High-fidelity self-assembly pathways for hydrogen-bonding molecular semiconductors

Area of Science:

• Materials Science
• Organic Chemistry
• Supramolecular Chemistry

Background:

• Designing molecular systems with hierarchical self-assembly is crucial for understanding structure-function relationships and controlling organic material properties.
• High-fidelity self-assembly pathways are essential for predictable material organization and function.

Purpose of the Study:

• To report a high-fidelity self-assembly system using two hydrogen-bonding molecular semiconductors with regioisomerically attached short alkyl chains.
• To investigate the selective formation of hydrogen-bonding motifs and their influence on higher-order architectures and material properties.

Main Methods:

• Synthesis of hydrogen-bonding molecular semiconductors with regioisomerically attached short alkyl chains.
• Analysis of self-assembly behavior in homogeneous solution and at liquid-solid interfaces.
• Characterization of thin films and bulk materials, including structural organization and miscibility with fullerene derivatives.
• Evaluation of photovoltaic performance in electron donor-acceptor blend films.

Main Results:

• Two regioisomers selectively formed either cyclic or linear hydrogen-bonding motifs due to highly directional interactions.
• These assemblies organized into columnar and lamellar architectures in thin films and bulk.
• Contrasting structures led to different miscibility with fullerene derivatives and distinct photovoltaic performance, despite similar optoelectronic properties.

Conclusions:

• The molecular design, specifically the absence of long aliphatic chains, enables high-fidelity control over self-assembly pathways.
• This precise control over self-assembly dictates material morphology and ultimately influences device performance.
• The findings highlight the importance of molecular design in achieving predictable self-assembly for functional organic materials.