With an increasing awareness of green and clean energy, zinc oxide-based solar cells were found to be suitable candidates for cost-effective and environmentally friendly energy conversion devices. In this paper, we have reported the green synthesis of zinc oxide nanoparticles (ZnONPs) by thermal method and under microwave irradiation using the aqueous extract of tomatoes as non-toxic and ecofriendly reducing material. The synthesised ZnONPs were characterised by UV脌visible spectroscopy (UV脌vis), infra-red spectroscopy, particle size analyser, scanning electron microscopy (SEM), atomic force microscopy (AFM) and X-ray diffraction study (XRD). A series of ZnO nanocomposites with titanium dioxide nanoparticles (TiO 2 ) and graphene oxide (GO) were prepared for photovoltaic application. Structural and morphological studies of these nanocomposites were carried out using UV脌vis, SEM, XRD and AFM. The current脌voltage measurements of the nanocomposites demonstrated enhanced power conversion efficiency of 6.18% in case of ZnO/GO/ TiO 2 nanocomposite.