Ultrafast THz Spectroscopy Group: Investigation of conductivity and shielding efficiency of the free-standing PVA-GO-Ag composite thin films in terahertz regime using time domain terahertz spectroscopy
In this work, the researchers from ultrafast and THz lab at IISER Kolkata have prepared five free-standing films of PVA-GO-Ag composites by varying AgNP weight fractions (0.0 wt. % to 0.64 wt. %) and investigated them using our home-built THz-TDS setup in 0.45 to 2.45 THz range. Complex THz conductivities of these materials have been fitted using universal dielectric relaxation (UDR) and Drude-Smith (DS) models, both of which have widespread appreciation in modelling AC conductivity of disordered solids. Interpretations of the fitting parameters for these two models along with percolation theory helped them to construct a microscopic picture of AC conduction mechanism of these composites. Strong localization of charge carriers, which mostly reduces with increment AgNP weight fraction, are found in these systems. A comparison between the applicability and utility of the UDR and DS model in the context of analysing our THz conductivity data has also been made. Their studies indicate that the DS model is a better fit for explaining THz conductivity of the disordered solids due to its unambiguous interpretations and the ability to provide a more detailed picture of the charge transport mechanism. The samples being lightweight and flexible and having sub-100 µm thickness, show electromagnetic interference shielding efficiency (SE) of ∼ 2-3 dB below 1 THz that increases linearly between 4-8 dB above 1 THz. These SE values are found to arise mainly from the absorption and they are estimated to increase to ∼ 10-50 dB of magnitude when the thickness is ∼ 500 µm indicating their high potential application as shielding materials in rapidly growing THz communication technology. Congratulations to the whole team As a first author of this work, Mr. Soumya Mukherjee presented this work as a poster at the recently conducted Indo-France Conference 2023 at Mahindra University, Hyderabad ((ifcfpm.com/user/home)) and won the best poster award. Congratulations to Soumya Mukherjee. "Investigation of conductivity and shielding efficiency of the free-standing PVA-GO-Ag composite thin films in terahertz regime using time domain terahertz spectroscopy " has been published in Applied Physics A (APA). PhD students of DPS, Soumya Mukherjee and Anjankumar NM, and Prof. B. Karthikeyan from NIT, Trichy were involved in this research from UFTS group @ IISER kolkata.
Posted on: April 23rd, 2023