Light responsive active plasmonic surfaces
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Kemian tekniikan korkeakoulu |
Master's thesis
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CHEM3025
Language
en
Pages
92+8
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Abstract
The fascination with understanding light started in Greek ancient times. Light plays a vital role in how we perceive the world, which was the main reason behind studying it initially. However, the recent progress and development in technology allowed to harness light to design new applications and materials or enhance existing ones in a wide range of fields from astronomy to nanotechnology. Plasmonic surfaces are a prime example of that. Plasmonic surfaces exhibit unique properties that are traditionally difficult to be achieved in conventional materials, such as a high refractive index, quality factor and resonant absorbance. However, the high cost and the complexity of fabrication have limited plasmonic surfaces and materials. Thus, a system of active plasmonic surfaces is designed here to dynamically tune light for colouration. Initially, this work investigated an existing layer-by-layer (LBL) dip-coating system of polyelectrolytes (PEs) on a thin film of Au with silver nanocubes (AgNCs) used as plasmonic nanoantennas. Excellent colour tuning in the visible spectra region from green to red with good chromaticity was obtained by controlling the number of PEs layers. Moreover, resonant absorption greater than 90% was achieved with a quality factor up to ~ 16.7. Then, the LBL plasmonic surfaces were modified with a photoactive molecule (disperse red 1) to modulate light dynamically. The designed photoactive plasmonics surfaces were exposed to linearly and circularly polarized light for different time durations to tune their properties. Colour tuning in the visible region was possible within a wavelength range of ~ 112 nm. Additionally, the plasmonic sensitivity of the samples was estimated before and after exposure. Overall, the system exhibited an increase in the refractive index and sensitivity with the increase of irradiation time as well as encouraging values of the quality factor and the figure of merit. It is anticipated that the methodology developed in this thesis will advance the development of active plasmonic surfaces that are used for colouration and sensing due to its simplicity, efficiency and low cost compared to current techniques.Description
Supervisor
Elbahri, MadyThesis advisor
Kuzyk, AntonManuguri, Sesha Sarathchandra