Segmented Common Layer Suppresses Lateral Leakage in OLED Pixels
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Solution Overview
Problem
In organic EL display devices, lateral leakage currents between pixels of different colors lead to unintended light emission, compromising display properties, as increasing the distance between vapor deposition patterns to prevent this reduces the pixel aperture ratio and hinders high-definition displays.
Innovation Solution
The display device incorporates a common layer separated in the direction between pixels of different colors, using the organic material's covering properties to limit the lateral leakage current, and the light emitting layers are designed to overlap only where necessary, ensuring light emission is confined to the intended pixel regions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the distance between vapor deposition patterns is increased to prevent lateral leakage currents, then lateral leakage current is suppressed, but the pixel aperture ratio decreases
Solution Approach 1:
The common layer is segmented into multiple regions (first region overlapping first pixel electrode, second region between first and third pixel electrodes, third region overlapping third pixel electrode) with the second region spaced apart from the first and third regions. This segmentation creates discontinuities in the common layer that block lateral leakage current paths between adjacent pixels of different colors, while allowing the pixel electrodes to maintain their original vapor deposition patterns and aperture ratios.
Solution Approach 2:
The common layer exhibits different structural qualities at different locations: it is continuous in regions overlapping pixel electrodes (first and third regions) to ensure proper electrical connection, but discontinuous in regions between pixel electrodes of different colors (second region spaced apart). This local variation in layer continuity selectively blocks lateral leakage current between different color pixels while maintaining electrical functionality within each pixel.
2Manufacturing precision
If the pixel aperture ratio is increased for high-definition display, then display definition is improved, but lateral leakage currents increase causing unintended light emission
Solution Approach 1:
The common layer is divided into separated regions with gaps between them, creating discontinuities that act as barriers to lateral leakage current. This allows pixel electrodes to be placed closer together (higher aperture ratio) while the segmented common layer prevents electrical leakage between adjacent pixels of different colors, thus enabling high-definition display without unintended light emission.
Solution Approach 2:
The organic insulating layer serves as an intermediary structure between pixel electrodes of different colors. The common layer is arranged to overlap this insulating layer in specific regions, and the spaced-apart second region of the common layer creates an insulating barrier that mediates the electrical interaction between adjacent pixels, blocking lateral leakage current while allowing the pixel structure to maintain high aperture ratio.
Data Source
AI summary
A display device includes a first pixel electrode on an insulating surface, a second pixel electrode spaced apart from the first pixel electrode in a first direction, a third pixel electrode spaced apart from the first pixel electrode in a second direction, an organic insulating layer overlapping a part of the first pixel electrode and a part of the second pixel electrode in the first direction, a first common layer on the first pixel electrode, the second pixel electrode, the third pixel electrode, and the organic insulating layer, a first light emitting layer on the first common layer and continuously overlapping the first pixel electrode, the second pixel electrode, and the organic insulating layer, a second light emitting layer on the first pixel electrode and overlapping the third light emitting layer, and a counter electrode on the first light emitting layer and the second light emitting layer.