In this paper, we report the fabrication of Schottky solar cell based on spray pyrolysed lead oxide semiconductor thin films. The non-linear junction were created by using high work function metal alloy of Au-Pd with hydrogen treated undoped and Indium doped lead oxide films. The output of Schottky device with different thickness of absorber layer is presented. The electrical parameters of the device are ascertained from the I-V measurements. The device with 2 mu m thickness of absorber layer gives a Voc value of 148 mV and Jsc value of 0.21 mA/cm2. The high ideality factor obtained for all varying thickness is attributed to both the surface states generated under illumination and non-homogeneous interface due to the rough surfaces of spray pyrolysed films. In case of Indium doped lead oxide films, an enhanced Voc value of 570 mV and Jsc of 0.11 mA/cm2 is observed. The pristine films and doped films have been characterized by X-Ray diffraction, Raman spectroscopy and scanning electron microscopy.

Si nano-spheres have been electrodeposited at room temperature on polycrystalline Au and graphene coated Cu substrate potentiostatically using SiCl4 as precursor in water contaminated ionic liquid. Detail cyclic voltammetric studies show that a two-step process is involved for the electro-reduction of Si4+ to elemental Si. The electrodeposition takes place in the over-potential domain at -1.5 V (vs. Pt) for both the working substrates. Formation of Si nano-spheres is found to be governed by the templating effect of bound water structures in BMImTf2N in the presence of SiCl4. While the distribution of particle size is broad for both the substrates, the average particle size varies from 170-180 nm for Au and graphene coated Cu substrates. XRD results show poor crystalline to amorphous nature of the Si nano-spheres which is supported by TEM studies and band-gap energy estimation. XPS results confirm the deposition of elemental Si with trace of surface oxygenated species. The growth of Si nano-spheres on Au substrate is found to follow first order kinetics while a second order kinetics seems to present the case for the deposition on graphene coated Cu substrate.

CuO films on transparent, conductive substrates (fluorine doped tin oxide, FTO), obtained by spray pyrolysis, were analyzed photoelectrochemically in neutral and alkaline solutions. The photoresponse was typical for a p -type semiconductor in a junction with an electrolyte. In absence of an electron scavenger in solution, cathodic photocurrents decayed rapidly (within minutes). This is ascribed to photogenerated conduction band electron initiated reduction of the electrode material to Cu2O. Such films could be reactivated by annealing in air, which resulted in the reconstruction of the CuO phase and complete recovery of photocurrents. Reducible species (methylviologen, ferricyanide, oxygen) were added to the electrolyte in order to compete with the photoelec-trochemical auto-reduction of the semiconducting layer. In the case of O-2 as scavenger, formation of a product in solution, H2O2, was observed, although with a Faradaic efficiency of only 2 percent. In all cases, only minor long-term stabilization was achieved. This was because sufficiently high concentrations of electron scavengers could not be used when high cathodic dark currents were developed (case of ferricyanide), or when the solubility was limited (case of oxygen). In addition, reduction of the semiconductor by the reduced photoactive species (case of methylviologen) can occur.

The reduction of Cu(II) has been investigated in the presence of Alizarin Red S in two different background solutions namely KCl and acetate buffer through this study. The electroactive intermediate species have been extensively characterised by using Direct Current Polarography and Deferential Pulse Polarography techniques. It has been observed that Cu2+ was reduced to elemental copper in a two-step single-electron transfer process. However, the kinetics of charge transfer is dampened in the presence of Alizarin due to the complexation of active copper ions with ionised Alizarin, making the electrodeposition more controlled. In the first technique, the peaks of the 57 mM-Cu2+ reduction and for the 57 mM-Alizarin reduction have been observed. Using the second technique, the voltammograms exhibit the peaks at pH = 2, 3, where the first peak is for the reduction process of two carbonyl groups in Alizarin, and the second one is for Cu2+ reduction as one-step two-electron transfer. At pH = 5, the complex formation reveals that copper can be hardly reduced on the cathode, whereas Alizarin has two small peaks for two carbonyl groups after being in the investigated alkali mediums. The clear peak at pH = 11 indicates that copper is no more in the structure of a complex. The stoichiometries of the salt and complex have been also verified where both are (1:1). Coating experiments were carried out at 25 °C, 35 °C and 60 °C to investigate the relations between the current efficiency and pH, current density, molarity concentration and time and obtain the optimal operating conditions for copper electrodeposition on steel and stainless steel.

