End-Extended Conjugation Strategy to Reduce the Efficiency-Stability-Mechanical Robustness Gap in Binary All-Polymer...

Area of Science:

• Materials Science
• Organic Electronics
• Photovoltaics

Background:

• Commercialization of all-polymer solar cells (APSCs) requires high efficiency, mechanical robustness, and thermal stability.
• Polymer chain entanglement in APSCs often leads to complex morphology, hindering fill factors and stability.

Purpose of the Study:

• To address challenges in APSC morphology and stability.
• To develop an end-group extended polymer acceptor for improved device performance.

Main Methods:

• Synthesis of a novel end-group extended polymer acceptor, PY-NFT.
• Morphology analysis to study molecular packing and phase separation.
• Fabrication and testing of PM6:PY-NFT based solar cells.
• Thermal aging studies and mechanical testing of the polymer blend films.

Main Results:

• The PM6:PY-NFT blend demonstrated tightly ordered molecular packing and favorable phase separation.
• Achieved a record power conversion efficiency (PCE) of 19.12% for binary APSCs.
• The blend exhibited excellent morphological stability, retaining 90% of initial efficiency after 1500 hours at 65°C.
• Demonstrated outstanding mechanical ductility with a crack onset strain of 24.1%.

Conclusions:

• Rational chemical structure innovation, specifically conjugation extension, is key to optimizing APSC performance.
• The PY-NFT acceptor enables favorable phase separation and stable morphology, leading to high efficiency and durability.
• This work provides a viable strategy for developing high-performance, stable, and mechanically robust APSCs.