High quality graphene-semiconducting oxide heterostructure for inverted organic photovoltaics

In this work, we demonstrate damage-free direct growth of high-quality semiconducting ZnO thin films on thermal chemical vapor deposition (CVD)-grown graphene transferred onto a plastic substrate. A mist pyrolysis CVD (MPCVD) method based on a non-vacuum process at a low growth temperature of 160 °C is introduced for the successful direct growth of ZnO on graphene without any additional treatments or processes. ZnO thin films that did not exhibit damage to the structural and electrical properties of graphene were successfully grown on graphene. The MPCVD-grown ZnO thin films revealed more uniform surface morphology and better structural property than ZnO thin films deposited using sol-gel and sputtering. Using the ZnO/graphene heterostructure, we fabricated bulk heterojunction inverted organic photovoltaics with a power conversion efficiency of 1.55%.