High-Efficiency Organic Photovoltaics using Eutectic Acceptor Fibrils to Achieve Current Amplification

Area of Science:

• Materials Science
• Organic Electronics
• Photovoltaics

Background:

• Organic solar cells (OSCs) performance is dictated by donor (D) and acceptor (A) material properties and film morphology.
• Ternary blends offer a route to fine-tune these characteristics for improved device output.

Purpose of the Study:

• To investigate the use of intimate eutectic mixing in nonfullerene-acceptor-based D-A1-A2 ternary blends.
• To optimize bulk heterojunction (BHJ) thin film morphology and electronic properties for enhanced OSC performance.

Main Methods:

• Fabrication of D-A1-A2 ternary blends utilizing eutectic mixing principles.
• Characterization of thin film morphology, crystallinity, and electronic properties.
• Analysis of charge transfer, transport, and recombination dynamics.

Main Results:

• Eutectic mixing led to the formation of fibrillar lamellae, enhancing thin film crystallinity and carrier transport.
• Reduced defect state density and suppressed recombination channels were observed.
• Achieved a significant short-circuit current (JSC) amplification and a power conversion efficiency (PCE) of 17.84%.

Conclusions:

• Specific material interactions through eutectic mixing are crucial for controlling crystalline habit and optimizing BHJ morphology.
• This strategy effectively enhances charge transfer and transport, leading to superior OSC performance.
• The findings pave the way for next-generation OSCs targeting over 20% PCE.