OLED Display TFT Surface Topography for Fast Switching and Grayscale
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Solution Overview
Problem
The manufacturing process of organic light emitting display devices is complicated and costly due to the need for different semiconductor materials and structures for thin film transistors with varying electrical characteristics in pixels and gate driving circuit units, leading to non-uniform operation and fast switching characteristics.
Innovation Solution
The organic light emitting display apparatus employs a substrate with distinct portions for different thin film transistors, where one portion features a planarized polycrystalline semiconductor pattern and another with an oxide semiconductor pattern having protrusions, ensuring uniform operation characteristics and rich grayscale expression.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If different semiconductor materials and structures are used for thin film transistors in pixels and gate driving circuit units to achieve different electrical characteristics, then the electrical characteristics can be optimized for specific functions, but the manufacturing process becomes complicated and manufacturing cost increases
Solution Approach 1:
The patent applies local quality by creating different surface topographies in different regions of the same semiconductor layer. The pixel region has a planarized surface while the gate driving circuit region has protrusions, allowing each region to have optimized electrical characteristics without using different semiconductor materials. This resolves the contradiction by achieving functional differentiation through surface morphology rather than material composition.
Solution Approach 2:
The patent changes the surface topology parameter of the semiconductor layer to achieve different electrical characteristics. By planarizing the pixel region and creating protrusions in the gate driving circuit region, the patent optimizes carrier transport and threshold voltage characteristics for each function without complicating the manufacturing process with multiple material systems.
2Reliability
If different semiconductor materials are used for thin film transistors in pixels and gate driving circuit units, then uniform operation characteristics can be achieved, but the manufacturing process complexity and cost increase
Solution Approach 1:
The patent uses local quality by applying different surface treatments to different regions of the same oxide semiconductor layer. The pixel region is planarized for uniform operation while the gate driving circuit region retains or develops protrusions for optimized switching characteristics, achieving regional performance differentiation without material complexity.
Solution Approach 2:
The patent employs a single oxide semiconductor material for all thin film transistors in both pixel and gate driving circuit regions, making the material system universal. The different operational characteristics are achieved through surface topology control rather than material selection, simplifying the manufacturing process while maintaining functional differentiation.
3Speed
If a planarized polycrystalline semiconductor pattern is used, then fast switching characteristics are achieved, but grayscale expression capability is reduced
Solution Approach 1:
The patent applies local quality by planarizing only the pixel region where grayscale expression is critical, while allowing the gate driving circuit region to have protrusions for fast switching. This regional differentiation resolves the contradiction by optimizing each region for its primary function without compromising the other.
Solution Approach 2:
The patent segments the semiconductor layer surface treatment into distinct regions: planarized pixel regions for grayscale control and protrusion-rich gate driving regions for fast switching. This segmentation allows each region to independently optimize its electrical characteristics without affecting the other region's performance.
Data Source
AI summary
An organic light emitting display apparatus is disclosed that comprises a substrate including a first portion and a second portion; a first thin film transistor having a first polycrystalline semiconductor pattern, the first thin film transistor on the first portion of the substrate; a second thin film transistor having a first oxide semiconductor pattern, the second thin film transistor on the second portion of the substrate; and an organic light emitting device configured to emit light, the organic light emitting device connected to the second thin film transistor; wherein the first polycrystalline semiconductor pattern includes a surface that is planarized and the first oxide semiconductor pattern includes a surface that includes a plurality of protrusions.