1487 J. Indian Chem. Soc., Vol. 92, October 2015, pp. 1487-1490 Synthesis of ZnO nanocomposites for photovoltaic applications Monica Debbarma, Prasanta Sutradhar and Mitali Saha* Department of Chemistry, National Institute of Technology, Agartala-799 046, Tripura, India E-mail : mitalisah@gmail.com Manuscript received online 24 February 2015, revised 02 March 2015, accepted 13 March 2015 Abstract : Nano structured zinc oxide (ZnO) have received considerable attention due to their distinguished performance in the electronic, optical and photonic devices. In this paper, we have prepared thin film of nanocomposites using different ratios of ZnO, TiO 2 and GO by simple mechanical stirring and ultra sonication. The single zinc oxide nanostructured particle was characterised by UV-Vis and its band gap energy was investigated. The prepared composite samples were further characterized using scanning electron microscope (SEM) to get the surface morphology. The current-voltage (I-V) characteristics of thin films of ZnO/TiO 2 and ZnO/TiO 2 /GO nanocomposites were investigated. The FF (fill factor), I SC (short circuit photocurrent), V OC (open-circuit photo-voltage) and  (efficiency of the composite material for solar cell) were measured for all the nano-composites. Keywords : ZnO, nanocomposites, band gap energy, I-V characteristics, TiO 2 , GO. Introduction Composites of semiconducting oxides are extensively used as part of numerous electronic and optoelectronic devices like thin-film transistor (TFT), sensors and solar cells 1–7 . A major limitation in all the thin film solar cell technologies is that their absorbance of near-bandgap light is ineffective, in particular for the indirect-band gap semi- conductor silicon. Therefore, structuring the solar cell so that light is trapped inside, in order to increase the ab- sorptance, is very important. Among metal oxides, zinc oxide (ZnO) is found to be most suitable and preferable, compared to other metal oxide since it is easily available semiconducting material and non-toxic. Titanium dioxide (TiO 2 ) thin films have also the po- tential to greatly reduce the production costs of commer- cially produced silicon solar cells. To enhance the photo degradation efficiency of zinc oxide nanocomposites, coupled semiconductor nanocomposites of ZnO/TiO 2 have been prepared by several different processes, such solid- state reaction method 8,11 , thermal evaporation 9,10 , hy- drothermal reaction 12,13 , magnetron sputtering 13 , templating 14 , electro spinning 15 , deposition on other sub- strate 16,17 and sol-gel process 12,18–26 etc. Zinc oxide nano- composites using titanium oxide and graphene oxide has been reported by hydrothermal method also. In order to reduce the cost of photovoltaic’s, fabrication costs also need to be decreased while maintaining high efficiencies. In the present study, ZnO nanocomposites were pre- pared using TiO 2 and graphene oxide (GO) using a simple method of mechanical stirring and ultra sonication. We have synthesized ZnO nanoparticles via microwave irra- diation method 27 and the synthesised ZnO nanoparticles were mixed with different ratios of TiO 2 and GO in order to get different types of nanocomposites for their suitable applications in solar cell. The current-voltage (I-V) char- acteristics of thin films of ZnO/TiO 2 and ZnO/TiO 2 /GO nanocomposites were investigated. Short circuit photo- current (J SC ), open-circuit photovoltage (V OC ), fill factor (FF) and efficiency of the solar cell () were measured for all the nanocomposites. Experimental Synthesis of materials : Zinc oxide (ZnO) nanoparticles were prepared by our own method using microwave irradiation 27 . Titanium oxide (TiO 2 , 99%) and natural graphite powder (extra pure) were purchased from Sigma Aldrich. Graphene oxide (GO) was prepared from natural graphite using Hummers method 28 . Double distilled water has been used during the experiments.