Self-assembling fullerenes for improved bulk-heterojunction photovoltaic devices

Area of Science:

• Materials Science
• Organic Electronics
• Photovoltaics

Background:

• Fullerene adducts are crucial components in organic solar cells.
• Molecular shape dictates the self-assembly and performance of organic electronic materials.
• Controlling nanoscale morphology is key to improving bulk-heterojunction solar cell efficiency.

Purpose of the Study:

• To investigate the impact of molecular shape on the formation of 1-D wire-like domains in fullerene adducts.
• To evaluate the potential of stacking fullerene adducts for enhanced performance in bulk-heterojunction organic solar cells.
• To compare the photovoltaic efficiency of solar cells utilizing stacking versus nonstacking fullerene adducts.

Main Methods:

• Synthesis and characterization of fullerene adducts 1a (stacking) and 1b (nonstacking).
• Fabrication of bulk-heterojunction organic solar cells using blends of fullerene adducts with regioregular poly(3-hexylthiophene-2,5-diyl) (P3HT).
• Photovoltaic performance testing and efficiency measurements of the fabricated solar cells.

Main Results:

• Fullerene adduct 1a, with a shape promoting 1-D stacking, formed wire-like domains.
• Fullerene adduct 1b, with a hindering molecular shape, did not form significant 1-D stacks.
• Solar cells incorporating the stacking fullerene 1a exhibited greatly enhanced photovoltaic efficiency compared to those with nonstacking fullerene 1b.

Conclusions:

• Molecular shape is a critical determinant for achieving ordered 1-D fullerene structures in organic solar cells.
• Promoting the formation of 1-D stacks through molecular design significantly boosts the performance of bulk-heterojunction organic solar cells.
• Stacking fullerene adducts represent a promising strategy for developing next-generation high-efficiency organic solar cells.