Physical properties of anatase TiO2 nanocrystallites: based photoanodes doped with Cr2O3

Abstract

In this paper the effect of doping based-TiO2 nanocrystallites photoanodes with chromium oxide (Cr2O3) has been studied. Photoanodes of dye-sensitized solar cells (DSSCs) were synthesized with the composition TiO2–(Cr2O3)x where 0 ≤ x ≤ 0.5 wt% by the conventional solid-state reaction method. The crystal structure and optical properties of photoanodes were analyzed by XRD, SEM, EDX and UV–visible spectroscopy techniques. The photovoltaic characteristics for the prepared samples have been studied by employing J–V measurements. X-ray diffraction study showed that the dominating phase in the samples is the anatase tetragonal phase with space group I41/amd. Another rhombohedral phase of Cr2O3 was observed in doped samples and found to increase with increasing of Cr2O3 content. A reduction in particle size with increasing of the dopant content was reported and attributed to crystallites growth suppression due to the presence of Cr3+ at the grain boundary. The UV–visible spectroscopy absorption improved by increasing Cr2O3 content in doped samples which may be recognized by presence of novel electronics states in band gap of TiO2. Data obtained from the UV–visible spectroscopy measurements reflects a decrease in the optical energy gap (Eoptical) and an increase in optical refractive index with increasing of the dopant. J–V photovoltaic characteristics confirms that the DSSCs photoanodes doped with Cr2O3 have higher value for conversion efficiency (η), fill factor, and short circuit current density (Jsc) compared with sample without doping.