Room temperature deposition of ultra sharp ZnO nanospike arrays on metallic, non-metallic and flexible carbon fabrics: Efficient field emitters

Synthesis of large scale arrays of ZnO nanospikes with ultra sharp tips (<10 nm) is achieved through a newly developed chemical methodology. This is the first room temperature report of growing 1D ZnO nanostructures on heterogeneous substrates. The deposition was performed on various substrates including planar (silicon, conducting glass, copper foil), cylindrical (metallic wire) and flexible carbon cloth. The deposition technique is a universal one in the sense that it is compatible with complex shape substrates as well as independent of the nature of the substrate material. The arrangement of the nanospikes over the substrates may be altered from a dense array to a distributed flower like structure depending on the substrate pretreatment. The nanospikes exhibit excellent field emission performance caused by their emission beneficial geometry with turn-on and threshold fields showing significant dependence on the growth substrate. The turn-on field and the field enhancement factor are found to be the lowest and the highest for the ZnO deposited on carbon cloth substrates having values of 0.7 V μm−1 and 2.6 × 104 respectively. These are the best values compared to all reported chemically synthesized ZnO nanostructures and comparable to the best results of vapor phase deposited ZnO nanostructures. The synthesis method reported here will open-up a new door for future development of nano-based flexible electronics.