OLED Anode Segmentation for Reflectivity and Resistance
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Solution Overview
Problem
Conventional OLED devices face issues with optical property degradation due to simultaneous exposure of the reflective layer and anode to electrolyte solutions, and increased resistance when using equally thick anodes for top and bottom-emitting devices, which affects brightness and reliability.
Innovation Solution
The OLED device employs a stacked structure with a lower anode and a reflective layer pattern in one region, and a double or triple layered anode structure in another region, using a thicker lower anode and a thinner upper anode, with a reflective layer of silver to enhance reflectivity and prevent short circuits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a reflective layer and anode are formed in a stacked structure for top-emitting OLED, then the device achieves high aperture ratio and miniaturization, but the reflective layer and anode are simultaneously exposed to electrolyte solutions causing optical property degradation
Solution Approach 1:
The patent divides the anode structure into separate regions: a first anode region with a stacked structure (reflective layer + anode) for top-emitting OLED, and a second anode region with only anode for bottom-emitting OLED. This segmentation allows each region to be optimized independently, preventing the reflective layer from being exposed to electrolyte solutions in the bottom-emitting region while maintaining the benefits of the stacked structure in the top-emitting region.
Solution Approach 2:
The patent applies different structural configurations to different regions of the OLED device. The first anode region uses a stacked structure with reflective layer for top-emitting functionality, while the second anode region uses a simple anode structure for bottom-emitting functionality. This local quality approach ensures that each region has the optimal structure for its specific function, avoiding optical property degradation where it would occur.
2Ease of manufacture
If equally thick anodes are used for both top-emitting and bottom-emitting OLED devices, then manufacturing is simplified, but resistance increases affecting brightness and reliability
Solution Approach 1:
The patent specifies different thickness requirements for anodes in different regions: the first anode in the top-emitting region has a thickness of 50-200 nm optimized for that configuration, while the second anode in the bottom-emitting region has a thickness of 100-300 nm optimized for its configuration. This local quality approach allows each anode to have the optimal thickness for its specific function, reducing resistance and improving brightness while maintaining manufacturing feasibility through standardized processes.
3Illumination intensity
If a reflective layer is formed to create top-emitting OLED, then aperture ratio is improved, but the device cannot achieve dual top and bottom emission functionality
Solution Approach 1:
The patent segments the OLED device into distinct first and second regions with different emission functionalities. The first region is configured for top-emitting operation with a reflective layer, while the second region is configured for bottom-emitting operation without a reflective layer. This segmentation enables the single device to achieve both top and bottom emission capabilities simultaneously, enhancing versatility while maintaining high aperture ratio in the top-emitting region.
Solution Approach 2:
The patent creates a universal OLED device structure that can perform multiple functions: top-emitting display, bottom-emitting display, and dual-display functionality. By incorporating both a first anode region with stacked structure and a second anode region with simple structure, the device achieves multi-functionality, allowing it to serve as both primary and secondary display windows in applications like portable telephones.
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 improves optical properties, reduces resistance, and enhances the reliability of OLED devices by maintaining brightness and luminous efficiency while preventing short circuits and optical property degradation.
Implementation Method 1
A reflective layer may be formed of a metal having high reflectivity, such as aluminum (Al), molybdenum (Mo), titanium (Ti), gold (Au), silver (Ag)... to enhance reflectivity
Implementation Method 2
an OLED device is an emissive display device that emits light by electrically exciting fluorescent organic compounds
Data Source
AI summary
An organic light emitting display device including a thin film transistor in first and second regions on a transparent insulating substrate, a lower anode coupled to the thin film transistor, a reflective layer pattern formed on the lower anode in the first region, an upper anode formed on the reflective layer pattern in the first region and on the lower anode in the second region, and an organic layer formed on the upper anode in the first and second regions.