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

摘要

Blends of polymer donors (P_Ds) and small molecule acceptors (SMAs)have afforded highly efficient polymer solar cells (PSCs). However, mostof the efficient PSCs are processed using toxic halogenated solvents, andthey are mechanically fragile. Here, a new series of P_Ds by incorporatinga hydrophilic oligo(ethylene glycol) flexible spacer (OEG-FS) is developed,and efficient PSCs with a high power conversion efficiency (PCE) of 17.74%processed by a non-halogenated solvent are demonstrated. Importantly,the incorporation of these OEG-FSs into the P_Ds significantly increases themechanical robustness and ductility of resulting PSCs, making them suitablefor application as stretchable devices. The OEG-FS alleviates excessivebackbone rigidity of the P_Ds while enhancing their pre-aggregation inthe non-halogenated solvent. In addition, the OEG-FS in the P_Ds enhancesPD-SMA interfacial interactions and improves blend morphology, resulting inefficient charge generation and mechanical stress dissipation. The resultingPSCs demonstrate a superior PCE (17.74%) and high crack-onset strain(COS = 10.50%), outperforming the PSCs without OEG (PCE = 15.64% andCOS = 2.99%). Importantly, intrinsically stretchable (IS) PSCs containing theP_D featuring OEG-FS exhibit a high PCE (12.05%) and stretchability (maintaining80% of the initial PCE after 22% strain), demonstrating their viabilityfor wearable applications.