Tailoring the optoelectronic properties of spray pyrolyzed SnO2 thin films through cerium doping

Tin (IV) oxide (SnO2) thin films with varying cerium (Ce) concentrations were synthesized utilizing a cost-effective chemical spray pyrolysis process. The concentration of Ce was varied between 2 at% to 10 at% and thereby the consequences of the doping on the structural, morphological, elemental and optical properties of the SnO2 thin film was analysed through variety of characterization techniques. X-ray diffraction (XRD) studies revealed the rutile tetragonal structure of the prepared thin films having polycrystalline nature. The formation of SnO2 was further supported by Raman spectroscopic results. Further, a decrement in the crystallite size with increase in the Ce-doping concentration was observed. Scanning electron microscopic (SEM) results and energy dispersive spectroscopy (EDS) measurements corroborates that the films were uniform and nearly stoichiometric. Optical properties of all the thin films were analysed using absorption spectra. Optical bandgap was found to vary from 3.31eV to 2.99eV with cerium doping which demonstrates the effective bandgap tailoring potential of cerium. The lowest bandgap of 2.99eV was obtained for 6 at% Ce doped SnO2 thin film. Further, density functional theory (DFT) calculations were carried out to validate the structural stability along with electronic band gap and optical absorption spectra calculations for all samples. Combined theoretical investigations are well matched with experimental results. The highest emission intensity in photoluminescence spectra was found for 6 at% Ce doped SnO2 thin film. The optical studies reveals that 6 at% Ce doped SnO2 thin film has the most desirable properties that can be utilized for a varieties of optoelectronic applications.