Simple-Structured Acceptor with Highly Interconnected Electron-Transport Pathway Enables High-Efficiency Organic...

Area of Science:

• Materials Science
• Organic Electronics
• Photovoltaics

Background:

• High-performance organic solar cells (OSCs) require efficient charge transport pathways.
• Molecular packing significantly influences charge mobility in organic semiconductors.
• Nonfused-ring electron acceptors (NFREAs) offer potential for low-cost OSCs but often face charge transport limitations.

Purpose of the Study:

• To investigate the impact of alkyl-chain topology on molecular packing in NFREAs.
• To establish a 3D electron transport network for enhanced charge mobility.
• To achieve high power conversion efficiency (PCE) in NFREA-based OSC devices.

Main Methods:

• Synthesis of NFREAs with branched alkyl side-chains.
• Tuning molecular packing arrangements through side-chain engineering.
• Fabrication and characterization of OSC devices incorporating the modified NFREAs.

Main Results:

• Branched alkyl side-chains induced a 3D network stacking of NFREA molecules.
• This 3D network facilitated a highly interconnected pathway for electron transport.
• NFREA-based devices achieved a record-breaking power conversion efficiency of 17.38% (certified 16.59%).

Conclusions:

• Molecular packing, regulated by alkyl-chain topology, is crucial for high-performance OSCs.
• Branched side-chains in NFREAs can effectively promote 3D electron transport pathways.
• This strategy offers a promising route for developing low-cost and high-efficiency OSCs.