Patterned Cathode Structure for Transparent OLED Transmittance
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Solution Overview
Problem
Existing transparent organic light emitting display devices have limited external-light transmittance due to the metal cathode, which restricts their application and performance.
Innovation Solution
The design includes a substrate with pixels having separate light emission and transmission regions, with a patterned cathode structure where the second electrode is only deposited on the third organic layer in the light emission region, and a method of manufacturing involving thin film transistors, island-shaped first electrodes, and specific organic layers to enhance transmittance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a metal cathode is used in the organic light emitting display device, then the device can maintain its light emission functionality, but the external-light transmittance is limited
Solution Approach 1:
The cathode is segmented into multiple regions: a first cathode region in the light emission region that emits light, and a second cathode region in the transmission region that transmits external light. This segmentation allows different parts of the cathode to have different functions, resolving the contradiction between light emission and light transmission.
Solution Approach 2:
Different regions of the cathode are given different properties: the first cathode region is designed for light emission with appropriate thickness and material composition, while the second cathode region is designed for light transmission with reduced thickness or different material composition. This local differentiation enables simultaneous achievement of both light emission functionality and high external-light transmittance.
2Illumination intensity
If the cathode is made transparent to improve transmittance, then external-light transmittance increases, but the manufacturing precision and uniformity deteriorate
Solution Approach 1:
The cathode manufacturing process is segmented into distinct steps for different regions. The first cathode region is formed with standard precision requirements, while the second cathode region is formed with adjusted parameters (reduced thickness or different deposition conditions) to achieve transparency without compromising overall manufacturing precision.
Solution Approach 2:
The thickness and material composition parameters of the cathode are changed locally in different regions. By controlling the deposition thickness and material properties differently in the light emission region versus the transmission region, the patent achieves high transmittance in the transmission region while maintaining manufacturing precision through controlled parameter variations.
3Ease of manufacture
If the cathode structure is simplified to improve manufacturing ease, then manufacturing stability improves, but the light emission efficiency and transmittance control worsen
Solution Approach 1:
The cathode is designed as a multi-region structure that can be manufactured using standard thin-film deposition techniques. By segmenting the cathode into distinct regions with different properties, the patent maintains manufacturing stability through conventional processes while achieving controlled light emission efficiency and transmittance characteristics in each region.
Solution Approach 2:
The cathode structure incorporates local quality variations where different regions have different thicknesses or material compositions. This allows the manufacturing process to remain stable and straightforward while the local variations in the cathode structure provide precise control over light emission efficiency in the emission region and transmittance in the transmission region.
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
This configuration significantly increases external-light transmittance while maintaining the display's functionality, reducing distortion and improving manufacturing stability and uniformity of the cathode.
Implementation Method 1
each pixel having a first region configured to emit light
Data Source
AI summary
An organic light emitting display device includes a substrate, a plurality of pixels on the substrate having a first region configured to emit light and a second region configured to transmit external light, a plurality of pixel circuit units, a plurality of first electrodes, a first organic layer on the plurality of first electrodes, a second organic layer on the first organic layer, the second organic layer including an emission layer, a third organic layer on the second organic layer, the third organic layer being positioned in the first region and outside a central portion of the second region, and a second electrode having a first portion only on the third organic layer.