Incorporation of a Metal Oxide Interlayer using a Virus-Templated Assembly for Synthesis of Graphene-Electrode-Based Organic Photovoltaics

Transition metal oxide (TMO) thin films have been exploited as interlayers for charge extraction between electrodes and active layers in organic photovoltaic (OPV) devices. Additionally, graphene-electrode-based OPVs have received considerable attention as a means to enhance device stability. However, the film deposition process of a TMO thin-film layer onto the graphene electrode is highly restricted owing to the hydrophobic nature of the graphene surface; thus, the preparation of the device should rely on a vacuum process that is incompatible with solution processing. In this study, we present a novel means for creating a thin tungsten oxide (WO₃) interlayer on a graphene electrode by employing an engineered biotemplate of M13 viruses, whereby nondestructive functionalization of the graphene and uniform synthesis of a WO₃ thin interlayer are concurrently achieved. As a result, the incorporated viruslated WO₃ interlayer exhibited solar-conversion efficiency that was 20% higher than that of conventional OPVs based on the use of a (3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) interlayer. Notably, bilayer-structured OPVs with synergistically integrated WO₃/PEDOT:PSS achieved >60% enhancement in device performance. Virus scan: The synthesis and incorporation of a WO₃ interlayer into graphene-electrode-based organic photovoltaic (OPV) devices is developed by using an engineered biotemplate of M13 viruses. Owing to uniform deposition of the WO₃ layer and maintenance of the electrical properties of the graphene electrode, a remarkable increase in the photoconversion efficiency (>20%) relative to that of conventional OPVs can be obtained.