Production of ZnO Cauliflowers Using the Spray Pyrolysis Method

Abstract

Zinc oxide (ZnO) is a semiconductor material with direct wide bandgap energy (3.37 eV) and a large exciton binding energy (60meV) at room temperature. It currently attracts worldwide intense interests because of its importance in fundamental studies, and its numerous applications, especially as optoelectronic materials, UV lasers, light-emitting diodes, solar cells, nanogenerators, gas sensors, photodetectors, and photocatalyst. ZnO micro−/nano-cauliflower arrays are of potential use for electrochemical sensing, dye-sensitized solar cells, an electron transporting layer, and photocatalytic applications. In this work, ZnO cauliflowers were produced as thin films on glass substrates at a substrate temperature of 350 ± 5°C using the low-cost spray pyrolysis (SP) method. Zinc chloride (ZnCl2) was used to prepare the precursor solution. The produced films were characterized using X-ray diffraction and scanning electron microscopy and X-ray energy-dispersive spectroscopy (SEM- EDS). X-ray diffractogram revealed that the films have hexagonal structure with preferential orientation along the (002) line. EDS analysis showed that the films are nonstoichiometric and they contain chlorine. ImageJ software was used to estimate the size distributions of the cauliflowers.