Here we propose that hybrid heterostructures, composed of inorganic nanostructures grown directly on 2-dimentional layered materials such as graphene, are the most promising material system for flexible device applications. In particular, the hybrid heterostructures composed of high-quality GaN thin films or nanostructures grown directly on graphene offer a novel material system for transferable and/or flexible optoelectronics. The inorganic nanostructures in the hybrid nanomaterials exhibit excellent electrical and optical characteristics, including high carrier mobility, radiative recombination rate, and long-term stability. Meanwhile, for the flexible devices based on the hybrid structures, the graphene layers, which have excellent electrical and thermal conductivity, high mechanical strength and elasticity, and/or optical transparency, act as a novel substrate offering new functionalities such as transferability or flexibility. Here I will present on position- and morphology-controlled growths of ZnO nanostructures using catalyst-free metal-organic vapor phase epitaxy and describe the methods to fabricate flexible LEDs based on nitride coated ZnO nanostructures grown on graphene, which exhibit strong light emission after the transfer onto foreign substrates, such as metal, glass, and plastic. We believe that our unique technology to make hybrid nanomaterials will make paradigm shift from rigid to flexible and planar to three-dimensional inorganic semiconductor structures and devices.
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