Organic Semiconductor Ink Stability via Cis-Decalin Solvent

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Solution Overview

Problem

Organic semiconductor materials with thiophene rings tend to aggregate and precipitate when dissolved in organic solvents, leading to instability and variability in the formation of organic semiconductor layers, which affects the reliability and performance of thin-film transistors and related devices.

Innovation Solution

The use of an organic semiconductor composition that includes an organic solvent with cis-decalin, which prevents aggregation by reducing steric hindrance, combined with a substance like trans-decalin that has a smaller second virial coefficient, enhances stability and carrier mobility, and incorporates a Π-conjugated structure and alkyl chains to maintain planarity and solubility.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If organic semiconductor material with thiophene ring is dissolved in organic solvent, then the organic semiconductor layer can be formed by liquid phase process, but the material aggregates and precipitates over time causing instability

Engineering Contradiction:

Improveliquid phase process capabilityVSAvoidink stability

Core Design Contradiction:

Ease of manufactureVSStability of the object's composition

Solution Approach 1:

A dendrimer compound is introduced as an intermediary substance between the organic semiconductor material and the organic solvent. The dendrimer prevents aggregation of the semiconductor material through steric hindrance provided by its bulky structure, while maintaining solubility and stability of the ink composition over time.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The invention creates a composite ink composition consisting of three components: organic semiconductor material, organic solvent, and dendrimer compound. This composite formulation combines the advantages of liquid phase processing with enhanced stability by using the dendrimer to mediate interactions between the semiconductor and solvent.

Inventive Principle:

Principle #40Composite materials

2Reliability

If organic semiconductor material aggregates around thiophene ring, then precipitation occurs, but this makes it hard to obtain stable ink

Engineering Contradiction:

Improvedevice reliabilityVSAvoidink stability

Core Design Contradiction:

ReliabilityVSStability of the object's composition

Solution Approach 1:

The dendrimer compound acts as a spacer that physically separates the organic semiconductor material molecules, preventing them from aggregating around the thiophene ring. This intermediary structure maintains molecular dispersion in the solvent, ensuring ink stability and consistent device performance.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Manufacturing precision

If ink is applied evenly to form organic semiconductor layer, then device characteristics improve, but aggregation causes variability in layer formation

Engineering Contradiction:

Improvelayer formation uniformityVSAvoidink stability

Core Design Contradiction:

Manufacturing precisionVSStability of the object's composition

Solution Approach 1:

The dendrimer compound provides steric stabilization that prevents aggregation during ink application and layer formation. This ensures uniform distribution of organic semiconductor material in the ink and consistent film quality, improving manufacturing precision.

Inventive Principle:

Principle #24Intermediary (Mediator)

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 results in a stable organic semiconductor layer with improved carrier mobility and reliability of thin-film transistors, enabling the production of high-performance active matrix devices and electronic apparatuses.

Implementation Method 1

prevents aggregation by reducing steric hindrance

Methodology Applied

Scientific EffectSteric hindrance reduction:

Implementation Method 2

a substance whose second virial coefficient to the organic semiconductor material is smaller than that of cis-decalin

Methodology Applied

Scientific EffectSecond virial coefficient effect:

Implementation Method 3

the alkyl chain contracts, preventing steric hindrance between adjacent alkyl chains and improving planarity of the molecule structure

Methodology Applied

Scientific EffectMolecular planarity improvement:

Implementation Method 4

The Π conjugated structure can prevent decrease of carrier mobility of molecules caused by inclusion of other structures than the one including at least one thiophene ring into the structural unit

Methodology Applied

Scientific EffectΠ-conjugation:

Data Source

PatentUS7601279B2Organic semiconductor composition containing cis-decalin

Publication Date: 2009.10.13 E INK CORP

AI summary

An organic semiconductor composition comprises: an organic semiconductor material having a structural unit including at least one thiophene ring as a repeating unit; and an organic solvent including cis-decalin.