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Thin films of CdSe were deposited by potentiostatic mode on different substrates such as stainless steel, titanium and fluorine tin-oxide (FTO) coated glass using non-aqueous bath. The preparative parameters were optimized to get good quality CdSe thin films. These films were characterized by X-ray diffraction (XRD), optical absorption and photoelectrochemical (PEC) techniques. XRD study revealed that the films were polycrystalline in nature with hexagonal phase. Optical absorption study showed that CdSe films were of direct band gap type semiconductor with a band gap energy of 1·8 eV. PEC study revealed that CdSe film deposited on FTO coated glass exhibited maximum values of fill factor (FF) and efficiency (η) as compared to the films deposited on stainless steel and titanium substrate.

Transparent conducting thin films of F:SnO2 have been deposited onto preheated glass substrates by a spray pyrolysis technique using pentahydrate stannic chloride (SnCl4·5H2O) and ammonium fluoride (NH4F) as precursors and mixture of water and propane-2-ol as solvent. The concentration of SnCl4·5H2O and NH4F is kept fixed and the ratio of water and propane-2-ol solvent in the spraying solution is varied. A fine spray of the source solution using air as a carrier gas has grown films of thickness up to 995 nm. Optical absorption, X-ray diffraction, Van der Pauw technique for measurement of a sheet resistance and Hall effect measurements at room temperature for determination of carrier density and conductivity have been used. The as-deposited films are of polycrystalline SnO2 with a tetragonal crystal structure and are preferentially having orientation along the (200) direction with texture coefficient as high as 6.16. The average grain size for the as-deposited sample is found to be of the order of 44 nm. The films have moderate optical transmission (up to 70–85% at 550 nm). The figure of merit (ϕ) values vary from 1.95 · 10− 3 to 35.68 · 10− 3 Ω− 1. The films are heavily doped, degenerate and exhibit n-type electrical conductivity. The lowest sheet resistance (Rs) for the optimized sample is 5.1 Ω. The films have a resistivity of 5.43 · 10− 4 Ω cm and mobility around 7.38 cm2 V− 1 s− 1.

The CdSe and Fe doped CdSe (Fe:CdSe) thin films have been electrodeposited potentiostatically onto the stainless steel and fluorine doped tin oxide (FTO) glass substrates, from ethylene glycol bath containing (CH 3 COO) 2 ·Cd·2H 2 O, SeO 2 , and FeCl 3 at room temperature. The doping concentration of Fe is optimized by using (photo) electrochemical (PEC) characterization technique. The deposition mechanism and Fe incorporation are studied by cyclic voltammetry. The structural, surface morphological and optical properties of the deposited CdSe and Fe:CdSe thin films have been studied by X-ray diffraction, scanning electron microscopy (SEM) and optical absorption techniques respectively. The PEC study shows that Fe:CdSe thin films are more photosensitive than that of undoped CdSe thin films. The X-ray diffraction analysis shows that the films are polycrystalline with hexagonal crystal structure. SEM studies reveal that the films with uniformly distributed grains over the entire surface of the substrate. The complete surface morphology has been changed after doping. Optical absorption study shows the presence of direct transition and a considerable decrease in bandgap, E g from 1.95 to 1.65 eV.

Semiconducting n-CdIn 2 S 4 thin films have been deposited on amorphous and fluorine-doped tin oxide (FTO) coated glass substrates by using a well-known spray pyrolysis technique. With the objective of finding the optimum conditions for the deposition of CdIn 2 S 4 thin films, the influence of substrate temperature on properties of the films have been studied. Photoelectrochemical (PEC) technique has been employed to optimize substrate temperature. The films are characterized by the techniques such as X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive analysis by X-rays (EDAX) and PEC studies. The SEM studies reveal the compact morphology with large number of grains. EDAX studies show that the material formed at optimized substrate temperature is nearly stoichiometric. Measured values of efficiency ( η ) and fill factor (FF) for the PEC cell are 1.06% and 0.47, respectively. Various physical parameters of cadmium indium sulphide (CdIn 2 S 4 ) film are estimated. Energy band diagrams for CdIn 2 S 4 and polysulphide electrolyte, before and after making junction have been constructed.

Polycrystalline CdSe thin films have been electrodeposited at room temperature on stainless steel (ss) and fluorine doped tin oxide (FTO) coated glass substrate from aqueous electrolytes containing salts of cadmium acetate and selenium dioxide. The pH of the bath is varied from 1.75, at the interval of 0.25, to 3. The effect of pH on the photoelectrochemical (PEC), structural and optical properties of the deposited film is studied. The pH of the bath is optimized by the PEC technique and is observed to be 2.75. The analysis of the XRD patterns show that the deposited CdSe material is polycrystalline with a hexagonal crystal structure. SEM study shows that the total substrate surface is well covered by uniformly distributed spherical shaped grains. The optical absorption studies reveal that the pH of the electrolytic solution has a significant effect on the band gap of the CdSe thin film. The transition involved is direct with band gap energy Eg of 1.72 eV.

CdSe thin films have been electrodeposited potentiostatically onto stainless-steel and fluorine-doped tin oxide-coated glass substrates from an aqueous acidic bath using cadmium acetate ((CH 3 COO) 2 Cd·2H 2 O) as a Cd ion source. Preparative parameters such as deposition potential, solution concentration, bath temperature, pH of the electrolytic bath and deposition time have been optimized by using photoelectrochemical (PEC) technique to obtain well adherent and uniform thin films. The electrodeposits were dark brown in colour. The films have been characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and optical absorption techniques. XRD studies reveal that films are polycrystalline, with hexagonal crystal structure. SEM shows that the films are compact, with spherical grains. Optical absorption studies reveal that the material exhibits a direct optical transition having band gap energy ∼1.72 eV. PEC study shows that the films are photoactive.

