Solomon Offiah - Academia.edu (original) (raw)

Papers by Solomon Offiah

Research paper thumbnail of Study of the extrinsic properties of ZnO:Al grown by SILAR technique

Journal of Solid State Electrochemistry, 2017

Research paper thumbnail of Chemical Bath Synthesis and physico-chemical Characterizations of NiO-CoO Composite Thin Films for Supercapacitor applications

International Journal of Electrochemical Science

Research paper thumbnail of STRUCTURAL AND SPECTRAL ANALYSIS OF CHEMICAL BATH DEPOSITED COPPER SULFIDE THIN FILMS FOR SOLAR ENERGY CONVERSIONS

chalcogen.infim.ro

Copper sulfide chalcogenide thin films have been successfully deposited on glass substrates using... more Copper sulfide chalcogenide thin films have been successfully deposited on glass substrates using copper II chloride, thiourea, TEA and ammonium hydroxide in a solution bath. Structural and optical characterizations were carried out with the aid of X-ray Diffractometer and Unico-UV-2102PC spectrophotometer respectively. The effects of varying the annealing temperatures on the structural and spectral properties were also investigated. The presence of both chalcocite (Cu 1.96 S) and digenite (Cu 9 S 5 ) phases of the copper sulfide thin films with average grain sizes between 12.55nm and 14.22nm were confirmed by XRD analysis. The thermally treated Cu x S thin films have very high transmittance, between 85% and 95%, and low reflectance, less than 21% at both the visible and the NIR regions of the electromagnetic spectrum. They have optical band gap energy between 2.1eV and 2.5eV. The refractive index, extinction coefficient, optical conductivity and the dielectric properties were also studied. The analysis show that the thin films could serve as good materials for the fabrication of solar cell and other optical devices.

Research paper thumbnail of ELECTROCHEMICAL STUDIES OF PVP-CAPPED PbS THIN FILM DEPOSITED BY POLYMER-ASSISTED CHEMICAL BATH DEPOSITION (PACBD)

Chalcogenide Letters, 2015

PbS thin films were deposited on glass and stainless steel substrates using PACBD method. The as-... more PbS thin films were deposited on glass and stainless steel substrates using PACBD method. The as-deposited and annealed films were characterized for structural, morphological, compositional, optical and electrochemical properties. Cyclic voltammetry indicated a reversible redox reaction with electrochemical interfacial capacitance of 101mF/cm

Research paper thumbnail of Weibull distribution-based model for prediction of wind potential in Enugu, Nigeria

Advances in Applied Science Research, 2012

Modeling and prediction of wind characteristics are essential design inputs in the development of... more Modeling and prediction of wind characteristics are essential design inputs in the development of wind power systems for different locations. In this paper, the daily wind data for Enugu (6.3 0 N; 7.3 0 E; 450m), Nigeria, over a period of 13 years (1995 ‐ 2007), is modeled in ter ms of the Weibull distribution function, in order twind energy potential of the location. The daily, monthl y, and annual wind speed probability density distri butions at 10m meteorological height are modeled and the mean wind speed, skew, shape- and scale factors are determin ed with values of 2.5 ± 0.3m/s, -0.46, 2.21 and 4.31m/s res pectively. The results suggest that while the wind speed is more concentrated at higher values above the mean, the d istribution for Enugu departs significantly from th e standard Raleigh distribution, with error of 10.5%. The coef ficient of determination of the model is 0.74. Furt her statistics suggest that the model can be used, with acceptable accuracy, for prediction of...

Research paper thumbnail of Influence of cadmium precursor concentrations on the structural, optical and electrochemical impedance properties of CdZnS thin films

Research paper thumbnail of Method to Control the Optical properties: Band Gap Energy of Mixed Halide Organolead Perovskites

Arabian Journal of Chemistry

Research paper thumbnail of Delineation of Groundwater Saturation Indicators and their Distributions in the Complex Argillaceous Geological Units of Ezza North Local Government Area of Ebonyi State, Nigeria

