Influence of Deposition Time on Performance of Nanocrystalline CdTe Thin Films Used as Photoelectrode in Photoelectrochemical Solar Cell

Abstract

In order to overcome the energy deficit in the future, a number of alternative energy sources are considered. Solar energy is renewable and carbon-free and is the most abundant energy source. Currently the solar cells are considered as a potential energy source for the future. Among them the photo electrochemical cells are low cast solar cells. The new and emerging technology is ‘nanocrystalline thin film technology'. Nanocrystalline CdTe thin film was synthesized by a wet chemical route at pH 11.2 using cadmium chloride and potassium telluride as starting materials. The reaction was carried out by the   refluxing the mixture of starting materials at 90⁰ C for 5 hrs. Addition of 2-propanol to the solution produced suspension of CdTe nanocrystals. Nanocrystalline thin films of cadmium telluride have been grown on glass and indium tin oxide (ITO) substrates by rotating them in the solution At ambient temperature, transparent films have been synthesized and annealed at 200 ºC for 2hrs. The prepared thin films were characterized using X-ray diffractogram (XRD), and Atomic Force Microscopy (AFM). X-ray diffractogram reveals the presence of tetragonal phase. The thickness, crystallite size and grain size were observed to increase with increase in deposition time while optical band gap energy slightly decreases. Effect of deposition time on physical, structural, microstructural, and electrical properties of these films and photovoltaic effect was studied. Prepared thin films shows good response towards photoconduction in presence and absent of light.