Organic electronics from perylene to organic photovoltaics: painting a brief history with a broad brush

The past ten years have witnessed the development of bulk-heterojunction (BHJ) solar cells, which have emerged as an attractive renewable energy source in response to rising energy costs and environmental pollution. In such a solar cell, charge transfer at the donor-acceptor interface is a crucial aspect that significantly affects overall device efficiency. Therefore, the choice of these two components and their design are important factors for the optimization of plastic solar cells (PSCs). This feature article correlates the performance of the device to the active layer composites, analyzing the motivations behind specific BHJ designs. Several low-bandgap polymers are described based on their different donor-acceptor units and their influence on both the optical absorption and the electrochemical properties. As for the accepting materials, we examine the effect of chemical functionalization in a series of fullerene derivatives, carbon nanotubes and non-fullerene based compounds on their performances in PSCs. The understanding of film-morphology control is also briefly discussed.