AMOLED Driving TFT Gate Electrode Stacking for Aperture Ratio
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Active matrix organic light emitting diode (AMOLED) displays face challenges in achieving precise gray level control and increasing the pixel aperture ratio due to the area occupied by connection circuitry between thin film transistors, which limits the display's efficiency and image quality.
Innovation Solution
The solution involves a driving TFT with its gate electrode disposed over an interlayer dielectric (ILD) rather than a gate insulator layer, allowing direct electrical connection to the circuit switching TFT, reducing the area occupied by connection circuitry and increasing the pixel aperture ratio, while also enhancing gray level control by increasing the voltage range applied to the gate electrode.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If connection circuitry between TFTs is placed in the conventional configuration, then the structural integrity and electrical connection are maintained, but the pixel aperture ratio is reduced due to the area occupied by connection circuitry
Solution Approach 1:
The first gate electrode is positioned in a different vertical layer (above the ILD) rather than in the same layer as the second gate electrode, creating a three-dimensional stacked configuration. This dimensional change allows electrical connection between TFTs without requiring lateral space for connection circuitry, thereby increasing the pixel aperture ratio while maintaining structural integrity.
2Measurement precision
If the gate electrode is placed closer to the channel, then the device structure is simpler, but the voltage range applied to the gate electrode is limited, reducing gray level control precision
Solution Approach 1:
By increasing the separation distance between the first gate electrode and the first channel through the ILD layer, the electrical characteristics of the TFT are modified. This parameter change enables a wider voltage range to be applied to the gate electrode, which directly improves the precision of gray level control in the AMOLED display.
Data Source
AI summary
Devices and methods for increasing the aperture ratio and providing more precise gray level control to pixels in an active matrix organic light emitting diode (AMOLED) display are provided. By way of example, one embodiment includes disposing a gate insulator and an interlayer dielectric material between a gate electrode of a thin-film transistor of a driving circuit and a channel of the thin-film transistor. The improved structure of the driving circuit facilitates a higher voltage range for controlling the gray level of the pixels, and may increase the aperture ratio of the pixels.