Optimization of electrolyte co-additives, TiO₂ thickness, and dye concentration for the enhanced performance of dye-sensitized solar cells

The performance of dye-sensitized solar cells (DSSC) primarily depends upon many factors, such as the thickness of the semiconductor layer at the working electrode, dye/sensitizer concentration, and electrolyte. A methodical study is required in one place to deliberate the impact of all these factors on DSSC performance for better understanding and further advancement of the technology. This work emphasizes optimizing the absorption layer, specifically investigating the relationship between the thickness of the TiO₂ layer and the concentration of N719 dye. The objective is to elucidate the interconnected effects of these parameters on the overall performance of the device. Additionally, the optimization of electrolyte composition was done with varying concentrations of additives, such as iodine, 4-tert-butyl-pyridine (TBP), guanidinium thiocyanate (GuNCS), and 1-butyl-3-methylimidazolium iodide (BMII) of electrolyte. Initially, the devices with varying TiO₂ absorption layers were fabricated. The efficiency, fill factor (FF), open-circuit voltage (V_OC), and short-circuit current (I_SC) of devices were studied. The drop in open-circuit voltage (V_OC) was noticed with the increase in thickness of the TiO₂ layer. The highest efficiency was observed at 7.17% with the device fabricated using 6 absorption layer (17.46 μm) of TiO₂, 0.7 mM concentration of N719 dye, and 0.03-M iodine, 0.1-M GuNCS, 0.5-M TBP, and 0.6-M BMII in electrolyte. Future developments in this research could focus on further fine-tuning these parameters for improved efficiency and exploring additional innovations in DSSC technology, ultimately contributing to the advancement of sustainable and efficient solar energy conversion systems.