Tagetes erecta (marigold) flower extract in the different solvents used as a capping agent and sensitizer for TiO2 photoanode based DSSC

This study utilizes acetonitrile (ACN), DI-water, and hexane as solvents, investigating their extraction efficiency from Tagetes erecta ( TE ) flowers. The UV–visible spectral study revealed greater absorbance for the hexane extract compared to ACN and DI-water extracts. HR-MS revealed the key constituents present in extracts obtained in different solvents. Functional characterization of TE extracts was carried out using FT-IR studies. DFT calculations highlighted HOMO and LUMO levels along with the role of various key constituents in photoelectron transfer to the TiO 2 conduction band. Further, this study explores the utilization of TE flower extracts, focusing on two applications: capping agents for synthesizing TiO 2 nanoparticles and natural sensitizers in DSSCs. For the capped TiO 2 , XRD analyses confirmed the anatase phase. FT-IR spectra showed the functionality of synthesized TiO 2 material, and HRTEM analysis indicated a smaller particle size (14.54 nm) for hexane extract-based-capped TiO 2 . EIS studies revealed that the hexane extract-based device has lower charge transfer resistance and longer electron lifetimes than acetonitrile, DI-water and un-capped samples. DSSC assembled with hexane-extract-based capped-TiO 2 demonstrated higher efficiency than its un-capped counterpart. When TE extracts were utilized as a sensitizer, UV–visible spectra of photoanode sensitized by hexane extract exhibited greater light harvesting than ACN and DI-water based extracts. DSSC assembled utilizing hexane-based sensitizers demonstrated higher efficiency, outperforming ACN and DI-water-based sensitizers as well as that of bare TiO 2 . These findings underline the potential of hexane as an effective solvent for extracting bioactive compounds from TE and its further use as sensitizer dye for TiO 2 based DSSC. • Solvent extraction study of Tagetes erecta (marigold) flower using acetonitrile, DI-water and hexane. • Hexane was the most effective solvent in extracting the active phytoconstituents. • Tagetes erecta flower extracts utilized as a capping agent for TiO 2 nanoparticle synthesis and as a sensitizer dye in DSSC. • TiO 2 capped with hexane extract exhibited a photo-conversion efficiency of 1.21 %.