*3.1.1 The open circuit voltage VOC*

The open circuit voltage is the electrical potential between anode and cathode of an OPVD when illuminated and the circuit id left open. This means that no electrical current passes between the electrodes. Chemically the VOC is related to the energetic difference between the LUMO of the acceptor and the HOMO of the

#### **Figure 7.**

*J/V-diagram with the graphical representation of the form factor ff as relation between the light blue and violet areas.*

donor material. The larger the difference between both orbitals the higher is the voltage that can be achieved in the solar cell. In **Figure 7** you can see that VOC can be determined graphically as the point where the curve passes through the x-ax of the diagram as here the current displayed on the y-ax is zero.
