Use of non-fullerene type acceptor molecules in organic solar cells

Soluble non-fullerene acceptor type molecules have attracted significant attention due to their easy synthesis, low cost, high absorption in the UV region and easily tailored electronic energy levels (HOMO-LUMO) for organic solar cell applications. In this thesis, structural, spectroscopical and electronic properties of novel soluble non-fullerene CPCPFA and BPCPFA small molecules, which contain strong electron withdrawing cyano (CN) groups, have been investigated both theoretically and experimentally. Both traditional and inverted type organic solar cells have been fabricated using small molecules of CPCPFA and BPCPFA with P3HT and AnPV-stat polymers as donors for the first time. Morphological and structural properties of active layers have been investigated using XRD, SEM and AFM measurements. Inverted organic solar cells that contain AnPV-stat:CPCPFA and AnPV-stat:BPCPFA mixtures yield high open circuit voltages (Voc) of 1112 mV and 1059 mV, respectively. Finally, HOMO-LUMO energy levels have been calculated for non-fullerene acceptor of FTTB using density functional theory (DFT). In inverted type organic solar cells, four different electron transport layers (PEIE, PEIE/ZnO, ZnO ve ZnO/PEIE) have been used to produce P3HT:FTTB (Donor:Acceptor) blend devices for the first time. Morphological and photovoltaic properties have been studied by means of IPCE, SEM and AFM measurements. We achieved power conversion efficiency of 2.0% for inverted type organic solar cells in which P3HT:FTTB blend is used as active layer.