Green synthesis and characterization of nanostructured ZnO thin films using Citrus aurantifolia (lemon) peel extract by spin-coating method

Green synthesis of nanostructured ZnO is becoming increasingly importance as eco-friendly alternative to traditional production process because of its growing industrial application. In this study, we produced two nanostructured ZnO thin films for comparison. The first thin film was produced using Zn(Ac)2·2H2O solution in Citrus aurantifolia (lemon) peel extract by spin-coating system. The second thin film was produced using Zn(Ac)2·2H2O solution in distilled water (dH2O). The solutions which prepared in Citrus aurantifolia peel extract and dH2O were named as SA, and SB, respectively. The ZnO thin films were named as TF1 and TF2, produced using SA and SB, respectively. TF1 and TF2 were characterized by XRD and indexed as wurtzite structure. Average crystallite sizes were calculated to be 35 and 45 nm, for TF1 and TF2, respectively, using Scherrer equation. Morphological properties of the ZnO thin films was determined with FE-SEM and average particle sizes are found to be 50 nm and 1 μm, for TF1 and TF2, respectively. Electrical conductivity measurements of the ZnO thin films were carried out via four probe dc system. The electrical conductivity values of the nanostructured ZnO films are between 6.0 × 10−9 and 2.8 × 10−4 Ω−1 cm−1, at 30 and 550 °C, respectively. Optical spectra of the ZnO thin films were measured and band gap (Eg) was found to be 3.36 eV for the both films in Uv/vis range.