Enhanced structural, optical and morphological properties of ZnO thin film using green chemical approach

In this work, ZnO thin film is fabricated by a green chemical approach using Uncaria gambir leaf extract on a glass substrate. The hexagonal wurtzite structure of ZnO does not change with the use of extracts. While ZnO fabricated without extract does not show preferred orientation, the ZnO prepared with extract shows c-axis orientation. The crystallite size is also significantly reduced from 41 nm to 32 nm. The visible transmittance increases from 71% to 76%, while the bandgap energy increases from 3.66 eV to 3.70 eV. The intensity of infrared transmission of ZnO with extract is lower than ZnO without extract because of the smaller crystallite size. The surface morphology of the film with extract is smoother, flatter, more homogeneous, and has smaller grain sizes, and uniform distribution.