Computation-Guided Placement of Nonfullerene Acceptor Core Halogenation for High-Performance Organic Solar Cells

Area of Science:

• Materials Science
• Organic Electronics
• Photovoltaics

Background:

• Nonfullerene acceptors (NFAs) are critical for high-efficiency organic solar cells (OSCs).
• Strategic molecular design of NFAs is key to improving OSC performance.
• Halogen substitution is a promising avenue for tuning NFA properties.

Purpose of the Study:

• To investigate the impact of halogen substitution (F, Cl, Br) on quinoxaline-based NFAs (Qx-PhHal).
• To understand how molecular design influences the performance of organic solar cells.
• To explore the potential of brominated NFAs in ternary solar cell architectures.

Main Methods:

• First-principles theoretical computation to design and analyze NFAs.
• Fabrication and characterization of organic solar cells with varying halogenated NFAs.
• Analysis of film morphology, miscibility, and charge transport properties.

Main Results:

• Brominated NFAs (Qx-PhBr) yielded the highest power conversion efficiency (PCE) of 17.58% in OSCs.
• Bromination improved electrostatic interactions, miscibility, crystallinity, and film morphology.
• Ternary solar cells with brominated NFAs achieved a PCE of 20.14%.

Conclusions:

• Bromine substitution is a highly effective strategy for enhancing NFA performance in OSCs.
• Improved material properties due to bromination lead to higher exciton dissociation and balanced charge mobility.
• These findings offer valuable insights for designing next-generation high-performance NFAs for solar energy applications.