Functionalized Graphene Oxide Enables a High-Performance Bulk Heterojunction Organic Solar Cell with a Thick Active...

Area of Science:

• Materials Science
• Organic Electronics
• Nanotechnology

Background:

• Conjugated polymers and graphene oxide (GO) are key materials in organic electronics.
• Traditional GO has limitations in dispersion due to hydrophilicity and oleophobicity.
• Achieving high-performance thick-film organic solar cells (OSCs) remains a challenge.

Purpose of the Study:

• To fabricate functionalized graphene oxide (P-GO) with improved dispersion in organic solvents.
• To investigate the mechanism of P-GO incorporation into OSCs.
• To explore the potential for high-performance thick-film OSC fabrication.

Main Methods:

• Fabrication of P-GO via ethanol-mediated mixing.
• Incorporation of P-GO into poly[[4,8-bis[(2-ethylhexyl)oxy]benzo[1,2-b:4,5-b']dithiophene-2,6-diyl][3-fluoro-2-[(2-ethylhexyl)carbonyl]thieno[3,4- b]thiophenediyl]] (PTB7):[6,6]-phenyl C71 butyric acid methyl ester (PC71BM) blend films.
• Analysis of P-GO's effect on film morphology, charge transport, and device performance.

Main Results:

• P-GO exhibited enhanced dispersion in organic nonpolar solvents.
• P-GO incorporation decreased π-π stacking distance and enlarged polymer coherence length.
• Optimized phase separation, enhanced charge dissociation, reduced recombination, and balanced charge transport were observed.
• OSCs with 1% P-GO showed a thickness-insensitive fill factor of 57.8% and PCE of 7.31% for 250 nm thick films.
• A 34% PCE enhancement was achieved compared to control devices.

Conclusions:

• Functionalized graphene oxide is a promising material for improving OSC performance.
• P-GO facilitates the fabrication of high-performance thick-film OSCs.
• The enhanced properties of P-GO lead to significant improvements in device efficiency and stability.