Preparation of paraboloid-like VO2@SiO2 nanostructured arrays for enhanced transmission

An uniform nanostructured array of VO2@SiO2 was grown via depositing VO2 film on SiO2 monolayer array. VO2 films were fabricated by rapid thermal annealing (RTA) of sputtered vanadium films, and SiO2 arrays with diameter of about 600 nm were formed using direct assembly at the air-water interface. Much interestingly, the surfaces of SiO2 nanospheres could be regarded as double-sided surfaces with paraboloid-like arrays which offered a gradual refractive index between air and the surface of SiO2. This SiO2 array was used as biomimetic antireflective structure (ARS) for enhanced transmission. In addition, with the change of oxygen flow rate, VO2@SiO2 array exhibited adjustable preferred orientation and more uniform grains compared with planar film. More importantly, VO2 film deposited on ARS array showed enhanced transmittance which would be important for future applications in smart windows. (C) 2015 Elsevier B.V. All rights reserved.