Liquid Crystal Gate Insulator for Low-Temperature Organic Transistors
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Solution Overview
Problem
The challenge is to develop a transistor with high hole mobility and a cost-effective manufacturing process for organic field effect transistors, as existing gate insulators like silicon oxide are difficult to apply due to the need for high-temperature thermal treatment, which is not suitable for organic transistors.
Innovation Solution
A transistor design incorporating a liquid crystal layer as a gate insulating material, which connects the channel and gate electrodes, allowing for low-temperature processing and high hole mobility, using nematic liquid crystal molecules like 4-cyano-4′pentylbiphenyl and a protective polymer film to protect the liquid crystal layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If silicon oxide (SiOx) is used as gate insulator, then the transistor can be manufactured with established process, but high-temperature thermal treatment (>150°C) is required which is not suitable for organic field effect transistor
Solution Approach 1:
The patent changes the gate insulator material from silicon oxide to liquid crystal material, which allows the transistor to operate at low temperatures (below 150°C) while maintaining manufacturing feasibility. This parameter change in material composition resolves the contradiction between ease of manufacture and temperature requirements.
2Ease of manufacture
If organic semiconductor materials are used, then low-cost plastic logic and flexible display backplane can be manufactured, but the hole mobility does not reach the level of inorganic field effect transistor
Solution Approach 1:
The patent uses a composite structure combining organic semiconductor layer with liquid crystal gate insulator. This composite material approach enables the transistor to maintain the low-cost and flexible advantages of organic materials while achieving improved hole mobility through the unique properties of the liquid crystal gate insulator that enhances charge generation and transport.
3Temperature
If liquid crystal layer is used as gate insulator, then low-temperature processing is enabled, but the liquid crystal layer must be properly connected to both channel and gate electrode
Solution Approach 1:
The liquid crystal layer serves multiple functions simultaneously: it acts as the gate insulator providing electrical isolation, serves as the dielectric layer for capacitance formation, and enables low-temperature processing. This multi-functionality simplifies the overall device structure despite the unique connection requirements.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enables the production of transistors with high hole mobility and low process costs, utilizing a flexible and cost-effective manufacturing method suitable for organic field effect transistors, with the liquid crystal layer functioning as an effective insulator and allowing for flexible and transparent displays.
Implementation Method 1
a liquid crystal layer formed on the substrate to connect the channel layer and the gate electrode to each other
Implementation Method 2
the liquid crystal layer includes liquid crystal molecules of which molecular orientations are changed according to a voltage of the gate electrode
Data Source
AI summary
The present invention relates to a transistor and a method for manufacturing the same. The transistor according to an embodiment of the present invention includes a substrate, a drain electrode formed on the substrate, a source electrode formed on the substrate and spaced apart from the drain electrode, a channel layer formed on the substrate and including a channel region electrically connecting the drain electrode and the source electrode to each other, a gate electrode formed on the substrate and spaced apart from the channel region, and a liquid crystal layer formed on the substrate to connect the channel layer and the gate electrode to each other.