Current Science, 2016

Twelve vertical electrical soundings (VES) employing Schlumberger electrode configuration were ca... more Twelve vertical electrical soundings (VES) employing Schlumberger electrode configuration were carried out in parts of Ezza north local government area of Ebonyi state, Nigeria, where extraction of potable groundwater has posed challenges to the dwellers of the area who are currently relying on surface water sources and some scattered seasonal open wells that cause health problems. The present study was undertaken to determine the hydrogeological characteristics, indicators that predict groundwater potential of the study area. The study indicates that the aquifer resistivity ranges between 12 and 504 m with an average value of 95.42 m. Water resistivity ranges between 9.6 and 73.0 m with an average of 26.34 m. The aquifer thickness ranges from 34.1 to 214.7 m with an average of 71.97 m. Also, the formation factor varies between 1.25 and 6.9 with an average of 2.76. Porosity ranges between 5.34% and 29.47% with an average of 15.91%. Similarly, hydraulic conductivity ranges from 1.1645 to 38.0491 m/day, the average being 12.8312 m/day, and K values range between 0.0023 and 3.1695 S/day with a mean value of 0.6273 S/day. Using surfer software package, contour distributions of geo-hydrodynamic properties were generated which show the distribution of the aquifer parameters in the study area. The distributions of these properties reflect the regions with high and low potential groundwater in the area. The diagnostic models and the inherent and intrinsic constants can be employed in quantitative prediction of groundwater potential in the adjoining regions of the study area which show similar hydrogeological properties.

Research paper thumbnail of Nio-CoO

Research paper thumbnail of INFLUENCE OF PRECURSOR CONCENTRATION ON OPTICAL PROPERTIES OF MnxOy THIN FILMS

Journal of Ovonic Research

Precursor concentration dependent manganese oxide (MnxOy) nanocrystalline thin films prepared by ... more Precursor concentration dependent manganese oxide (MnxOy) nanocrystalline thin films prepared by CBD techniques within the pores of PVP on glass slides at 343K were studied. The films turned out to be MnO2 nanocrystals with grain size range of 76.11nm – 12.96nm for increasing precursor concentration. The deposited films were annealed at 403K and characterized for structural and optical properties. XRD analyses revealed their crystalline nature. The absorbance, transmittance reflectance, refractive index and absorption coefficient were found to vary inversely with precursor concentration, though irregularly. The absorption spectra showed that the energy band-gap of the films lies in the range of 2.34eV – 2.75eV

Research paper thumbnail of Electrochromic and electrochemical supercapacitive properties of Room Temperature PVP capped Ni(OH)2/NiO Thin Films

Electrochimica Acta, 2015

ABSTRACT Porous-structured Ni(OH)2 and NiO thin films are good materials to enhance the performan... more ABSTRACT Porous-structured Ni(OH)2 and NiO thin films are good materials to enhance the performance of electrochromic devices as they provide an easy pathway for electrolyte penetration required for the improvement of electrochemical (EC) activity. In this paper, we present the results of our room temperature chemical bath deposition (CBD) of highly porous nanostructured PVP-capped Ni(OH)2/NiO thin films. We investigate the effects of post-deposition thermal treatment and the contribution of the substrate surface on the morphological, structural and electrochemical properties of these films as well as the role of the capping agent during the film growth process. Randomly oriented and well interconnected nanorods of individual lengths of about 600 nm were deposited on both stainless steel and Fluorine doped tin Oxide (FTO). The incorporation of PVP helps to moderate the size and length of the nanorods in the films as well as delayed the transformation of nickel hydroxide to oxide films. The optical density and the colouration efficiency obtained for the as-deposited (Ni(OH)2 films are 0.985 and 55.89 cm2/C respectively. The highest specific capacitance of 1184.52 F/g is obtained for the as-deposited film on stainless steel. We can deduce that the incorporation of PVP in the films enhanced the electrochemical capacitive properties of the Ni(OH)2 films to a very good extent.

