Invited Paper SE+PS-ThM5
Innovative PVD Strategies for the Design of Novel TiO₂-based Photoanode Utilized in Dye-sensitized Solar Cells

Thursday, October 24, 2019, 9:20 am, Room A215

In view of the environmental challenges that our societies face, it is accepted that the development of alternative and renewable energy sources is a must. If solar energy is recognized as one of the most promising, it is still necessary to improve the solar cell technologies. Among others, Dye Sensitized Solar Cells (DSSC) are often seen as one of the ideal technological approach if several issues are fixed. One of the key problem associated with the implementation of these cells if related to the photoanode performances, specifically in terms of charge transport. Indeed, the standard photoanode based on TiO powder often exhibit a too high electrical resistivity associated with the intrinsic properties of the material.

During the past years, we have worked on the development of alternatives TiO₂-basedmaterial in order to solve the encountered problems. More precisely we have studied the growth of (N-doped) nano-sculpted TiO₂ films by using reactive magnetron sputtering in glancing angle deposition. Concerning the doping, co-reactive deposition as well as ion implantation have been evaluated. All samples have been thoroughly characterized by state-of-the-art techniques and, for most of them, tested in DSSCs.

The results demonstrate that our approach is versatile allowing to control the morphology of the TiO₂ films at the nanoscale, and therefore to tune the capability of the material to adsorb the active dye. Specifically, we showed that a combination of our films with conventional TiO₂ nanoparticles could be a promising approach. In addition, we also demonstrate that the phase constitution of the nano-sculpted films can be optimized in the form of a core-shell anatase/rutile structure in order to improve the charge transport. On the other hand, the study of the N doping reveals that it is possible to finely control the position of the N atom (substitutional vs intersticial) as a function of the experimental parameters. In this context, we demonstrated that the O vacancies density favor the substitutional doping. Finally, w e even showed that p type TiO₂:N films presenting good electrical and optical properties can be synthesized. This last result is of particular interest for the development of “full TiO₂” tandem DSSCs.