Large area hybrid/organic solar cell, toward nanocarbon materials implementation

During the PhD, most of the efforts have been spent to study and to optimize the performance of third generation solar cells, such as dye sensitized solar cells (DSSCs) and hybrid organic/inorganic Perovskite solar cells (PSCs). In particular, the attention has been focused on optimization of the fabrication process and on the implementation of carbon based materials to optimize different aspects of the cell. An original technique, the Vacuum-vapor assisted solution processing (V-VASP) was designed and developed to deposit glassy perovskite films without an inert atmosphere, therefore with lower fabrication costs with respect to other deposition techniques. Both small (0.1 cm2) devices and large area modules (8.8 cm2) were fabricated with V-VASP showing good stability in air and humidity conditions without encapsulation. Moreover, the aforementioned technique was used to embed the carbon nanostructures (CNSs) such as single-wall carbon nanotubes (SWCNTs) and graphene nanoplatelets (GNPs) as conductive nanofillers in the P3HT hole transporting layer with the purpose to extend the life time and the power conversion efficiency (PCE) of PSCs. The acquire knowledge on graphene was exploited in DSSC technology to develop large area (43.3cm2) module replacing the conventional expensive platinum, necessary to catalyse the redox reaction of liquid electrolyte mediator at the counter electrode (CE). A graphene-based ink, produced by liquid phase exfoliation of graphite, was sprayed onto a transparent conductive oxide substrate to realize a large area, semi-transparent and cheaper CE. As a follow up of this activity, a tandem configuration was designed for large area DSSC module proving a PCE improvement respect to the single structure as well. Beyond photovoltaic applications, perovskite materials have the required properties to become winning materials for many optoelectronic devices. In this work, as a side activity, the perovskite was also used to fabricate a solution process photodiode. The good values of responsivity, detectivity and bandwidth measured, demonstrated the excellent versatility of perovskites and will pave the way for future implementation in low cost and high performance optoelectronics applications.