A Solution-Processable meso-Phenyl-BODIPY-Based n-Channel Semiconductor with Enhanced Fluorescence Emission.

Area of Science:

• Materials Science
• Organic Electronics
• Photophysics

Background:

• Organic semiconductors are crucial for electronic devices.
• Developing materials with both high fluorescence and efficient charge transport is challenging.
• BODIPY dyes are known for their fluorescence but often lack good charge transport properties.

Purpose of the Study:

• To design, synthesize, and characterize a novel A-D-A semiconductor BDY-Ph-2T-Ph-BDY.
• To investigate the relationship between molecular structure, photophysical properties, and charge transport characteristics.
• To achieve high fluorescence efficiency and n-channel OFET performance in a single BODIPY-based material.

Main Methods:

• Molecular design and synthesis of BDY-Ph-2T-Ph-BDY.
• Characterization using optical spectroscopy, cyclic voltammetry, and single-crystal X-ray diffraction.
• Fabrication and testing of n-channel organic field-effect transistors (OFETs).
• Photophysical studies in solution and solid state.

Main Results:

• The synthesized A-D-A semiconductor BDY-Ph-2T-Ph-BDY has an optical band gap of 2.32 eV and stabilized HOMO/LUMO levels.
• Single-crystal XRD revealed a D-A dihedral angle of ~66° and strong intermolecular C-H···π interactions.
• The material demonstrated good fluorescence efficiency (ΦF = 0.30) and n-channel OFET mobility (μe = 0.005 cm²/V·s) with high on/off ratios (10⁴–10⁵).
• A 6-fold improvement in fluorescence quantum yield was observed compared to BDY-4T-BDY.
• Transitions between locally excited (LE) and twisted intramolecular charge-transfer (TICT) states were observed and controllable.

Conclusions:

• The molecular design strategy successfully yielded a high-performance BODIPY-based n-channel semiconductor.
• Restricted intramolecular rotations and intermolecular interactions contribute to enhanced fluorescence and charge transport.
• This work presents the first highly emissive BODIPY-based n-channel semiconductor, opening avenues for advanced organic electronic applications.