The band bending effect of LiI/NaI treated TiO2photoanodes on the performance of dye-sensitized solar cells

A new method has been developed for surface treatment of TiO(2)photoanodes with LiI/NaI to enhance the photocurrent and, subsequently, the performance efficiency of the fabricated dye-sensitized solar cells (DSSCs). Three different concentrations (0.1, 0.25, and 0.5 mmol%) of LiI and NaI solutions were used to investigate the effect of this surface treatment on the device performance of DSSCs. A positive shift in the energy level of TiO(2)has been experienced by surface treated devices, which is predominantly supported by the decrease inV(OC). Furthermore, the introduction of LiI/NaI onto the TiO(2)surface resulted in a reduction in the crystallite size, indicating an increase in the surface area which helps in more dye adsorption leading to higherJ(SC)values of the devices. Besides, modification of the conduction band energy level, it also allows a fast electron injection process by shifting the density of states. Thus, this approach offers a simple but efficient route to enhance the photocurrent and efficiency of DSSCs.