In the present invention, there are provided self-assembled ZnO nanotips grown on relatively low temperatures on various substrates by metalorganic chemical vapor deposition (MOCVD). The ZnO nanotips are made at relatively low temperatures, giving ZnO a unique advantage over other wide bandgap semiconductors such as GaN and SiC. The nanotips have controlled uniform size, distribution and orientation. These ZnO nanotips are of single crystal quality, show n-type conductivity and have good optical properties. Selective growth of ZnO nanotips also has been realized on patterned (100) silicon on r-sapphire (SOS), and amorphous SiO₂ on r-sapphire substrates. Self-assembled ZnO nanotips can also be selectively grown on patterned layers or islands made of a semiconductor, an insulator or a metal deposited on R-plane (01 12) Al₂O₃ substrates as long as the ZnO grows in a columnar structure along the c-axis [0001] of ZnO on these materials. Such self-assembled ZnO nanotips and nanotip arrays are promising for applications in field emission displays and electron emission sources, photonic bandgap devices, near-field microscopy, UV optoelectronics, and bio-chemical sensors.

In the present invention, there are provided self-assembled ZnO nanotips grown on relatively low temperatures on various substrates by metalorganic chemical vapor deposition (MOCVD). The ZnO nanotips are made at relatively low temperatures, giving ZnO a unique advantage over other wide bandgap semiconductors such as GaN and SiC. The nanotips have controlled uniform size, distribution and orientation. These ZnO nanotips are of single crystal quality, show n-type conductivity and have good optical properties. Selective growth of ZnO nanotips also has been realized on patterned (100) silicon on r-sapphire (SOS), and amorphous SiO₂ on r-sapphire substrates. Self-assembled ZnO nanotips can also be selectively grown on patterned layers or islands made of a semiconductor, an insulator or a metal deposited on R-plane (01{overscore (12) Al₂O₃ substrates as long as the ZnO grows in a columnar stucture along the c-axis [0001] of ZnO on these materials. Such self-assembled ZnO nanotips and nanotip arrays are promising for applications in field emission displays and electron emission sources, photonic bandgap devices, near-field microscopy, UV optoelectronics, and bio-chemical sensors.

A method for preparing zinc oxide nanostructures using arc discharge is disclosed. The method comprises the provision of an anode and a cathode in an arc discharge chamber. Current is supplied to the anode and the cathode to establish an arc discharge between the cathode and the anode to vaporise the anode and produce zinc oxide nanostructures. Contemplated is the use of the zinc oxide nanostructures to produce components that have applications in, for example, optoelectronics, energy storage devices, field emission devices, and sensors such as UV photosensors, gas sensors and humidity sensors. Disclosed is a gas sensor and method for its production, where said method comprises the provision of a sensor substrate comprising a conducting thin film at least partially covering at least two regions on at least one surface of a sensor substrate material to define a gap in the conducting thin film, the application of a mixture of zinc oxide nanostructures and a non-ionic polymer to at least a portion of the gap i the conducting thin film to thereby bridge the gap. Optionally contemplated is a step of annealing the mixture of zinc oxide nanostructures and non-ionic polymer applied to said sensor substrate to produce the sensor component.

The invention relates to a method for producing zinc oxide nanoparticles having an average particle size in the range of from 3 to 50 nm. Said method is characterized by reacting in step a) one or more precursors for the nanoparticles in an alcohol to give the nanoparticles, b) terminating, once the absorption edge has achieved the desired value in the UV/VIS specter of the reaction solution, growth of the nanoparticles by adding at least one modifier which is a precursor for silica, optionally c) modifying the silica coat by adding at least one additional surface-modifying agent selected from the group comprising organofunctional silanes, quaternary ammonium compounds, phosphonates, phosphonium and sulfonoium compounds or mixtures thereof, and optionally d) removing the alcohol from step a) and replacing it by another organic solvent. The invention also relates to the nanoparticles so obtained and to their use for UV protection in polymers.

The invention relates to zinc oxide nanoparticles having an average particle size in the range from 3 to 50 nm, dispersed in an organic solvent, according to one or more of claims 1 to 6 , characterised in that in a step a) one or more precursors of the nanoparticles are converted into the nanoparticles in an alcohol, in a step b) the growth of the nanoparticles is terminated by addition of at least one modifier, which is a precursor of silica, when the absorption edge in the UV/VIS spectrum of the reaction solution has reached the desired value, in a step c) the silica coating is modified by addition of at least one further surface modifier selected from the group consisting of organofunctional silanes, quaternary ammonium compounds, phosphonates, phosphonium and sulfonium compounds or mixtures thereof, and optionally, in step d), the alcohol from step a) is removed and replaced by another organic solvent, to isolated nanoparticles, and to the use thereof for UV protection in polymers.

The disclosure relates to zinc oxide (ZnO) nanoparticle dispersions and to such dispersions having a defined color, and films obtained from such dispersions. The zinc oxide dispersions can be used as a UV-absorber, for catalytic applications, electronic applications, production of antifungal or antibacterial materials, sensors, actuators, photovoltaic devices, conductive coatings, among other applications.

The disclosure relates to zinc oxide (ZnO) nanoparticle dispersions and to such dispersions having a defined color, and films obtained from such dispersions. The zinc oxide dispersions can be used as a UV-absorber, for catalytic applications, electronic applications, production of antifungal or antibacterial materials, sensors, actuators, photovoltaic devices, conductive coatings, among other applications.

Devices and methods of fabrication of ZnO based single and multi-junction photovoltaic cells are disclosed. ZnO based single and multi-junction photovoltaic cells, and other optoelectronic devices include p-type, n-type, and undoped materials Of Zn_xA₁- _xO_yB_1-y. wherein the alloy composition A and B, expressed by x and y, respectively, varies between 0 and 1. Alloy element A is selected from related elements including Mg, Be, Ca, Sr, Cd, and In and alloy element B is selected from a related elements including Te and Se. The selection of A, B, x and y, allows tuning of the material's band gap. The band gap of the material may be selected to range between approximately 1.4 eV and approximately 6.0 eV. Zn_xA_1-xOyB_1-y based tunnel diodes may be formed and employed in Zn_xA_1-x O_yB _1-y based multi -junction photovoltaic devices. Zn_xA_1-xO_yB_1-y based single and multi-junction photovoltaic devices may also include transparent, conductive heterostructures and highly doped contacts to ZnO based substrates.