Research paper thumbnail of Resistivity Survey for Groundwater in Ezza North Using Vertical Electrial Sounding

Abstract- Vertical electrical resistivity soundings were conducted in order to delineate the grou... more Abstract- Vertical electrical resistivity soundings were conducted in order to delineate the groundwater potentials at some locations in Ezza North Local Government of Ebonyi State. Twelve vertical electrical soundings were obtained using the Schlumberger configuration with the aid of the OHMEGA terramenter (SAS1000).The field data were subjected to interpretation by employing the method of manual partial curve matching techniques using the master curves and the corresponding auxiliary curves. A computer programme (RESOUND) was also used to interpret the data. The parameters obtained were used to determine the resistivities and thicknesses of the subsurface layers. The major lithologic units of the area are shales, sandstone and mudstone. The water bearing rocks were interpreted to exist at depths between 20m and 130m. The results fairly correlated with some logged boreholes close to the survey area. The aquifers have resistivities ranging between 9Ωm and 110Ωm. The geophysical sear...

Research paper thumbnail of 91005837 FEzema Coll

Research paper thumbnail of Spectral Analysis of Chemical Bath Deposited Copper Selenide Thin Films

ABSTRACT Copper selenide thin films were successfully deposited on glass substrates using the che... more ABSTRACT Copper selenide thin films were successfully deposited on glass substrates using the chemical bath deposition technique at room temperature. The chemical bath was composed of copper II chloride dihydrate (CuCl2.2H2O) as the source of the Cu 2+ and Sodium selenosulphate solution (Na2SeSO3) as the source of the Se 2-. Ammonium hydroxide solution (NH4OH) was used as the complexing agent. Some of the films were subjected to post deposition thermal treatments. Spectral analyses of the films were done in order to study their optical absorbance and transmittance, with the aid of Unico-UV 2102 PC spectrophotometer at the normal incidence of light at room temperature. The samples of the films exhibited absorbance ranging from 50 to 85% in the VIS region but showed low absorbance in the NIR regions of the electromagnetic spectrum. The range of the optical band gap is between 1.85eV and 1.95eV. XRD analysis shows that thermal treatments enhanced the crystalline nature of the films and also increased their crystallite sizes.

Research paper thumbnail of ELECTROCHEMICAL STUDIES OF PVP-CAPPED PbS THIN FILM DEPOSITED BY POLYMER-ASSISTED CHEMICAL BATH DEPOSITION (PACBD)

PbS thin films were deposited on glass and stainless steel substrates using PACBD method. The as-... more PbS thin films were deposited on glass and stainless steel substrates using PACBD method. The as-deposited and annealed films were characterized for structural, morphological, compositional, optical and electrochemical properties. Cyclic voltammetry indicated a reversible redox reaction with electrochemical interfacial capacitance of 101mF/cm 2 and 75mF/cm 2 for as-deposited and 200 o C-annealed films repectively at 20mV/s scan rate. Phase angle of impedance was less negative than that of a perfect capacitor (-90), indicating frequency dispersion. Constant phase element was used to fit interfacial capacitance in the corresponding equivalent circuit. Incoporation of PVP into PbS matrix enhanced its electrochemical properties compared to typical PbS film.

Research paper thumbnail of COMPARATIVE STUDY OF CuxS and CuySe THIN FILMS GROWN BY CBD

Chalcogenide …, 2012

Chalcogenide thin films of Cu x S and Cu y Se were grown on glass substrates using the chemical b... more Chalcogenide thin films of Cu x S and Cu y Se were grown on glass substrates using the chemical bath growth technique. The bath precursors for the synthesis of the Cu x S include thiourea ((NH 2) 2 SC), ammonium hydroxide (NH 4 OH) solution and triethanolamine, TEA (N(CH 2 CH 2 OH) 3) while those for the preparation of the Cu y Se thin are sodium selenosulphate solution (Na 2 SeSO 3) and ammonium hydroxide (NH 4 OH) solutions. Copper II dihydrate (CuCl 2 .2H 2 O) was used as the starting material in each case. The effects of thermal treatment on the structural and spectral properties of the thin films were studied using X-Ray diffractometer and UV-VIS spectrophotometer respectively. The structural studies show the presence of chalcocite (Cu 1.96 S) and digenite (Cu 9 S 5) phases with average grain size of 13.39nm for Cu x S thin films. Tetragonal Cu 3 Se 2 (umangite) and cubic Cu 2 Se with average crystallite size of 35.79nm were observed for the Cu y Se thin films. The optical band gap energy for the Cu x S thin films is between 2.30eV and 2.45eV while the band gaps of the Cu y Se thin films fall between the range 1.80eV and 1.95eV. Unlike the Cu x S, the XRD analysis also revealed that thermal treatment significantly improved the crystalline structure of the CuySe.

