Organic Semiconductor TFT Buffer Layer Crystallization
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Solution Overview
Problem
The existing methods for fabricating thin film transistors using organic semiconductor materials face challenges such as damage from organic solvents, increased contact resistance, and reduced mobility due to the weak structure of semiconductor layers formed at low temperatures, which affect the performance of flexible plastic substrates in LCD devices.
Innovation Solution
A top gate type thin film transistor structure is developed, where a small molecule organic semiconductor layer is formed on source and drain electrodes with a gate insulating layer of similar size, and a gate electrode is placed on the gate insulating layer, along with a buffer layer to enhance crystallization and protect the semiconductor layer from damage, while maintaining low-temperature processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If low-temperature processing is used to maintain flexibility of plastic substrates, then substrate flexibility is improved, but semiconductor layer structure becomes weak and mobility decreases
Solution Approach 1:
The patent changes the processing temperature parameter to maintain substrate flexibility while improving semiconductor layer quality through optimized low-temperature fabrication processes and material selection
Solution Approach 2:
The patent uses composite material structures including buffer layers, gate insulating layers, and semiconductor layers with specific material combinations (e.g., silicon oxide buffer, organic semiconductors) to achieve both flexibility and structural integrity
2Ease of manufacture
If conventional TFT fabrication methods are used, then manufacturing process is simple, but organic semiconductor layer is damaged by organic solvents
Solution Approach 1:
The patent introduces a buffer layer as an intermediary between the substrate and the organic semiconductor layer, protecting the semiconductor from direct contact with damaging organic solvents during fabrication processes
Solution Approach 2:
The buffer layer is formed beforehand to provide protective cushioning against solvent damage before the organic semiconductor layer is deposited and subsequently processed
3Reliability
If gate insulating layer size is reduced to match semiconductor layer, then contact resistance is minimized, but gate control area is reduced
Solution Approach 1:
The patent applies local quality by having the gate insulating layer extend beyond the semiconductor layer in non-active regions, providing localized electrical control and minimizing contact resistance where needed while maintaining adequate gate control coverage
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 configuration minimizes contact resistance and protects the organic semiconductor layer from damage, improving the electrical characteristics and mobility of the TFT, enabling better performance and flexibility for LCD devices on plastic substrates.
Implementation Method 1
a buffer layer to enhance crystallization and protect the semiconductor layer from damage
Data Source
AI summary
A substrate having a thin film transistor includes a buffer layer on a substrate, source and drain electrodes on the buffer layer, a portion of the buffer layer exposed between the source and drain electrodes, a small organic semiconductor layer on the source electrode and the drain electrode, the organic semiconductor layer contacting the exposed portion of the buffer layer, a gate insulating layer on the organic semiconductor layer, the gate insulating layer having substantially the same size as the organic semiconductor layer, a gate electrode on the gate insulating layer, a passivation layer over the surface of the substrate including the gate electrode; and a pixel electrode on the passivation layer, the pixel electrode electrically connected to the drain electrode.