Oxide TFT Pixel Structure Using Emitter Overlap for Higher Aperture
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Solution Overview
Problem
Existing light-emitting display devices face challenges in achieving a high aperture ratio, which is crucial for high-definition displays, particularly in 3D and 4K2K applications, due to the limitations of thin film transistors made from amorphous silicon and crystalline silicon.
Innovation Solution
The use of an oxide semiconductor layer in the thin film transistor, extended beyond the edge of the wiring region, overlapping with the light-emitting element, and connected through specific wiring configurations to enhance the aperture ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If amorphous silicon is used for thin film transistor channel, then the transistor can be formed over larger glass substrate, but the field effect mobility is low
Solution Approach 1:
The patent changes the material parameter of the thin film transistor channel from amorphous silicon to oxide semiconductor, which fundamentally alters the electrical properties and achieves high field effect mobility while maintaining compatibility with large-area glass substrates
2Speed
If oxide semiconductor is used for thin film transistor channel, then the field effect mobility is high, but the aperture ratio is reduced due to wiring layout requirements
Solution Approach 1:
The patent extends the oxide semiconductor layer in the vertical dimension beyond the wiring region, allowing the semiconductor layer to overlap with the light-emitting element in the vertical direction. This dimensional extension enables the aperture ratio to be increased without compromising the transistor's electrical performance
Solution Approach 2:
The oxide semiconductor layer is segmented into different functional regions: a first region overlapping the scan line wiring for electrical connection, and a second region extending beyond the wiring edge to overlap the light-emitting element, optimizing both electrical and optical functions
Data Source
AI summary
An object is to provide a light-emitting display device in which a pixel including a thin film transistor using an oxide semiconductor has a high aperture ratio. The light-emitting display device includes a plurality of pixels each including a thin film transistor and a light-emitting element. The pixel is electrically connected to a first wiring functioning as a scan line. The thin film transistor includes an oxide semiconductor layer over the first wiring with a gate insulating film therebetween. The oxide semiconductor layer is extended beyond the edge of a region where the first wiring is provided. The light-emitting element and the oxide semiconductor layer overlap with each other.