Electric-field assisted spray technique for controlled pore filling of nanostructured films: device applications

A novel pore-filling system was prepared using spray as the key-technique, for solar cells and various other applications. High performance in perovskite, dye-sensitized and eta cells is often achieved using metal oxide layers or their mesoporous analogues. One dimensional scaffold materials such as nanorods or nanotubes are also employed in order to improve charge collection. Herein, we introduce a method to more efficiently fill the pores in the most common nanostructure architecture namely mesoporous, nanorods or nanotubes. The method employs the use of spray technique with applied DC voltage (through two different voltage supplies) as the cost-effective technology for time efficient pore filling. SnS nanoparticles and N719 dye have been pore-filled onto a previously deposited ZnO nanorods and mesoporous TiO2 film, respectively, using the novel setup. Scanning electron microscopy images revealed an improved pore-filling, the complementary enhancement of ~ 24% in the DSSC efficiency and ~ 16% and 7% in terms of current density and fill factor, respectively has been found in comparison to the reference standard device. It is attributed to an increase in the concentration of dye molecules into the pores of TiO2 nanostructures due to better dye loading and hence observed an improvement in light absorption, electron transportation and charge collection. This pioneer pore filling technique exponentially reduced the dye loading time duration from overnight immersion of photo anodes in dye solution to 15–20 min.