S.H. Pawar

Growth of Bi2S3 film using a solution-gas interface technique

Abstract Uniform large-area Bi2S3 films about 0.3 μm thick were prepared using a solution-gas interface technique. The surface of a Bi(NO3)3 solution was exposed to H2S gas and a thin solid film was formed. The electrical and optical properties of films prepared in this way were studied. The band gap energy of Bi2S3 films estimated from electrical measurements was found to be in fair agreement with the value estimated from the optical measurements.

Optical and transport properties of chemical bath deposited CdS: Al films

Abstract Aluminium doped and undoped CdS films are deposited on the glass substrates by chemical bath deposition technique. Their optical and transport properties are studied and the effect of dopant concentration on these properties is discussed at length.

Electrochemical photovoltaic cells for solar energy conversion

Abstract Photoelectrochemical cells have attracted much more attention recently due to their feasibility as low-cost solar energy conversion devices and hence a number and variety of papers have appeared. Although some review papers have been published, no comprehensive review of electrochemical photovoltaic cells has been made. The present review is devoted to a survey of most of the dimensions of ECPV cells. Starting with photoelectrochemical processes, relevant theoretical background is presented including redox potentials, interface of the semiconductor-liquid junction and Butler-Volmer relation, etc. Much emphasis is given to the requirements of semiconductor electrodes, electrolytes, counter electrods and various cell configurations in ECPV cells. Results on photocorrosion, stability, etc. of the electrodes and the effect of temperature on the performance of the ECPV cell are discussed. Up-to-date data on various ECPV cells are presented and the current situation is discussed. In the light of this, various new materials are attractive. Finally, results on ECPV storage cells and their potential applications are discussed.

Effect of substrate temperature on transport and optical properties of sprayed Cd1−xZnxS films

Abstract Polycrystalline Cd 1−x Zn x S films are prepared by the spray pyrolysis technique on amorphous substrate, at different substrate temperatures. The dark conductivity and thermoelectric power are measured and applied to calculate the electron density and mobility. The electron density decreases with increase in substrate temperature. However, mobility is higher for the films prepared at 400°C substrate temperature. The variation of electron density and mobility with substrate temperature is explained in terms of crystallanity of the film and chlorine concentration in the films. The optical absorption of the films are studied and revealed that there is not much change in band gap with substrate temperature.

Studies on properties of spray deposited Bi2S3 films and electrochemical photovoltaic cells formed with Bi2S3 films

Abstract Bismuth sulfide films are deposited by a spray pyrolysis technique on conducting and amorphous glass substrates at optimised preparative parameters and their electrical and optical properties are studied. The electrochemical photovoltaic (ECPV) cells with a configuration Bi 2 S 3 /NaOH - Na 2 S - S / C, are formed and the results on I-V characteristics, spectral response and C-V measurements are reported and discussed.

Studies on photoelectrochemical storage celis formed with CdS:Cu electrode

Abstract Copper doped and undoped CdS films are deposited on the stainless steel strips by chemical bath deposition technique and two compartment photoelectrochemical storage cells are formed with these films as photoanodes. The results on photovoltaic energy conversion and storage of these cells are reported and discussed.

Electrodeposition of CuInTe2 films

CuInTe2 films have been deposited on a titanium substrate from acidic as well as from alkaline baths. The as-deposited films were uniform and adhered well to the substrate. Structural and compositional studies showed that the as-deposited films were amorphous or consisted of fine grains and were stoichiometric in composition.

Effect of aluminum doping on the properties of PEC cells formed with CdS:Al films

Aluminum doped and undoped CdS films were prepared by chemical bath deposition technique and the photoelectrochemical (PEC) properties have been studied by forming doped CdS/NaOHNa2SS/C junction. Better results are obtained with 0.1 wt% Al doped CdS films. These results are discussed with the help of the optical and transport properties of the Al doped CdS films.

Photoconducting properties of cadmium sulphide-lithium thin films formed by the chemical bath deposition method

Abstract The cadmium sulphide-lithium thin films used in this work were prepared by the chemical bath deposition technique. In this simple process uniform large-area films of semiconducting and photoconducting cadmium sulphide can be formed on rotating substrates. The photoconducting and optical properties of these films were studied. The photoconducting properties studied included the rise and decay of the photoconductivity, the spectral response of the photoconductivity and the variation of the time constants with the wavelength of excitation and with the intensity of excitation. The photoconductivity rise curve for the first excitation was analysed considering the role of photodesorption of oxygen to determine the oxygen trap level, which is 0.78 eV below the conduction band. Although it was analysed using an old method developed by R.H. Bube, the oxygen trap level obtained is in good agreement with that found from the decay curve. The variation of the time constants with the intensity of illumination is explained on the basis of quasi-Fermi levels and the pinning of the quasi-Fermi levels somewhere in the band gap. This pinning arises from the high density of the filled traps at quasi-Fermi levels.

Thermally stimulated luminescence of CaS : Bi : Pd phosphors

Abstract CaS phosphors co-activated with Bi+3 and Pd+2 impurities in varying concentrations have been prepared and their thermoluminescence has been systematically studied. The general features of the curves are discussed and the activation energies have been estimated in three different ways. The escape frequency factor is determined using the theoretical model of Randall and Wilkins. Conclusions are drawn regarding the type of kinetics involved in the thermoluminescence process.