Impact of Sequential Fluorination of Donor and/or Acceptor Polymers on the Efficiency and Morphology of All-Polymer Solar Cells AITranslate

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DOI：https://doi.org/10.1021/acsapm.1c00288

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To fine-tune all-polymer solar cells (all-PSCs), fluorine atoms were introduced on the bithiophene of thiophene-flanked dioxo-benzodithiophene-based donor polymers (P2T-0F and P2T-2F) and/or on the bithiophene of naphthalenediimide (NDI)-based acceptor polymers (NDI-0F and NDI-2F). The resultant four combinations [P2T-0F:NDI-0F (or NDI-2F) and P2T-2F:NDI-0F (or NDI-2F)] exhibited dramatically different morphologies, surface free energies (polar and dispersion components), and electrical properties, largely reflected in their power conversion efficiencies (PCEs). Notably, the highest PCE (3.28%, P2T-2F:NDI-0F blend) correlated with the polar components of the surface free energies of the donor and acceptor polymers and improved charge transport properties. The other fluorinated (P2T-0F:NDI-2F and P2T-2F:NDI-2F) and non-fluorinated (P2T-0F:NDI-0F) blends exhibited lower PCE values owing to their poor miscibility and edge-on-rich orientation. We demonstrate a delicate but significant impact of sequential fluorination on the studied polymer blends, which is informative for key structure–property relationships of all-PSCs.