Research paper thumbnail of Effects of post-thermal treatments on morphological and optical properties of NiO/Ni(OH)2 thin films synthesized by solution growth

Optik - International Journal for Light and Electron Optics, 2014

Room temperature deposition of PVP capped nanostructured NiO/Ni(OH) 2 thin film, the morphologica... more Room temperature deposition of PVP capped nanostructured NiO/Ni(OH) 2 thin film, the morphological and optical characterizations by solution growth technique are reported. The nanostructured thin films which were deposited on optical glass substrates were annealed at different temperatures and then subjected to structural, morphological and optical characterizations. X-ray diffraction measurements of the films revealed that higher temperatures during the thermal treatment enhanced the crystallinity of the thin films. The SEM surface micrographs show non-interconnected uniformly deposited fibre-like structures with approximate lengths between 400 and 1200 nm. The optical band gap energy roughly decreased from about 2.7 eV to about 2.2 eV with thermal treatment. The absorbance of the thin films annealed at 300 and 400 • C was as high as 90% in the visible region of the electromagnetic spectrum. These materials could be useful in solar thermal conversion processes.

Research paper thumbnail of Effects of Deposition Media and Thermal Annealing on Chemical Bath Deposited Zinc Oxide Thin Films

ABSTRACT ZnO thin films were successfully deposited on glass substrates by the method of chemical... more ABSTRACT ZnO thin films were successfully deposited on glass substrates by the method of chemical bath. The precursors include zinc sulphate, ammonium solution and deposition medium. The ZnO films were strongly adhered to the substrates. They were subjected to different post deposition annealing temperatures. The optical effects of using PVA, PVP and water media respectively, as the deposition media, were studied. The optical absorbance, transmittance and reflectance of the films were characterized by the Unico UV-2102 PC spectrophotometer in the wavelength range of 200nm – 1000nm, at normal incidence of light. The strong absorbance of the annealed samples of the ZnO thin films grown using the PVP medium suggests that they can possibly be used in the fabrication of solar cells. The films annealed at 400 o C have high transmittance in the NIR region.

Research paper thumbnail of Structural and Spectral Analysis of Chemical Bath Deposited Copper Sulfide Thin Films for Solar Energy Conversions

chalcogen.infim.ro

... Press, Massachusetts (1982) [6] T. Markvart, Solar Electricity John Wiley and Sons Inc, New Y... more ... Press, Massachusetts (1982) [6] T. Markvart, Solar Electricity John Wiley and Sons Inc, New York (1992) [7] HT Evans, American Mineralogist 66 ... Indian Journal of Applied Physics 44, 690 (2006) [24] FI Ezema, PU Asogwa, ABC Ekwealor, PE Ugwuoke, RU Osuji, Journal of the ...

Research paper thumbnail of Variations of Optical and Structural Properties of Thin Films with Thermal Treatment

Indian Journal of Materials Science, 2014

The effects of thermal treatment on the optical and structural properties of cobalt oxideCoxOythi... more The effects of thermal treatment on the optical and structural properties of cobalt oxideCoxOythin films synthesized in the pores of PVP by chemical bath deposition technique were investigated. Films deposited were crystalline. The optical properties of the films were got from absorbance, transmittance reflectance, refractive index, absorption coefficient, and extinction coefficient measurements. The synthesizedCoxOyfilms turned out to be cobalt oxyhydroxide , CoO(OH), nanocrystals. The crystals obtained were of size 41.84 nm; however, as annealing temperature increased, the size decreased to 16.28 nm. The absorption coefficient, refractive index, and extinction coefficient were found to increase with increase in annealing temperature though not sequentially. For the same energy ranges of the incident photons, the absorption coefficient and refractive index ranged from 0.2 to 1.8 and from 1.4 to 2.3, respectively. The energy band-gap of the films ranged from 1.96 eV to 2.22 eV.

