The Photovoltaic Performance of Sensitizers for Organic Solar Cells Containing Fluorinated Chalcones with Different Halogen Substituents

Two newly halogenated chalcones, derivatives of C15H10ClFO (CH-ClF) and C15H10F2O (CH-FF), were synthesized using the Claisen–Schmidt condensation method. Both compounds were crystallized using a slow evaporation method, forming a monoclinic crystal system with a space group of P21 and P21/c, respectively. The compounds were further analyzed using spectroscopic techniques such as Fourier Transform Infrared (FTIR), Nuclear Magnetic Resonance (NMR), and Ultraviolet–Visible (UV–vis) analyses. The single crystal X-ray diffraction method revealed the existence of C−H⋯O and C−H⋯F intermolecular interactions in CH-FF. Hirshfeld surface analysis was performed to confirm the existence of intermolecular interactions in the compounds. The molecular geometries obtained from the X-ray structure determination were further used to optimize the structures using density functional theory (DFT), with the B3LYP/6-311G++(d,p) basis set in the ground state. The TD-DFT/B3LYP method was used to obtain the electronic properties and the HOMO–LUMO energy gap. Both compounds exhibited A-π-A architecture with different halogen substituents in which the CH-FF, containing -fluoro substituents, possessed good electron injection ability due to its electronegative properties. This increased the flow of the charge transfer for the dye regeneration process and enhanced the efficiency of the dye-sensitized solar cell (DSSC).