OLED Bank Structure With Through-Connection for Maskless Emission
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Solution Overview
Problem
Existing display devices face challenges in forming light emitting elements without a mask process, particularly in integrating separate light emitting elements with a pad portion made of the same material as the display area structure, which can lead to manufacturing issues and reliability concerns.
Innovation Solution
A display device design that includes a bank structure with a first and second bank layer, where the second bank layer protrudes from the sidewall, allowing light emitting elements to be formed without a mask process and ensuring electrical connection to power lines through through portions, while preventing lifting phenomena due to gas generation during manufacturing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a mask process is used to form light emitting elements, then manufacturing precision is improved, but device complexity and manufacturing cost increase
Solution Approach 1:
The patent extracts and removes the mask process from the manufacturing sequence by introducing a bank structure that defines emission areas through physical barriers rather than photomask patterns. The bank structure with its sidewalls and openings directly forms the emission areas without requiring subsequent mask processes, thereby simplifying the overall manufacturing process while maintaining precision.
Solution Approach 2:
The bank structure is divided into multiple functional segments: the bank layer forming sidewalls, the openings defining emission areas, and the through portions enabling electrical connections. This segmentation allows each component to perform its specific function independently, eliminating the need for a unified mask process while maintaining manufacturing precision.
2Productivity
If separate light emitting elements are formed without a mask process, then manufacturing efficiency is improved, but reliability concerns arise due to potential gas discharge
Solution Approach 1:
The bank structure serves as an intermediary element between the power connection electrode and the emission areas. It physically separates and isolates different functional regions, preventing gas discharge from affecting adjacent components. The bank structure's sidewalls and openings act as barriers that contain potential gas generation within specific zones, thereby maintaining reliability while enabling maskless manufacturing.
Solution Approach 2:
The bank structure is designed in advance to prevent gas discharge issues before they can occur. By incorporating the bank structure with its isolating sidewalls and controlled openings during the formation of light emitting elements, the design proactively counteracts potential gas discharge problems, ensuring reliability without requiring subsequent corrective measures.
3Ease of manufacture
If pad portion is made of same material as display area structure, then manufacturing simplicity is improved, but electrical connection reliability deteriorates
Solution Approach 1:
The pad portion is given different material properties in specific locations to ensure electrical connectivity. While the pad portion may use the same base material as the display area structure, local variations in material composition or properties are introduced at critical interfaces to guarantee reliable electrical connections. This allows manufacturing simplicity to be maintained while addressing reliability concerns through localized material differentiation.
Data Source
AI summary
A display device includes: a display area and a non-display area; anode electrodes in the display area; an inorganic insulating layer on the anode electrodes; a bank structure on the inorganic insulating layer, and including openings overlapping with the anode electrodes; light emitting layers on the anode electrodes and in the openings; cathode electrodes on the light emitting layers and in the openings; a first power line in the non-display area; and a power connection electrode including through portions partially overlapping with the first power line, and between the first power line and the display area. The bank structure includes: hole patterns on the power connection electrode in the non-display area, and overlapping with the through portions; a first bank layer; and a second bank layer on the first bank layer. The second bank layer includes a tip protruding from a sidewall of the first bank layer.