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▼ [13p-1F-11] Silicon Nanocrystal-based Nanocomposite for Super Thermal Insulating Material
Keywords:ballistic phonon transportation,silicon nanocrystal,thermal conductivity
Silicon nanocrystals (SiNCs) with grain size less than 10 nm has been widely researched for its size-dependent optical and electronic properties. It has been used as material for electronic devices such as hybrid solar cells, transistors and thermoelectric devices. As for thermal properties, research on silicon nanocrystal showed promising result of adjustable thermal conductivity properties of silicon, by controlling the particle grain size. Nanocomposite is mainly produced to increase the thermal conductivity of polymer based nanocomposite material. In contrast, in thermoelectric applications, overall thermal conductivity of nanocomposite material has to be reduced significantly while high electrical conductivity is maintained. Thermal conductivity is determined by the electron and phonon transport property of the composite materials. It has been reported the significant decrease of thermal conductivity with smaller silicon particles of 64 nm – 550 nm, with samples prepared by mechanical pressing, followed by high-temperature annealing with more than 1200 ºC.
In this work, nanocrystalline silicon particles with mean size of 6 nm were produced. In this case, NC size is much smaller than the phonon mean-free-path (MFP); therefore phonons experience significant number of shattering at the boundary, which is known as ballistic phonon transportation. As a result, significant decrease of thermal conductivity is expected. Moreover, polymer forms nanostructured network where phonons also experience significant number of scattering at the NC/polymer interfaces: Thermal conductivity of the nanocomposite material is expected to decrease significantly. Additionally, with low temperature processes, unique size dependent property (quantum size effect) can be preserved and low cost fabrication is highly possible.
In this work, nanocrystalline silicon particles with mean size of 6 nm were produced. In this case, NC size is much smaller than the phonon mean-free-path (MFP); therefore phonons experience significant number of shattering at the boundary, which is known as ballistic phonon transportation. As a result, significant decrease of thermal conductivity is expected. Moreover, polymer forms nanostructured network where phonons also experience significant number of scattering at the NC/polymer interfaces: Thermal conductivity of the nanocomposite material is expected to decrease significantly. Additionally, with low temperature processes, unique size dependent property (quantum size effect) can be preserved and low cost fabrication is highly possible.