Tandem OLED Aperture Ratio via Photolithography
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Solution Overview
Problem
Conventional display apparatuses face challenges in achieving high aperture ratios, high resolution, low power consumption, and reliable performance, particularly due to limitations in manufacturing methods using metal masks which result in low dimensional accuracy and increased power consumption.
Innovation Solution
The display apparatus employs a tandem structure with separate light-emitting devices emitting different colors, utilizing a photolithography method to form island-shaped light-emitting layers with a mask layer for protection, and an insulating layer to reduce damage and enhance reliability, allowing for closer pixel electrode spacing and higher aperture ratios.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If metal mask method is used for manufacturing, then light-emitting layers can be formed, but dimensional accuracy is low and power consumption is high
Solution Approach 1:
The patent replaces the mechanical metal mask method with a photolithography process. Instead of using physical metal masks to define patterns, the invention uses photoresist layers that are exposed to light through photomasks, followed by chemical development to create precise patterns. This substitution of mechanical masking with optical-chemical processes achieves higher dimensional accuracy and reduces power consumption associated with metal mask handling and alignment systems.
2Area of moving object
If pixel electrodes are spaced closer to increase aperture ratio, then display area increases, but manufacturing precision requirements increase
Solution Approach 1:
The photolithography process enables precise control of pixel electrode spacing by using optical exposure through photomasks with accurately defined patterns. The chemical development process creates sharp edges and consistent dimensions that are difficult to achieve with mechanical metal mask methods. This allows pixel electrodes to be spaced closer together with maintained precision, thereby increasing the aperture ratio.
Solution Approach 2:
The invention changes the manufacturing approach from mechanical to optical-chemical parameters. By controlling exposure time, light intensity, photoresist composition, and development conditions, the process achieves high precision in defining pixel electrode positions and dimensions, enabling closer spacing while maintaining manufacturing precision.
3Reliability
If tandem structure with multiple light-emitting units is used, then display quality improves, but device complexity increases
Solution Approach 1:
The patent merges multiple light-emitting units into a tandem structure where multiple organic light-emitting layers are stacked between a single pair of electrodes. This integration approach improves display quality by combining the emission characteristics of different organic compounds while maintaining a relatively simple overall device structure. The shared electrodes reduce the number of components compared to having separate devices for each light-emitting unit.
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 enables the production of display apparatuses with high aperture ratios, improved reliability, and reduced power consumption, achieving higher resolution and longer device lifetime while minimizing manufacturing complexities.
Implementation Method 1
By voltage application to this element, light emission can be obtained from the light-emitting organic compound
Data Source
AI summary
A display apparatus with a high aperture ratio is provided. The display apparatus includes first and second light-emitting devices, a first conductive layer, a second conductive layer, and a first insulating layer. The first light-emitting device includes a first pixel electrode, a first EL layer, and a common electrode over the first EL layer. The second light-emitting device includes a second pixel electrode, a second EL layer, and the common electrode over the second EL layer. The first conductive layer is provided over the common electrode. The first insulating layer is provided over the first conductive layer. The second conductive layer is provided over the first insulating layer. Any one or both of the first and second conductive layers overlap with a region interposed between the first EL layer and the second EL layer. One side surface of the first EL layer and one side surface of the second EL layer are provided to face each other. The first light-emitting device emits light of a color that is different from a color of light emitted from the second-light-emitting device. The first EL layer includes a first light-emitting unit, a first charge-generation layer, and a second light-emitting unit. The second EL layer includes a third light-emitting unit, a second charge-generation layer, and a fourth light-emitting unit.