OLED Pixel Circuit Using Oxide and Silicon Transistors for Low Flicker
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Solution Overview
Problem
Existing OLED display devices face challenges in achieving transistors with small leakage current, high on/off ratio, low hysteresis, wide driving range, and high charge mobility, while also requiring minimal masks in manufacturing, which affects display quality and efficiency.
Innovation Solution
The use of specific transistor configurations, including bottom gate oxide transistors for driving and switching, and top gate oxide transistors with polysilicon emission control transistors, optimized for low leakage current, high on/off ratio, and wide driving range, along with a reduced number of masks in the manufacturing process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional transistor configurations are used in OLED display devices, then the manufacturing process is simpler, but the leakage current is high and the on/off ratio is low
Solution Approach 1:
The transistor gate is divided into two separate gates (first gate electrode and second gate electrode) positioned at different heights, allowing independent control of threshold voltage and channel formation. This segmentation enables the transistor to achieve high on/off ratio while maintaining manageable manufacturing complexity through modular design
Solution Approach 2:
The patent introduces a vertical dimension by positioning gate electrodes at different heights above the semiconductor layer, creating a three-dimensional gate structure. This dimensional change allows simultaneous optimization of electrical characteristics (low leakage, high on/off ratio) without significantly complicating the planar manufacturing process
2Adaptability or versatility
If conventional transistor configurations are used, then device structure is simpler, but hysteresis is large and driving range is limited
Solution Approach 1:
The dual-gate structure enables dynamic adjustment of transistor characteristics by independently controlling the first and second gate electrodes. This dynamic control allows the transistor to adapt to different driving conditions, reducing hysteresis and expanding the driving range while maintaining a structured design that doesn't overly complicate manufacturing
3Reliability
If more masks are used in manufacturing heterogeneous transistors, then transistor characteristics can be optimized, but the manufacturing process becomes more complex
Solution Approach 1:
The patent merges the formation of source and drain electrodes into a single conductive layer that is patterned once to create both electrodes simultaneously. This merging reduces the number of masking steps required while still achieving the optimized transistor characteristics needed for high-performance display devices
4Use of energy by moving object
If transistor leakage current is not controlled, then manufacturing is easier, but power consumption increases and display quality deteriorates
Solution Approach 1:
The dual-gate structure is designed to establish optimal threshold voltage and channel formation before the transistor begins operation. By pre-configuring the gate structure to control leakage current, the transistor achieves low power consumption without requiring complex additional control mechanisms during operation
Data Source
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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.