White Subpixel Electrode Spacing for OLED Short-Circuit Prevention
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Solution Overview
Problem
In organic light emitting display devices with a RGBW subpixel structure, the short vertical distance between the underlying wire and the first electrode of the white subpixel leads to increased susceptibility to short-circuiting or overcurrent due to impurities, causing potential device failure.
Innovation Solution
The white subpixel's first electrode is designed to be non-overlapping and spaced apart from the underlying wire, with a specific insulating film structure that includes both exposed and unexposed areas to reduce the risk of short-circuiting, while maintaining the white subpixel's smaller step difference and light emission characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the white subpixel uses a conventional structure with overlapping first electrode and underlying wire, then the manufacturing process is simpler, but the reliability decreases due to short-circuiting or overcurrent from impurities
Solution Approach 1:
The white subpixel structure is segmented into distinct regions: an exposed area where the first electrode contacts the insulating film, and a non-exposed area where the underlying wire is covered. This segmentation prevents direct contact between the first electrode and underlying wire, eliminating the short-circuiting problem while maintaining manufacturing feasibility through defined patterning regions.
Solution Approach 2:
The insulating film serves as an intermediary layer between the first electrode and the underlying wire. By configuring the insulating film to have both exposed and non-exposed areas, it mediates the interaction between electrodes, providing electrical isolation in the non-exposed area while allowing necessary contact in the exposed area, thus preventing harmful short-circuits.
2Reliability
If the first electrode is spaced apart from the underlying wire to prevent short-circuiting, then the reliability improves, but the manufacturing precision requirement increases
Solution Approach 1:
The insulating film is formed with pre-defined exposed and non-exposed areas before electrode deposition. This preliminary configuration of the insulating film structure establishes the spatial relationship between electrodes in advance, guiding subsequent electrode patterning and ensuring proper spacing without requiring high-precision alignment during electrode formation.
Solution Approach 2:
The insulating film exhibits different properties in different regions: in the exposed area, it allows electrode contact; in the non-exposed area, it provides electrical isolation. This local differentiation of the insulating film's functional properties enables reliable electrode isolation while simplifying manufacturing precision requirements through region-specific design.
3Use of energy by moving object
If the white subpixel maintains its smaller step difference structure, then the light emission efficiency is improved, but the susceptibility to impurity-induced short-circuiting increases
Solution Approach 1:
The white subpixel structure is differentiated into local regions with different protective characteristics. The non-exposed area provides enhanced protection against impurity-induced short-circuiting, while the exposed area maintains the necessary electrical connections. This local quality differentiation allows the white subpixel to retain its smaller step difference structure for efficient light emission while protecting against harmful impurity effects in critical isolation regions.
Solution Approach 2:
The potential harm of having a smaller step difference structure that increases susceptibility to short-circuiting is converted into a benefit by strategically configuring the insulating film's exposed and non-exposed areas. The smaller step difference maintains light emission efficiency, while the insulating film configuration compensates for the increased vulnerability by providing targeted electrical isolation where impurities are most likely to cause problems.
Data Source
AI summary
An organic light emitting display device comprises: a lower substrate; a underlying wire formed on the lower substrate; and red, green, and blue subpixels each comprising a transistor section formed on the lower substrate and an organic light emitting diode, wherein the white subpixel comprises a first electrode which is non-overlapped with the underlying wire and is spaced apart from the underlying wire.