Spongy TiO2 layers deposited by gig-lox sputtering processes: Contact angle measurements.

The use of nanostructured materials is increasingly widespread thanks to their particular properties that can improve the performance of devices in various scientific applications. One of them is in the architecture of perovskite solar cells characterized by high photoconversion efficiency values that make them able to compete with silicon solar cells. In this framework, we deposited TiO 2 sponges by reactive sputtering based on a grazing-incidence geometry combined with the local oxidation of species. The deposited material gains 50% porosity in volume through depths of hundreds of nanometers and consists of a forest of uniform rods separated by mesopores (pipelines) arising from the grazing geometry. Many previous studies showed how TiO 2 can improve the efficiency of perovskite solar cells. In this article, we investigated the change of the wettability values of the TiO 2 samples before and after a postdeposition thermal annealing treatment. For comparison, the influence of the annealing on the wettability of the glass substrate is also reported. [ABSTRACT FROM AUTHOR]