From dye sensitized to perovskite solar cells: processes and materials for the forthcoming era of photovoltaic technology

Abstract

In the context of the serious environmental issues, that Earth is facing, among which atmospheric CO2 increase is a crucial one, implementation of clean technologies is mandatory. The present PhD thesis concerns the study of two new third-generation PV technologies: Dye Sensitized Solar Cells (DSSCs) and Perovskite Solar Cells (PSCs). A typical DSSC is a low cost device of easy fabrication, widely investigated for indoor application, where the dye is used to collect light. In the former study, the research focused on natural dye extraction and the electrolyte optimization in the cell in accordance with a natural pigment. We realized and presented, for the first time in literature, a natural dye-based solar module of 8.7 cm2 with 1 % of power conversion efficiency (PCE), stable for 1000 hours. A PSC is a kind of solar cell that includes a perovskite-structured compound, most commonly a hybrid organic-inorganic lead halide-based material, as the light-harvesting active layer. Unlike DSSC, in PSC the liquid electrolyte has been replaced by a solid-state hole transport material (HTM), and since 2009 the run for boosting the PCE of PSC has started. In the latter study, the research focuses therefore on the optimization of an easy and low-cost PSC structure with a carbon layer replacing the HTM and gold usually used in a conventional high efficiency PSC. Despite all controversial studies on how moisture badly affects perovskite, it has been observed a beneficial water effect on the perovskite growth and formation in a 2-step deposition, which enhances the PCE of 12 % with respect to the non-treated cell.