Squaraine dyes gained significant attention as dye-sensitized solar cell (DSSCs) materials. In present study; we have studied the important parameters which influence the performance of DSSCs by considering the TiO 2 clusters as acceptor material. We have investigated the structural, electro-optical and charge transport properties of six indole-based squaraine dyes (Cis-SQ1-SQ3 and Trans-SQ1-SQ3). The ground state geometries have been optimized by using density functional theory (DFT) then excitation energies and oscillator strengths were computed by time-dependent DFT in solvent. We shed light on the frontier molecular orbitals (highest occupied and lowest unoccupied molecular orbitals), electron injection (ΔG inject), relative electron injection (ΔG r inject), electronic coupling constants (|V RP |), light harvesting efficiencies (LHE), short-circuit current density (J sc) and open-circuit voltage (V oc). The ΔG inject , ΔG r inject and |V RP | of six sensitizers have been compared with some previously studied sensitizers. The effect of donor (-OCH 3) and acceptor (-COOH) groups has been investigated and discussed on said properties of interests. The Cis/Trans geometric effect has been studied on the structural parameters, absorption wavelengths, ΔG inject , |V RP |, LHE, V oc and factors affecting the J sc . It has been discussed that which geometric isomer would be more favorable to enhance the performance of DSSCs.