1. All-organic photovoltaic cells

1.1 Principle

An organic photovoltaic cell is a device comprising an organic active layer (based on polymers or small molecules) on the order of a hundred nm thick, inserted between two electrodes. One of these must be semi-transparent to allow light penetration. The active layer consists of two materials, one an electron acceptor and the other an electron donor (figure 1 ). The photovoltaic process is initiated by the absorption of a photon by the electron donor and/or electron acceptor, leading to the formation of an excited state corresponding to the creation of a bonded electron-hole pair called an exciton. Unlike inorganic cells, the electron-hole pair constituting this exciton is tightly bound,...