Research paper thumbnail of Study of the extrinsic properties of ZnO:Al grown by SILAR technique

Journal of Solid State Electrochemistry, 2017

Research paper thumbnail of Chemical Bath Synthesis and physico-chemical Characterizations of NiO-CoO Composite Thin Films for Supercapacitor applications

International Journal of Electrochemical Science

Research paper thumbnail of STRUCTURAL AND SPECTRAL ANALYSIS OF CHEMICAL BATH DEPOSITED COPPER SULFIDE THIN FILMS FOR SOLAR ENERGY CONVERSIONS

chalcogen.infim.ro

Copper sulfide chalcogenide thin films have been successfully deposited on glass substrates using... more Copper sulfide chalcogenide thin films have been successfully deposited on glass substrates using copper II chloride, thiourea, TEA and ammonium hydroxide in a solution bath. Structural and optical characterizations were carried out with the aid of X-ray Diffractometer and Unico-UV-2102PC spectrophotometer respectively. The effects of varying the annealing temperatures on the structural and spectral properties were also investigated. The presence of both chalcocite (Cu 1.96 S) and digenite (Cu 9 S 5 ) phases of the copper sulfide thin films with average grain sizes between 12.55nm and 14.22nm were confirmed by XRD analysis. The thermally treated Cu x S thin films have very high transmittance, between 85% and 95%, and low reflectance, less than 21% at both the visible and the NIR regions of the electromagnetic spectrum. They have optical band gap energy between 2.1eV and 2.5eV. The refractive index, extinction coefficient, optical conductivity and the dielectric properties were also studied. The analysis show that the thin films could serve as good materials for the fabrication of solar cell and other optical devices.

Research paper thumbnail of ELECTROCHEMICAL STUDIES OF PVP-CAPPED PbS THIN FILM DEPOSITED BY POLYMER-ASSISTED CHEMICAL BATH DEPOSITION (PACBD)

Chalcogenide Letters, 2015

PbS thin films were deposited on glass and stainless steel substrates using PACBD method. The as-... more PbS thin films were deposited on glass and stainless steel substrates using PACBD method. The as-deposited and annealed films were characterized for structural, morphological, compositional, optical and electrochemical properties. Cyclic voltammetry indicated a reversible redox reaction with electrochemical interfacial capacitance of 101mF/cm

Research paper thumbnail of Weibull distribution-based model for prediction of wind potential in Enugu, Nigeria

Advances in Applied Science Research, 2012

Modeling and prediction of wind characteristics are essential design inputs in the development of... more Modeling and prediction of wind characteristics are essential design inputs in the development of wind power systems for different locations. In this paper, the daily wind data for Enugu (6.3 0 N; 7.3 0 E; 450m), Nigeria, over a period of 13 years (1995 ‐ 2007), is modeled in ter ms of the Weibull distribution function, in order twind energy potential of the location. The daily, monthl y, and annual wind speed probability density distri butions at 10m meteorological height are modeled and the mean wind speed, skew, shape- and scale factors are determin ed with values of 2.5 ± 0.3m/s, -0.46, 2.21 and 4.31m/s res pectively. The results suggest that while the wind speed is more concentrated at higher values above the mean, the d istribution for Enugu departs significantly from th e standard Raleigh distribution, with error of 10.5%. The coef ficient of determination of the model is 0.74. Furt her statistics suggest that the model can be used, with acceptable accuracy, for prediction of...

Research paper thumbnail of Influence of cadmium precursor concentrations on the structural, optical and electrochemical impedance properties of CdZnS thin films

Research paper thumbnail of Method to Control the Optical properties: Band Gap Energy of Mixed Halide Organolead Perovskites

Arabian Journal of Chemistry

Research paper thumbnail of Delineation of Groundwater Saturation Indicators and their Distributions in the Complex Argillaceous Geological Units of Ezza North Local Government Area of Ebonyi State, Nigeria

