Insight into the impact of the substituent modification on the photovoltaic performance of ferrocenyl chalcones based DSSCs

The design, synthesis, spectroscopic, computational and solar cell performance studies of two new ferrocenyl chalcones (Fc-O1 and Fc-S2) were synthesized by the Claisen-Schmidt condensation reaction. In the synthesized molecules, the enone moiety acts as an efficient p-bridge that links the donor ferrocene derivative with methylfuran (Fc-O1) and bithiophene (Fc-S2) substituents which permits good viability in fine-tuning the intramolecular charge transfer (ICT) and optical absorption spectrum. The chemical structure of the compounds have been elucidated by proton and carbon NMR as well as FTIR spectroscopies. The comparison study between the structures of these ferrocenyl chalcones were done by XRD and computational investigations. The substitution of bithiophene derivative on the Fc-S2 revealed the improvement of the structure planarity as compared to slightly twisted structure of Fc-O1. Fc-O1 and Fc-S2 exhibited large maximum absorption wavelength within the UV-Vis region (similar to 485 nm), suggesting their potential as dye sensitizer in DSSC application. The compounds also possessed suitable energy levels of HOMO and LUMO for utilization as sensitizer in DSSC to ensure the process of electron injection and dye regeneration. A good ICT due to its planarity, large absorption maximum in visible range and low-lying HOMO energy level of Fc-S2 give rise to the higher conversion efficiency in DSSC study as in comparison to Fc-O1.