Potentiostatic deposition of CdTe thin films from acetate-anion based ionic liquid, 1-butyl-3-methylimidazolium acetate ([BMIM][Ac]) bath has been carried out at 90 degrees C. A molar concentration ratio i.e. molar Cd/Te = 2 has been taken to electrochemically synthesize CdTe films under different dynamic conditions. FE-SEM showed the formation of homogeneous CdTe films over fluorine doped tin oxide (FTO) substrates. EDX revealed the formation of nearly stoichiometric CdTe films at optimal stirring rate of similar to 400 rpm. The optical band gap of similar to 1.45eV were observed with cubic zinc blende CdTe structure. XRD, RAMAN and XPS analysis confirmed the formation of pure CdTe phase with ultra-thin oxide overlayer. Photoelectrochemical studies of CdTe photoelectrodes prepared by electrodeposition technique was investigated in K2Sx and KH2PO4. Mott-Schottky analysis demonstrated the formation of p-CdTe with a flatband (V-fb) potential of similar to 0.95V(RHE). A high photocurrent density of 1.23 mA/cm(2) has been achieved with solar conversion efficiency (eta(c)) of 1.50% for the pristine electrodeposited CdTe/FTO photocathode i.e. without surface modification, under chopped monochromatic illumination. This illustrates that the prepared CdTe photocathode can be a promising semiconductor candidate for application in photo-electrochemical hydrogen evolution from water. The use of acetate-anion based IL bath always resulted in p-type CdTe thin films. (c) 2019 Elsevier Ltd. All rights reserved.

A new, non-enzymatic, low-cost sensor based on tellurium nanoparticles (TeNPs) for the analytical determination of H2O2 has been proposed. An economically viable electrochemical technique was employed for the synthesis of TeNPs based non-enzymatic H2O2 sensor. Thin films of TeNPs were successfully electrodeposited on fluorine-doped tin oxide (FTO) substrate using [BMIM] [Ac] ionic liquid at 90 degrees C. The effect of deposition potential on the morphology, phase formation, and electrochemical characterisation of nanostructured Te films has been studied. Field emission scanning electron microscopy, X-ray diffraction, Raman and X-ray photoelectron spectroscopy were employed to characterize the nanostructured Te films on Fro surface. The electro-catalytic performance of the proposed TeNPs/FTO sensor has been studied by cyclic voltammetry (CV) and chronoamperometry (CA) in phosphate buffer (Argon saturated) in the absence and presence of H2O2. TeNPs/FTO fabricated at applied potential of -1.40 V showed an excellent electro-catalytic activity towards H2O2 reduction. The proposed TeNPs/FTO sensor shows an excellent sensitivity of 757 A mu M-1 cm(-2). The sensor possess good selectivity and stability with an excellent amperometric response time of about 5 s. The present study also demonstrates that TeNPs/FTO is a promising sensing material suitable for determination of H2O2 in practical samples.

Nanostructured CdS thin film was successfully deposited on glass by chemical bath deposition (CBD) at 80 degrees C. The effect of deposition time on the morphology, composition, optical and optoelectronic properties of nanostructured CdS thin films has been studied. The CBD-grown CdS thin films showed random arrangement of interconnected nanoparticles in 2D morphology. Nanostructured CdS thin films exhibited metastable cubic phase having uniform, compact and defect-free structure with enhanced crystallinity. Tauc plot of CBD-grown nanostructured CdS thin film showed an optimum band gap of 2.30 eV and a resonant Raman peak at 302 cm(-1). The transverse optics (TO) mode, multi-phonon scattering and high-order replicas of nanostructured CdS thin films were also observed. Metal-semiconductor-metal (MSM) based CdS Photodetector (PD) showed an excellent photodetectivity of 2.6 x 10(13) Jones. Photoconductive performance such as photo-sensitivity (207%) and - responsivity (0.38 A/W @ 420 nm) under an illumination condition was obtained for application in visible-light photodetector.