Current Science, 2016

Twelve vertical electrical soundings (VES) employing Schlumberger electrode configuration were ca... more Twelve vertical electrical soundings (VES) employing Schlumberger electrode configuration were carried out in parts of Ezza north local government area of Ebonyi state, Nigeria, where extraction of potable groundwater has posed challenges to the dwellers of the area who are currently relying on surface water sources and some scattered seasonal open wells that cause health problems. The present study was undertaken to determine the hydrogeological characteristics, indicators that predict groundwater potential of the study area. The study indicates that the aquifer resistivity ranges between 12 and 504 m with an average value of 95.42 m. Water resistivity ranges between 9.6 and 73.0 m with an average of 26.34 m. The aquifer thickness ranges from 34.1 to 214.7 m with an average of 71.97 m. Also, the formation factor varies between 1.25 and 6.9 with an average of 2.76. Porosity ranges between 5.34% and 29.47% with an average of 15.91%. Similarly, hydraulic conductivity ranges from 1.1645 to 38.0491 m/day, the average being 12.8312 m/day, and K values range between 0.0023 and 3.1695 S/day with a mean value of 0.6273 S/day. Using surfer software package, contour distributions of geo-hydrodynamic properties were generated which show the distribution of the aquifer parameters in the study area. The distributions of these properties reflect the regions with high and low potential groundwater in the area. The diagnostic models and the inherent and intrinsic constants can be employed in quantitative prediction of groundwater potential in the adjoining regions of the study area which show similar hydrogeological properties.

Research paper thumbnail of Nio-CoO

Research paper thumbnail of INFLUENCE OF PRECURSOR CONCENTRATION ON OPTICAL PROPERTIES OF MnxOy THIN FILMS

Journal of Ovonic Research

Precursor concentration dependent manganese oxide (MnxOy) nanocrystalline thin films prepared by ... more Precursor concentration dependent manganese oxide (MnxOy) nanocrystalline thin films prepared by CBD techniques within the pores of PVP on glass slides at 343K were studied. The films turned out to be MnO2 nanocrystals with grain size range of 76.11nm – 12.96nm for increasing precursor concentration. The deposited films were annealed at 403K and characterized for structural and optical properties. XRD analyses revealed their crystalline nature. The absorbance, transmittance reflectance, refractive index and absorption coefficient were found to vary inversely with precursor concentration, though irregularly. The absorption spectra showed that the energy band-gap of the films lies in the range of 2.34eV – 2.75eV

Research paper thumbnail of Electrochromic and electrochemical supercapacitive properties of Room Temperature PVP capped Ni(OH)2/NiO Thin Films

Electrochimica Acta, 2015

ABSTRACT Porous-structured Ni(OH)2 and NiO thin films are good materials to enhance the performan... more ABSTRACT Porous-structured Ni(OH)2 and NiO thin films are good materials to enhance the performance of electrochromic devices as they provide an easy pathway for electrolyte penetration required for the improvement of electrochemical (EC) activity. In this paper, we present the results of our room temperature chemical bath deposition (CBD) of highly porous nanostructured PVP-capped Ni(OH)2/NiO thin films. We investigate the effects of post-deposition thermal treatment and the contribution of the substrate surface on the morphological, structural and electrochemical properties of these films as well as the role of the capping agent during the film growth process. Randomly oriented and well interconnected nanorods of individual lengths of about 600 nm were deposited on both stainless steel and Fluorine doped tin Oxide (FTO). The incorporation of PVP helps to moderate the size and length of the nanorods in the films as well as delayed the transformation of nickel hydroxide to oxide films. The optical density and the colouration efficiency obtained for the as-deposited (Ni(OH)2 films are 0.985 and 55.89 cm2/C respectively. The highest specific capacitance of 1184.52 F/g is obtained for the as-deposited film on stainless steel. We can deduce that the incorporation of PVP in the films enhanced the electrochemical capacitive properties of the Ni(OH)2 films to a very good extent.

