Enhanced performance in organic photovoltaic cells with chemically modified indium-tin oxide anode electrode

Surface modification of indium tin oxide (ITO) coated substrates through the use of self-assembled monolayer (SAM) of molecules with permanent dipole moments has been used to control the anode work function and device performance in organic photovoltaic (PV) cells based on donor/accepter layer. The organic PV cells are fabricated, with the cell configuration of ITO/Zinc phthalocyanine (ZnPc) (40 nm)/fullerene (C₆₀) (40 nm)/Al with and without bathocuproine (BCP) (10 nm) in between C60 and Al. The cell performance under illumination with white Xe light illumination with intensity of 100 mW cm^-2 is measured. By the use of para-substituted benzenesulfonyl chlorides with different terminal of (H-), (Cl-), and phenylphosphoryl dichloride (-P) groups, the energy offset at the ITO/ZnPc interface is tuned widely depending upon the interface dipoles and thus the correlation between the change in the ITO work function and the performance of the PV cells by chemical modification is examined.