Effect of Applying Cold Plasma on Structural, Antibacterial and Self Cleaning Properties of α-Fe2O3 (HEMATITE) Thin Film

Objective: In this study, α-Fe2O3 thin film was formed on a glass substrate to study the impact of adding cold plasma on the self-cleaning and antibacterial properties of the samples. Method: The samples were synthesized using the chemical spray pyrolysis (CSP) method at 450°C. X-ray powder diffraction (XRD), scanning electron microscope (FESEM), energy-dispersive X-ray spectroscopy (EDS), and atomic force microscope were used to investigate the morphological and structural characteristics of α-Fe2O3 thin layers prior to and following plasma injection. Finding: The degree of wettability and antibacterial characteristics of iron oxide (hematite) thin film were evaluated in the presence of gram-negative and gram-positive bacteria prior to and following plasma injection, given the great potential of plasma injection in the surface modification of thin films. Novelty: The findings indicate that exposing plasma to α-Fe2O3thin film produces substantial changes in morphology, self-cleaning, and antibacterial characteristics. Doi: 10.28991/ESJ-2022-06-01-06 Full Text: PDF

Optimization of the Sb2S3 Shell Thickness in ZnO Nanowire-Based Extremely Thin Absorber Solar Cells

Extremely thin absorber (ETA) solar cells made of ZnO/TiO2/Sb2S3 core–shell nanowire heterostructures, using P3HT as the hole-transporting material (HTM), are of high interest to surpass solar cell efficiencies of their planar counterpart at lower material cost. However, no dimensional optimization has been addressed in detail, as it raises material and technological critical issues. In this study, the thickness of the Sb2S3 shell grown by chemical spray pyrolysis is tuned from a couple of nanometers to several tens of nanometers, while switching from a partially to a fully crystallized shell. The Sb2S3 shell is highly pure, and the unwanted Sb2O3 phase was not formed. The low end of the thickness is limited by challenges in the crystallization of the Sb2S3 shell, as it is amorphous at nanoscale dimensions, resulting in the low optical absorption of visible photons. In contrast, the high end of the thickness is limited by the increased density of defects in the bulk of the Sb2S3 shell, degrading charge carrier dynamics, and by the incomplete immersion of the P3HT in the structure, resulting in the poor hole collection. The best ETA solar cell with a short-circuit current density of 12.1 mA/cm2, an open-circuit voltage of 502 mV, and a photovoltaic conversion efficiency of 2.83% is obtained for an intermediate thickness of the Sb2S3 shell. These findings highlight that the incorporation of both the absorber shell and HTM in the core–shell heterostructures relies on the spacing between individual nanowires. They further elaborate the intricate nature of the dimensional optimization of an ETA cell, as it requires a fine-balanced holistic approach to correlate all the dimensions of all the components in the heterostructures.

Synthesis of ZnO thin film by chemical spray pyrolysis using its nano powder

The deposition of metal oxides powder faces several problems, including poor adhesion to the bases deposited on them, the presence of many cracks, poor thickness control, and other disadvantages. The current study gives a new and simple idea to deposit thin films using two ZnO powders with nano and microparticle sizes on glass substrates. This was done by transforming the powders to Zinc acetate and then using chemical spray pyrolysis to deposit ZnO thin films. Scanning electron microscope (SEM) images showed that the prepared film from the nanopowder (ZnONano) lost the independence of powder’s nanoparticles and became a homogeneous film with nano projections. But the deposited one from the micro powder (ZnOMicro) had both nanorods and nanoplates. The different shapes and sizes of ZnO particles in ZnOMicro powder were disappeared after the Spray process. The two deposited films were homogeneous, crack-free and there were controllable thicknesses during the deposition. X-ray spectroscopy (EDS) was used to measure weights and atomic percentages of elements for the deposited films. The structures of the deposited films were approximately identical as the X-ray diffraction (XRD) technique showed. The optical properties of these two films were studied and their parameters were measured and calculated.

Spray Pyrolysed Nanostructured Gold-Doped Tin Oxide (Auto) Thin Films

Nanostructured SnO2 thin films were grown by the chemical spray pyrolysis (CSP) method. Homemade spray pyrolysis technique is employed to prepare thin films. SnO2 is wide band gap semiconductor material whose film is deposited on glass substrate. A gold nanoparticle-doped tin oxide thin film (AuTO) was also prepared. UV-VIS (ultraviolet visible) spectroscopy and four-point probe analysis are done for optical and electrical analysis. UV-Visible absorption spectra show that the band gap of SnO2 thin film is 3.78 eV and 3.82 eV for AuTO. Band gap of SnO2 thin film can be tuned that it can be used in optical devices. The films have transmittance increases (to about 60%) and the absorbance decreases in the visible region of the electromagnetic spectrum. The electrical conductivity of the Tin Oxide is enhanced by functionalizing with the Gold nanoparticles. It is higher than that of the Tin oxide only; 0.77 x 10-2 (Ohm cm)-1 and 3.55 x 10-2 (Ohm cm)-1 for SnO2 and AuTO respectively. These properties reveal that Tin Oxide doped with gold can actually be a good material for a transparent conducting oxide to be used in photovoltaic fabrication and in electronics.

