Top-performance organic solar cells (OSCs) consisting of conjugated polymer donors and nonfullerene small molecule acceptors (NF-SMAs) deliver rapid increases in efficiencies. Nevertheless, many of the polymer donors exhibit high stiffness and small molecule acceptors are very brittle, which limit their applications in wearable devices. Here we report a simple and effective strategy to improve the stretchability and reduce the stiffness of high-efficiency polymer:NF-SMA blends and simultaneously maintain the high efficiency by incorporating a low-cost commercial thermoplastic elastomer, SEBS (As shown in Figure 1). The microstructure, mechanical properties, and photovoltaic performance of PM6:N3 with varied SEBS contents, and the molecular weight dependence of SEBS on microstructure and mechanical properties were thoroughly characterized. This strategy for mechanical performance improvement exhibits excellent applicability in some other OSC blend systems, e.g., PBQx-TF:eC9-2Cl, PBDB-T:ITIC. More crucially, the elastic modulus of such ternary blends can be nicely predicted by a mechanical model. Therefore, incorporating thermoplastic elastomers is a widely applicable and cost-effective strategy to improve mechanical properties of nonfullerene OSCs and beyond.

Thermoplastic elastomer tunes phase structure and promotes stretchability of high-efficiency organic solar cells

ACS Spring 2022

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.