One-pot synthesis of hollow sphere TiO2/Ag nanoparticles co-sensitized with peonidin: pelargonidin for dye-sensitized solar cells applications

Hollow sphere titanium dioxide/silver nanoparticles (HST/AgNPs) were synthesized using a one-pot sol–gel method with ascorbic acid as a reducing agent. This approach aims to enhance the efficiency of dye-sensitized solar cells (DSSCs) by improving light harvesting. The synthesized HST/AgNPs were characterized using scanning electron microscopy (SEM), X-ray diffraction (XRD), ultraviolet–visible spectroscopy (UV–Vis), and transmission electron microscopy (TEM) to analyze their structural, optical, and morphological properties. XRD results confirmed the anatase phase of TiO₂ and the presence of AgNPs, which enhanced scattering effects and promoted electron transfer. SEM and TEM analyses showed a uniform distribution of AgNPs on the hollow TiO₂ spheres, suggesting successful integration of silver. Optical properties assessed by UV–Vis spectroscopy revealed a broad absorption in the visible range due to localized surface plasmon resonance effects from AgNPs. DSSCs incorporating HST/AgNPs demonstrated a 52% increase in efficiency compared to those using standard P25 TiO2, as shown by I–V meter analysis. However, a higher concentration of AgNPs reduced DSSC efficiency, likely due to decreased dye loading. The study also explored co-sensitization using peonidin (Pn) and pelargonidin (Pg) to broaden the visible light absorption range. While co-sensitization increased the absorption area under the visible spectrum curve, it did not significantly expand the absorption band. These findings emphasize the need to balance nanoparticle concentration and dye loading to optimize DSSC performance, contributing to the development of efficient solar cells and optoelectronic devices.