Grooved nanowires from self-assembling hairpin molecules for solar cells

Area of Science:

• Materials Science
• Organic Electronics
• Nanotechnology

Background:

• Bulk heterojunction organic solar cells require organized films for efficient phase separation of donor and acceptor components.
• Achieving optimal nanostructure morphology is crucial for high power conversion efficiency.

Purpose of the Study:

• To investigate the use of self-assembling hairpin-shaped sexithiophene molecules for creating grooved nanowires in organic solar cells.
• To understand how molecular self-assembly and thermal annealing influence film morphology and device performance.

Main Methods:

• Fabrication of photovoltaic devices using spin-casting and solvent evaporation.
• Utilizing hairpin-shaped sexithiophene molecules for self-assembled nanowire formation.
• Employing thermal annealing to optimize nanostructure morphology and domain growth.

Main Results:

• Self-assembled grooved nanowires formed a percolating network with fullerene acceptors.
• Thermal annealing increased power conversion efficiencies by promoting domain growth while maintaining the nanostructure network.
• Devices utilizing non-one-dimensional forming sexithiophene derivatives showed lower efficiencies due to excessive phase separation.

Conclusions:

• The unique hairpin shape of sexithiophene molecules facilitates receptor-ligand interactions at the heterojunction, enhancing device efficiencies by 23%.
• Self-assembly and controlled nanostructure formation are key strategies for improving organic solar cell performance.