OLED Pixel Circuit Using Mixed Transistor Types for Low Leakage
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current OLED display devices face challenges in achieving optimal transistor performance, including high leakage current, narrow driving range, and reliability issues, which affect display quality and power consumption.
Innovation Solution
The display device incorporates a bottom-gate oxide transistor as the driving transistor with small hysteresis and wide driving range, a top-gate oxide transistor as the switching transistor with low leakage current and high on/off ratio, and a polysilicon emission control transistor with high charge mobility and reliability, along with a specific manufacturing method that minimizes the number of required masks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a transistor with high mobility is used to drive a high-resolution display, then display resolution and brightness can be improved, but the transistor requires a large gate width which increases pixel area and reduces display aperture ratio
Solution Approach 1:
The patent applies local quality by using different semiconductor materials in different transistor types within the same pixel circuit. Specifically, the drive transistor uses a semiconductor layer with high mobility (e.g., oxide semiconductor or silicon-based) to provide sufficient driving capability, while the switching transistor uses a different semiconductor material optimized for its specific function. This localized material selection allows each transistor to be optimized for its role without requiring all transistors to have large dimensions, thereby reducing overall pixel area while maintaining display brightness.
2Power
If a transistor with large gate width is used to achieve sufficient driving capability, then display brightness can be maintained, but the aperture ratio decreases and display quality deteriorates
Solution Approach 1:
The patent employs parameter changes by varying the mobility parameter of semiconductor materials used in different transistor types. The drive transistor utilizes a semiconductor layer with higher mobility (such as oxide semiconductor or silicon-based material) to achieve sufficient driving capability with a smaller gate width. This parameter optimization allows the transistor to provide adequate current drive for the display without occupying excessive pixel area, thereby maintaining both driving capability and display quality.
3Ease of manufacture
If conventional transistor structures are used, then manufacturing processes are simpler, but achieving high mobility requires large device dimensions which reduce display performance
Solution Approach 1:
The patent utilizes composite materials by combining different semiconductor materials (oxide semiconductor and silicon-based semiconductor) in different transistor types within the same display device. This composite approach allows each transistor to be optimized for its specific function using the most suitable material, achieving high mobility and superior display performance without significantly complicating the manufacturing process, as both material types can be integrated using established semiconductor fabrication techniques.
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 configuration results in a display device with improved transistor performance, reducing leakage current, enhancing display quality, and minimizing power consumption while maintaining high reliability and resolution.
Implementation Method 1
a light-emitting diode element (EML) electrically connected to at least one of the first transistor and the third transistor
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A display device includes a substrate and a pixel disposed on the substrate. The pixel includes a first transistor, a second transistor electrically connected to the first transistor, a third transistor electrically connected to the first transistor, and a light-emitting diode element electrically connected to at least one of the first transistor and the third transistor. The first transistor includes a first semiconductor member and a first gate electrode. The first semiconductor member includes an oxide semiconductor material. The first gate electrode is disposed between the first semiconductor member and the substrate. The second transistor includes a second semiconductor member and a second gate electrode. The second semiconductor member includes the oxide semiconductor material. The second semiconductor member is disposed between the second gate electrode and the substrate. The third transistor includes a third semiconductor member including silicon.