A modeling study on utilizing low temperature sprayed In2S3 as the buffer layer of CuBaSn(S, Se) solar cells

This study represents the investigation of In2S3 thin films as an electron transport layer in the CuBaSn(S, Se)-CBT(S, Se) solar cells, which have been deposited using the Chemical Spray Pyrolysis method. For studying the electrical properties of films such as conduction and valence band, carrier densities, Fermi level, flat band potential, and semiconductor type, the Mott–Schottky analysis has been used. UV–VIS, XRD, and FESEM have been applied to investigate the optical properties of the layers and the layer’s morphologies. The experimental CBT(S, Se) solar cell has been simulated and validated as the next step. After that, the In2S3 layer has been used as the electron transport layer. The results represent that the In2S3 layer is a suitable substitution for toxic CdS. Finally, the In2S3 properties are varied in reasonable ranges, which means different electron transport layers are screened.

Synthesis and Characterization of Nanocrystalline Ba-doped Mn3O4 Hausmannite Thin Films for Optoelectronic Applications

In the present work, nanocrystalline hausmannite Mn3O4:Ba thin films have been deposited on glass substrates by chemical spray pyrolysis (CSP). Then, we investigated the impact of Ba doping concentrations on the structural, morphological and optical properties. The structural characteristics were investigated by X-ray diffraction technique and clearly show the films have a spinel Mn3O4 polycrystalline structure, the degree of crystallinity was improved by increasing Ba concentrations in Mn3O4 matrix with crystallite size range of 15–33[Formula: see text]nm. The lattice parameters, the unit cell volume and the (Mn-O) bond length of tetrahedral and octahedral sites, were varied by increasing Ba concentrations. SEM micrographs show that the films are homogeneous with nanoparticles dispersed on the surface with sizes range 30–132[Formula: see text]nm. The optical properties were estimated by UV-Vis-NIR spectrophotometer and exhibited that the optical transmittance and band gap were improved by increasing Ba doping concentration. Empirical equations were suggested to estimate some correlated variables with excellent agreement with the experimental data. The optimum condition was recorded in films doped with 3% of Ba where a better crystallinity, a preferable surface morphology and outstanding optical properties have been achieved.

SYNTHESIS AND CHARACTERIZATION OF NANOCRYSTALLINE Co-DOPED ZnO THIN FILMS PREPARED BY CHEMICAL SPRAY PYROLYSIS FOR OPTOELECTRONIC APPLICATIONS

ZnO:Co thin films were synthesized by the chemical spray pyrolysis (CSP) on glass substrates. Then, investigated the impact of Co doping concentration on its physical properties. XRD analyses show that all films have a polycrystalline structure of hexagonal ZnO. The crystallite size increased from 18[Formula: see text]nm to 25[Formula: see text]nm with Co doping concentrations. Furthermore, the unit cell volume increased from 47.485[Formula: see text]Å to 47.831[Formula: see text]Å, and the Zn–O bond length expanded from 1.97588[Formula: see text]Å to 1.98071[Formula: see text]Å. SEM observations reveal the formation of fiber-like nanostructures in the Co-doped thin films. The diameter of nanofibers increased with Co doping concentration from 260[Formula: see text]nm to 700[Formula: see text]nm. The optical characteristics were studied by the UV-Visible spectrophotometer and manifest the optical transparency vary with Co doping. In addition, the band gap decreases from 3.27[Formula: see text]eV to 2.73[Formula: see text]eV with increasing Co doping concentrations. The conductivity varied from 3.35[Formula: see text]S[Formula: see text][Formula: see text][Formula: see text]m[Formula: see text] to 19.88[Formula: see text]S[Formula: see text][Formula: see text][Formula: see text]m[Formula: see text] with Co doping concentrations. Empirical models were proposed to evaluate the correlated variables with excellent accuracy with the experimental data. The best result was accomplished in ZnO:Co1% films, where good transparency and high conductivity were achieved.

Influence of Solvents on Properties of ZnS Thin Films Synthesized by Chemical Spray Pyrolysis Technique

In this paper, the influence of solvents on the structural, optical, surface and electrical properties of spray-deposited ZnS thin films has been studied. Different precursor mixtures were prepared from ethylene glycol, deionized water and alcohol solvents and sprayed on heated glasses via a simple and cost-effective technique known as spray pyrolysis. XRD patterns confirmed cubic and tetragonal phases of synthesized ZnS material. The optical analysis of the synthesized ZnS films showed that films prepared using ethylene glycol solvent have the highest transmittance and the best bandgap (3.61 eV). Surface morphology showed the absence of voids and pinholes in the Scanning Electron Micrograph of ZnS film prepared from ethylene glycol and electrical studies showed that ZnS films prepared using the same solvent have the lowest resistivity. Keywords: ZnS, Thin film, Spray pyrolysis, Bandgap, Morphology.