Template-free TiO₂ photoanodes for dye-sensitized solar cell via modified chemical route

Surfactant and template-free Titanium dioxide (TiO₂) spheres have been deposited via ultrasonic rinsing assisted modified successive ionic layer adsorption and reaction (M-SILAR) method. The effect of M-SILAR cycle variation on the growth of TiO₂ films and power conversion efficiency (PCE) of dye-sensitized solar cells (DSSCs) has been reported. Also, the significant influence of the dye adsorption time of photoelectrodes on the overall PCE of TiO₂ based DSSCs has been investigated systematically. The SEM images reveal that the TiO₂ microspheres are made up of densely packed and interconnected nanospheres. After dye loading maximum absorption peak around 500nm is seen with broader coverage in the visible region of the solar spectrum. The excess amount of dye for dye loading time 15h did not contribute to current and is suspected to be present either in multilayers or physisorbed on the surface of TiO₂. The DSSC prepared using photoelectrode TO₁₂₅ and dye loading time of 12h exhibited the highest power conversion efficiency (PCE) of 1.16% with short-circuit current density (J_sc) of 8.17mA/cm², open circuit voltage (V_oc) of 0.42V and fill factor of 0.34. The PCE is attributed to the large molecular interconnected TiO₂ spheres diffusing visible light to enhance the light absorption. Also, it possesses relatively superior 3-D microsphere like structure and thus provides the effective pathway to the photogenerated electrons with low recombination rate, leading to attaining the high PCE.