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Organoboron compounds provide a new method to tune photoelectric properties of π-conjugated materials. In this paper, we developed an organoboron compound (MBN-3Th), which composed of an organoboron core unit (BNBP4P) and two electron withdrawing groups linked by two π bridging units (trithiophene). Due to MBN-3Th has unique electronic structure, i.e. the LUMO is delocalized on the whole π-conjugated structure and the HOMO is localized on trithiophene units and the core unit. MBN-3Th exhibits broad absorption spectrum and possesses appropriate LUMO/HOMO energy levels, the ELUMO/EHOMO values are -3.88 eV and -5.24 eV. Extending π bridging units increase HOMO level, blue shift wavelength absorption peak, and improves crystallinity in thin film. Organic solar cells (OSCs) with MBN-3Th as electron acceptor have power conversion efficiency (PCE) of 3.18% and broad photoresponse of 300- 800 nm.
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