Structural and Optical Phenomena of Thermally Treated Fullerene-Based Nanocomposites with Metal Nanoparticles for Sensing Applications

The phenomena of structural and optical modifications in metal-fullerene nanocomposite thin films (Cu-fullerene, Ag-fullerene, and Au-fullerene) by thermal annealing at different temperatures have been discussed in this chapter. With the help of thermal co-evaporation unit, the metal-fullerene nanocomposite thin films are grown on glass substrates using different noble metals with fullerene matrix. To enhance the optical and structural properties of nanocomposite especially for tuning of surface plasmon resonance (SPR) wavelength in the visible region, thermal annealing is performed at different temperatures. Both, fullerene C60 and C70 have been used as matrix to incorporate metal nanoparticles. In each case, low and high metal concentrations are chosen to investigate the SPR tuning with the size of metal nanoparticles. The growth of Cu, Ag, and Au nanoparticles with increasing temperature is investigated with the help of transmission electron microscopy (TEM). Maximum growth of 32.6 nm is obtained in the case of Ag-C70 nanocomposite with larger metal concentration; whereas the maximum SPR shift of ~101 nm is obtained for Au nanoparticles in C60 matrix at a temperature of 400 °C. In all three metal nanoparticles, a blue shift followed by a redshift is obtained up to 300 °C. The shift towards lower wavelength is mainly due to the transformation of fullerene into the form of amorphous carbon. At higher temperatures, the redshift due to the growth of metal nanoparticles leads over the blue shift which was due to the variation in refractive index of the matrix, and an overall redshift is obtained. The tuning of SPR wavelength of different metal nanocomposites has been demonstrated for their application in sensing-based devices.