Over 20.5% Efficiency of Halogen-Free Solvent-Processed Organic Solar Cells Achieved by Anti-Solvent Strategy

Area of Science:

• Materials Science
• Renewable Energy
• Organic Electronics

Background:

• Halogen-free solvent processing is crucial for sustainable, industrial-scale organic solar cell (OSC) production.
• Current halogen-free methods often lead to lower efficiencies due to molecular aggregation and poor phase separation.

Purpose of the Study:

• To develop an effective anti-solvent (AS) strategy for improving OSC efficiency using halogen-free solvents.
• To enable high-performance, environmentally friendly OSC fabrication suitable for large-scale deployment.

Main Methods:

• An innovative anti-solvent (AS) strategy was employed, involving the timed introduction of orthogonal solvents.
• This method accelerates photovoltaic material precipitation, reduces solubility, and enhances volatilization to control aggregation.
• The strategy was tested on PM6:D18:L8BO-X based OSCs and scaled up for large-area module fabrication.

Main Results:

• The AS strategy optimized phase separation and fibrous morphology, leading to efficient exciton dissociation and charge utilization.
• PM6:D18:L8BO-X based OSCs achieved a power conversion efficiency of 20.51% (certified 20.12%), surpassing conventional methods.
• A record module efficiency of 17.23% was achieved for large-area fabrication (active area > 10.0 cm²).

Conclusions:

• The proposed AS strategy offers a practical solution for high-efficiency, eco-friendly OSC fabrication.
• This approach demonstrates broad applicability across various photovoltaic materials and solvent systems.
• The study paves the way for the industrial-scale deployment of advanced organic solar cells.