Three-Dimensionally Ordered Sub-Micron Structure Thin Films Fabrication And Their Optical Properties

Three-dimensionally ordered sub-micron structure thin film, thickness of which was in micron range, consisted of sub-micron units which were assem-bled into long distance like crystal structure. Due to the interactions between light and their periodic structure, these films can be used as photonic crystals to shield light and reinforce reflex. Because of that, recently, many researches were focused on their preparations and properties in nano-micron electronics, thermal electronics, biosensors and so on.This project aimed at discovery of 3D full photonic band gap materials through colloidal crystal template oriented method using a variety of infiltrated technologies. So, for the purpose of the project, some films'optical properties needed to be investigated.During the preparation procedure, firstly, as template bases of colloidal crystal, polystyrene and sub-micron polymethyl methacrylate spheres were synthesized by emulsifier-free polymerization. Results showed that polystyrene spheres had diameter of 380nm, while PMMA 250nm. And both of these partilces'deviations were less than 5%. Secondly,380 nm PS spheres were assembled into colloidal crystal film on FTO conductive slide by vertical deposition technology. The optimized experimental conditions were ethanol as dispersed phase,0.5% w.t. alcoholic solution and 30℃for growth temperature. Under those conditions, the prepared colloidal crystal films could be low ratio of defects, ordered structure and relatively high affinity for the slide, with thickness of 4μm. In spectrum tests, these films exhibited their photonic band gaps in 400～450 nm.In the next step, colloidal crystal templates were transformed into macroporous materials, including silica, alumina, nickel, silver and PANI, by sol-gel, electrodepostion and chemical synthesis methods. For the macroporous silica film, the reforce reflex and transmission attenuation ranges were around 450nm.After that, two-step template was used to fabricate sub-micron silver spheres array by electrodepositing silver in macroporous silica film. The silver particles obtained were monodispersed and arranged into ordered structure.