Solution-Processable BODIPY-Based Small Molecules for Semiconducting Microfibers in Organic Thin-Film Transistors

Area of Science:

• Organic electronics
• Materials science
• Semiconductor physics

Background:

• Electron-deficient π-conjugated small molecules are key for electron-transporting semiconductors.
• BODIPY-based organic semiconductors have not been extensively developed despite unique properties.

Purpose of the Study:

• To design and synthesize novel, solution-processable BODIPY-based small molecules for organic thin-film transistors (OTFTs).
• To investigate the structure-property relationships and performance of these new BODIPY semiconductors.

Main Methods:

• Synthesis of BODIPY-based small molecules (BDY-3T-BDY and BDY-4T-BDY).
• Comprehensive characterization using NMR, mass spectrometry, electrochemistry, spectroscopy, thermal analysis, and X-ray diffraction.
• Fabrication and testing of solution-sheared organic thin-film transistors (OTFTs).

Main Results:

• Achieved electron mobilities up to 0.01 cm²/V·s and current on/off ratios exceeding 10⁸.
• Observed formation of aligned crystalline fibers in BDY-4T-BDY films, leading to charge-transport anisotropy (μ∥/μ⊥ ≈ 10).
• Demonstrated efficient long-range charge transport facilitated by microfiber alignment along the conduction channel.

Conclusions:

• BODIPY is a promising building block for high-performance, solution-processed electron-transporting semiconductor films.
• The developed BODIPY semiconductors exhibit the highest OTFT performance reported to date for this class of materials.
• Fiber alignment in solution-processed films is crucial for optimizing charge transport in organic semiconductors.