Organic photovoltaics

In the last ten years, the highest efficiency obtained from organic photovoltaics (OPVs), such as bulk heterojunction polymer: fullerene solar cells, has risen from 2.5 to 11 %. This rapid progress suggests that the commercialization of OPVs should be realized soon if we can solve some technical issues. The advances in the development of OPVs can be attributed to four fronts: (i) a better understanding of the mechanism of photon-to-electron conversion; (ii) new materials with tailored energy levels and solubility; (iii) new processing approaches to induce optimal microstructures in the active layer; and (iv) new device architectures with novel interfacial layers. Herein, we review the materials, the microstructures of the active layers, the device structures, the interfacial layers that have been developed recently for OPVs, and provide future perspectives for this promising technology.