Organic Light Emitting Display with Dual-Thickness Organic Layers
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Solution Overview
Problem
Organic light emitting display apparatuses face a trade-off between improving light efficiency through micro-cavity implementation and maintaining a wide color viewing angle, as micro-cavities enhance front brightness but degrade lateral brightness and color viewing angle characteristics.
Innovation Solution
The design incorporates two regions with different thicknesses within the organic layers of each sub-pixel, allowing for enhanced light efficiency in one region and improved color viewing angle in another without additional processes or components, by adjusting the thickness of the organic layers between the cathode and anode.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a micro-cavity is implemented to improve light efficiency, then front brightness is increased, but lateral brightness and color viewing angle are decreased
Solution Approach 1:
The organic light emitting display apparatus is divided into multiple sub-pixels (red, green, blue), and each sub-pixel is further segmented into a first region with a micro-cavity structure and a second region without the micro-cavity structure. This segmentation allows different regions to serve different functions: the first region enhances front brightness through the micro-cavity effect, while the second region maintains wide viewing angle characteristics
Solution Approach 2:
The micro-cavity structure is applied locally to specific regions (first regions) of specific sub-pixels rather than uniformly across the entire display. The thickness of organic layers in the micro-cavity region is precisely controlled to create constructive interference for forward-emitted light, while adjacent regions maintain different thickness characteristics to preserve lateral viewing properties
2Productivity
If the thickness of organic layers is adjusted to implement micro-cavity, then light efficiency is improved, but device complexity increases
Solution Approach 1:
The micro-cavity structure is integrated within the existing organic light emitting device architecture by adjusting the thickness of organic layers (hole injection layer, hole transport layer, electron transport layer, electron injection layer) that are already present in the device. No separate micro-cavity component is added; instead, the existing organic layers are configured to form the micro-cavity structure, thereby improving light efficiency without significantly increasing device complexity
Solution Approach 2:
The invention implements the micro-cavity effect by changing the thickness parameter of organic layers to a specific range (50-200 nm) that creates the desired optical interference effect. This parameter adjustment transforms the optical properties of the existing structure to achieve enhanced light efficiency without requiring fundamental structural changes
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 approach effectively balances light efficiency and color viewing angle, ensuring improved performance without increasing costs or complexity, by creating a micro-cavity in one region and optimizing the viewing angle in another through varying organic layer thicknesses.
Implementation Method 1
The micro-cavity allows light to be repeatedly reflected between two layers spaced from each other by an optical length, and, thus, the light having a specific wavelength is amplified through constructive interference.
Implementation Method 2
Although the cathode is light-transmissive, a part of the light emitted from the organic light-emission layer is reflected from the cathode toward an anode and reflected again from the anode. Thus, light is repeatedly reflected between the anode and the cathode.
Data Source
AI summary
An organic light emitting display apparatus includes a first electrode on a substrate and a plurality of organic layers on the first electrode and including a first region and a second region. The organic light emitting display apparatus further includes a second electrode on the plurality of organic layers. A thickness of the plurality of organic layers in the first region can be different from a thickness of the plurality of organic layers in the second region.