Dye sensitized solar cells (DSSCs) have great potential to challenge the traditional silicon-based semiconductor solar cells in the photovoltaic (PV) market because of their low cost and medium efficiency. This type of solar cell has achieved an impressive photo-to-energy conversion efficiency of over 10%. In a dye sensitized solar cell, the charge separation is initiated at the adsorbed dye, which was bound at the interface of an inorganic semiconductor film and a hole transport material. The dye is the key component in such cells. In order to optimize the performance of such devices, it is important to design suitable dyes with tunable spectroscopic and electrochemical properties. Careful modification of the structures of the sensitizers can improve light harvesting in the visible and near-IR region with high optical extinction coefficients and enhance the performance of the devices. Its necessary to optimize the properties of the dye in conjunction with other factors in order to best exploit and be fully compatible with other cell modifications in the development of cheap and efficient photovoltaic systems. In this review, current strategies for the molecular engineering of the dyes based on ruthenium complexes possessing different functionalized ligands are discussed.