Band gap and superior refractive index tailoring properties in nanocomposite thin film achieved through sol-gel co-deposition method

► Nanocomposite ZrO2-SnO2 thin films with varying molar ratio ZrO2/SnO2 are synthesized from zirconium oxychloride octahydrate and tin(II) chloride dihydrate by sol-gel dip coating method. ► XRD spectra show the growth of orthorhombic ZrSnO4 phase in ZS55 sample with molar ratio 0.5/0.5 of ZrO2/SnO2 at 2θ = 51.7° and 62.7° along with tetragonal ZrO2 and tetragonal SnO2 phase at the annealing temperature 500 °C. ► XPS spectra reveal the presence of oxygen vacancies in the nanocomposite ZrO2-SnO2 thin film. ► Band gap and superior refractive index tailoring is observed in the nanocomposite ZrO2-SnO2 thin films, which have opened up a new dimension in optical applications. ► The PL emission peak at 424 nm indicates the presence of oxygen vacancies in ZrSnO4 which interact with interfacial atoms of zirconium and tin giving rise to photoluminescence.