Self-Assembled PCBM Nanosheets: A Facile Route to Electronic Layer-on-Layer Heterostructures

Area of Science:

• Materials Science
• Organic Electronics
• Nanotechnology

Background:

• Organic semiconductors are crucial for flexible electronics.
• Controlling morphology and interfaces is key for device performance.
• Large-area, solution-processable organic materials are in demand.

Purpose of the Study:

• To report the self-assembly of semicrystalline [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) nanosheets.
• To demonstrate the fabrication of electronically active organic/organic heterostructures using these nanosheets.
• To investigate the semiconductor properties of PCBM nanosheets in field-effect transistors (FETs).

Main Methods:

• Self-assembly of PCBM nanosheets at a hydrophobic solvent-water interface.
• Facile transfer techniques for PCBM nanosheets onto various surfaces.
• Fabrication and characterization of single-layer PCBM nanosheet FETs.
• Construction and testing of planar organic/organic heterostructure FETs.

Main Results:

• Achieved large-area (>1 cm²) semicrystalline PCBM nanosheets.
• Demonstrated successful transfer of PCBM nanosheets to hydrophobic and hydrophilic substrates.
• Measured electron mobility of 1.2 × 10⁻² cm²/V·s and an on-off ratio of ~1 × 10⁴ in PCBM nanosheet FETs.
• Fabricated ambipolar FETs with a PCBM nanosheet/poly(3-hexylthiophene-2,5-diyl) heterostructure, showing electron mobility of 8.7 × 10⁻⁴ cm²/V·s and hole mobility of 3.1 × 10⁻⁴ cm²/V·s.

Conclusions:

• Semicrystalline PCBM nanosheets can be controllably self-assembled over large areas.
• These PCBM nanosheets exhibit promising semiconductor properties for electronic device applications.
• The developed platform enables the fabrication of high-performance organic/organic heterostructures.