Polymerized-Small-Molecule Acceptors Featuring Siloxane-Terminated Side Chains for Mechanically Robust All-Polymer...

Area of Science:

• Materials Science
• Organic Electronics
• Polymer Chemistry

Background:

• Flexible and stretchable organic solar cells (OSCs) are crucial for wearable electronics.
• Achieving high power conversion efficiency (PCE) and excellent stretchability simultaneously in OSCs remains a challenge.
• Current high-performance OSCs often use polymer donors (PDs) and small-molecule acceptors (SMAs).

Purpose of the Study:

• To synthesize and evaluate a novel polymerized-small-molecule acceptor (P-SMA) with siloxane-terminated side chains (PY-SiO).
• To compare the photovoltaic and mechanical properties of PY-SiO against a reference P-SMA with ethylhexyl-terminated side chains (PY-EH).
• To investigate the potential of siloxane-terminated side chains for high-performance, stretchable OSCs.

Main Methods:

• Synthesis of PY-SiO and PY-EH polymerized-small-molecule acceptors.
• Fabrication of all-polymer solar cells (all-PSCs) using PBDB-T as the polymer donor.
• Characterization of photovoltaic performance (PCE) and mechanical properties (crack-onset strain).
• Evaluation of device performance under mechanical strain.

Main Results:

• PY-SiO incorporation optimized film morphology, enhancing molecular aggregation and charge transport.
• All-PSCs based on PBDB-T/PY-SiO achieved a higher PCE (12.04%) compared to PBDB-T/PY-EH (10.85%).
• Siloxane-terminated side chains improved film crack-onset strain (18.32% for PY-SiO vs. 11.15% for PY-EH).
• Stretchable all-PSCs with PY-SiO maintained >70% PCE under 20% strain, outperforming PY-EH-based devices.

Conclusions:

• Siloxane-terminated side chains are effective in simultaneously enhancing PCE and stretchability in OSCs.
• The optimized molecular aggregation and film morphology contribute to improved device performance.
• PY-SiO represents a promising material for developing next-generation high-performance, stretchable organic electronics.