https://chemistry.beloit.edu/classes/nanotech/ZnO/mattoday10_05_40.pdf

ZnO - nanostructures, defects, and devices

Recent status of chemical bath deposited metal chalcogenide and metal oxide thin films

CuInS2/In2S3 thin film solar cell using spray pyrolysis technique having 9.5% efficiency

The physical properties and photoelectrochemical characterization of aluminium doped hematite α-Fe2O3, synthesized by spray pyrolysis, have been investigated in regard to solar energy conversion. Stable Al-doped iron (III) oxide thin films synthesized by a spray pyrolysis technique reveals an oxygen deficiency, and the oxide exhibits n-type conductivity confirmed by anodic photocurrent generation. The preparative parameters have been optimized to obtain good quality thin films which are uniform and well adherent to the substrate. The deposited iron oxide thin films show the single hematite phase with polycrystalline rhombohedral crystal structure with crystallite size 20–40 nm. Optical analysis enabled to point out the increase in direct band-gap energy from 2.2 to 2.25 eV with doping concentration which is attributed to a blue shift. The dielectric constant and dielectric loss are studied as a function of frequency. To understand the conduction mechanism in the films, AC conductivity is measured. The conduction occurs by small polaron hopping through mixed valences Fe2+/3+ with an electron mobility 300 K of 1.08 cm2/(Vs). The α-Fe2O3 exhibits long term chemical stability in neutral solution and has been characterized photoelectrochemically to assess its activity as a photoanode for various electrolytes using white light to obtain I — V characteristics. The Al-doped hematite exhibited a higher photocurrent response when compared with undoped films achieving a power conversion efficiency of 2.37% at 10 at % Al:Fe2O3 thin films along with fill factor 0.38 in NaOH electrolyte. The flat band potential Vfb (−0.87 VSCE) is determined by extrapolating the linear part to C−2 = 0 and the slope of the Mott-Schottky plot.

https://iopscience.iop.org/article/10.1088/1674-4926/32/1/013001/pdf

Physical properties of hematite α -Fe 2 O 3 thin films: application to photoelectrochemical solar cells

The physical properties and photoelectrochemical characterization of aluminium doped hematite - Fe2O3, synthesized by spray pyrolysis, have been investigated in regard to solar energy conversion. Stable Al-doped iron (III) oxide thin films synthesized by a spray pyrolysis technique reveals an oxygen deficiency, and the oxide exhibits n-type conductivity confirmed by anodic photocurrent generation. The preparative parameters have been optimized to obtain good quality thin films which are uniform and well adherent to the substrate. The deposited iron oxide thin films show the single hematite phase with polycrystalline rhombohedral crystal structure with crystallite size 20-40 nm. Optical analysis enabled to point out the increase in direct band-gap energy from 2.2 to 2.25 eV with doping concentration which is attributed to a blue shift. The dielectric constant and dielectric loss are studied as a function of frequency. To understand the conduction mechanism in the films, AC conductivity is measured. The conduction occurs by small polaron hopping through mixed valences Fe 2C=3C with an electron mobility 300 K of 1.08 cm 2 /(V s). The -Fe2O3 exhibits long term chemical stability in neutral solution and has been characterized photoelectrochemically to assess its activity as a photoanode for various electrolytes using white light to obtain I - V characteristics. The Al-doped hematite exhibited a higher photocurrent response when compared with undoped films achieving a power conversion efficiency of 2.37% at 10 at% Al:Fe2O3 thin films along with fill factor 0.38 in NaOH electrolyte. The flat band potential Vfb (-0.87 VSCE/ is determined by extrapolating the linear part to C 2 D 0 and the slope of the Mott-Schottky plot.

Physical properties of hematite -Fe2O3 thin films: application to photoelectrochem- ical solar cells

Thin films of undoped and In-doped zinc oxide, prepared using chemical spray pyrolysis, were investigated using x-ray diffraction, optical transmission and absorption spectra, SEM, resistivity measurements, x-ray photoelectron spectroscopy and photoluminescence studies. A doping level of 1 at% indium was found to give lowest resistive films and enhanced optical transmission. But increasing the doping percentage resulted in lower optical transmission. XPS investigations revealed the presence of elemental chlorine in the In-doped film. Undoped ZnO thin films gave a strong blue-green emission. Doping with indium apparently resulted in a competitive phenomenon that overshadows the blue-green emission and gave rise to three emissions at 408, 590 and 688 nm.

http://iopscience.iop.org/article/10.1088/0268-1242/20/2/003/pdf

On the properties of indium doped ZnO thin films

Indium sulfide thin films have been prepared using the chemical spray pyrolysis technique. Samples with different substrate temperatures and indium-to-sulfur (In/S) ratios have been prepared and characterized using x-ray diffraction (XRD), x-ray photoelectron spectroscopy, photosensitivity measurements and optical absorption studies. XRD studies have revealed that the samples are β-In2S3. The optical bandgap has been found to decrease from 2.81 to 2.64 eV with the In/S ratio varying from 2/1 to 2/8. The photoresponse of the samples can be improved by changing either the In/S ratio in the solution or the substrate temperature. From this study we observe that, in terms of crystallinity, bandgap and photoresponse, the sample with the In/S ratio of 1.2/8 is very suitable for any photovoltaic application.

https://iopscience.iop.org/article/10.1088/0268-1242/18/6/317/pdf

Characterization of spray pyrolysed indium sulfide thin films

Chemically deposited thin films of cadmium sulfide (CdS) nanoparticles are analyzed using different techniques to estimate the origin of quantum confinements of CdS clusters in the film. The increase of Cd(OH)2 in the sample with the increase of pH of the bath, observed in XPS depth profiles, depicts the possibility that the CdS clusters of finite size are embedded in Cd(OH)2 surroundings, which ultimately makes the clusters electrically isolated and hence providing carrier confinements. X-ray diffraction and optical absorption studies on these films indicated clear clustering and subsequent carrier confinement effects. An XPS of the same film, after 1 month, shows the conversion of surface layers of Cd(OH)2 into CdO, which is rather a conducting compound.

Y Kashiwaba

Papers

On the properties of indium doped ZnO thin films

Characterization of spray pyrolysed indium sulfide thin films

How quantum confinement comes in chemically deposited CdS?—A detailed XPS investigation