High Efficiency (∼18%) Organic Solar Cells with 500 nm-Thick Toluene Cast Active Layer by Aggregation Manipulation...

Area of Science:

• Materials Science
• Organic Electronics
• Photovoltaics

Background:

• Thick-film organic solar cells (OSCs) are vital for scalable manufacturing.
• Current methods using high-vapor-pressure solvents limit morphological control and efficiency.
• Achieving high performance in thick-film OSCs requires precise control over active layer morphology.

Purpose of the Study:

• To engineer the morphology of thick-film OSCs for improved performance.
• To investigate the effect of solid additives on active layer structure and electronic properties.
• To enhance the thickness tolerance and power conversion efficiency (PCE) of organic solar cells.

Main Methods:

• Systematic solvent and additive engineering strategy.
• Utilized two oligomers derived from polymer donors (PM6 and D18-Fu) as solid additives.
• Characterized active layer morphology, molecular orientation, and electronic properties.

Main Results:

• D18-Fu-derived oligomer enhanced interactions between donor (D18-Fu) and acceptor (L8-BO-X), suppressing electron-phonon coupling.
• Achieved more balanced donor-acceptor fibrillation and enhanced face-on molecular orientation.
• Devices with D18-Fu-derived oligomer showed improved PCE and thickness tolerance.
• Thick-film (500 nm) OSCs processed with toluene achieved a certified PCE of ~18%, a record for thick-film devices.

Conclusions:

• Solid additive engineering is effective for controlling morphology in thick-film OSCs.
• The D18-Fu-derived oligomer significantly improves device performance and thickness tolerance.
• Nonhalogenated solvents like toluene can be used to achieve high PCE in thick-film OSCs with excellent performance retention.