Ternary chalcogenides with appropriate bandgap energy have been attracting a great deal of attention because of their potential applications in photovoltaics. CdIn2Se4 in the form of thin films is prepared at different substrate temperatures by a simple and economical spray pyrolysis technique. The films have been characterized by PEC, XRD, EDAX, and electrical measurement techniques. The photoelectrochemical characterization shows that both Isc and Voc are at their optimum values at the optimized substrate temperature of 280 °C. The annealing study reveals that the films annealed for 4 h show relatively maximum values of Isc and Voc. The XRD patterns show that the films are polycrystalline with crystallite size 24.8 nm for the film deposited at optimized preparative parameters. Compositional analysis reveals that the material formed is nearly stoichiometric at the optimized substrate temperature. The electrical resistivity measurement shows that the films are semiconducting at minimum resistivity. The thermoelectric power measurement reveals that the thermoelectric power is relatively maximum at substrate temperature 280 °C.

Non-stoichiometric ternary chalcogenides (Zn,Fe)S were prepared in the film form by pyrolytic spray deposition technique, using air/nitrogen as the carrier gas. The precursor solution comprised of ZnCl2, FeCl2 and thiourea. The depositions were carried out under optimum conditions of experimental parameters viz. carrier gas (air/nitrogen) flow rate, concentration of precursor constituents, nozzle substrate distance and temperature of quartz substrate. The deposited thin films were later sintered in argon at 1073 K for 120 min. The structural, compositional and optical properties of the sintered thin films were studied. X-ray diffraction studies of the thin films indicated the presence of (Zn,Fe)S solid solution with prominent cubic sphalerite phase while surface morphology as determined by scanning electron microscopy (SEM) revealed a granular structure. The chemical composition of the resulting thin films as analyzed by energy dispersive X-ray analysis (EDAX) reflected the composition of the precursor solutions from which the depositions were carried out with Fe at% values ranging from 0.4 up to 33. SEM micrographs of thin films reveal that the grain sizes of the thin films prepared using air as carrier gas and N2 as carrier gas are in the vicinity of 300 and 150 nm, respectively. The diffuse transmittance measurements for thin films, as a function of wavelength reveal the dependence of direct optical band gap on Fe content and type of phase.

In the recent years, cadmium chalcogenide compounds have been extensively investigated because of their potential applications in solar energy conversion. Thin films of CdSe have been deposited onto the stainless steel and fluorine doped tin oxide (FTO) coated glass substrates using simple and inexpensive electrodeposition technique. The non-aqueous solvent ethylene glycol (CH 2 OHCH 2 OH) containing precursors of Cd and Se with ethylenediaminetetraacetic acid (EDTA) tetra sodium salt as a complexing agent is used to obtain stoichiometric deposits. Deposition potential was estimated from polarization curves and other preparative parameters such as bath temperature and concentration of solution were optimized. X-ray diffraction (XRD) analysis reveals that the films are polycrystalline with cubic structure. PEC study shows the CdSe films are photoactive. Optical absorption study shows the presence of direct transition with band gap energy 1.72 eV. The energy dispersive analysis by X-rays (EDAX) reveals that the substrate is well covered with large number of grains indicating compact structure. The average ratio of the atomic percentage of Cd:Se is 50.31:49.69, showing that the deposited films are almost stoichiometric.

The cadmium oxide (CdO) thin films have been deposited onto amorphous and fluorine doped tin oxide (FTO) glass substrates using spray pyrolysis technique. The aqueous solution containing precursor of Cd has been used to obtain good quality deposits at optimized preparative parameters. The films have been characterized by techniques such as X-ray diffraction (XRD), optical absorption, electrical resistivity and thermoelectric power (TEP) measurements. The XRD study reveals that the films are polycrystalline with cubic structure. Optical absorption studies reveal that the value of absorption coefficient is in the order of 10 4 cm −1 , indicating direct band to band transition with band gap energy 2.26 eV, close to its value of intrinsic band gap energy. The electrical characterization shows that the electrical resistivity ( ρ ) is of the order 10 −3 Ω cm and it decreases with increase in temperature indicate the samples are semiconducting in nature. The value of activation energy is found to be 0.077 eV. TEP measurement shows the thermoelectric voltage for CdO films is positive towards the hot end, indicating n-type behavior of sample. The value of TEP increases with increase in temperature. The Hall effect measurement study reveals that the carrier concentration ( n ), Hall coefficients ( R H ) and carrier mobility ( μ H ) are of the order of 10 23 cm −3 , 10 −8 cm 3 /C and 10 −4 cm −2 /V s, respectively.

In the present work ternary chalcogenide p-type semiconductor Zn 1− x Fe x S has been prepared by co-precipitation method for x =0.18 and 0.4 concentrations of Fe. The precipitate was repeatedly sintered at 800 °C in sealed quartz ampoules for a total of 165 h The material was then characterized by X-ray diffraction, X-ray fluorescence (XRF), EDAX, EPMA, diffuse reflectance spectroscopy, thermoelectric, electrochemical and capacitance measurement techniques. Compositional analysis techniques, viz. XRF, EDAX and EPMA reflected the composition of the solutions from which precipitation was carried out while X-ray reveals a sphalerite crystal structure. Capacitance measurements indicate that the relaxation effects are enhanced with increasing Fe substitution. Thermoelectric measurements indicate p-type conductivity in agreement with the results obtained by electrochemical analysis. The flat band potential V fb has values 2.94 V ( x =0.18) and 2.66 V ( x =0.4) as obtained by Mott–Schottky plot. Similarly the optical band gap was found to decrease with increase in Fe concentration.

