Auxiliary Electrode via Inhibiting Layer for OLED Resistance
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Solution Overview
Problem
Organic light emitting display apparatuses face issues with high electrode resistances leading to increased power consumption and luminance non-uniformity, particularly in large-area displays.
Innovation Solution
The solution involves forming a metal formation inhibiting layer on top of the cathode electrode with a high resistance and connecting an auxiliary electrode to it, which minimizes the sheet resistance of the cathode electrode and voltage drop in power supply wiring, thereby enhancing the display apparatus' reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional electrode structures are used in large-area displays, then manufacturing is simpler, but electrode resistance increases leading to higher power consumption and luminance non-uniformity
Solution Approach 1:
The electrode structure is segmented into multiple functional layers: a base electrode layer, an auxiliary electrode layer with through-holes, and a reflective electrode layer. This segmentation allows each layer to contribute differently to electrical conduction, with the auxiliary electrode providing additional conduction paths through the insulating layers, thereby reducing overall electrode resistance and improving luminance uniformity across large display areas.
Solution Approach 2:
A reflective electrode layer is introduced as an intermediary component between the auxiliary electrode and the organic light-emitting layer. This reflective electrode serves dual functions: it provides an additional electrical conduction path to reduce resistance, and it reflects light to improve display efficiency. The intermediary layer enables simultaneous achievement of low resistance and high luminance uniformity without directly modifying the base electrode structure.
2Reliability
If thicker electrode layers are used to reduce resistance, then power consumption decreases, but device complexity and manufacturing difficulty increase
Solution Approach 1:
The auxiliary electrode is designed with a specific pattern of through-holes rather than being a continuous solid layer. This local quality approach allows electrical conduction to be enhanced at critical locations where resistance is highest, while maintaining transparency and light emission in other areas. The through-holes are strategically positioned to provide conduction paths without requiring the entire electrode layer to be thick or continuous, thus reducing overall device complexity.
Solution Approach 2:
The electrode system employs a composite structure combining conductive metal layers (such as aluminum or silver) with insulating and reflective layers. The auxiliary electrode layer contains through-holes that expose the underlying reflective electrode, creating a composite structure that leverages the high conductivity of metal, the insulation properties of dielectric layers, and the reflectivity of the reflective electrode. This composite approach achieves superior conductivity without requiring any single layer to be excessively thick or complex.
3Reliability
If additional auxiliary electrodes and metal formation inhibiting layers are added, then luminance uniformity improves, but manufacturing precision requirements increase
Solution Approach 1:
The auxiliary electrode is designed to create equipotential regions across the display area by providing multiple conduction paths through the insulating layers. By distributing the auxiliary electrode patterns strategically, the structure equalizes electrical potential across different regions of the display, compensating for voltage drops in large-area displays. This equipotential approach improves luminance uniformity without requiring extremely tight alignment tolerances, as the multiple conduction paths provide redundancy.
Solution Approach 2:
The metal formation inhibiting layer uses selective etching parameters and material properties to create the through-hole pattern in the auxiliary electrode. By controlling etch depth, etch selectivity ratios, and deposition conditions, the manufacturing process achieves the required precision through parameter optimization rather than relying solely on mechanical alignment. The through-holes are formed self-alignedly with the auxiliary electrode pattern, reducing the need for high-precision alignment between different layers.
Data Source
AI summary
An organic light emitting display apparatus according to an embodiment can include a display area configured to display images, a thin-film transistor disposed in the display area, at least one planarization layer disposed over the thin-film transistor and including at least one contact hole, a light emitting device disposed over the planarization layer and including a light emitting layer defining a first opening, a bank disposed in the first opening, a metal formation inhibiting layer disposed over the light emitting device and defining a second opening, and an auxiliary electrode disposed above the bank and in the second opening.