Tungsten and fluorine co-doping induced morphology change and textured growth of spray-pyrolyzed SnO2 thin films viable for photocatalytic application

Physicochemical aspects of numerous metal oxide based thin films are crucial for various optoelectronic applications. Cationic (W) and anionic (F) co-doping strategy into SnO2 thin film has been adapted in order to tune the optoelectronic parameters. X-ray diffraction pattern reveals successful doping of 'W' and 'F' into the SnO2 lattice and textured growth along (111) plane direction at the expense of suppression of the (211) plane. X-ray photoelectron spectroscopy confirmed the charge states of Sn4+, W6+, O2- and F1- elements present in the films. Scanning electron microscopy shows that tetragonal morphology of pure and F-doped SnO2 changes to a network-like feature upon 'W' co-doping and the elemental composition is also ensured. The contact angle measurement gives the surface wettability nature, which indicates all the films are hydrophilic. The 10 wt.% Fdoped SnO2 shows a maximum transmittance of 89.36 % at 550 nm with a direct band gap of 3.82 eV. Electrical transport parameters are measured using linear four-probe and Hall effect techniques. Photocatalytic activity of methylene blue dye degradation showing a maximum efficiency for pure and solely F-doped SnO2 thin films are explained based on the obtained optoelectronic parameters.