Dimerized Acceptors with Conjugate-Break Linker Enable Highly Efficient and Mechanically Robust Organic Solar Cells

Area of Science:

• Materials Science
• Organic Electronics
• Photovoltaics

Background:

• Designing efficient and mechanically robust acceptors is crucial for intrinsically stretchable organic solar cells (IS-OSCs).
• Existing stretchable polymer acceptors have limited efficiency, while high-performance small molecular acceptors are brittle.

Purpose of the Study:

• To synthesize and evaluate novel dimerized acceptors using a thienylene-alkane-thienylene (TAT) conjugate-break linker.
• To investigate the impact of connecting sites and halogen substitutions on molecular properties and device performance.

Main Methods:

• Synthesis of four dimerized acceptors with varying connecting sites and halogen substitutions.
• Characterization of electronic structures, aggregation behaviors, and charge transport properties.
• Fabrication and testing of rigid and intrinsically stretchable organic solar cells (OSCs).

Main Results:

• Molecular structure optimization led to rational phase separation in blend films, enhancing exciton dissociation and suppressing charge recombination.
• FDY-m-TAT based rigid OSCs achieved a power conversion efficiency (PCE) of 18.07%.
• FDY-m-TAT based IS-OSCs demonstrated a high PCE of 14.29% and a crack-onset strain (COS) of 18.23%, outperforming Y6-based counterparts.

Conclusions:

• Dimerized acceptors with conjugate-break linkers show significant potential for developing highly efficient and mechanically robust organic solar cells.
• The design strategy offers a pathway to overcome the trade-off between efficiency and stretchability in IS-OSCs.