Intrinsically-Stretchable and Non-Halogenated Solvent Processed Polymer Solar Cells Enabled by Hydrophilic Flexible Spacer-Incorporated Polymers

Abstract

A series of polymer donors (PDs) with a hydrophilic flexible spacer (FS) is synthesized and afford high-performance and mechanically robust polymer solar cells (PSCs) processed by toluene. The hydrophilic FS promotes repulsion interaction between polymer and toluene, retaining sufficient aggregation of the PDs in the solution. Also, the FS enhances PD/small molecule acceptor (SMA) interfacial interactions and consequently improves the blend morphology, leading to efficient charge generation and mechanical stress dissipation. Therefore, the associated PSC with 5 mol% of FS incorporating PD shows superior PCE (17.74%) and crack-onset strain (10.50%) values, outperforming the PSCs without the FS (PCE = 15.7% and COS = 2.99%). Importantly, intrinsically stretchable PSC (IS-PSC) with the FS containing PD accomplishes the best performances in terms of both PCE (12.05%) and stretchability (retaining 80% of the initial PCE after 22% strained).