Attaining 19.12% solar cell efficiency for non-fused ring electron acceptors via multi-dimensional charge transport

Non-fused ring electron acceptors (NFREAs) exhibit substantial commercial application potential. Nevertheless, their subpar electron transport performance results in slightly low power conversion efficiencies (PCEs) of organic solar cells (OSCs). Herein, we put forward an innovative supramolecular side-chain-induced multi-dimensional charge transport strategy to exploit two NFREAs 3TT-Ph2 and 3TT-Ph4 with terminal phenyl/fluorinated phenyl side chains. In comparison to the unfunctionalized control molecule 3TT-2, both 3TT-Ph2 and 3TT-Ph4 form additional phenyl-acceptor (Ph-A) supramolecular interactions between the phenyl side groups and the cyanoindanone end groups. Meanwhile, these fluorinated terminal phenyl groups can induce the formation of multiple supramolecular interactions, including F···F, F···H and F···C. The synergistic effect of these supramolecular interactions promotes the tight and ordered stacking of molecules, facilitates the construction of multi-dimensional charge transport channel. Finally, D18:3TT-Ph4-based device achieved a record-breaking PCE of 19.12% and a fill factor of 80.65%. Our research pave an effective strategy for the molecular design of high-performance NFREAs. Non-fused ring electron acceptors (NFREA) are limited by their electron transport efficiencies for solar cells. Here, the authors introduce supramolecular interaction sites on the side groups of NFREAs to construct multi-dimensional charge transport channels for higher performance solar cells.