Synthesis of conjugated perylene diimide-based copolymer with 5,5′-bis(4-aminophenyl)-2-2′-bifuryl moiety as an active material for organic photovoltaics

In this study, we have synthesized conjugated n-type perylene tetracarboxylic diimide-based copolymer with 5,5′-bis(4-aminophenyl)-2-2′-bifuryl segment (PTCDI-PFDA) as an active material for the fabrication of bulk heterojunction photovoltaic device of type ITO/PEDOT:PSS/rr-P3HT:PTCDI-PFDA/Al. The synthesized n-type copolymer (an oligomer with a relatively low molecular weight) was characterized by 1H NMR, gel permeation chromatography and thermo gravimetric analysis. The electronic and structural properties of the copolymer were investigated by UV–vis and fluorescence spectroscopy. The copolymer exhibited an optical band gap of about 1.59 eV. The HOMO and LUMO energy levels were calculated using cyclic voltammetry and density functional theory (DFT). The resulting copolymer was experimentally found to possess low-lying HOMO (ca. −5.24 eV) and high-lying LUMO (ca. −3.9 eV) energy levels. The fabricated device (D1) delivered an efficiency (η) of about 0.34% with a high open circuit voltage (Voc = 0.92 V), current density (Jsc = 2.83 mA/cm2), and fill factor (FF = 13%) under 100 mW/cm2 white light.