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CdCl 2 treatment is a crucial step in development of CdS/CdTe solar cells. Although this processing step has been used over a period of three decades, full understanding is not yet achieved. This paper reports the experimental evidence for improvement of composition of CdTe layers during CdCl 2 treatment. This investigation makes use of four selected analytical techniques; Photoelectro-chemical (PEC) cell, X-ray diffraction (XRD), Raman spectroscopy and Scanning electron microscopy (SEM). CdTe layers used were electroplated using three Cd precursors; CdSO 4 , Cd(NO 3 ) 2 and CdCl 2 . Results show the improvement of stoichiometry of CdTe layers during CdCl 2 treatment through chemical reaction between Cd from CdCl 2 and elemental Te that usually precipitate during CdTe growth, due to its natural behaviour. XRD and SEM results show that the low-temperature (*85°C) electroplated CdTe layers consist of *(20-60) nm size crystallites, but after CdCl 2 treatment, the layers show drastic recrystallisation with grains becoming a few microns in size. These CdCl 2 treated layers are then comparable to high temperature grown CdTe layers by the size of grains.

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Graphene and chemically modified graphene can be fabricated via numerous routes each with its own merits concerning ease of processability, cost-effectiveness for large-scale production, and also health and safety. One of the promising applications of graphene-based composites is gas sensing, which is mainly useful for environmental monitoring. We review some of the significant findings on graphene-based sensing materials for the detection of organic vapors, toxic gases, and chemical warfare agent simulants using an electrochemical method. Electrochemical sensing can be performed by inducing interactions between gas molecules and a graphene layer, such as charge transfer that gives a change in an electrical signal. The intrinsic properties of graphene and its role in some gas sensing applications will be discussed. Graphene and graphene oxide (GO) work as continuous conductive networks with a large number of surface adsorption sites for many gas molecules. Hybrid graphene devices incorporate semiconductors, metals, and molecular binders to enhance the capabilities of solidstate gas sensors. This article also addresses current approaches to the commercialization of graphene-based gas sensors.

Cadmium telluride (CdTe) thin films have been successfully prepared from an aqueous electrolyte bath containing cadmium chloride (CdCl2)·H2O and tellurium dioxide (TeO2) using an electrodeposition technique. The structural, electrical, morphological and optical properties of these thin films have been characterised using X-ray diffraction (XRD), Raman spectroscopy, optical profilometry, DC current-voltage (I-V) measurements, photoelectrochemical (PEC) cell measurement, scanning electron microscopy (SEM), atomic force microscopy (AFM) and UV-Vis spectrophotometry. It is observed that the best cathodic potential is 698 mV with respect to standard calomel electrode (SCE) in a three electrode system. Structural analysis using XRD shows polycrystalline crystal structure in the as-deposited CdTe thin films and the peaks intensity increase after CdCl2 treatment. PEC cell measurements show the possibility of growing p-, i-and n-type CdTe layers by varying the growth potential during electrodeposition. The electrical resistivity of the as-deposited layers are in the order of 10 10884(1.48-1.52) eV reduce to (1.45-1.49) eV after CdCl2 treatment. Full characterisation of this material is providing new information on crucial CdCl2 treatment of CdTe thin films due to its built-in CdCl2 treatment during the material growth. The work is progressing to fabricate solar cells with this material and compare with CdTe thin films grown by conventional sulphate precursors.