Electrodes and interface layers
Organic solar cells : materials, nano-morphology and device engineering

To begin on this point, we can take up the general schematic of a volume heterojunction cell whose active layer consists of P3HT and PC₆₁BM (Figure 13a) and the corresponding energy levels (Figure 13b). It should be noted that these energy levels are sometimes extracted using different techniques and they are given for information only.

The structure shown in figure 13 is called a direct structure because light enters the active layer through the electrode, which collects the holes. Once the free charges are formed, the electron is transported...