Research paper thumbnail of Resistivity Survey for Groundwater in Ezza North Using Vertical Electrial Sounding

Abstract- Vertical electrical resistivity soundings were conducted in order to delineate the grou... more Abstract- Vertical electrical resistivity soundings were conducted in order to delineate the groundwater potentials at some locations in Ezza North Local Government of Ebonyi State. Twelve vertical electrical soundings were obtained using the Schlumberger configuration with the aid of the OHMEGA terramenter (SAS1000).The field data were subjected to interpretation by employing the method of manual partial curve matching techniques using the master curves and the corresponding auxiliary curves. A computer programme (RESOUND) was also used to interpret the data. The parameters obtained were used to determine the resistivities and thicknesses of the subsurface layers. The major lithologic units of the area are shales, sandstone and mudstone. The water bearing rocks were interpreted to exist at depths between 20m and 130m. The results fairly correlated with some logged boreholes close to the survey area. The aquifers have resistivities ranging between 9Ωm and 110Ωm. The geophysical sear...

Research paper thumbnail of 91005837 FEzema Coll

Research paper thumbnail of Spectral Analysis of Chemical Bath Deposited Copper Selenide Thin Films

ABSTRACT Copper selenide thin films were successfully deposited on glass substrates using the che... more ABSTRACT Copper selenide thin films were successfully deposited on glass substrates using the chemical bath deposition technique at room temperature. The chemical bath was composed of copper II chloride dihydrate (CuCl2.2H2O) as the source of the Cu 2+ and Sodium selenosulphate solution (Na2SeSO3) as the source of the Se 2-. Ammonium hydroxide solution (NH4OH) was used as the complexing agent. Some of the films were subjected to post deposition thermal treatments. Spectral analyses of the films were done in order to study their optical absorbance and transmittance, with the aid of Unico-UV 2102 PC spectrophotometer at the normal incidence of light at room temperature. The samples of the films exhibited absorbance ranging from 50 to 85% in the VIS region but showed low absorbance in the NIR regions of the electromagnetic spectrum. The range of the optical band gap is between 1.85eV and 1.95eV. XRD analysis shows that thermal treatments enhanced the crystalline nature of the films and also increased their crystallite sizes.

Research paper thumbnail of ELECTROCHEMICAL STUDIES OF PVP-CAPPED PbS THIN FILM DEPOSITED BY POLYMER-ASSISTED CHEMICAL BATH DEPOSITION (PACBD)

PbS thin films were deposited on glass and stainless steel substrates using PACBD method. The as-... more PbS thin films were deposited on glass and stainless steel substrates using PACBD method. The as-deposited and annealed films were characterized for structural, morphological, compositional, optical and electrochemical properties. Cyclic voltammetry indicated a reversible redox reaction with electrochemical interfacial capacitance of 101mF/cm 2 and 75mF/cm 2 for as-deposited and 200 o C-annealed films repectively at 20mV/s scan rate. Phase angle of impedance was less negative than that of a perfect capacitor (-90), indicating frequency dispersion. Constant phase element was used to fit interfacial capacitance in the corresponding equivalent circuit. Incoporation of PVP into PbS matrix enhanced its electrochemical properties compared to typical PbS film.

Research paper thumbnail of COMPARATIVE STUDY OF CuxS and CuySe THIN FILMS GROWN BY CBD

Chalcogenide …, 2012

Chalcogenide thin films of Cu x S and Cu y Se were grown on glass substrates using the chemical b... more Chalcogenide thin films of Cu x S and Cu y Se were grown on glass substrates using the chemical bath growth technique. The bath precursors for the synthesis of the Cu x S include thiourea ((NH 2) 2 SC), ammonium hydroxide (NH 4 OH) solution and triethanolamine, TEA (N(CH 2 CH 2 OH) 3) while those for the preparation of the Cu y Se thin are sodium selenosulphate solution (Na 2 SeSO 3) and ammonium hydroxide (NH 4 OH) solutions. Copper II dihydrate (CuCl 2 .2H 2 O) was used as the starting material in each case. The effects of thermal treatment on the structural and spectral properties of the thin films were studied using X-Ray diffractometer and UV-VIS spectrophotometer respectively. The structural studies show the presence of chalcocite (Cu 1.96 S) and digenite (Cu 9 S 5) phases with average grain size of 13.39nm for Cu x S thin films. Tetragonal Cu 3 Se 2 (umangite) and cubic Cu 2 Se with average crystallite size of 35.79nm were observed for the Cu y Se thin films. The optical band gap energy for the Cu x S thin films is between 2.30eV and 2.45eV while the band gaps of the Cu y Se thin films fall between the range 1.80eV and 1.95eV. Unlike the Cu x S, the XRD analysis also revealed that thermal treatment significantly improved the crystalline structure of the CuySe.

