Influence of number of deposited layers on the microstructure, hydrophobicity and electro-optical properties of electrospun Al-doped ZnO thin films

Abstract

The present study focused on the electro-optical properties of mono and multilayer Al-doped ZnO (AZO) thin films (TFs) using the electrospinning method. The microstructures of 1, 3, and 5 layered TFs were studied using field emission scanning electron microscopy (FESEM), energy dispersive spectroscopy (EDS), and X-ray diffraction (XRD) techniques. The results revealed that the monolayered TF was formed by attaching homogeneous nanoparticles (NPs) with a size of 21 nm. With increasing the number of layers, the agglomerates of AZO NPs covered the surface of TFs, the homogeneity decreased, the thickness of TFs increased from 340 nm to 1.8 µm, and the transparency decreased from 97.3% to 85.3%. With the deconvolution of photoluminescence spectra, it was found that the point defects between valence and conduction bands of AZO TFs did not change drastically. However, their optical band gap increased from 3.24 eV monolayered TFs to 3.32 in multilayered TFs. The sheet resistance of mono and multilayered TFs was 17.3 kΩ•sq−1 and 102.2 kΩ•sq−1, respectively. This study suggests electrospinning as a controllable method for the fabrication of transparent conductive oxides (TCOs).