Organic solar cells: Principles, materials, and working mechanism

The most significant advances in the development of organic solar cells (OSCs) along the last three decades are presented. The key aspects of OSCs such as the photovoltaic principles regarding the mechanism for the generation of the exciton and the transport of the carriers to the respective electrodes are explained. Furthermore, the most common organic materials used as the photoactive layer are discussed, highlighting those that have been more successful and extensively studied in the literature such as donor polymers (PM6), fullerene acceptor ([60]PCBM), or small-molecule acceptors (ITIC and Y6 families). The evolution of the efficiency of OSCs with the introduction of these innovative materials has also been included. Other critical issue for a better understanding of OSCs, namely the control of the morphology in the device fabrication is also considered by gathering the most important advances on this critical photovoltaic parameter. In addition, the review presents some technology metrics regarding the cost of the energy, the durability of the devices, or the environmental impact that are critical for the coming commercialization of this advanced technology.