One-dimensional (1D) nanostructure materials have been extensively studied because of their potential applications in nanoelectronic devices

such as field-effect transistors

single-electron transistors

photodiodes

and chemical sensors. Among these 1D semiconducting nanomaterials

there has been considerable attention focused on low-dimensional ZnO nanostructures on account of its many interesting properties

such as a wide band gap (3.37 eV)

a large exciton binding energy (60 meV)

excellent chemical and thermal stability

transparency

biocompatibility

and wide electrical conductivity range. ZnO has probably the richest family of nanostructures among all materials

which exhibits the most splendid and abundant configurations of nanostructures. Single crystal ZnO nanorod is of particular interest due to its potential applications in an emerging area of nanotechnology. Up to now

numerous experimental attempts have been reported to fabricate ZnO nanorod materials

such as molecular beam epitaxy (MBE)

pulsed laser deposition (PLD)

sputtering

electrochemical deposition

vapor phase transport (VPT)

chemical vapor deposition (CVD)

thermal evaporation and so on. However

these methods usually require expensive equipment and high operation temperature

which are not compatible with organic substrates for applications in flexible and wearable electronics. Compared with the methods mentioned above

the hydrothermal method as a high performance growth technique for ZnO nanorod/nanowire is especially attractive due to its obvious advantages of low-cost

low temperature operation and environmental friendliness. Moreover

this technique can be carried out at low temperatures and large scale on all kinds of substrates

regardless of whether it is crystalline or amorphous. The synthesis and properties of Co-doped ZnO nanomaterials have been reported

most attention was paid to their its magnetic properties

but little report is focused on the optical properties of the nanomaterials.In this paper

Co-doped ZnO nanorod arrays were successfully prepared on quartz substrate by hydrothermal method at temperature of 95 ℃. The crystal structure

morphology

and optical properties were characte-rized with X-ray diffraction (XRD)

scanning electron microscopy (SEM)

photoluminescence (PL) and reflectance analytic approaches

respectively. XRD results illustrated that Co-doped ZnO nanorod arrays with wurtzite structure are grown densely and vertically on the substrates. SEM images showed that the Co-doped ZnO nanorod arrays have smaller diameter than pure ZnO nanorod arrays. The high-intensity near-band edge ultraviolet (UV) emission peak was observed in room temperature photoluminescence (PL) spectra for the ZnO nanorod arrays on all samples

yet the usually observed defect related to deep level emission is very weak

indicating high optical quality ZnO nanorod arrays can be achieved via this low-temperature easy-process chemical approach. Moreover

the small shift in the UV emission indicated that Co

2+

ions are substituted for Zn

2+

in ZnO nanorods.