Non-stiochiometric ternary chalcogenides Zn 1− x Fe x S, were prepared in the bulk form by co-precipitation of ZnS and FeS by Na 2 S from aqueous solution containing FeSO 4 and ZnSO 4 and sintering of pellets of the co-precipitate repeatedly at 1073K in vacuum sealed quartz ampoules. Concomitant with the bulk form; thin fims of (Zn,Fe)S were synthesized by pyrolytic spray deposition method on quartz substrates from aqueous precursor solution containing ZnCl 2 , FeCl 2 and thiourea in varying concentration under optimized conditions of substrate temperature (653K) carrier gas flowrate (11 l min −1 ) and solution flow rate (8–6 ml min −1 ). The structure, chemical composition, optical and thermoelectrical properties of the (bulk) pellets and thin films are studied as a function of initial solution concentration. X-ray diffraction of the pellets and thin films indicated the presence of solid solutions Zn 1− x Fe x S (sphalerite), while surface morphology as determined by SEM revealed a granular structure. Electrical resistivity of pellets and thin films, measured using two probe method (for pellets) and four probe van der Pauw method (for thin films) indicated that they are semiconducting while resistivity studies could not be carried out for a few thin films due to their high resistance (>20 MΩ). The chemical composition of the resulting solids as analyzed by X-ray fluorescence and that of thin films as analyzed by energy dispersive X-ray, reflected the composition of the solutions from which precipitation (for pellets) and deposition (for thin films) was carried out, with Fe contents up to x =0.4. SEM micrograph of pellets and thin films reveal that later have smaller grain size. Thermoelectric studies revealed that both solids and thin films possess the ability of ‘n’ as well as ‘p’ type conductivity. The diffuse optical reflectance measurements of pellets and transmittance measurements for thin films; as a function of wavelength reveal the dependence of direct optical band-gap on Fe content.

Thin films of cadmium indium selenide have been deposited onto amorphous glass substrates using a simple and low-cost spray pyrolysis technique. The aqueous solutions containing precursors of Cd, In and Se have been used to obtain good quality deposits at optimized substrate temperature. The preparative parameters such as concentration, substrate temperature, etc. have been optimized by photoelectrochemical technique. The films have been characterized by techniques such as X-ray diffraction, scanning electron microscope, EDAX and electrical characterization. The photoelectrochemical characterization shows that both short-circuit current (I sc ) and open-circuit voltage (V oc ) are at their optimum values at the optimized substrate temperature of 280C and concentration (0.0125 M). The XRD patterns show that the films are polycrystalline with cubic structure. The SEM studies reveal the compact morphology with large number of grains. Compositional analysis reveals that the material formed is nearly stoichiometric at the optimized preparative parameters. The electrical resistivity shows that the films are semiconducting and the resistivity is found to be minimum at optimized substrate temperature. The thermoelectric power (TEP) measurement reveals that the TEP is relatively maximum at same substrate temperature of 80°C. Photovoltaic output characteristics study reveals that the fill factor and efficiency; to be 69% and 3%, respectively.

In electrodeposition, substrate besides providing mechanical support to the electrodeposit, affects significantly the structural and morphological properties of a film. Electrodeposition and characterization of EuTe thin films onto different substrates such as stainless steel (SS), titanium (Ti), copper (Cu), fluorine-doped tin oxide (F:SnO 2 ) covered glasses have been described. The deposition potentials have been estimated from the polarization curves. The reaction mechanism is proposed for the formation of EuTe electrodeposits. Preparative parameters such as deposition potential, current density, and deposition time are studied. The films have been characterized by X-ray diffraction, scanning electron microscopy (SEM), atomic force microscopy (AFM) and energy dispersive analysis by X-rays (EDAX) techniques. The electrodeposited EuTe films are polycrystalline on all the substrates with same cubic crystal structure. The SEM studies reveal that the surface morphology is different for the substrates studied. However, no cracks have been observed in the SEM micrographs. The AFM images show large spherical grains supporting the polycrystalline nature of the samples. The EDAX analysis shows that the EuTe films are nearly stoichiometric, slightly rich in tellurium.

Semiconducting As 2 Se 3 thin films have been prepared from an aqueous bath at room temperature onto stainless steel and fluorine-doped tin oxide (F.T.O.)-coated glass substrates using an electrodeposition technique. It has been found that As 2 O 3 and SeO 2 in the volumetric proportion as 4:6 and their equimolar solutions of 0.075 M concentration forms good quality films of As 2 Se 3 . The films are annealed in a nitrogen atmosphere at temperature of 200 °C for 2 h. The films are characterised by scanning electron microscopy, X-ray diffraction and optical absorption techniques. Studies reveal that asdeposited and annealed thin films are polycrystalline in nature. The optical band gap has been found to be 2.15 eV for the above-mentioned composition and concentration of the film.

Antimony trisulphide thin films have been prepared by a spray pyrolysis technique using various concentrations of complexing agent (tartaric acid) in the spray solution. These films are characterized for structural, electrical and optical properties. The results of XRD studies reveal that the films are polycrystalline. The crystallinity and direction of growth is found to be a function of the concentration of complexing agent. It is found that resistivity varies with the concentration of complexing agent. The resistivity of the films is 106–107 Ω cm−1. The band gap energy also varies with the concentration of the complexing agent from 1.92 to 2.13 eV.

