Poly(dimethylsiloxane)-block-PM6 Polymer Donors for High-Performance and Mechanically Robust Polymer Solar Cells

Area of Science:

• Materials Science
• Polymer Chemistry
• Renewable Energy

Background:

• Wearable polymer solar cells (PSCs) require both high power conversion efficiency (PCE) and stretchability.
• Existing efficient photoactive films often lack mechanical flexibility, limiting their application.

Purpose of the Study:

• To design and synthesize block copolymer (BCP) donors to achieve both high PCE and mechanical robustness in PSCs.
• To investigate the effect of poly(dimethylsiloxane) (PDMS) block length on the performance and stretchability of PSCs.

Main Methods:

• Synthesis of PM6-b-PDMSx block copolymers with varying PDMS block lengths (5k, 12k, 19k).
• Fabrication and characterization of PSCs using these BCP donors blended with L8-BO acceptor.
• Evaluation of device performance (PCE) and mechanical properties (crack-onset strain, strain at 80% PCE).

Main Results:

• PSCs based on PM6-b-PDMS_19k achieved a high PCE of 18% and a crack-onset strain (COS) of 18%, a significant improvement over control devices.
• Increased PDMS block length enhanced PSC stretchability, with PM6-b-PDMS_19k showing 9 times higher COS than PM6:L8-BO PSCs.
• Ternary blends incorporating PDMS resulted in macrophase separation, leading to inferior PCE and stretchability.

Conclusions:

• Covalently linking stretchable PDMS blocks to PM6 donor polymers is an effective strategy for creating highly efficient and mechanically robust PSCs.
• The developed BCP strategy offers a promising pathway for advanced, stretchable photovoltaic materials for wearable electronics.
• This work highlights the importance of molecular design in achieving dual performance metrics for next-generation solar cells.