Transparent Auxiliary Electrode for See-Through OLED
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Solution Overview
Problem
See-through organic light emitting display devices face challenges in maximizing the see-through region's transparency and transmissivity due to increased line resistance and voltage drop issues, particularly with the use of opaque metal auxiliary electrodes, which compromise luminance uniformity and transmissivity.
Innovation Solution
A transparent auxiliary electrode formed of transparent conductive oxide is disposed in the see-through region, minimizing parasitic capacitance and line resistance, and the organic light emitting layer is designed to cover the partition wall minimally, ensuring equal contact area between the cathode and auxiliary electrode, thereby enhancing luminance uniformity and transmissivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a transparent auxiliary electrode is used to reduce line resistance and improve voltage uniformity, then luminance uniformity is improved, but the area of the see-through region is reduced
Solution Approach 1:
The auxiliary electrode is positioned only in the non-see-through region, creating a local solution that reduces line resistance where needed without affecting the see-through region. This spatial differentiation allows the system to maintain luminance uniformity while preserving the transparency function of the see-through region.
2Illumination intensity
If the cathode is formed to have a very thin thickness to increase transmissivity, then transmissivity is improved, but line resistance of the cathode increases
Solution Approach 1:
The transparent auxiliary electrode acts as an intermediary that provides an additional current path. By connecting the voltage supply pad to the cathode through this auxiliary electrode, the system compensates for the high line resistance of the thin cathode, allowing the cathode to remain thin for high transmissivity while maintaining adequate current delivery.
3Measurement precision
If the distance from voltage supply pad to sub-pixel is increased to accommodate more sub-pixels, then resolution is improved, but voltage drop increases causing non-uniformity in luminance
Solution Approach 1:
The voltage supply path is segmented into multiple routes by introducing the transparent auxiliary electrode as an intermediate connection point. This segmentation creates parallel current paths that reduce the effective distance and resistance, allowing more sub-pixels to be accommodated while maintaining voltage uniformity across the display.
Data Source
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AI summary
A see-through organic light emitting display device including a light emitting region having a transparent anode, an organic light emitting layer, and a transparent cathode, and a see-through region having a transparent auxiliary electrode, which is configured to transmit external light. The transparent auxiliary electrode can be made from the same material as the transparent anode and separated from the transparent anode, and the transparent cathode extends into the see-through region so as to be electrically connected with the transparent auxiliary electrode.