Dye-sensitized solar cell (DSC) that mimics natural photosynthesis in the conversion of solar energy is expected to contribute significantly in next generation of photovoltaics. The high efficiency of the DSC associated with low cost, and ease of production attracted the attention of many research groups focussing on fundamental aspects of dye sensitized solar cell components. In these cells on of the key component is the sensitizer containing acceptor/donor ligands that controls light harvesting, charge injection and charge separation assisted with donor thiocyanate ligands. Attempts to replace thiocyanate donor ligand however, met with limited success in obtaining high efficiency. In this presentation we report thiocyanate free novel cyclometalleted ruthenium sensitizer (YE05) and its application in DSC. Solar cell using the YE05 sensitizer exhibit remarkable incident monochromatic photon-to-current conversion efficiency 83%, and a short circuit photocurrent density of 17 mA/cm², the open circuit voltage was 809 mV and a fill factor of 0.73, corresponding to an overall conversion efficiency of 10.04% at standard AM 1.5 sunlight. The structural, electronic and optical properties of the cyclometalleted ruthenium sensitizer were investigated using both spectroscopic, and density functional and time dependent density functional theory.