The thin films of cadmium indium selenide (CdIn 2 Se 4 ) have been deposited onto amorphous glass substrates using simple and low cost spray pyrolysis technique. The aqueous solutions containing precursors of Cd, In and Se have been used to obtain good quality deposits at different substrate temperatures. The preparative parameters, such as substrate temperature and concentration of precursor solution have been optimized and are found to be 280 °C and 0.0125 M, respectively. The films have been characterized by X-ray diffraction (XRD), optical absorption and energy dispersive analysis by X-rays (EDAX) techniques. The spray-deposited CdIn 2 Se 4 films are polycrystalline with cubic crystal structure. The optical absorption studies reveal that the transition is direct with band gap energy E g =1.92 eV. The EDAX studies reveal that the films obtained at substrate temperature 280 °C are nearly stoichiometric.

Semiconducting Sb 2 Se 3 thin films have been prepared onto the stainless steel and fluorine doped tin oxide coated glass substrates from non-aqueous media using an electrodeposition technique. The electrodeposition potentials for different bath compositions and concentrations of solution have been estimated from the polarization curves. SbCl 3 and SeO 2 in the volumetric proportion as 1:1 with their equimolar solution concentration of 0.05 M form good quality films. The films are characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) and optical absorption techniques. The SEM studies show that the film covers the total substrate surface with uneven surface morphology. The XRD patterns of the films obtained by varying compositions and concentrations show that the as-deposited films are polycrystalline with relatively higher grain size for 1:1 composition and 0.05 M concentration. The optical band gap energy for indirect transition in Sb 2 Se 3 thin films is found to be 1.195 eV.

Electrodeposition and characterization of EuSe thin films onto different substrates such as stainless steel (SS), Ti, Cu, fluorine-doped tin oxide (F-SnO2) covered glasses is described. The films have been prepared in potentiostatic mode using aqueous acidic electrolyte containing Eu and Se precursors at 70 °C bath temperature and pH 4. The disodium salt of ethylenediaminetetraacetic acid (Na2-EDTA) is used as a complexant. The results of polarization studies reveal that the deposition potential for EuSe thin films is different for different substrates. The films have been characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy disperse analysis by X-rays (EDAX) and optical absorption techniques. The electrodeposited EuSe films are polycrystalline. The SEM investigation revealed that the deposit surface is rough when deposited on copper, titanium and SS, however, it is relatively smooth and fine-grained on F-SnO2 glass substrate. The surface patterns are spherical for titanium and F-SnO2 substrates, while for SS and copper, they are cauliflower- and leaf-like, respectively. The optical absorption studies revealed that the transition is direct and band gap energy Eg is 1.75 eV.

Thin chalcogenide films of antimony have been attracting a great deal of attention because of their some special applications in optoelectronic devices and solar cells. The Sb2S3 and Sb2Se3 thin films have been prepared by a spray pyrolysis technique at their optimized conditions of substrate temperature and solution concentrations from the aqueous and non-aqueous media. The studies reveal that the films prepared from aqueous medium are amorphous and those obtained from non-aqueous medium are polycrystalline; especially the Sb2Se3 prepared from non-aqueous become polycrystalline after annealing. The optical absorption studies show the values of optical gap to be 1.1 and 1.28 eV, respectively, for Sb2S3 and Sb2Se3 for the aqueous medium while the same materials have direct band gap energies of 1.8 and 2.14 eV, respectively, when prepared from non-aqueous medium. When heated in nitrogen atmosphere for 2 h at optimized annealing temperature, the films of Sb2S3 and Sb2Se3 remain amorphous but those obtained from non-aqueous medium show enhancement in the crystallinity. The electrical resistivity for both films studied in the temperature range 300–500 K shows that the resistively is of the order of 106–107 Ω cm. The Sb2S3 and Sb2Se3, irrespective of preparation medium, are found to be n- and p-type, respectively. Both the materials are found to be photoactive when used in photoelectrochemical solar cells.

The photocatalytic oxidation of wastewater with TiO2 and coupling effect of different advanced oxidation processes onto the oxidation of wastewater has been studied. A basic mechanism involved during oxidation has been reported. The role of hydroxyl radical in the breakdown of the wastewater is elucidated through determining the degradation rates, kinetics, analyzing transformation intermediates and studies using computational chemistry methods. In order to realize a complete mineralization of wastewater COD, BOD and TOC analysis has been carried out.

Highly transparent pure and Au doped TiO2 thin films are successfully deposited by using simple chemical spray pyrolysis technique. The effect of Au doping onto the structural and physicochemical properties has been investigated. The PEC study shows that, both short circuit current (Isc) and open circuit voltage (Voc) are (Isc=1.81mA and Voc=890mV) relatively higher at 3at.% Au doping percentage. XRD study shows that the films are nanocrystalline in nature with tetragonal crystal structure. FESEM images show that the film surface covered with a smooth, uniform, compact and rice shaped nanoparticles. The Au doped thin films exhibit indirect band gap, decreases from 3.23 to 3.09eV with increase in Au doping. The chemical composition and valence states of pure and Au doped TiO2 films are studied by using X-ray photoelectron spectroscopy. The photocatalytic degradation effect is 49% higher in case 3at.% Au doped TiO2 than the pure TiO2 thin film photoelectrodes in the degradation of benzoic acid. It is revealed that Au doped TiO2 can be reused for five cycles of experiments without a requirement of post-treatment while the degradation efficiency was retained.

