Triggered by the outstanding worldwide growth of the photovoltaic market as well as by the need of alternative energy sources in future, organic solar cells are the object of vivid interest from both industrial and academic sides. Based on the semiconducting properties of organic conjugated macromolecules, these devices possess the potential to be processed by common printing techniques. Besides being easily upscalable on rigid as well as on flexible substrates, they open the route of roll-to-roll production of low cost renewable energy sources. Today, up to 5% power conversion efficiencies are reported in this kind of plastic solar cells.