Figure 3: Schematic energy level diagram showing the HOMO level of the organic semiconductors used.

These values are obtained from cyclic voltammetry. Dotted and dashed lines are guides for the eyes for comparing the HOMO level of P3HT with DAEs in their closed form, and BTBT with DAEs in their open form. DAEs are highlighted in a rectangle and the arrows indicate the change of the energy level on irradiation with either ultraviolet or visible light.