Synthesis and Photophysical Properties of Aromatic Fused Ring Small Molecule Acceptor Materials Based on Two-dimensional indacenodithiazole for Organic Solar Cells

A new two-dimensional conjugated core unit 2DIDTz was synthesized based on indacenodithiazole with thiophene side chain. Then, a linear two-dimensional conjugated small molecule acceptor material, namely IDTzIID, based on 2DIDTz as core unit and (E)-1,1'-bis(2-ethylhexyl)-[3,3'-biindolinylidene]-2,2'-dione (IID) as end-groups was designed and synthesized through Still coupling reaction. There is a strong intermolecular charge transfer (ICT) between the IID and 2DIDTz. The structure and purity of the IDTzIID target compound was examined by 1H NMR. The IDTzIID showed good solvent properties in organic solvents. The IDTzIID showed wide and broad absorption with a band gap of 1.63 eV which can be matched with polymer donor materials for advanced organic solar cells.