A series of Carbazole based Donor-Acceptor-pi Bridge-Acceptor (D-A-pi-A) dyes that contain different alkyl side chains with different lengths have been synthesized. Electrochemical and optical properties of these dyes were demonstrated by impedance spectroscopy, cyclic voltammetry, UV-Vis absorption and fluorescence spectroscopy, respectively. Herein, we report PV performance of dye-sensitized solar cells depending on the molecular structure of the dyes in terms of comparison of alkyl chain length on the carbazole moiety using an ionic liquid based electrolyte under standard AM 1.5 illumination. The results demonstrate that the dye containing alkyl chain with 4C atoms exhibited better performance compared to alkyl chains with 2C, 6C and 12C atoms. (C) 2016 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.