Five new metal free organic dyes festooned with fluorene and fused thiazine structural units such as FPAA1, FPAA2 and FPTAA1–FPTAA3 have been synthesized by adopting multistep synthetic strategy and investigated nanocrystalline TiO₂ based dye-sensitized solar cell performance by utilizing the same as sensitizers. Further, electrochemical, photophysical, and computational studies have been explored. Computational studies have been carried out to determine the electronic distribution within the molecules. Of the devices fabricated, the ones incorporated with cyanoacrylic acid acceptor exhibit greater power conversion efficiencies along with superior electron life time, short-circuit current and open-circuit voltage than the others integrated with (4-oxo-2-thioxothiazolidin-3-yl)acetic acid acceptor. Among them, the dye FPAA1 possessing device exhibited highest PCE of 7.54% besides open circuit voltage (V_OC) of 751 mV, short circuit current density (J_SC) of 15.65 mA cm⁻², and fill factor (ff) of 0.60.