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Thin films of CdTe/CdS were prepared using the thermal evaporation technique with pressure 2 × 10−5 mbar on substrate from glass. The thickness of CdCl2 layer around 150 nm was deposited making as-deposited CdTe/CdS films. The films covered by cadmium chloride (CdCl2) layer were annealed in atmosphere of (O2 + Ar) at different temperatures of 400 °C, 450 °C and 480 °C for 15 min. The effect of CdCl2 as a top layer on morphological, structural and optical properties was studied, and the results were compared with as-deposited films and also with (O2 + Ar) annealing process. The refractive index in whole wavelength and film thickness was estimated by Cauchy dispersion relation and Swanepoel's envelope method, respectively. Furthermore, many optical parameters such as transmittance, absorbance, reflectance, and optical band gap, Urbach energy, film thickness, electronic polarizability, lattice dielectric constant were calculated also in this study. The heat treatment of our films with depositing CdCl2 layer in (O2 + Ar) flow lowered the energy gap which led CdTe/CdS films to be a candidate to work in thin-film solar cells as an absorber layer. [ABSTRACT FROM AUTHOR]

Abstract: Polymeric films composed of mixture of ethyl cellulose (EC) and hydroxypropyl cellulose (HPC) are prepared from casting combined solvent (methylene chloride and methanol in 1:1 ratio) containing 8% weight/volume of both polymers (EC to HPC in 1:3 weight ratio). The structural and optical studies of the films are carried out by X-ray diffraction and UV–vis spectrophotometer. The films are polycrystalline structure with an average grain size from 23.15 to 10.79nm. The possible optical transition in these films is found to be allowed direct transition. The optical band gap energy (E g ) is estimated to be 5.02eV for HPC–EC plain film and then decreases with increasing the filler content reaching to 4.24eV for the film filled with maximum Se80Te14Sn6 content of 1w%. This suggests that Se80Te14Sn6, as filler, is a good choice to control the optical properties of HPC–EC blend film. [Copyright &y& Elsevier]

The current work focused on studying the optical and structural properties of (CdS) 1-x (ZnS) x thin films fabricated by thermal vacuum evaporation approach. The evaporation was implemented at room temperature from bulk samples synthesis by sintering approach. The energy gap, index of refraction, extinction coefficient and absorption coefficient were estimated from the experiment and employed in our theoretical model to estimate quantitatively the solar cell efficiency and short-circuit current density of CdS:ZnS/CdTe structure. The calculations of cell efficiency as well as short-circuit current density were computed on the bases of the optical losses caused by reflection at interfaces and absorption process occurred in the frontal charge-collecting and window layers and the recombination losses at front and back surface of CdTe. The XRD analysis showed that the intensity and position of predominant peak of CdS gradually changes with increasing the ZnS content indicating a success of forming CdS:ZnS alloy. The films exhibited direct band-to-band transitions and the optical energy gap increased from 2.40 eV to 3.10 eV with increasing of ZnS content up to x = 0.50. The short-circuit current density increased from 16.50 mA/cm2 to 21 mA/cm2 and the cell efficiency increased from 13.10% to 17.10% due to the increase of the ZnS content from x = 0 to x = 0.50. [ABSTRACT FROM AUTHOR]

Cadmium Selenide, CdSe, thin films deposited on different substrate types; FTO/glass,/glass, and ITO/glass substrates were produced by thermal evaporation method in the room temperature. The influence of different types of substrates on the structural, optical and electrical properties of the films was studied by X-ray diffraction and absorption photo spectroscopy respectively. X-ray diffractions revealed that all the CdSe films have a polycrystalline with cubic structure having preferred orientation (111) at 2θ ≈ 25.1°. The optical energy band, E g , values support the fact that the films have semiconductor behavior which can be attributed to the quantum confinement effect. It was observed that the optical properties such as transmittance, reflectance, optical bandgap, and refractive index and some another parameters of CdSe films were strongly affected by types of substrates. The electrical properties were measured at room temperature using two probe methods. • Influence of the substrate on the structural, optical and electrical properties of CdSe thin films. • Swanepoel's involved methods were used to calculating the film thickness and refractive index. • Cauchy's equation used to fitting the refractive index in whole wavelength. • Electrical resistivity for CdSe films were measured in room temperature. [ABSTRACT FROM AUTHOR]