Research paper thumbnail of Effects of post-thermal treatments on morphological and optical properties of NiO/Ni(OH)2 thin films synthesized by solution growth

Optik - International Journal for Light and Electron Optics, 2014

Room temperature deposition of PVP capped nanostructured NiO/Ni(OH) 2 thin film, the morphologica... more Room temperature deposition of PVP capped nanostructured NiO/Ni(OH) 2 thin film, the morphological and optical characterizations by solution growth technique are reported. The nanostructured thin films which were deposited on optical glass substrates were annealed at different temperatures and then subjected to structural, morphological and optical characterizations. X-ray diffraction measurements of the films revealed that higher temperatures during the thermal treatment enhanced the crystallinity of the thin films. The SEM surface micrographs show non-interconnected uniformly deposited fibre-like structures with approximate lengths between 400 and 1200 nm. The optical band gap energy roughly decreased from about 2.7 eV to about 2.2 eV with thermal treatment. The absorbance of the thin films annealed at 300 and 400 • C was as high as 90% in the visible region of the electromagnetic spectrum. These materials could be useful in solar thermal conversion processes.

Research paper thumbnail of Effects of Deposition Media and Thermal Annealing on Chemical Bath Deposited Zinc Oxide Thin Films

ABSTRACT ZnO thin films were successfully deposited on glass substrates by the method of chemical... more ABSTRACT ZnO thin films were successfully deposited on glass substrates by the method of chemical bath. The precursors include zinc sulphate, ammonium solution and deposition medium. The ZnO films were strongly adhered to the substrates. They were subjected to different post deposition annealing temperatures. The optical effects of using PVA, PVP and water media respectively, as the deposition media, were studied. The optical absorbance, transmittance and reflectance of the films were characterized by the Unico UV-2102 PC spectrophotometer in the wavelength range of 200nm – 1000nm, at normal incidence of light. The strong absorbance of the annealed samples of the ZnO thin films grown using the PVP medium suggests that they can possibly be used in the fabrication of solar cells. The films annealed at 400 o C have high transmittance in the NIR region.

Research paper thumbnail of Structural and Spectral Analysis of Chemical Bath Deposited Copper Sulfide Thin Films for Solar Energy Conversions

chalcogen.infim.ro

... Press, Massachusetts (1982) [6] T. Markvart, Solar Electricity John Wiley and Sons Inc, New Y... more ... Press, Massachusetts (1982) [6] T. Markvart, Solar Electricity John Wiley and Sons Inc, New York (1992) [7] HT Evans, American Mineralogist 66 ... Indian Journal of Applied Physics 44, 690 (2006) [24] FI Ezema, PU Asogwa, ABC Ekwealor, PE Ugwuoke, RU Osuji, Journal of the ...

Research paper thumbnail of Variations of Optical and Structural Properties of Thin Films with Thermal Treatment

Indian Journal of Materials Science, 2014

The effects of thermal treatment on the optical and structural properties of cobalt oxideCoxOythi... more The effects of thermal treatment on the optical and structural properties of cobalt oxideCoxOythin films synthesized in the pores of PVP by chemical bath deposition technique were investigated. Films deposited were crystalline. The optical properties of the films were got from absorbance, transmittance reflectance, refractive index, absorption coefficient, and extinction coefficient measurements. The synthesizedCoxOyfilms turned out to be cobalt oxyhydroxide , CoO(OH), nanocrystals. The crystals obtained were of size 41.84 nm; however, as annealing temperature increased, the size decreased to 16.28 nm. The absorption coefficient, refractive index, and extinction coefficient were found to increase with increase in annealing temperature though not sequentially. For the same energy ranges of the incident photons, the absorption coefficient and refractive index ranged from 0.2 to 1.8 and from 1.4 to 2.3, respectively. The energy band-gap of the films ranged from 1.96 eV to 2.22 eV.