict panel size, pixel resolution, and substrate size, and leave behind organic material particles that disrupt OLED performance.
Innovation Solution
The use of inorganic overhang structures in sub-pixel circuits, combined with evaporation deposition, to form sub-pixels without the need for a lift-off process, ensuring precise deposition of OLED materials and cathodes while maintaining the inorganic overhang structures in place.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If organic encapsulation layers are used, then the fabrication process is simple and low-cost, but the moisture barrier performance is insufficient leading to short device lifetime
Solution Approach 1:
The patent uses a composite encapsulation structure combining organic encapsulation layers with inorganic barrier layers. The organic layers provide flexibility and step coverage, while the inorganic layers provide superior moisture barrier performance. This composite approach resolves the contradiction by achieving both ease of manufacture and high reliability.
Solution Approach 2:
The patent implements a nested encapsulation structure where inorganic barrier layers are deposited within and between organic encapsulation layers. The inorganic layers are nested within the organic matrix, creating a multi-layered protective structure that combines the advantages of both material types while maintaining fabrication simplicity.
2Reliability
If inorganic encapsulation layers are deposited to improve moisture barrier, then device lifetime increases, but fabrication complexity and cost increase
Solution Approach 1:
The patent segments the encapsulation function into distinct organic and inorganic layers, each performing specific roles. The organic layers handle flexibility and conformal coverage, while the inorganic layers provide the moisture barrier. This segmentation allows for optimized fabrication of each layer type using appropriate techniques, reducing overall complexity.
Solution Approach 2:
The patent introduces organic encapsulation layers as intermediary structures between the inorganic barrier layers. These organic layers serve as mediators that provide mechanical flexibility, stress relief, and conformal coverage, enabling the integration of rigid inorganic barrier layers into the flexible OLED structure without excessive fabrication complexity.
3Reliability
If multiple thin inorganic barrier layers are deposited, then moisture barrier performance improves, but deposition time and production cost increase
Solution Approach 1:
The patent applies preliminary protective action by depositing inorganic barrier layers within the organic encapsulation structure during the fabrication process. This preliminary integration of barrier layers prevents moisture ingress from the beginning, eliminating the need for additional post-fabrication barrier treatments and reducing total process time.
Solution Approach 2:
The patent merges the encapsulation and barrier functions into a single integrated multi-layer structure. By combining organic encapsulation layers with inorganic barrier layers in one fabrication sequence, the patent achieves superior moisture barrier performance without requiring separate deposition processes, thereby reducing total deposition time and production cost.
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 increases pixel-per-inch density and improves OLED performance by eliminating particle issues and enhancing throughput.
Implementation Method 1
inorganic encapsulation barrier layers have been developed to overcome the shortcomings of the organic encapsulation layers
Implementation Method 2
the organic encapsulation layers conformally cover the substrate surfaces and have high flexibility
Implementation Method 3
The organic encapsulation layers are formed by a spin-coating process
Data Source
Figure 1A~1B
Figure 1C~1D
Figure 2
AI summary
Embodiments described herein relate to sub-pixel circuits and methods of forming sub-pixel circuits that may be utilized in a display such as an organic light- emitting diode (OLED) display. The device includes a plurality of sub-pixels, each sub-pixel of the plurality of sub-pixels defined by adjacent pixel-defining layer (PDL) structures with inorganic overhang structures disposed on the PDL structures, each sub-pixel having an anode, organic light-emitting diode (OLED) material disposed on the anode, and a cathode disposed on the OLED material. The device is made by a process including the steps of: depositing the OLED material and the cathode by evaporation deposition, and depositing an encapsulation layer disposed over the cathode.