Effects of Ag doping on compact TiO2 thin films synthesized via one-step sol–gel route and deposited by spin coating technique

Abstract

In this paper, we present a novel one-step, easy and cost-effective method for the synthesis of Ag-doped TiO2 sol and deposition of its compact thin films by spin coating technique. The effects of dopant quantity (0–5% by weight) on structural, morphological, optical and electrical properties of TiO2 thin films have been investigated and reported. The X-ray Diffraction (XRD) spectra revealed single anatase phase having no secondary phases. The scanning electron microscopy (SEM) showed pinholes-free/compact thin films composed of spherical nanoparticles where the particle size has been demonstrated to decrease with increasing Ag doping. The atomic force microscopy (AFM) confirmed smooth and compact TiO2 thin films, however, the surface roughness tends to grow with increasing the dopant quantity. The X-ray fluorescence spectroscopy (XRF) revealed the presence of Ag mass percentage in the relevant samples, which has been demonstrated to grow with increasing the amount of dopant. The UV–Vis spectroscopy concluded the bandgap reduction of pure anatase phase of TiO2 (3.38 eV) as the Ag doping reaches to its maximum value of 5% (3.18 eV). Spectroscopic Ellipsometry has been employed to determine the thickness of thin films which was found to be in the range of ~ 100 nm, while electrical properties have been measured through DC-Hall Effect technique. It was found that the conductivity of thin films improved from 5.74 × 10–2 to 2.72 × 10–1 Ω−1 cm−1 on glass while on FTO-coated glass substrates, a higher value of 1.51 × 104 Ω−1 cm−1 was achieved.