Recent past has witnessed that a logical molecular design of sensitizers in combination of cobalt complex based redox electrolytes has led to the photoconversion efficiency (PCE) > 14 % with nearly quantitative photon harvesting in the visible wavelength region. This imparts a hope for the further enhancement in the PCE by design and development novel near-infra-red (NIR) dyes by panchromatic photon harvesting. Although iodine based redox electrolyte (I₃^-/I^-) has been widely utilized since the inception of DSSC but its corrosiveness geared the search for alternate redox electrolytes. Cobalt complex based redox shuttles are less colored, less corrosive and exhibit relatively deeper redox potential providing them as a legitimate alternative to the commonly used I₃^-/I^- redox electrolytes. In spite of several merits of cobalt based electrolytes for DSSCs, to their bulkier nature and slow ionic diffusion make them relatively more prone to charge recombination. This has compelled to the judicious selection of not only the suitable sensitizers but also strict surface passivation of conducting substrate (FTO) as well as mesoporous TiO₂. Importance of cobalt redox shuttle with visible sensitizers have already been demonstrated aiming towards high efficiency DSSCs but with NIR dyes such reports are rare. It has been found that dyes having multiple and long alkyl chains out-perform with cobalt electrolyte due to the effective surface passivation by dye molecules. We have recently shown that there was tremendous enhancement in the photon harvesting of DSSCs using NIR dyes when both of the FTO substrate and mesoporous TiO₂ were subjected to surface treatments using aqueous TiCl₄ forming compact TiO₂ layer. Using unsymmetrical squaraine dyes as a representative of NIR dyes, efforts have also been directed to investigate the implication of various compact metal oxides for their effectiveness towards surface passivation and implication of final device performance. Synergistic and panchromatic photon harvesting was also demonstrated utilizing our newly designed NIR dye (SQ-110) with complementary light harvesting commercial dye (D-35). Our results reveled that TiCl₄ treatment on both of the FTO and TiO₂ perform better as compared to other metal oxides under investigation. Optimization of surface passivation utilizing a dye cocktail of SQ-110 and D-35 indicated that a single layer of compact TiO₂ on FTO and a bilayer of compact TiO₂/MgO was optimum for surface passivation leading to PCE of 7.2% which was much higher as compared to the DSSCs utilizing single constituent dyes.