Various doping percentage of Au were successfully introduced into the Fe2O3 photocatalysts via a spray pyrolysis method different. The effect of Au doping on photoelectrochemical, structural, optical and morphological properties of these deposited thin films is studied. The PEC characterization shows that, the photocurrent increases gradually with increasing Au content initially up to 2at.% indicating the maximum values of short circuit current (Isc) and open circuit voltage (Voc) are (Isc=90μA and Voc=220.5mV) and then decreases after exceeding the optimal Au doping content. Therefore, the photocurrent of Au doped Fe2O3 photocatalysts can be adjusted by the Au content. Deposited films are polycrystalline with a rhombohedral crystal structure having (104) preferred orientation. SEM and AFM images show deposited thin films are compact and uniform. The photocatalytic activities of the Fe2O3 and Au:Fe2O3 photocatalyst were evaluated by photoelectrocatalytic degradation of salicylic acid under sunlight irradiation. The results show that the Au:Fe2O3 thin film photocatalyst exhibited about 45% more degradation of pollutants than the pure Fe2O3. Thus, in Au doped Fe2O3 photocatalysts, the interaction between Au and Fe2O3 reduces the recombination of photogenerated charge carriers and improve the photocatalytic activity.

A simple and low-cost electrodeposition technique is used to investigate the codepostion of EuSe from aqueous acidic solutions containing europium and selenium ions on stainless steel cathodes. The europium ions are complexed with disodium ethelenediaminetetraacetic acid (Na2-EDTA). The preparative parameters such as deposition potential, deposition time, bath temperature, pH, etc., are optimized to obtain good-quality electrodeposits. The optimized preparative parameters are: deposition potential −560 mV versus SCE, deposition time 75 min, bath temperature 70°C, electrolyte bath [(0.01 M EuCl2 + 0.05 M Na2-EDTA) + 0.001 M SeO2] in 1:1 volumetric proportions at pH 4.0 The electrodeposits were bluish brown and about 1 to 2 μm thick. The EuSe films characterized by XRD studies reveal that films are polycrystalline with intense peaks along the planes (111) and (200). The ratio of complexant concentration to the metal ion concentration is 5, and is found sufficient for the material formation. SEM studies show a cauliflower-like morphology of EuSe fully covering the stainless steel substrates. The EDAX analysis shows that the EuSe electrodeposit is rich in selenium. The magnetic studies of the material reveal that the prepared films are magnetic in nature.

Semiconducting Bi2Se3 thin films have been electrodeposited from nonaqueous medium at room temperature using selenium dioxide as a selenium ion source. The electrodeposition potentials for different bath compositions and concentrations of solution have been estimated from the polarization curves. It has been found that Bi(NO3)3·5H2O and SeO2 in various volumetric proportions varying from 9:1 to 1:9 with their equimolar solutions of 0.1 M form the Bi2Se3 films. The films are characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), and optical absorption techniques. The SEM studies show that the film covers total substrate surface with uneven surface morphology. The XRD patterns of the films show that the as-deposited films are polycrystalline with relatively more peak intensity at composition 9:1 and equimolar concentration 0.1 M. The optical band gap energy for direct transition in Bi2Se3 thin films is found to be 0.79 eV.

Europium metal thin films have been electrodeposited potentiostatically onto the fluorine-doped tin-oxide (FTO) covered glass substrates from an aqueous acidic bath, complexed with a citric acid. Bath pH value of 2–2.5 and citric acid as complexing agent play an important role in bringing down the deposition potential and thus making the deposition process possible. The effects of preparative parameters such as deposition potential and bath temperature are studied. The films are exposed to atmospheric oxygen for their conversion into europium oxide and are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and optical absorption. The XRD studies reveal that the material formed on FTO covered glass substrates is europium oxide and polycrystalline one. The grain size for the deposited material is about 300 A. The SEM studies show that total substrate surface is covered by the film with small grains.

Thin films of arsenic trisulphide have been prepared by spray pyrolysis method from aqueous medium. The disodium salt of ethylene diamine tetra acetic acid (EDTA) is used as a complexing agent. Four different samples of these films are prepared with various concentrations of EDTA. The prepared films are amorphous. The effect of concentration of complexing agent on the structural, electrical and optical properties of the films are studied and reported.

Antimony doped SnO2 films have been prepared by spray pyrolysis. The films deposited at an optimised substrate temperature of 520°C were found to have a resistivity as low as 0.4×10−4 Ω cm. Doping concentration of Sb in the spraying solution was varied from 0.5 to 5%, keeping the spray rate constant. The sheet resistance was as low as 6 Ω cm−2. About 80% average transmission in the visible region was obtained for 1% Sb doped films. The refractive index increased from 1.62 to 2.64 with increasing the Sb content from 0 to 5%. Van-der-Pauw’s four probe technique of conductivity measurement was used to measure electrical conductivity (σ), Hall coefficient (RH), carrier concentration (n) and Hall mobility (μH) of the Sb:SnO2 films. The films deposited using 1% Sb doping showed the best properties.

Bi2S3 thin films were prepared without complexing agent and with different concentrations of tartaric acid as a complexing agent by a spray pyrolysis technique. The effect of concentration of the complexing agent on the properties of Bi2S3 thin films was studied by characterizing the films by X-ray diffraction, scanning electron microscopy, optical absorption, and dark electrical resistivity measurement techniques. These studies revealed that all films were polycrystalline. The band gap energy for films grown without complexing agent was observed to be 1.72 eV. However, the band gap energy for different concentrations of complexing agent was observed to be 2.0 eV. The electrical resistivity of the films with complexing agent was higher than that of the film prepared without complexing agent. The electrical resistivity increased with increasing concentration of complexing agent.

