Transparent OLED Cathode Windows for External Light Transmittance
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Solution Overview
Problem
The transmittance of transparent organic light emitting display devices is limited due to the metal cathode, hindering the visibility of external images.
Innovation Solution
A transparent organic light emitting display device design with transmission windows in the second electrode, allowing external light to pass through regions devoid of thin film transistors and other devices, and a method to form these windows using a simple mask process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a metal cathode is used in transparent organic light emitting display devices, then the device can be manufactured with conventional materials and processes, but the transmittance of external light is limited
Solution Approach 1:
The cathode is segmented into multiple discrete metal islands positioned over the organic light emitting layer, rather than forming a continuous layer. This segmentation allows light to pass through the gaps between islands, achieving transmittance while maintaining electrical functionality for device manufacture
Solution Approach 2:
The cathode structure transitions from uniform continuous coverage to non-uniform distributed islands with varying sizes and positions. This local quality variation optimizes both light transmittance in gap regions and electrical contact in island regions, resolving the contradiction between manufacturability and transmittance
2Illumination intensity
If transmission windows are formed in the second electrode, then external light transmittance is enhanced, but the manufacturing process becomes more complex
Solution Approach 1:
The transmission window formation is merged with the existing metal cathode deposition process. The same deposition equipment and techniques used for creating the metal islands are utilized to define transmission regions, eliminating the need for separate window formation steps and masks, thus enhancing transmittance without significantly increasing manufacturing complexity
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enhances external light transmittance, enabling clear observation of external images while maintaining image display functionality.
Implementation Method 1
an organic light emitting display device
Data Source
AI summary
An organic light emitting display device having high transmittance with respect to external light and a method of manufacturing the same. The organic light emitting display device includes a substrate; a plurality of pixels formed on the substrate, each of the pixels including a first region that emits light and a second region that transmits external light; a plurality of thin film transistors disposed in the first region of each pixel; a plurality of first electrodes disposed in the first region of each pixel and electrically connected to the thin film transistors, respectively; a second electrode formed opposite to the plurality of first electrodes and comprising a plurality of transmission windows corresponding to the second regions; and an organic layer formed between the first electrodes and the second electrode. The transmission windows can be formed in the second electrode, that is, a cathode.