Organic Semiconductor Material Segmentation for Solubility and Heat Resistance

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Solution Overview

Problem

Existing organic semiconductor materials face challenges in achieving high solubility in organic solvents at room temperature, storage stability, and heat resistance, which are essential for efficient production of organic electronic devices using printing processes.

Innovation Solution

An organic compound represented by General Formula (A) with specific alkyl and aromatic/heterocyclic groups is developed, ensuring solubility of 0.3 mass% or higher in organic solvents at 25°C, no phase transition below 150°C, and high heat resistance, enabling the formation of organic thin films and devices with improved mobility and heat resistance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If the number of fused rings is increased to improve heat resistance, then heat resistance improves, but solubility in organic solvent deteriorates

Engineering Contradiction:
Improveheat resistanceVSAvoidsolubility in organic solvent
Core Design Contradiction:
TemperatureVSQuantity of substance

Solution Approach 1:

The fused ring system is segmented by introducing sp3-hybridized carbon atoms (saturated carbon atoms) that break the continuous conjugation. This segmentation reduces the planarity and pi-pi stacking tendency of the molecule, thereby maintaining solubility even as the number of fused rings increases for improved heat resistance

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The hybridization state of carbon atoms is changed from sp2 (unsaturated) to sp3 (saturated) at specific positions in the fused ring system. This parameter change introduces tetrahedral geometry that disrupts molecular planarity and stacking, resolving the contradiction between heat resistance (requiring extended conjugation) and solubility (requiring disrupted stacking)

Inventive Principle:
Principle #35Parameter changes

2Quantity of substance

If alkyl chains are introduced to improve solubility, then solubility improves, but phase transition occurs at low temperatures deteriorating heat resistance

Engineering Contradiction:
Improvesolubility in organic solventVSAvoidphase transition temperature
Core Design Contradiction:
Quantity of substanceVSTemperature

Solution Approach 1:

Instead of uniformly substituting all positions with alkyl chains, saturated carbon atoms are strategically placed at specific local positions (2, 7, and/or 12 positions) in the benzothieno[3,2-b][1,4]naphthothiophene core. This local quality approach provides sufficient solubility enhancement without excessive alkyl substitution that would lower phase transition temperatures

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The molecule combines aromatic fused rings (for heat resistance and semiconductor properties) with saturated carbon atoms (for solubility) in a composite structure. This composite approach integrates the beneficial properties of both aromatic systems (thermal stability) and saturated systems (solubility) within a single molecular framework

Inventive Principle:
Principle #40Composite materials

Data Source

PatentEP3275884B1Organic compound, organic semiconductor material, organic thin-film and method for producing same, organic semiconductor composition, and organic semiconductor device
Publication Date: 2019.05.08 NIPPON KAYAKU CO LTD
  • EP3275884B1 patent drawingFigure 1(a)~1(f)
  • EP3275884B1 patent drawingFigure 2(a)~2(f)
  • EP3275884B1 patent drawingFigure 3

AI summary

An object is to provide: an organic compound which has excellent solubility in an organic solvent at room temperature, excellent storage stability in a solution state, and excellent heat resistance; an organic semiconductor material containing the organic compound; an organic thin film obtained by a printing process at room temperature using the organic semiconductor material; and an organic semiconductor device containing the organic thin film and having high mobility and high heat resistance. The organic compound is represented by Formula (A) below, and the organic semiconductor material contains this organic compound, wherein one of R1 and R2 represents an alkyl group, an aromatic hydrocarbon group having an alkyl group, or a heterocyclic group having an alkyl group, and another of R1 and R2 represents an aliphatic hydrocarbon group, an aromatic hydrocarbon group, or a heterocyclic group, with a proviso that R1 and R2 are not alkyl groups simultaneously.