Investigation the effect of doping concentration in Ruthenium-doped TiO2 thin films for solar cells and sensors applications

Abstract

Thin films of Ru doped TiO2 have been deposited on glass substrates at different doping concentration (0.05, 0.07, 0.09, 0.11 mol l−1) by the sol gel method. The prepared thin films were studied: their structural, morphological, optical and photocatlytic properties. The XRD spectra confirm that all the samples have anatase phase with preferential orientation along (101) plane. The position of (101) peaks shift to higher angles with increase doping concentration and 0.07 mol l−1 sample have a sharp and high intensity diffraction peak. Due to condensation and agglomeration effect. The thickness of the thin films increases from 110 nm to 255 nm with the increment of Ru concentrations. AFM images show that the films had good quality and pyramidal shape was distributed over their entire surface. Transmittance and absorbance spectra of the un-doped and Ru doped TiO2 thin films were recorded by UV–vis spectrometer. The optical band gap of the thin films increases from 3.66 eV to 3.85 eV as the Ru amount increases; this is due to the Moss-Burstein effect. Calculated results show that both the excitation coefficient (k) and refractive index (n) decreases with wavelength at all Ru concentration. Optical conductivity can improve after doping which can be a suitable material for use in sensor and solar cell applications. The photocatalytic activity was investigated by monitoring the degradation of methylene blue (MB) under visible and sun light. The results revealed that the photocatalytic activity under sun light was higher comparing to UV light for all films. Ru doped TiO2 thin films enhance the efficiency of its photocatalytic activity. It was found that the percentage of degradation was higher in 0.11 mol l−1 Ru doped TiO2 when compared with other films.