Investigations on the Thermal Stability of Fullerene-Based (Ag-C70) Nanocomposite Thin Films

Abstract

Fullerene-based bi-functional nanocomposite thin film (Ag nanoparticles embedded in fullerene C70 matrix) is synthesized by thermal co-deposition method. Thermal stability of Ag-C70 nanocomposite is investigated by annealing the nanocomposite thin film at different temperatures from 80 to 350 °C for 30 min. Optical and structural properties of nanocomposite thin film with respect to high temperature are studied by UV-visible spectroscopy and x-ray diffraction, respectively. Transmission electron microscopy is performed to observe the temperature-dependent size evolution of Ag nanoparticles in fullerene C70 matrix. A large growth of Ag nanoparticles is observed with temperature especially above 200 °C due to enhanced diffusion of Ag in fullerene C70 at higher temperature and Ostwald ripening. The properties of metal-fullerene nanocomposite is not significantly affected up to a temperature of 150 °C. With a further increase in temperature, a major blue shift of ~ 33 nm in SPR wavelength is seen at a temperature of 300 °C due to the thermal induced structural transformation of fullerene C70 matrix into amorphous carbon. A very large-sized Ag nanoparticle with a wide size distribution varying from 27.8 ± 0.6 to 330.0 ± 4.5 nm is seen at 350 °C and due to which, a red shift of ~ 16 nm is obtained at this temperature. This study throws light on the thermal stability of the devices based on metal-fullerene bi-functional nanocomposite.