Controlled synthesis of hierarchical TiO2 nanostructures using alcoholysis and ultrasound for enhanced photovoltaic performance

This study presents the controlled synthesis of hierarchical TiO₂ nanostructures using the sol-gel method, with particular emphasis on the alcoholysis of titanium alkoxide precursors. The influence of polyhydroxy alcohols namely ethylene glycol (bearing two hydroxyl groups) and glycerol (with three hydroxyl groups) on the resulting TiO₂ morphology was systematically examined. Scanning Electron Microscopy (SEM) analysis revealed that the morphology of TiO₂ can be finely tuned by selecting the appropriate polyhydroxy alcohol during the alcoholysis step. X-ray diffraction (XRD) patterns confirmed the formation of TiO₂ in the pure anatase phase, with nanometric crystallite sizes, estimated using the Scherrer and Williamson-Hall methods. UV-Vis reflectance spectroscopy highlighted notable variations in the optical band gap among the synthesized samples, reflecting changes in their electronic structures. Furthermore, photovoltaic tests conducted on a P3HT + 20% TiO₂ nanocomposite active layer showed marked enhancements in both short-circuit current and open-circuit voltage, underscoring the superior photovoltaic performance of these tailored nanostructures. Notably, the spontaneous self-assembly of TiO₂ into microspherical architectures contributed to improved interfacial contact between the organic and inorganic components, further boosting device efficiency. Overall, this work highlights the strong potential of hierarchical TiO₂ nanostructures in the development of next-generation solar energy conversion systems.

Graphical Abstract

The main objective is to highlight the polyhydroxy alcohol effect that controls the morphology of TiO₂ microstructures through particle self-assembly. Secondly, to explore and optimize the photovoltaic properties of nanoparticles incorporating these TiO₂ microstructures, in order to potentially improve solar cell efficiency through enhanced light absorption and charge transport capabilities.