Effect of Solvents and Stabilizer Molar Ratio on the Growth Orientation of Sol-Gel-Derived ZnO Thin Films

Abstract

This work targets to control the growth orientation of sol-gel-derived ZnO thin films in order to allow different modes of excitation (longitudinal and transverse) when targeted to be used in piezoelectric applications. For that, the effect of solvents and stabilizer molar ratio on the structural and optical characteristics of the obtained films is investigated by means of X-ray diffraction (XRD), scanning electron microscopy (SEM), and UV-Vis spectrophotometry. The XRD results show clearly that the synthesized films exhibit hexagonal wurtzite structure without any secondary phases and that the crystallite average size, estimated by the Scherrer formula, is ranged between 13 and 30 nm. The main finding of this work is to show that the control of the crystalline growth orientation is possible simply by varying the solvent nature and/or the stabilizer molar ratio. These later parameters are therefore considered as key factors when seeking to develop the ZnO-based transducers. Actually, the ZnO thin films synthesized with propanol as solvent are oriented only along the c-axis; meanwhile, when using the isopropanol or ethanol, other preferential orientations appear. Additionally, the effect of MEA molar ratio (r) has been studied on the propanol-derived films (the unfavorable case). It has been found that this parameter has a direct effect on the crystalline growth orientation of these films and that a new preferential orientation (100) appears at low r. On the other hand, SEM images show the formation of homogeneous nanocrystalline thin films with an average grain size ranged between 19 and 35 nm. Moreover, the ZnO thin films exhibit a high transparency in the visible region, and the measured transmittance is ranged from 85 to 97%. However, the change of ZnO film orientation has no significant effect on the direct bandgap energy which is closed to 3.30 eV.

Performance of Dye Sensitized Solar Cells (DSSCs) with ZnO Nanorod Electrode in Different Seed Solution

“…The absorbance spectrum of ZnO nanorods with isopropanol resulted in higher absorption than methoxy. The results of this work are in accordance with the research that has been done previously which proves that isopropanol has been shown to act as an appropriate solvent to control the growth orientation of ZnO thin films due to its suitable structural and optical properties [17]. The presence of isopropanol grows a larger area of rods and thus potentially results in higher absorbance levels.…”

“…Based on previous research, it is known that isopropanol as a solvent or seed solution has more stable properties because it acts as a proton donor [19]. Previous research results have confirmed that the ZnO thin film preference growth axis indicates that the isopropanol is the best one [17]. This proves that the size of the diameter and absorbance at the photoanode which is influenced by a good seed solution will affect the performance of DSSCs.…”

The Potential of Pandanus amaryllifolius Leaves Extract in Fabrication of Dense and Uniform ZnO Microrods

“…The relative intensity ratio of I (002) of ZnO synthesized on Zn-HMTA seed layer is 0.92, which is significantly improved compared to that reported by [40] and [41]. On the other hand, Figure 5 shows the XRD pattern of ZnO nanostructures synthesized on Zn-Pandan seed layer at temperatures of 100, 200, 300, 400, and 500 It was found out that the (100) peak is dominant compared to (002) suggesting the formation of rod-like shape of nanoparticles is dominant compared to highly dense nanorods [36].…”

A Review on Reverse Osmosis and Nanofiltration Membranes for Water Purification

“…Finally high temperature sintering is applied to the membrane to optimize mechanical properties and pore structure [8,89]. In order to make homogeneous membranes with less defects, colloidal particles are dispersed uniformly in the solvent by stabilizers such as nitric acid, ethanolamine (MEA) and triethylenetetramine (TETA) [104,105,106]. Since complex fabrication process of multi-layered membranes as well as expensive precursor materials indicating high manufacturing cost, simplified synthesis method and use of cheap materials will reduce the production cost and accelerate the development and commercialization of ceramic membranes.…”