Photophysical and Physiochemical Study of New Pyrenyl Chalcone Derivatives as Sensitizers for Organic Solar Cells

Three pyrenyl chalcone derivatives namely, PCH1, PCH2, and PCH3 were synthesized by utilizing the Claisen-Schmidt condensation technique. Compound PCH1 was successfully recrystallized via the slow evaporation technique. To determine and refine the crystal structure, the single crystal is subjected to X-ray diffraction (XRD) analysis. Crystal packing reveals that intermolecular C-H···O interactions bind molecules in compound PCH1 in a head-to-head arrangement. Intramolecular charge transfer (ICT) between molecules has improved as a result of the compound’s C-H···O contacts. The compounds were then characterized using UV-Vis spectroscopy where all compounds have an energy gap that is within the low range, ranging from 2.89 to 2.94 nm. Furthermore, the HOMO-LUMO energy levels of the pyrenyl chalcones were examined by conducting CV analysis. The energy levels of the compounds essentially lie between the conduction band of TiO₂ and the redox potential ($I^{-}/I_3^{-}$) of the electrolyte. FESEM and EDX analyses were utilized in solar cell performance investigations to examine the surface topography and elemental mapping of the pyrenyl compound on the TiO₂ layer, correspondingly. Compound PCH2 emerges as the most effective dye-sensitizer in DSSC applications due to the anchoring of strong substituent groups in the compound, even though all three compounds demonstrated suitability as dye-sensitizer materials.