Development of novel two-dimensional materials for energy conversion applications

In the increasing energy demand scenario, the development of renewable technologies is considered the key solution to fulfil the energy request. The conversion of light energy in electricity and chemical fuels through photovoltaic (PV) and photoelectrochemical (PEC) cells represents a powerful strategy for sustainable fuel and chemical generation. In particular, aqueous PEC cells and perovskite solar cells (PSCs) represent emerging energy conversion technologies. To provide an eco-friendly footprint, these new systems must be realized using novel earth-abundant cheap and environmentally friendly materials. In this context, two-dimensional (2D) materials are attracting utmost interest for their unique and tunable optoelectronic properties. In this frame, the aim of my research work is the synthesis and characterization of solution-processed 2D materials, including graphene, transition metal dichalcogenides (TMDs) and group-III and group-IV metal monochalcogenides (MMCs). In particular, thanks to their adjustable band gap, high carrier mobility, large surface-to-volume ratio, I firstly studied in this thesis the GaSe, GaS, InSe and GeSe nanoflakes, produced in form of inks, as potential photocatalyst. The PEC properties of these materials were exploited to perform solar water splitting reactions i.e.: hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), as aiming for the design of PEC-type photodetectors operating in aqueous media. Furthermore, I focused on the incorporation of 2D materials in PSCs technology. In this context I developed a graphene-based electrically conductive pastes for the fabrication of noble metal-free PSCs, the so-called carbon perovskite solar cells (C-PSCs). Lastly, during my period abroad at École Politechnique Fédérale Lausanne (Lausanne, Switzerland) under the supervision of Prof. M. Graetzel, I worked on a novel strategy to improve the performances and stability of PSCs by incorporating solution-processed MoS2 nanoflakes into perovskite photoactive layers.