ZnO/graphene heterostructure nanohybrids for optoelectronics and sensors

The discovery of graphene has prompted an intensive exploration and research of heterostructure nanohybrids that integrate functionalities of semiconductor nanostructures with graphene's high charge carrier mobility, extraordinary mechanical strength, and flexibility for various applications. Among others, zinc oxide (ZnO) presents a promising candidate due to its unique physical properties including direct bandgap in ultraviolet spectrum, ferroelectricity, and hence piezoelectricity, moderate Debye length for electron depletion effect in ZnO nanostructures (quantum dots, nanowire, nanoparticles), etc. For ZnO/graphene heterostructure nanohybrids, the low thermal budget for growth of crystalline ZnO makes it possible for direct deposition of ZnO on graphene with controlled morphology and interface, enabling a large spectrum of devices including photodetectors, gas sensors, strain sensors, and self-power devices. In this Perspective, we discuss the recent progress made in ZnO/graphene heterostructure nanohybrids through understanding and engineering the ZnO/graphene interface to realize high performance. An overview of the remaining issues and future perspectives toward commercialization of the ZnO/graphene heterostructure nanohybrids will also be provided.