Thin films of photoactive alpha-PbO have been prepared on fluorine doped tin oxide substrates using spray pyrolysis in the range of 380 degrees C to 470 degrees C. SEM showed the formation of interconnected PbO grains with increase in grain size at elevated temperature. The Raman peak at 147 cm(-1) shows the formation of phase pure alpha-PbO. XPS indicates the phase purity of alpha-PbO as well as its stoichiometric nature. Photoelectrochemical studies of as-deposited alpha-PbO in 0.1 M potassium ferrocyanide (K4Fe(CN)(6)) or potassium iodide (KI) at pH 9.2 under visible light irradiation showed photoanodic and photocathodic current, indicating nearly intrinsic behavior. Photocurrent spectra showed the presence of a semiconductor with an indirect bandgap of 1.9 eV. Doping by inducing oxygen deficiency through annealing in hydrogen and addition of 2 at. % In, shifted the onset potential to more negative values (down to -0.5 vs. Hg/HgO) in KI, indicating successful conversion into n-type semiconducting material. The In doped hydrogen annealed alpha-PbO shows a flatband potential of -0.58 V vs. Hg/HgO. The IPCE (incident photon to current conversion efficiency) in KI electrolyte was found to be 0.016 in the plateau region (0.6 V vs. Hg/HgO) at an incident wavelength of 532 nm. (C) 2019 The Electrochemical Society.

( )Cadmium telluride thin films on transparent conducting oxide (TCO) substrate have been deposited galvanostatically from 1-butyl-3-methylimidazolium chloride at 80 degrees C. The effect of applied current density on surface morphology and elemental composition of as-deposited films has been presented. SEM micrographs show interconnected needle-like morphology for CdTe thin films. EDX reveals formation of stoichiometric CdTe films at an estimated optimal current density of 745 mu A/cm(2). Cubic zinc blend CdTe films were obtained with Te-rich or Cd-rich content with variation of applied current densities. The optical band gap of 1.49 eV were observed in the case of stoichiometric CdTe film having large crystallite sizes. The micro-Raman analysis of CdTe films showed a resonant peak at 164 cm(-1) which validated the formation of pure CdTe phase. A shift in the peak and an increase in the Huang-Rhys factor (I-2LO/I-1LO) can be associated with impurities/defects caused by excess of Cd or Te content in the CdTe matrix.

CdTe being a direct band gap semiconductor, is mostly used in photovoltaics. Here we present, the synthesis of CdTe thin film on fluorine doped tin oxide (FTO) substrate potentiostatically using 1-butyl-3-methylimidazolium acetate ([Bmim][Ac]) ionic liquid (IL) bath at 90 degrees C. Major advantages of using electrodeposition involves process simplicity, large scalability & economic viability. Some of the benefits offered by IL electrolytic bath are low vapour pressure, wide electrochemical window, and good ionic mobility. Cd(CH3COO)(2) (anhydrous) and TeO2 were used as the source precursors. The IL electrolytic bath temperature was kept at 90 degrees C for deposition, owing to the limited solubility of TeO2 in [Bmim][Ac] IL at room temperature. Cathodic electrodeposition was carried out using a three electrode cell setup at a constant potential of -1.20 V vs. platinum (Pt) wire. The CdTe/FTO thin film were annealed in argon (Ar) atmosphere. Optical study of nanostructured CdTe film were done using UV-Vis-IR and Raman spectroscopy. Raman analysis confirms the formation of CdTe having surface optics (SO) mode at 160.6 cm(-1) and transverse optics (TO) mode at 140.5 cm(-1). Elemental Te peaks at 123, 140.5 and 268 cm(-1) were also observed. The optical band gap of Ar annealed CdTe thin film were found to be 1.47 eV (absorbance band edge similar to 846 nm). The optimization of deposition parameters using acetate-based IL electrolytic bath to get nearly stoichiometric CdTe thin film is currently being explored.

