N-Benzoyl dithieno[3,2-b:2',3'-d]pyrrole-based hyperbranched polymers by direct arylation polymerization

Area of Science:

• Materials Science
• Polymer Chemistry
• Organic Electronics

Background:

• Poly(N-acyl dithieno[3,2-b:2',3'-d]pyrrole)s are known for stabilized energy levels.
• Hyperbranched polymers of this type have not been previously studied.
• This research introduces novel hyperbranched polymers incorporating these units.

Purpose of the Study:

• Synthesize novel hyperbranched polymers with N-benzoyl dithieno[3,2-b:2',3'-d]pyrrole acceptor and 3-hexylthiophene donor units.
• Investigate the structural, thermal, and optical properties of these new polymers.
• Explore their potential for organic solar cell applications.

Main Methods:

• Direct arylation polymerization of N-benzoyl dithieno[3,2-b:2',3'-d]pyrrole, 2,5-dibromo 3-hexylthiophene, and triphenylamine/triphenylbenzene monomers.
• Characterization using 1H NMR, FTIR, GPC, TGA, DSC, and XRD.
• Optical properties analyzed via UV-vis and fluorescence spectroscopy.

Main Results:

• Successfully synthesized organic solvent-soluble hyperbranched polymers with high yields (80-92%) and molecular weights around 18,000 g/mol.
• Branching structure hindered chain stacking, leading to less ordered crystalline domains compared to linear polymers.
• Hyperbranched polymer with triphenylbenzene branching showed a significant red-shift in absorption due to enhanced polymer stacking.

Conclusions:

• Hyperbranched polymers with triphenylamine/triphenylbenzene moieties exhibit high structural order in thin films.
• These polymers show promise for organic solar cell applications.
• The triphenylbenzene-containing polymer's red-shifted UV-vis absorption indicates a higher chain packing degree, beneficial for device performance.