Semiconducting Bi2S3 thin films were prepared on stainless steel and fluorine-doped tin oxide (FTO) coated glass substrates from non-aqueous media using the electrodeposition technique. It has been found that bismuth nitrate and thiourea in the volumetric proportions as 8:2 and their equimolar solutions of 0.05 M concentration form good quality films of Bi2S3. The characterization of the prepared films was carried out using the X-ray diffraction and optical absorption techniques. These studies reveal that, as deposited films are polycrystalline having an optical band edge (direct) 1.8 eV.

Sb2S3, in the thin film form, is important in view of its photosensitive and thermoelectric properties. Sb2S3 thin films have been spray deposited onto amorphous glass substrates using acetic acid (glacial) as a non-aqueous solvent. The films have been prepared by spraying, a mixture of equimolar SbCl3 and CS(NH2)2 dissolved in acetic acid, onto the glass substrates maintained at optimised conditions of substrate temperature (250°C) and solution concentration (0.1 M). The spray rate, during deposition of the films, was maintained to be 12 cm3 min−1. The films have been deposited with varying Sb:S volume ratio in the solution: 1:9, 2:8, 3:7, 4:6, 5:5, 6:4, 7:3, 8:2 and 9:1. The films have been characterised for their structural, optical and electrical properties. The X-ray diffraction studies reveal that the deposited material is polycrystalline Sb2S3. It has been found that as the composition of Sb increases from 1 to 4, crystallinity of the material increases continuously. It is relatively higher for 4:6 composition and continuously goes on decreasing for further subsequent compositions. The calculated lattice constants for orthorhombic crystal structure of Sb2S3 for the film deposited with composition 4:6 are a=11.18, b=11.33 and c=3.83 A , respectively. The grain size has been found to vary from 265 to 350 A with composition. The room temperature electrical resistivity is of the order of 107–108 Ω cm. The calculated activation energy is found to be 0.86 eV for the film with composition 4:6. Optical absorption studies reveal that the material formed has a direct energy gap of 1.88 eV.

Sb 2 S 3 thin films have been prepared by spraying the mixture of non-aqueous equimolar solutions of antimony trichloride [SbCl 3 ] and thiourea [CS(NH 2 ) 2 ] in acetic acid (glacial) onto fluorine doped tin oxide (FTO) coated glass substrates. The cell configuration n -Sb 2 S 3 /0.5M (KCl + KI) + 0.01M I 2 /C is used for studying the current–voltage ( I – V ) characteristics in dark and light, photovoltaic output, spectral response, photoresponse and photovoltaic rise and decay characteristics. The studies reveal that the Sb 2 S 3 thin films are n -type in conductivity. Using the Butler model, the optical band gap and minority carrier diffusion length ( L P ) are found to be 1.73 eV and 0.033 μm, respectively. The junction quality factor in dark ( n d ) and light ( n l ), series and shunt resistance ( R s and R sh ), fill factor ( FF ) and efficiency ( η ) for the cell have been estimated. The measured FF and η of the cell are 59.5 and 0.30%, respectively. Annealing and etching are found to improve the photoelectrochemical performance of the PEC cell.

Thin films of Sb 2 S 3 deposited by spray pyrolysis technique are characterized electrochemically and photoelectrochemically in a polyiodide electrolyte. The effect of substrates on the working of n -Sb 2 S 3 thin film/polyiodide/C photoelectrochemical (PEC) solar cells has been investigated. The role of substrates like titanium, stainless steel and fluorine doped tin oxide (FTO)-pre-deposited glass slides on the Mott–Schottky plots is investigated at various (1 kHz and 100 Hz) frequencies and the reasons for the dispersion observed have been explained. Band edges of spray deposited Sb 2 S 3 are located. Performance of the PEC cell is found to be improved on annealing and photoelectrochemical etching.

Bi2S3 thin films have been prepared without complexing agent and with different concentrations of ethylene diamine tetra acetic acid (EDTA) as complexing agent by a spray pyrolysis technique. The effect of concentrations of complexing agent on the properties of Bi2S3 thin films is studied by characterizing the films by X-ray diffraction, scanning electron microscopy (SEM), optical absorption and dark electrical resistivity measurement techniques. These studies reveal that all films are polycrystalline. The band gap energy for as deposited films is observed to be 1.72 eV. However, the band gap energy is observed to be 2.0 eV for different concentrations of complexing agent. The electrical resistivity of the films with complexing agent is higher than that of the films prepared without complexing agent. The electrical resistivity also depends upon the concentration of the complexing agent.

n -Sb 2 S 3 thin films were deposited using spray pyrolysis technique from non-aqueous medium. The semiconductor-septum (SC-SEP) storage cell is fabricated with the configuration | C | 0.5 M Polyiodide | n -Sb 2 S 3 | Ti || 0.1 M Fe(CN) 6 4− /Fe(CN) 6 3− | C |. The charging and discharging modes are studied and discussed. It was found that the storage of chemical energy in the semiconductor-septum cell is possible by using Sb 2 S 3 electrode.

Thin films of cadmium oxide are prepared on a glass substrate by a spray pyrolysis technique from an aqueous solution of cadmium acetate. The X-ray diffraction studies shows that the films are polycrystalline. The room temperature resistivity is of the order of 10 −2 Ω cm. From optical absorption data the bandgap energy of CdO is estimated to be 2.5 eV. Thermoelectric power measurement is carried out to understand the conduction mechanism.

