Dimeric naphthalene diimide based small molecule acceptors: synthesis, characterization, and photovoltaic properties

Herein, we present two naphthalene diimide (NDI) dimer based small molecule acceptors, Bis-NDI-T-EG and Bis-NDI-BDT-EG, in which two NDI units are bridged, respectively, by a thiophene (T) or a benzodithiophene (BDT), and further symmetrically substituted by 2-methoxylethoxyl (EG), both through the bay-region. These two NDI dimers exhibit broad absorption in the visible region of 300–650 (800) nm and display a HOMO/LUMO energy level of −5.88 eV/−3.80 eV and −5.46 eV/−3.78 eV, respectively. When PBDTTT-C-T was chosen as the polymer donor, Bis-NDI-T-EG and Bis-NDI-BDT-EG exhibited efficiencies of 1.31% and 1.24%, respectively.

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