Organic EL Pixel Electrode Offset for Short-Circuit Prevention
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Solution Overview
Problem
The existing methods for manufacturing organic electroluminescence (EL) display devices face challenges in achieving cost reduction while maintaining image quality, particularly due to the occurrence of electrical short-circuiting caused by thickness unevenness of the functional layer during film deposition, which is exacerbated by the need for additional inorganic layers to prevent short-circuiting.
Innovation Solution
The organic EL display device design features a pixel isolating film with apertures where the first electrode is partially or fully separated from the edge of the aperture, allowing the functional layer to form with reduced thickness unevenness and preventing electrical short-circuiting without the need for additional inorganic layers, thereby simplifying the manufacturing process and reducing costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a two-layer bank structure with inorganic material layer is added to prevent short-circuiting, then electrical short-circuiting is prevented, but the number of steps and parts increases and cost reduction becomes difficult
Solution Approach 1:
The invention extracts and eliminates the inorganic material layer from the bank structure, retaining only the organic pixel isolating film. By redesigning the aperture positioning and electrode placement, the patent achieves short-circuit prevention without the additional inorganic layer, thereby reducing the number of manufacturing steps and parts while maintaining reliability
Solution Approach 2:
The invention segments the bank structure into distinct functional zones: the pixel isolating film with apertures, the lower electrode positioned away from aperture edges, and the functional layer. This segmentation allows each component to perform its specific function independently, with the lower electrode positioned in a safe zone that prevents short-circuiting without requiring an additional inorganic barrier layer
2Area of stationary object
If the first electrode is positioned close to the aperture edge to maximize light emitting area, then the aperture ratio increases, but thickness unevenness of the functional layer occurs and electrical short-circuiting happens
Solution Approach 1:
The invention resolves the spatial conflict between maximizing light emitting area and ensuring functional layer uniformity by introducing a positional offset in the horizontal dimension. The lower electrode is deliberately positioned away from the aperture edge, creating a spatial separation that prevents the functional layer thinning zone from overlapping with the electrode, thus maintaining both large aperture ratio and uniform film thickness
Data Source
AI summary
An organic electroluminescence display device includes a pixel isolating film that is provided over a substrate and has a plurality of apertures, and a plurality of pixels provided corresponding to the plurality of apertures. Each of the plurality of pixels has a first electrode, a functional layer including at least an organic light emitting layer, and a second electrode sequentially from the side of the substrate, and part or whole of the first electrode is separate from an edge part of the aperture on the side of the substrate.