Boosting the Performance of Next- Generation Organic Solar Cells

One of humanity´s most urgent challenges in this century is reducing net carbon emissions to mitigate the effects of global warming. Photovoltaic technologies, such as crystalline silicon panels, have become widespread over the past twenty years due to reduced production costs and improved efficiencies, paving the way for green energy production. However, their rigidity and fixed bandgap, among other limitations, restricts their versatility and broader applicability.
Organic solar cells (OSCs) represent one of the most promising emerging photovoltaic technologies, offering a highly integrable and flexible alternative to silicon. Even if the efficiencies are not yet in pair with the inorganic counterparts, values as high as 20 % have been already reported. This remarkable progress has been largely driven by the development of a special class of electron-accepting small molecules, commonly referred to as non-fullerene acceptors (NFAs). Despite this advancement, the performance metrics remain below the theoretical limit. Furthermore, a comprehensive understanding of the morphology of OSC with NFAs, and their compatibility with transport layers is still lacking. This thesis addresses these challenges and proposes novel materials and fabrication strategies to make more efficient and stable devices. In chapters 2 and 3, we investigate the effect of processing conditions (e.g. post-annealing, additives) on the active layer optical and structural properties. In chapter 4,5 and 6 we focus on the engineering of several transport layers grown from solution and atomic layer deposition.