Lateral Photocurrent Scanning of Donor and Acceptor Polymers on Graphene Coated Substrates

Graphene provides a two-dimensional surface which can be utilized to interface with a variety of molecular species to modify opto-electronic processes. We use a scanning photocurrent technique to study the effect of graphene-coated anode substrates in semiconducting polymer device structures. The approach involves the measurement of the spatially varying photocurrent generated by an active semiconducting-polymer film sandwiched between a patterned substrate and a top electrode, where the narrow-incident light beam scans regions beyond the overlapping electrodes. We observe substantial difference in the spatial decay profile of the photocurrent upon introduction of graphene layers in the structure. Using simple circuit model and spreading impedance analysis we discuss the modification in carrier transport and recombination processes by underlying graphene layer in solar cell devices