Vertical Channel TFT Substrate for OLED Opening Ratio
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Solution Overview
Problem
High-resolution display apparatuses face issues with low brightness and high power consumption due to a relatively small opening ratio, which is a result of the limited design of thin film transistors in organic light-emitting display devices.
Innovation Solution
A thin film transistor (TFT) substrate design featuring a vertical channel structure with overlapping electrodes and a semiconductor layer, along with a method of manufacturing that includes forming a lower electrode, insulating layers, and a gate electrode in a shared mask process, optimizing the channel length and increasing the opening ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If high resolution display apparatus is designed with small size, then resolution and pixel integrity are improved, but brightness decreases and power consumption increases due to small opening ratio
Solution Approach 1:
The patent transitions from a planar channel structure to a vertical channel structure, changing the dimensional orientation of the semiconductor layer and electrode arrangement. This vertical configuration allows the channel to extend in the thickness direction rather than the planar direction, effectively reducing the footprint area of the TFT while maintaining functional performance, thereby increasing the opening ratio and improving brightness without sacrificing resolution
2Measurement precision
If high resolution display apparatus is designed with small size, then resolution and pixel integrity are improved, but power consumption increases due to small opening ratio
Solution Approach 1:
By reconfiguring the channel from horizontal to vertical orientation, the patent reduces the area occupied by the TFT in the pixel plane. This dimensional change increases the opening ratio, allowing more light to reach the organic light-emitting layer and reducing the energy required to achieve the same display brightness, thereby lowering power consumption while maintaining high resolution
3Ease of manufacture
If conventional TFT structure is used, then manufacturing process is simple, but opening ratio is limited due to TFT area occupation
Solution Approach 1:
The patent maintains manufacturing simplicity by using sequential layer deposition processes similar to conventional TFTs, while achieving higher opening ratios through the vertical channel configuration. The vertical structure allows the source and drain electrodes to be positioned at different heights, reducing their planar overlap and minimizing the TFT footprint without complicating the manufacturing sequence
Solution Approach 2:
The patent segments the channel into vertical sections with the semiconductor layer extending in the thickness direction, allowing the source and drain regions to be separated in the vertical dimension. This segmentation reduces the horizontal space required for the channel, increasing the opening ratio while maintaining a relatively simple manufacturing process through sequential layer formation
Data Source
AI summary
A thin film transistor (TFT) substrate includes a substrate and a first electrode disposed on the substrate. The first electrode is one of a source electrode and a drain electrode. The TFT further includes a first insulating layer disposed on the first electrode and a second electrode disposed on the first insulating layer. The second electrode is the other one of the source electrode and the drain electrode. The TFT additionally includes a semiconductor layer disposed on the first electrode, the first insulating layer, and the second electrode. The TFT further includes a second insulating layer disposed on the semiconductor layer. The TFT additionally includes a gate electrode disposed on the second insulating layer and overlapping the semiconductor layer. The TFT further includes a pixel electrode that includes a same material as the gate electrode and is electrically connected to the second electrode.