Intramolecular Locked Dithioalkylbithiophene-Based Semiconductors for High-Performance Organic Field-Effect...

Area of Science:

• Organic electronics
• Materials science
• Polymer chemistry

Background:

• Conventional 3,3'-dialkyl-2,2'-bithiophene semiconductors possess non-planar structures, limiting π-conjugation and charge transport.
• Achieving high planarity in organic semiconductors is crucial for efficient charge mobility.

Purpose of the Study:

• To synthesize and characterize novel 3,3'-dithioalkyl-2,2'-bithiophene (SBT)-based small molecular and polymeric semiconductors.
• To investigate the impact of the SBT core structure on planarity, π-conjugation, and charge transport properties.
• To correlate semiconductor performance with film morphology.

Main Methods:

• Synthesis of SBT-based small molecules and polymers via end-capping or copolymerization.
• Single-crystal X-ray diffraction for structural analysis.
• Molecular orbital computations for electronic structure.
• Optical and electrochemical measurements.
• Fabrication and characterization of organic field-effect transistors (OFETs).
• Grazing incidence X-ray diffraction (GIXD) for film morphology analysis.

Main Results:

• SBT core exhibits complete planarity due to intramolecular S(alkyl)⋯S(thiophene) locks, with a torsional angle <1°.
• SBT-based materials demonstrate high π-conjugation compared to conventional analogs.
• Solution-sheared films in OFETs show hole mobilities ranging from approximately 0.03 to 1.7 cm² V⁻¹ s⁻¹.
• Film morphology, analyzed by GIXD, influences charge transport variations within the SBT family.

Conclusions:

• The planar SBT core effectively enhances π-conjugation and enables good semiconducting properties.
• SBT-based materials represent a promising class of organic semiconductors for electronic applications.
• Understanding the relationship between molecular planarity, film morphology, and charge transport is key for designing high-performance organic electronic devices.