Scattering techniques for mixed donor-acceptor characterization in organic photovoltaics

Area of Science:

• Materials Science
• Physical Chemistry
• Renewable Energy

Background:

• Organic photovoltaic (OPV) bulk heterojunction (BHJ) morphology control is vital for power conversion efficiency.
• Interfacial regions between donor and acceptor molecules are critical for charge separation and recombination.
• The molecularly mixed donor-acceptor phase is well-studied in polymer:fullerene systems but poorly understood in polymer:non-fullerene acceptor blends.

Purpose of the Study:

• To provide accurate, quantitative characterization of the mixed phase within BHJ active layers.
• To unravel the importance of the mixed phase for charge separation and recombination processes.
• To review scattering techniques for BHJ characterization and discuss future challenges in non-fullerene acceptor systems.

Main Methods:

• Detailed X-ray and neutron scattering characterization techniques.
• Analysis methods for quantifying the mixed phase within BHJ active layers.
• Review of literature applying these techniques to various material systems and device performance.

Main Results:

• Established X-ray and neutron scattering as powerful tools for quantifying the mixed phase in BHJ active layers.
• Demonstrated the successful application of these techniques across different material systems.
• Correlated scattering-derived morphological data with device performance.

Conclusions:

• Quantitative characterization of the mixed phase is critical for understanding OPV performance.
• Scattering techniques offer robust methods for this characterization.
• Further research is needed to address challenges specific to non-fullerene acceptor systems.