Dual-Active-Layer Display Panel for TFT Uniformity and Low Leakage
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Solution Overview
Problem
Low temperature poly-Si and oxide (LTPO) backplane technology faces issues of nonuniformity in thin film transistors (TFTs) and high cut-off current, leading to poor display quality and high production costs in large-scale displays, limiting its application to small and medium-scale devices.
Innovation Solution
A display panel design incorporating a hybrid driving circuit with amorphous oxide semiconductor transistors for switching and polycrystalline oxide semiconductor transistors for driving, separated by an interlayer insulating layer, to improve uniformity and reduce leakage current, using materials like indium gallium zinc oxide (IGZO) and indium zinc tin oxide (IZTO) for enhanced stability and mobility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If LTPO backplane technology is used in large-scale display products, then variable refresh rate and Always-on display can be realized, but nonuniformity in TFT characteristics occurs due to nonuniform LTPS
Solution Approach 1:
The patent divides the semiconductor material into two distinct segments: LTPS for switching transistors and IGZO for drive transistors. This segmentation allows each material to be optimized for its specific function, with LTPS providing high mobility for switching and IGZO providing low off-state current for drive transistors, thereby resolving the uniformity issue while maintaining advanced display features
Solution Approach 2:
Different semiconductor materials are applied to different locations based on functional requirements: LTPS is used specifically for switching transistors where high carrier mobility is critical, while IGZO is used for drive transistors where low cut-off current and uniformity are paramount. This local quality approach ensures optimal performance in each region without compromising overall uniformity
2Adaptability or versatility
If LTPO backplane technology is used, then advanced display features are achieved, but production cost increases
Solution Approach 1:
The patent changes the material parameter selection by introducing IGZO as an alternative to traditional LTPS for drive transistors. IGZO can be processed at lower temperatures and with simpler annealing processes compared to LTPS, reducing manufacturing complexity and cost while maintaining the advanced display features enabled by the dual-material approach
3Speed
If polysilicon semiconductor materials are used for driving TFTs, then high carrier mobility is achieved, but cut-off current increases
Solution Approach 1:
The patent applies different semiconductor materials to different transistor types based on their electrical characteristics: LTPS is used for switching transistors where high carrier mobility is essential for fast switching, while IGZO is used for drive transistors where low cut-off current is the primary requirement. This local quality differentiation resolves the contradiction by matching material properties to functional needs
Solution Approach 2:
The patent segments the transistor population into two groups with different semiconductor materials: switching transistors use LTPS for high speed operation, while drive transistors use IGZO for low leakage performance. This segmentation allows each material's strengths to be utilized in the appropriate context, eliminating the need to compromise between mobility and cut-off current in a single material system
Data Source
AI summary
A display panel and a display device are provided. The display panel includes a first transistor, a second transistor, and a first interlayer insulating layer between the first transistor and the second transistor. The first transistor includes a first active layer, and a material of the first active layer is an amorphous oxide semiconductor. The second transistor includes a second active layer, and a material of the second active layer is a polycrystalline oxide semiconductor.