New 4,5-Diaza-9,9'-spirobifluorene Derivative—A Promising Electron Acceptor for Nonfullerene Polymer Solar Cells

Abstract

A new 4,5-diaza-9,9'-spirobifluorene derivative 8 containing two electron-withdrawing perylenediimide moieties has been synthesized. The compound has been characterized by NMR, elemental analysis, UV spectroscopy, and cyclic voltammetry. The HOMO/LUMO energies of compound 8 are –5.81 eV/–3.89 eV; the \(E_{{\text{g}}}^{{{\text{opt}}}}\) = 1.75 eV, and \(E_{{\text{g}}}^{{{\text{ec}}}}\) = 1.92 eV. Low HOMO/LUMO energies and strong absorption in the visible range of the UV spectrum point to the possibility to use compound 8 as a promising electron acceptor for nonfullerene polymer solar cells.