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

Abstract

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.