Abstract
Despite its large band gap, ZnO has wide applicability in many fields ranging from gas sensors to solar cells. ZnO was chosen over other materials because of its large exciton binding energy (60 meV) and its stability to high-energy radiation. In this study, ZnO nanorods were deposited on ITO glass via a simple dip coating followed by a hydrothermal growth. The morphological, structural and compositional characteristics of the prepared films were analyzed using X-ray diffractometry (XRD), field emission scanning electron microscopy (FESEM), and ultraviolet-visible spectroscopy (UV-Vis). Photoelectrochemical conversion efficiencies were evaluated via photocurrent measurements under calibrated halogen lamp illumination. Thin film prepared at 120 °C for 4 h of hydrothermal treatment possessed a hexagonal wurtzite structure with the crystallite size of 19.2 nm. The average diameter of the ZnO nanorods was 37.7 nm and the thickness was found to be 2680.2 nm. According to FESEM images, as the hydrothermal growth temperature increases, the nanorod diameter become smaller. Moreover, the thickness of the nanorods increase with the growth time. Therefore, the sample prepared at 120 °C for 4 h displayed an impressive photoresponse by achieving high current density of 0.1944 mA/cm2.
Highlights
The wide-band gap semiconductor, ZnO with a band gap value of 3.37 eV, belongs to the II–IV group, which is widely used in optoelectronic applications due to its high electron mobility [1]
Substrates that were coated with ZnO seed layers were treated with hydrothermal growth treatment in order to obtain the ZnO nanorods
This may lead to the interpretation that the precursor solution of Zn2+ used in the hydrothermal process to grow ZnO seeds into nanorods has evaporated as the boiling point of the zinc solution was 125 ◦ C
Summary
The wide-band gap semiconductor, ZnO with a band gap value of 3.37 eV, belongs to the II–IV group, which is widely used in optoelectronic applications due to its high electron mobility [1]. ZnO, there are various types of metal oxides being applied in photoelectrochemical, such as Fe2 O3 , Nb2 O5 , CeO2 , TiO2 and so on [2]. ZnO nanostructures exist in different forms, such as nanobelts [3], nanorings [4], nanohelices [5], nanorods [6], nanocombs [7] and a tetrapod [8] governed by its synthesis parameters [9]. ZnO thin films may play an important role in the development of advanced materials.
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