Advanced materials for Building-Integrated Photovoltaics: implementation of lanthanide complexes and organic chromophores in Luminescent Solar Concentrators

The integration of photovoltaic devices into the built environment via Building-Integrated Photovoltaics (BIPVs) is a promising approach to boost the energy efficiency of heavily urbanized areas. This thesis focuses on the design and characterization of innovative materials for Luminescent Solar Concentrators (LSCs), an emergent BIPV technology enabling energy-producing, transparent building elements such as photovoltaic windows. These devices exploit luminescent chemical species (luminophores) as their core component, which are embedded in a transparent material. The LSCs are coupled to photovoltaic cells that convert the luminophores’ emitted light into electricity. The thesis work evidences how different luminophores can be designed to yield materials and devices with application-tailored characteristics. In a first study, the development of highly transparent and colourless LSCs based on UV-absorbing, bright lanthanide complexes is described. The interesting UV-blocking properties of these materials are further exploited to design large area, visible-blind UV photodetectors. In a second LSC study, a series of strongly fluorescent oligothiophenes with enhanced Stokes shift is used to realized high-performing, coloured LSCs. Throughout the discussion, the existing correlation between the photophysical properties of the luminophores and the final electrical performances of the devices is highlighted. An investigation into a different BIPV approach than LSCs is also reported, as the development of a predictive model for the electrical behaviour of coloured PV modules. The effects of different colouring technologies on the electrical output and aesthetic properties of a silicon solar cell are simulated through the model, and validated with experimental data collected on a coloured PV stack prototype.