Organic Thin-Film Transistor OFF-State Current Suppression
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Solution Overview
Problem
Thin-film transistors with organic semiconductor layers face challenges in suppressing OFF-state current while maintaining high ON-state current, particularly when using thiophene-based materials, which results in undesirable current flow in the OFF state.
Innovation Solution
Incorporating a second insulating layer with compounds of the formula (1), containing electron-donating groups, to feed electrons into the organic semiconductor layer, thereby reducing positive charges and minimizing OFF-state current, while maintaining sufficient ON-state current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If organic semiconductor materials with p-type semiconducting properties are used to achieve high ON-state current, then current flow in ON state is improved, but OFF-state current increases undesirably
Solution Approach 1:
The patent applies local quality by introducing a second insulating layer specifically at the interface between the organic semiconductor layer and the substrate, rather than uniformly modifying the entire device structure. This localized intervention targets the specific region where positive charges accumulate and cause OFF-state current, while leaving the rest of the transistor structure unchanged to maintain high ON-state current characteristics
Solution Approach 2:
The second insulating layer acts as an intermediary between the substrate and the organic semiconductor layer. It mediates the interaction by providing electron donation to neutralize positive charges in the semiconductor layer, thereby eliminating the harmful OFF-state current without directly altering the semiconductor material's inherent high current-conducting properties
2Adaptability or versatility
If thiophene-based materials are used in the organic semiconductor layer, then material properties and characteristics are enhanced, but OFF-state current suppression becomes difficult
Solution Approach 1:
The patent segments the transistor structure into distinct functional layers, introducing a specialized second insulating layer between the substrate and the thiophene-based semiconductor layer. This segmentation allows the thiophene material to maintain its excellent electrophysical properties for high ON-state current while the separate insulating layer handles the charge neutralization function to suppress OFF-state current
Solution Approach 2:
The patent employs composite material structure by combining thiophene-based organic semiconductor material with a second insulating layer containing electron-donating groups. This composite approach leverages the advantages of both materials: the thiophene derivative provides superior charge transport properties, while the insulating layer with electron-donating groups provides charge neutralization capability
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
The solution effectively suppresses OFF-state current to near zero, improving transistor characteristics and performance, especially when using thiophene-based materials, without adversely affecting ON-state current.
Implementation Method 1
The second insulating layer contains one or more compounds of the following formula (1), so that electrons are fed from the second insulating layer into the organic semiconductor layer
Data Source
AI summary
A thin-film transistor includes a source electrode, a drain electrode arranged apart from the source electrode, an organic semiconductor layer arranged between the source electrode and the drain electrode so as to establish connection of the source electrode and the drain electrode, a first insulating layer arranged on one surface side of the organic semiconductor layer, a gate electrode arranged on a side of the first insulating layer opposite that on which the organic semiconductor layer lie, and a second insulating layer arranged on a side of the organic semiconductor layer opposite that on which the first insulating layer lie. The organic semiconductor layer contains an organic semiconductor material having p-type semiconducting properties. The second insulating layer contains one or more compounds of the following formula (1), so that electrons are fed from the second insulating layer into the organic semiconductor layer:wherein R1 and R2 independently represent a substituted or unsubstituted alkylene group; X1, X2, X3 and X4 each represent a hydrogen atom or an electron-donating group; and n represents 100 to 100,000, wherein at least one of X1, X2, X3 and X4 represents an electron-donating group.