Quinoxaline Terpolymer-Controlled Miscibility With Oligomeric Acceptors for Over 20% Efficiency, Highly Stable and...

Area of Science:

• Materials Science
• Organic Electronics
• Polymer Chemistry

Background:

• Oligomeric acceptors enhance polymer solar cell (PSC) stability, but performance and mechanical properties are limited by morphology.
• Tailored polymer donors are crucial for overcoming these limitations.

Purpose of the Study:

• To enhance miscibility and device performance in PSCs by strategically modifying the D18 polymer donor.
• To investigate the impact of incorporating a new quinoxaline (TQx) building block on PSC morphology and properties.

Main Methods:

• Developed D18-TQxn terpolymers via random copolymerization with varying TQx proportions (5%-15%).
• Utilized tethered dimeric acceptor (DY2) as a model acceptor for miscibility studies.
• Analyzed terpolymer surface energy, backbone conformation, and crystallization kinetics.

Main Results:

• The optimal D18-TQx10 terpolymer achieved a power conversion efficiency (PCE) of 20.21% with DY2, a high value for oligomeric acceptor devices.
• Enhanced thermodynamic miscibility and tuned crystallization kinetics were observed due to TQx incorporation.
• The D18-TQx10 blend showed significantly improved stretchability (nearly threefold increase in crack-onset strain).
• Good compatibility with various dimeric acceptors was demonstrated.

Conclusions:

• A dual-control strategy using quinoxaline terpolymers effectively regulates miscibility and crystallization kinetics in PSCs.
• This approach addresses key morphology control challenges for high-performance PSCs utilizing oligomeric acceptors.
• The developed terpolymers offer a promising pathway for efficient and mechanically robust PSCs.