TVT‐Based New Building Block with Enhanced π‐Electron Delocalization for Efficient Non‐Fused Photovoltaic Acceptor

Abstract To address the high‐cost issue that impedes the large‐scale fabrication and industrialization of organic solar cells (OSCs), it is crucial to design low‐cost photovoltaic materials with simplified synthesis procedures. In this study, a novel fully non‐fused acceptor, ATVT‐BO, featuring a triisopropylbenzene‐substituted ( E )‐1,2‐di(thiophen‐2‐yl)ethene (TVT) unit as the central core is designed and synthesized. A control acceptor, A4T‐BO, with the same alkyl chains but a bithiophene central core, is also synthesized for comparison. Theoretical calculations and practical measurements reveal that compared to A4T‐BO, the insertion of an ethylene bond in ATVT‐BO enhances the molecular planarity and reduces the aromaticity, leading to enhanced π‐electron delocalization and thus improved electron mobility and a red‐shifted optical absorption spectrum. The 3D molecular packing mode of ATVT‐BO, characterized by tight intermolecular interactions, also promotes efficient charge transport in OSCs. Consequently, when paired with the low‐cost polymer PTVT‐T, featuring an ester‐substituted TVT structure, as the photoactive layer, the PTVT‐T:ATVT‐BO‐based device achieves a remarkable power conversion efficiency of 14.8%, distinctly higher than that of PTVT‐T:A4T‐BO‐based cell. The result highlights the significant potential of TVT units in creating both low‐cost polymer donors and fully non‐fused acceptors, which opens up new possibilities for designing low‐cost photoactive materials in OSCs.