OLED TFT Double Gate Oxide Structure Aperture Ratio
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The existing OLED display devices using a 3T1C pixel circuit with top gate self-aligned amorphous oxide TFTs require a light-shielding layer to protect against ambient light, which adds an additional yellow light process but does not increase the on-state current of the device.
Innovation Solution
The OLED display device incorporates a double gate oxide thin film transistor and top gate self-aligned oxide thin film transistors, with a specific circuit configuration and manufacturing method using multiple photomasks to reduce channel width and parasitic effects, thereby increasing the pixel aperture ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a light-shielding layer is deposited to protect the TFT device from ambient light, then the device is protected from light-induced threshold voltage reduction, but an additional yellow light process is added and the on-state current is not increased
Solution Approach 1:
The patent combines the light-shielding function with the existing bottom gate electrode structure. The bottom gate electrode serves dual purposes: as the control electrode for the TFT and as the light-shielding layer. This integration eliminates the need for a separate light-shielding layer deposition process, thereby removing the additional yellow light process while maintaining protection from ambient light.
Solution Approach 2:
The bottom gate electrode is designed to perform multiple functions simultaneously: electrical control of the TFT channel and optical shielding against ambient light. By making the bottom gate electrode multi-functional, the patent avoids adding extra components or processes, thus reducing device complexity while ensuring reliable protection.
2Area of stationary object
If the channel width is reduced to increase pixel aperture ratio, then the display performance is improved, but the on-state current of the TFT device decreases
Solution Approach 1:
The patent transitions from a single top gate configuration to a dual gate structure with both top gate and bottom gate electrodes. This dimensional change in the gate architecture allows independent optimization: the channel width can be reduced to increase aperture ratio while the dual gate structure compensates for the current loss by enhancing field effect and carrier control, thereby maintaining adequate on-state current.
Solution Approach 2:
The patent changes the electrical parameters of the TFT by introducing a bottom gate electrode that provides additional gate control. This allows the device to achieve higher on-state current density with a narrower channel by optimizing the combined gate voltage from both top and bottom gates, thus resolving the trade-off between aperture ratio and current drive capability.
Data Source
AI summary
An OLED display device including an OLED pixel driving circuit is provided. A driving thin film transistor in the OLED pixel driving circuit is configured as a double gate oxide thin film transistor, and a switch thin film transistor is configured as a top gate self-aligned oxide thin film transistor. A manufacturing method of a TFT array substrate is also provided, and the TFT array substrate is used for preparing the OLED display device.