Asymmetrically Functionalized Electron-Deficient π-Conjugated System for Printed Single-Crystalline Organic...

Area of Science:

• Materials Science
• Organic Electronics
• Semiconductor Physics

Background:

• Large-area single-crystalline n-type organic semiconductor (OSC) thin films are crucial for advanced electronics.
• Existing molecular designs for n-type OSCs often lack a balance of charge transport, solution-processability, and robustness.
• Benzo[de]isoquinolino[1,8-gh]quinolinetetracarboxylic diimide (BQQDI) derivatives show promise but suffer from poor solubility.

Purpose of the Study:

• To design asymmetric BQQDI molecules that enhance solubility and solution-processability while retaining excellent charge transport.
• To develop an effective synthetic strategy for producing these novel asymmetric BQQDI derivatives.
• To investigate the structure-property relationships and electronic performance of the new materials.

Main Methods:

• Asymmetric molecular design incorporating alkyl chains onto the BQQDI core.
• Development of a synthetic route to produce asymmetric BQQDI derivatives (PhC2-BQQDI-Cn).
• Characterization of molecular conformation, aggregation behavior, and thin-film properties.
• Measurement of electron mobility and assessment of thin-film quality and scale.

Main Results:

• Asymmetric PhC2-BQQDI-Cn molecules with linear alkyl chains (n=5-7) adopted a stable gauche conformation.
• The asymmetric design significantly improved solubility and solution-processability compared to the parent PhC2-BQQDI.
• Asymmetric PhC2-BQQDI-C5 achieved high electron mobility and enabled the fabrication of centimeter-scale continuous single-crystalline thin films.
• The resulting films showed enhanced electron transport properties and allowed for the study of anisotropy.

Conclusions:

• The asymmetric molecular design strategy is effective for creating solution-processable n-type OSCs with high performance.
• PhC2-BQQDI-C5 represents a significant advancement, enabling large-area single-crystalline films for practical electronic applications.
• This work provides a pathway for developing next-generation organic electronic devices based on tailored molecular architectures.