Tailoring the structure of nanomaterials formed by light-induced synthesis

A light is an energy portion that plays a very important role in nature. A light particle or photon can be absorbed, scattered or reflected. In some cases, light can greatly influence the formation of a crystal and guide its growth into hierarchical nano or microstructure. This work explores the light-induced synthesis of nanomaterials (Au, Ag, CdS, ZnO) and light-induced polymer nanostructuration. This way of synthesizing nanomaterials is compared to other known routes. The main advantage of the synthesis method presented here is its ability to be used for water-based reactions at room temperature. This method can be applied to most water-based syntheses. In this work, results have been compared with template-assisted synthesis for Ag, CdS, and Au. The ZnO light-induced synthesis was used and compared to the hydrothermal ZnO synthesis method. First, the effect of light over the synthesis of ZnO, Ag and semiconducting polymer P3HT and its mixture with PC[70]BM is demonstrated. The main results from this work include that computer-assisted light control systems might provide a shape-selective synthesis of nano/microstructures at room temperature. Also, light-assisted synthesis provides crystal growth without the use of a capping agent or polymer template. Morphology control of polymer-monomer mixture is demonstrated which was achieved using Red and Blue LEDs. It was found that Red light increased the diameter of the voids in polymer films while on the contrary blue light decreased it. For ease of comparison, the mixed solvent study was carried out on the same polymers. The change of electrostatic interaction reflected on the change of the morphology of the polymer films. Templated Ag nanostructure synthesis was also performed showing different results when in the presence of light structures are more uniform and have VII higher surface area. The work also demonstrates template-assisted synthesis of CdS quantum dots. The use of PPI type dendrimer showed that self-assembly of CdS quantum dots in a nanofiber is achievable at room temperature. Au nanostructures were synthesized using another organic template oleic acid. Synthesis results showed unusual Au nanoparticle morphologies. Finally, low-power light was shown to influence the nanostructure synthesis and structuration at room temperature. The main effect was the change in the shape due to the vibration of water molecules. Water absorbs light mostly on the infrared region and very little in the visible range. Due to the low absorbance of visible light by water, it required longer time intervals in order to achieve the changes in morphology of the ZnO or Ag structures. Reaction time has been proven to be an important factor in lightmatter interaction. In this work, AFM, SEM, UV-vis, PL, NMR and TEM were used for the characterisation of materials synthesized at room temperature