Control of charge separation by electric field manipulation in polymer-oxide hybrid organic photovoltaic bilayer devices

Hybrid polymer/oxide organic photovoltaic (h-OPV) devices have the potential to replace the organic acceptor component with an inorganic, nano-structured oxide. This approach leverages the positive attributes of inorganic materials while maintaining the potential processing advantages of organic electronics. By manipulating the carrier concentration of the oxide acceptor layer in bilayer h-OPV devices, we demonstrate control of the electric field at the planar donor-acceptor interface. The effects of the electric field can be observed in both the J _SC and the fill factor of the h-OPV devices. Furthermore, interfacial layers of TiOx are used on ZnO to prevent recombination of geminate electron-hole pairs. It is shown that interfacial TiO _x successfully inhibits recombination only when the electric field is strong enough to sufficiently transfer charges to the ZnO layer. If the interfacial electric field is insufficient, then the TiO _x instead serves to enhance recombination at the donor-acceptor interface.