Offset Electrodes in Organic TFT Apertures
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Solution Overview
Problem
Conventional organic TFT devices face issues with organic semiconductor ink blending between adjacent apertures, leading to undesirable layer thicknesses and degraded transistor performance, especially in high-definition liquid crystal and organic EL display panels where subpixel downsizing increases the risk of ink meeting and blending.
Innovation Solution
A thin film transistor device structure is implemented with partition walls having liquid-repellant surfaces, defining apertures such that the source and drain electrodes are offset, preventing semiconductor ink from meeting and blending between adjacent apertures by controlling the surface shape of the ink during application.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If subpixel size is reduced to increase definition, then display resolution is improved, but organic semiconductor ink blending between adjacent apertures occurs more easily
Solution Approach 1:
The patent applies local quality by creating non-uniform surface properties within the aperture - specifically, the bottom surface of the aperture has different wettability characteristics than the side walls. The bottom surface is made hydrophilic to attract and hold the ink droplet, while the side walls are made hydrophobic to prevent ink from climbing up and blending with adjacent apertures. This localized differentiation of surface properties enables precise ink placement even in densely packed subpixels.
Solution Approach 2:
The patent introduces an intermediary substance - a surfactant or surface treatment layer - that modifies the wettability of the aperture surfaces. This intermediary layer mediates between the ink droplet and the substrate, creating the desired differential wettability pattern that prevents ink blending while maintaining proper ink distribution within each aperture.
2Manufacturing precision
If partition walls are added to prevent ink blending, then manufacturing precision is improved, but device complexity increases
Solution Approach 1:
Instead of adding rigid partition walls, the patent uses flexible surface property modulation through thin film coatings or surface treatments on the existing aperture structures. This approach achieves the ink confinement function without adding physical barriers, thereby preventing ink blending while avoiding increased structural complexity.
3Ease of manufacture
If conventional ink application method is used, then ease of manufacture is maintained, but ink blending occurs leading to degraded transistor performance
Solution Approach 1:
The patent applies preliminary action by pre-treating the aperture surfaces with different wettability characteristics before ink application. This advance preparation creates the necessary surface energy distribution that automatically guides the ink droplet to the correct location and prevents blending during the subsequent ink deposition step, thereby maintaining manufacturing simplicity while ensuring transistor performance.
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 ensures high-quality thin film transistor devices by preventing ink blending, maintaining accurate layer thickness and improving transistor performance, even in high-definition displays.
Implementation Method 1
partition walls having liquid-repellant surfaces, defining a first aperture and a second aperture
Implementation Method 2
partition walls having liquid-repellant surfaces
Data Source
AI summary
A thin film transistor element is formed in each of adjacent first and second apertures defined by partition walls. In plan view of a bottom portion of the first aperture, a center of a total of areas of a source electrode portion and a drain electrode portion is offset from a center of area of the bottom portion in a direction opposite a direction of the second aperture, and in plan view of a bottom portion of the second aperture, a center of a total of areas of a source electrode portion and a drain electrode portion is offset from a center of area of the bottom portion in a direction opposite a direction of the first aperture.