Semiconducting p-Sb 2 Se 3 thin films have been spray deposited using two Se sources viz. SeO 2 and (CSe(NH 2 ) 2 ) at their optimised preparative parameters of deposition. The film thickness is of the order of 0.5 μm. X-ray diffraction studies reveal that the as-deposited films prepared using SeO 2 as a Se source are amorphous while those prepared using (CSe(NH 2 ) 2 ) are polycrystalline with orthorhombic crystal structure. Optical gap of the amorphous film is found to be 1.28 eV, while that of the polycrystalline film has 1.26 eV. Polycrystalline films have dark resistivity in the order of 10 7 Ω cm whereas amorphous films have in the order of 10 5 –10 6 Ω cm. Thermoelectric power (TEP) measurement studies reveal that both the films show p-type conductivity with the Seebeck coefficient to be 45 μV/°C and 1.82 mV/°C for the polycrystalline and amorphous Sb 2 Se 3 thin films, respectively.

The Fe:CdSe thin films have been electrodeposited potentiostatically onto the stainless steel substrates, from non-aqueous bath containing (CH3COO)2 · Cd · 2H2O, SeO2 and FeCl3. The solar rechargeable (semiconductor–septum) storage cell is fabricated with the configuration C|1 M polysulphide|n-Fe:CdSe|stainless steel||1 M FeCl3 or 1 M K4Fe(CN)6|C. The charging and discharging modes are studied and discussed. The comparison of FeCl3 and K4Fe(CN)6 based solar rechargeable storage cells, showed that FeCl3 based storage cell is superior than that of K4Fe(CN)6 based electrolyte because relatively charging time is minimum and discharging time is maximum. Thus it is concluded that the storage cell works not only as a generator but also as the storage of electricity.

Thin films of Sb2Se3 have been electrodeposited from an aqueous acidic bath at room temperature using selenium dioxide as a selenium ion source. The electrodeposition potentials for different bath compositions and concentrations of solution are estimated from the polarization curves. It has been found that SbCl3 and SeO2 in the volumetric proportion as 9 : 1 and their equimolar solutions of 0.0075 M form a good quality films. The films are annealed in a nitrogen atmosphere at 200°C for 1 h. The films are characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) and optical absorption techniques. The XRD patterns of the films show that the as-deposited and annealed films are polycrystalline. The optical band gap energy for direct transition in Sb2Se3 thin films is found to be 1.55 eV.

Semiconducting thin films of sulphides of antimony and bismuth have been prepared onto glass substrates from non-aqueous medium using a spray pyrolysis technique. Transient photoconductivity measurement of the films in the microwave frequency is performed using the time resolved microwave conductivity (TRMC) method. From TRMC measurements the decay time of electrons is estimated to be 26 ns for Sb 2 S 3 and 50, 61 and 52 ns for Bi 2 S 3 thin films deposited at 220, 270 and 320°C temperatures, respectively.

Semiconducting antimony triselenide thin films were obtained by spray-depositing aqueous and nonaqueous media, at optimized substrate temperature and solution concentration, onto optically flat glass substrates. Film thickness was of the order of 0.5 μm. X-ray diffraction studies revealed that the as-deposited films prepared from the aqueous medium were polycrystalline, while those prepared from the nonaqueous medium were amorphous. The optical gap of the Sb2Se3 thin films prepared from the aqueous medium was 1.88 eV, due to direct interband transition. In contrast, the optical gap for the films prepared from the nonaqueous medium was 1.73 eV. Room-temperature electrical resistivity for the films prepared from both media was found to be of approximately the same order, 107 Ω-cm. Thermoelectric power (TEP) measurement studies revealed that the films prepared from both media showed p-type conductivity, with Seebeck coefficients of 46.2 and 18.3 μV/°C for the polycrystalline and amorphous Sb2Se3 thin films, respectively.

Thin films of Cd-Fe-Se have been prepared onto stainless steel substrates, for various compositions of Cd and Fe and solution concentrations by an electrodeposition technique. Cd 0.9 Fe 0.1 Se films, electrodeposited with a solution concentration of 10 mM, forming a photoelectrochemical (PEC) cell using ferri-ferrocyanide electrolyte, show a better PEC performance. The films deposited using optimized composition (9:1:10), solution concentration (10 mM), deposition time (30 min) and current density (1 mA/cm 2 ) have been used for further characterization by X-ray diffraction (XRD) and PEC techniques. It has been found that the as-grown films are polycrystalline in nature with orientations along the peaks of hexagonal CdSe and FeSe. It has also been found from the current-voltage and power output characteristics that n-Cd-Fe-Se/ferri-ferrocyanide junctions show good rectifying nature and the efficiency of the n-Cd 0.9 Fe 0 1 Se/ferri-ferrocyanide/C PEC cell is 0.41% with FF 50%.

Powders of Sb 2 S 3 are obtained by a bulk preparation technique using aqueous solutions of antimony trichloride and thioacetamide for two different complexing agents, namely, oxalic acid and tartaric acid. The concentration of solution is kept constant at 0.1 M and only the concentration of complexing agent is varied. The effect of concentration of the complexing agents on the properties of precipitated powder is studied. The powders precipitated using oxalic acid are grey, whereas the powders precipitated using tartaric acid are orange in colour. X-ray diffraction studies reveal that the powders are polycrystalline in nature. Crystallinity using the former acid is relatively higher than that with the latter. It has been observed that the crystallinity goes on decreasing as the concentration of complexing agents increases. Infrared spectroscopy studies indicate the presence of carbon and absorbed water in the powders complexed with oxalic acid. Optical absorption studies show that the direct bandgap energy of the precipitated powders prepared using oxalic acid varies from 1.59 to 1.98 eV and it is found to be higher (1.98 eV) for powder prepared using 0.25 M oxalic acid, while for powders prepared using tartaric acid, it varies from 1.92 to 2.02 eV and is found to be higher (2.02 eV) for the powder prepared using 0.75 M tartaric acid. Electrical resistivity study reveals that the room-temperature electrical resistivity of the powders prepared using oxalic acid is relatively lower (10 4 –10 6 Ω cm) than that of tartaric-acid-complexed powders (10 5 –10 7 Ω cm).

