Squaraine dyes (SQ) have acquired sufficiently great attention as dye-sensitized solar cell (DSSCs) materials. In the present study, we have synthesized and characterized of two novel symmetrical sensitizers dyes for dye-sensitized solar cells which contain electron withdrawing (−COOH) group with long alkyl ester chain (SQ1) and another without encoring group (SQ2). We have investigated the structural, electronic, photo-electrochemical, and charge transport properties of two SQ1& SQ2 indole-based squaraine dyes. The ground state geometry has been computed by applying density functional theory (DFT). The excitation energy and the oscillator strength were calculated by using time-dependent (DFT-TD) at DFT/B3LYP/6-31G** level of theory. We have focused and study on the frontier molecular orbitals (HOMO and LUMO), electron injection (ΔG inject ), light harvesting efficiency (LHE), open-circuit voltage (Voc), relative electron injection (ΔGr inject ), and short-circuit current density (Jsc). The effect of-COOH as (acceptor) and -OCH3 (donor) groups on SQ1 and SQ2 were investigated. The factors affecting, ΔG inject , LHE, Voc and Jsc revealed that SQ1 would be more favourable to enhance the performance of DSSCs. The theoretical calculations and absorbance results show that the electron density of LUMO of SQ1 is delocalized in the whole chromophore, leading to strong electronic coupling between SQ1 and TiO2 surface. So, the SQ1 sensitized solar cells exhibit better photovoltaic performance.