OLED Transistor Active Layer Oxygen Content for Sub-threshold Swing Control
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Solution Overview
Problem
In existing organic light-emitting display devices, the sub-threshold swings of the transfer characteristic curves for switching and driving thin film field-effect transistors are almost identical, failing to meet the distinct electric requirements for rapid switching and slow gray scale regulation.
Innovation Solution
The implementation of a switching thin film field-effect transistor with a first active layer to reduce sub-threshold swing and a driving thin film field-effect transistor with a second active layer to increase sub-threshold swing, where the oxygen content of the second active layer is greater than that of the first, allowing for quick switching and slow gray scale regulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the switching thin film field-effect transistor uses a standard active layer structure, then the device structure is simple and manufacturing is easy, but the sub-threshold swing is large which prevents quick switching
Solution Approach 1:
The active layer is segmented into multiple sub-layers (first active layer, second active layer, third active layer) with different compositions and functions. The first active layer provides high mobility for fast switching, the second active layer controls sub-threshold swing, and the third active layer provides additional channel control, allowing each layer to optimize for its specific function rather than requiring a single complex structure
Solution Approach 2:
Different regions of the active layer are given different local qualities through varying oxygen content and composition. The first active layer has lower oxygen content for high electron mobility, while the second active layer has higher oxygen content for better sub-threshold swing characteristics, allowing each region to perform its specific function optimally
2Speed
If the driving thin film field-effect transistor uses a standard active layer structure, then the device structure is simple and manufacturing is easy, but the sub-threshold swing is small which prevents slow gray scale regulation
Solution Approach 1:
The driving transistor's active layer incorporates a second active layer with specifically controlled higher oxygen content to increase sub-threshold swing, enabling slow gray scale regulation while maintaining overall structural compatibility with standard manufacturing processes
Solution Approach 2:
The oxygen content parameter is changed in the second active layer to achieve the desired sub-threshold swing characteristics. By controlling the oxygen concentration during deposition, the sub-threshold swing is increased to enable precise gray scale regulation without requiring completely different device architecture
3Adaptability or versatility
If both transistors use identical active layer structures, then manufacturing precision is maintained and production is efficient, but both transistors have identical sub-threshold swings which cannot meet different electric requirements
Solution Approach 1:
The patent applies local quality by creating different active layer compositions in specific regions. The first active layer has lower oxygen content for high mobility applications, while the second active layer has higher oxygen content for sub-threshold swing control, allowing electrical characteristic differentiation while using the same basic deposition process
Solution Approach 2:
By changing the oxygen content parameter during the deposition process for different active layers, the patent achieves different electrical characteristics (sub-threshold swing and mobility) while maintaining manufacturing consistency. The same IGZO material system is used, but with controlled compositional variations
Data Source
AI summary
Disclosed are an organic light-emitting display device and a method for manufacturing the same. In the organic light-emitting display device, a switching thin film field-effect transistor comprises a first active layer for reducing a sub-threshold swing of a transfer characteristic curve of the switching thin film field-effect transistor; and a driving thin film field-effect transistor comprises a second active layer for increasing a sub-threshold swing of a transfer characteristic curve of the drive film field-effect transistor.