Bi2S3 thin films are deposited by a spray pyrolysis technique using oxalic acid as a complexing agent. The films are characterized for their structural, optical and electrical properties. The results are compared with the properties of Bi2S3 thin films produced by the same technique without using the complexing agent. The XRD studies reveal that the growth of the film in a particular direction can be obtained just by controlling the quantity of the complexing agent. The resistivity of complexed films is more than that of as-deposited films. Thermoelectric power (TEP) measurement shows that the carrier concentration and mobility decrease with increasing quantity of oxalic acid. Optical absorption study reveals that the band gap energy, irrespective of the quantity of oxalic acid added to the material, is 1.75 eV.

Thin films of Bi 2 Se 3 have been prepared from an aqueous acidic bath at room temperature using selenium dioxide as a selenium ion source by a simple, inexpensive electrodeposition technique. The electrodeposition potentials for different bath compositions and concentrations are estimated from polarization curves. It has been found that Bi(NO 3 ) 3 and SeO 2 in the volumetric proportion as 7:3 and their equimolar solutions of 0.025 M form good quality films. The films are annealed in a nitrogen atmosphere at 200 °C for 2 h. The films are characterized by scanning electron microscopy, X-ray diffraction and optical absorption techniques. Studies reveal that as-deposited and annealed thin films are continuous and polycrystalline in nature. The optical band gap has been found to be 0.55 eV for the above-mentioned composition and concentration of the film.

The CoFe2O4 ferrite thin films have been prepared by spray pyrolysis technique at different substrate temperatures (Ts). The XRD patterns reveal a good (111) texture in the film prepared at Ts=325°C. The slow scan XRD studies show that the grain size is of the order of 150 A and is not varied much with the substrate temperature. The lattice parameter a calculated from XRD data is found to be larger than the bulk value. This indicates that the spray deposited CoFe2O4 films are under a compressive stress in the film plane. The electrical resistivity measurements show a increase in resistivity with decrease in temperature exhibiting a semiconducting behaviour. The thermoelectric power measurements reveal that the films prepared at Ts=325, 335 and 345°C showed n-type conductivity whereas that at Ts=355°C exhibited p-type conductivity. This change in conductivity can be attributed to change in cation distribution, which is found to be depend on substrate temperature.

Sb2S3 semiconducting thin films and precipitated powders have been prepared by a spray pyrolysis technique and bulk precipitation method, respectively. The concentration of solution is kept constant at 0.1 M and only the concentration of complexing agent (tartaric acid) is varied from 0.25 M to 1 M. The thickness of the film measured by weight difference method is found to be relatively higher for the film deposited with 0.5 M tartaric acid. The film thickness is of the order of 0.1 μm. As-deposited films are found to be uniform, dark grey and well adherent to the glass substrates. In contrast, the precipitated powders are orange in colour. X-ray diffraction studies reveal that the precipitated powders are polycrystalline whereas films are amorphous in nature. Also it has been found that the crystallinity of the precipitated powder is higher for 0.25 M concentration and decreases for the further concentrations of complexing agent. The direct bandgap of the thin films is found to be 2.7 eV irrespective of concentration of complexing agent, whereas the direct bandgap of the precipitated powder varies from 1.92 to 2.02 eV and is found to be higher (2.02 eV) for the powder prepared using 0.75 M tartaric acid. Electrical resistivity study reveals that at 0.5 M tartaric acid, the R.T. resistivity of the thin film is relatively lower (∼ 106 Ωcm) than that of precipitated powder (∼ 10su8–109 Ωcm).

Semiconducting Sb–Se thin films are prepared on glass substrates from a non-aqueous medium using a spray pyrolysis technique. The films are deposited at a fixed solution concentration of 0.1 M and at various substrate temperatures. The film thickness is of the order of 0.5 μ m and is found to be relatively higher for the film deposited at 175°C substrate temperature. X-ray diffraction studies reveal that the as deposited films are amorphous in nature, while after annealing in the N 2 atmosphere at 325°C for 2 h, the films deposited at 200°C turn into polycrystalline ones. The analysis of the absorption coefficient data reveals that as the substrate temperature increases, the optical bandgap value of the material increases. It has also been found, for the film deposited at 200°C and annealed in N 2 atmosphere, that the polycrystalline material follows the direct optical transition with energy gap Eg opt equal to 2.14 eV. The electrical resistivity at room temperature (300 K) is of the order of 10 6 –10 7 Ω cm, which changes slightly after annealing.

Bi2O3 thin films have been prepared by spray pyrolysis method onto the glass substrates at optimised substrate temperature of 450 °C. The spray rate was maintained to be constant during the deposition. These films have been converted into Bi2S3 thin films by a chemical method. The Bi2O3 thin films when dipped into a solution of sodium sulphide [Na2S] are found to be converted into Bi2S3 thin films. The structural, optical and electrical properties of both the Bi2O3 and Bi2S3 thin films are reported.