The present study reports a simple, fast and cost effective precipitation technique for synthesis of pure alpha-PbO powder. Lead monoxide powder with tetragonal structure was synthesized chemically at an elevated temperature using lead acetate and sodium hydroxide solution bath. XRD powder diffraction was used to find the structural properties as well as phase transition from alpha to beta. Study revealed that synthesized PbO powder was crystalline with tetragonal symmetry, having an average crystallite size of 70 nm and lattice constants; a=3.97 angstrom, b=3.97 angstrom, and c=5.02 angstrom. Phase transition from tetragonal to orthorhombic structure was studied by comparing the XRD data of the annealed samples in the temperature range from 200 degrees C to 600 degrees C. UV-Visible spectroscopy was used to find out the optical properties of prepared PbO powder. Diffuse reflectance and absorbance spectra confirmed the formation of alpha-PbO with obtained direct band gap of 1.9 eV. Synthesized lead monoxide (alpha-PbO) powder has promising application in energy conversion as well as energy storage applications.

Potentiostatic electrodeposition of Cadmium Telluride (CdTe) films from the alkaline ionic liquid (IL), butyl methyl imidazolium chloride (BmimCl) at 80 degrees C has been carried out at an applied potential of -1.45 V vs. platinum (Pt) wire. The influence of the substrate and electrolytic IL bath content on the morphology and composition of electrodeposited CdTe thin films has been presented. The sheet resistivity of the modified FTO substrate increases to similar to 17.7 Omega/sq. While treatment of the substrate prior deposition changes the individual CdTe morphology, the composition as well as the film compactness has been found to vary with the treatment of the IL based electrolytic bath. SEM micrograph shows inter-connected needle-like and herring bone morphology of electrodeposited CdTe along with agglomerated lumps of Te and flecks of Cd. Interdependency of surface morphology and elemental composition of electrodeposited CdTe films were observed by SEM & EDX analysis. It has been shown that hydroxylated Fro surface facilitates three dimensional (3D) nucleation and growth in the presence of O-2 in the electrolytic bath. 3D nucleation and growth mechanism leads to Cd-rich CdTe films. Electrodeposition that does not proceed through 3D nucleation and growth shows only Te-rich layer. Also, the net charge transfer was found more in Cd-rich CdTe layers as compared with Te-rich CdTe deposits.

Metallic lead (Pb) has been electrodeposited on FTO substrate at room temperature from aqueous nitrate solution under constant applied potential in the range of − 0.46 to − 0.8 V vs. SCE. Cyclic voltammetry shows that 3D nucleation and growth are the main feature at higher electrolyte concentration when the profile is recorded at 20 mVs−1. While a single step potential facilitates the deposition of faceted crystals of Pb, distinguished lead having cabbage-like morphology can be deposited by applying sequential two step potentials. The I-t response shows that the deposition is initiated through instantaneous 2D nucleation and growth at the shorter time domain followed by 3D nucleation and growth in 0.4 M Pb(NO3)2. Theoretical simulation of the closely matched experimental I-t profile for simple step potential provides a 2D rate constant of 2.00 ± 0.04 × 10−7 mol cm−2 s−1 while for 3D, the vertical and plane growth rate constant of 3.27 ± 0.05 × 10−5 mol cm−2 s−1 and 2.00 ± 0.04 × 10−7 mol cm−2 s−1, respectively. The formation of the cabbage morphology has been discussed on the basis of time evaluation of FE-SEM. The high surface area of unique lead deposits with cabbage morphology shows better life time and oxygen sensitivity in a typical oxygen sensor application.

We report the synthesis of photoactive lead monoxide thin films on fluorine doped tin oxide substrate by cost effective spray pyrolysis technique using aqueous solution of lead acetate trihydrate. Influence of substrate temperature on the structural and optical properties of thin films was studied. Polymorph of lead monoxide, litharge (alpha-PbO), was obtained when the substrate temperature was kept constant at 360 degrees C. XRD analysis revealed that the deposits were tetragonal structured with preferred orientation along 002 plane. Band gap value was found to be 1.93ev from diffuse reflectance spectra.