The enhanced light scattering effect of the submicron aggregates can affect the characteristics of Dye Solar Cell (DSC) namely short circuit current (sc) open circuit voltage (Voc) and fill factor (FF). This paper presents the simulation study of the TiO 2 nanoparticles, aggregates and composite TiO 2 for dye solar cell. As the input for simulation in ATHENA, the process simulator, modeling structure and parameters were captured from the experimental works. ATLAS, the device simulator, compiled and simulated the performance of DSC. The efficiency of the simulated dye solar cell was found to be comparable to the closest physical dye solar cell by others. TiO 2 composite of 20 nanoparticles and 80 aggregates was proven to have the highest efficiency due to maximum scattering by micron-sized aggregates and better connectivity by the presence of nanoparticles in between the voids. It had improvement of 28.539 compared to the simulated DSC utilizing TiO 2 nanoparticles. © 2018 IEEE.